proceedings of the 3 helmholtz retreat · 5 anema, helen grad. stud psn utrecht 6 baas, daan grad....

Proceedings ofProceedings of the 3the 3 rdrd Helmholtz Helmholtz RetreatRetreat

22-24 June 2005 Bergen, the Netherlands

Proceedings of the Third Helmholtz Retreat 22-24 April 2005

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Scientific director Prof.dr. E.H.F. de Haan Utrecht University Members of the board Prof.dr. A.V. van den Berg Utrecht University Prof.dr. J.J. Bolhuis Utrecht University Prof.dr.ir. W.A. Dreschler University of Amsterdam Prof.dr. C.J. Erkelens Utrecht University Dr.Ir. J.M. Festen Free University Amsterdam Prof.dr. J.J. Koenderink Utrecht University Prof.dr. G. F. Smoorenburg [chair] Utrecht University Dr. H. van der Steen Erasmus University Rotterdam Dr. H. Verschuure Erasmus University Rotterdam Prof.dr. F.A.J. Verstraten Utrecht University Scientific advisory council Prof.dr. D. Ballard University of Rochester, USA Prof.dr. A. Berthoz College de France, Paris, France Prof.dr. H. Bülthof Max Planck Institute for Biological Cybernetics, Tübingen, Germany Prof.dr. J.J. Eggermont University of Calgary, Canada Prof.dr. A.D. Milner University of Durham, UK Prof.dr. Ch.M.M. de Weert Radboud University Nijmegen, The Netherlands Office management Mrs. V. Maassen-Monrooij Utrecht University

Special thanks to Veronica Maassen-Monrooij,

Ans Horchner &

Janneke Kreek


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Proceedings of the Third Helmholtz Retreat

22-24 June 2005

Bergen The Netherlands

Organiser

Frans Verstraten


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Contents Welcome 5 Our keynote speakers 6 List of participants 7 Program in the fast lane 9 Program & Abstracts

Wednesday 11

Thursday 15

Friday 20


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Welcome… Welcome to the third retreat of the Helmholtz Research School. With more than 100 participants it is clear that our retreats have become a great success. Having learned from previous meetings we have now come to a format of our meeting that appeals to many of us. Moreover, the choice of the venue in Bergen, for a second time, also demonstrates that the extra-scientific elements of the meeting are well appreciated. May 15, 1992, was the date that the four founders of the Utrecht Institute of Biophysics initiated the establishment of a Research School of Biophysics and Informatics of Autonomous Systems. We received accreditation of the research school from the National Academy of Sciences in 1994. The research school was named the Helmholtz Research School. The choice of naming the school after a great scientist in our field appeared to be a lucky one because many people did not quite understand the description “Biophysics and Informatics of Autonomous Systems”. The mission of the school at that time was “Understanding of fundamental mutual relationships between autonomous systems and their physical environment at the level of information processing and behaviour ”. This included the study of sensing, perception, motor control, and perceptual-motor integration. The participating groups covered topics from neuro-ethology to robotics. Since then the configuration has changed, groups working on informatics, computer vision and robotics left the school and groups working in the neurosciences, cognition and audiology joined the school. The focus of the school moved to “Information processing in the human brain related to perception of the environment”. The change resulted in a more homogeneous school, a school within which the participants like to meet one another as reflected in our retreats. I would like to thank Frans Verstraten who organised this meeting for the second time. On behalf of the board of the school and the education committee I like to welcome you to this third retreat trusting that it will become another success. Guido F. Smoorenburg Chairman of the board of the Helmholtz Research School


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Our keynote speakers

Ian Thornton PhD. University of Oregon, Eugene. USA. Professor of Experimental Psychology, University of Wales Swansea. Ian Thornton studied Psychology & Computer Science at Lancaster and Cambridge in the UK. Having taught and worked in Japan and Australia he obtained his PhD in Psychology from the University of Oregon in 1997. His post-doc was at Cambridge Basic Research, an industry

funded lab based at MIT (1997-2000), and he then became a research scientist and group leader at the Max-Planck Institute for Biological Cybernetics in Tübingen Germany (2000-2005). Since March 2005 he has been Professor of Cognitive Psychology at the University of Wales Swansea. His research interests focus around the internal representation of time and the importance of change-over-time for perception, cognition and action. This work is organised into 4 main themes, Biological Motion, Object Localisation, Face Processing and Implicit Perception.

Suncica Zdravkovic PhD. Rutgers University, Newark, USA. Associate Professor of Cognitive Psychology, University of Novi Sad. Suncica Zdravkovic studied psychology at the University of Belgrade. She did her graduation diploma work and master level program under mentorship of Dejan Todorovic, working on depth-from-motion perception. She continued graduate school in Alan Gilchrist’s lab at

Rutgers University, Newark, New Jersey, where she obtained MA in Cognitive Neuroscience [depth and motion visual pathways (supervised by Ben Bly)] and PhD in Psychophysics [lightness percepetion (supervised by Alan Gilchrist)]. She was post-doc in Tiziano Agostini’s lab in Trieste, Italy. Since 2004 she is an associate professor at the University of Novi Sad, specialized on cognitive psychology. Her research interests include lightness in complex visual scenes and spatial and temporal characteristics of illumination.


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List of Participants

# Name Position Dept 1 Aarnoutse, Eric Post-doc Funct. Neurobio 2 Aivar, Pili Post-doc Neuroscience R’dam 3 Agterberg, Martijn Grad. Stud Audiol. Utrecht 4 Alphen, Bart van Grad. Stud Neuroscience R’dam 5 Anema, Helen Grad. Stud PSN Utrecht 6 Baas, Daan Grad. Stud PSN Utrecht 7 Joke Baas Assis. Prof PSN Utrecht 8 Battu, Balaraju Grad. Stud Physics of Man 9 Beers, Rob van Post-doc Neuroscience R’dam 10 Bergman Tiest, Wouter Post-doc Physic of Man 11 Beurden, Maarten van Grad. Stud Audiol. AMC A’dam 12 Bolhuis, Johan Prof Behav. Bio 13 Borra, Tobias Grad. Stud PSN Utrecht 14 Benjamins, Jeroen Grad. Stud PSN Utrecht 15 Berg, Bert van den Prof Funct. Neurobio 16 Bours, Roger Grad. Stud Funct. Neurobio 17 Boxtel, Jeroen van Grad. Stud Physics of Man 18 Brascamp, Jan Grad. Stud Funct. Neurobio 19 Brenner, Eli Assis. Prof Neuroscience R’dam 20 Brouwer, Gijs Grad Stud Physics of Man 21 Bullens, Jessie Grad Stud PSN Utrecht 22 Dam, Loes van Grad Stud Physics of Man 23 Dijkerman, Chris Assis. Prof PSN Utrecht 24 Dobbelsteen, John van den Post-doc Neuroscience R’dam 25 Doumen, Michelle Grad. Stud Physics of Man 26 Duynhouwer, Jacob Grad. Stud Funct. Neurobio 27 Ee, Raymond van Assoc. Prof Physics of Man 28 Eeuwes, Lonneke Grad. Stud Funct. Neurobio 29 Erkelens, Casper Prof Physics of Man 30 Esch, Thamar van Audiol. AMC A’dam 31 Festen, Joost Assoc .Prof VU MC 32 Frens, Maarten Assoc. Prof Neuroscience R’dam 33 Fonteijn, Hubert Grad. Stud PSN Utrecht 34 Geest, Jos van der Post-doc Neuroscience R’dam 35 George, Erwin Grad. Stud VU MC 36 Gobes, Sharon Grad. Stud Behav. Bio 37 Goede, Maartje de Grad. Stud PSN Utrecht 38 Granzier, Jeroen Grad. Stud Neuroscience R’dam 39 Haan, Edward de Prof PSN Utrecht 40 Hermans, Erno Grad. Stud PSN Utrecht 41 Hilkhuysen, Gaston Audiol. Utrecht 42 Honk, Jack van Assis. Prof PSN Utrecht 43 Hoof, Oscar van Grad. Stud. Physics of Man 44 Hooge, Ignace Assis. Prof PSN Utrecht 45 Horst, Bernard van der Grad. Stud Physics of Man 46 Houben, Rolph Post-doc Audiol. AMC A’dam 47 Kammers, Marjolijn Grad. Stud PSN Utrecht 48 Kamphuisen, Allard Grad. Stud Physics of Man 49 Klis, Sjaak Assoc. Prof Hearing Lab Utrecht 50 Knapen, Tomas Grad. Stud Physics of Man 51 Kappers, Astrid Prof. Physics of Man 52 Kenemans, Leon Prof. PSN Utrecht 53 Kessels. Roy Assis. Prof PSN Utrecht 54 Koenderink, Jan Prof Physics of Man 55 Kroeze, Jan Prof PSN Utrecht 56 Lagers-van Haselen Post-doc Neuroscience R’dam 57 Lankheet, Martin Assoc. Prof Funct. Neurobiology 58 Lansbergen, Marieke Grad. Stud PSN Utrecht 59 Liesker, Hanneke Grad. Stud Neuroscience R’dam 60 Lortije, Jeannette Grad. Stud Funct. Neurobio 61 Stefan Louw Post-doc Neuroscience R’dam 62 Mierlo, Christa van Grad. Stud Neuroscience R’dam


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63 Mol, Nissan Grad. Stud PSN Utrecht 64 Muller, Chris Grad. Stud Neuroscience R’dam 65 Mury, Alexander Grad. Stud Physics of Man 66 Neggers, Bas Assis. Prof PSN Utrecht 67 Nijboer, Tanja Grad. Stud PSN Utrecht 68 Noest, Andre Assis. Prof Funct. Neurobio 69 Nys, Gudrun Grad. Stud PSN Utrecht 70 Overvliet, Krista Grad. Stud Neuroscience R’dam 71 Peters, Rob Assoc. Prof Funct. Neurobio 72 Piekema, Carinne Grad. Stud PSN Utrecht 73 Pont, Sylvia Assis. Prof Physics of Man 74 Postma, Albert Prof. PSN Utrecht 75 Putman, Peter Grad. Stud PSN Utrecht 76 Pas, Susan te Assis. Prof PSN Utrecht 77 Reader, Simon Assis. Prof Behav. Bio 78 Richter, Janneke Grad. Stud Neuroscience R’dam 79 Rijn, Sophie van Grad. Stud PSN Utrecht 80 Rijpkema, Mark Post-doc PSN Utrecht 81 Sanders, Bram Grad. Stud Physics of Man 82 Schutter, Dennis Post-doc PSN Utrecht 83 Schonewille, Martijn Neuroscience R’dam 84 Slijper, Harm Post-doc Neuroscience R’dam 85 Smagt, Maarten van der Assis. Prof PSN Utrecht 86 Smeets, Jeroen Assoc. Prof Neuroscience R’dam 87 Smoorenburg, Guido Prof Audiolo. Utrecht 88 Sterck, Liesbeth Assis. Prof Behav. Bio 89 Thornton, Ian Prof. University of Wales Swansea 90 Tolboom, Michiel Grad. Stud Funct. Neurobio 91 Versnel, Huib Assis. Prof Audiol. Utrecht 92 Verstraten, Frans Prof PSN Utrecht 93 Verstijnen, Ilse Assis. Prof PSN Utrecht 94 Vlaskamp, Bjorn Grad. Stud PSN Utrecht 95 Volcic, Robert Grad. Stud Physics of Man 96 Vries, Han de Research

Associate Behav. Bio

97 Wanrooij, Mark van Post. Doc Neuroscience R’dam 98 Wertheim, Lex Prof PSN Utrecht 99 Wezel, Richard van Assis. Prof Funct. Neurobio 100 Wijntjes, Maarten Grad. Stud Physics of Man 101 Wismeijer, Dagmar Grad. Stud Physics of Man 102 Wout, Mascha van ‘t Grad. Stud PSN Utrecht 103 Winkelman, Beerend Neuroscience R’dam 104 Zdravkovic, Suncica Assis. Prof Univerity of Novi Sad 105 Zuidhoek, Sander Grad. Stud. PSN Utrecht 106 Zandvoort, Martine van Assis. Prof PSN Utrecht


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Program Wednesday 22 JUNE 9.30 – 10.30 Arrival, coffee/tea & cake 10.45 Opening and History of the Helmholtz School in the fast lane – Prof. Dr. Guido

Smoorenburg (chairman of the board) Session 1 – Functional Neurobiology (Moderator: Bert van den Berg) 11.00 – 11.20 Lonneke Eeuwes – Prey detection in catfish 11.20 – 11.40 Jeanette Lortije – Motion adaptation modulates implied motion processing 11.40 – 12.00 Jan Brascamp – A common standard for measuring motivational and physical

variables in binocular rivalry 12.00 – 12.20 Rogier Bours – Spatio-temporal tuning in macaque area MT 12.30 – 14.00 Lunch & sniff-some-good-air-time Session 2 – Neurosciences Rotterdam (Moderator: John van den Dobbelsteen) 14.00 – 14.20 Krista Overvliet – Haptic serial search with three fingers is slower than with one

finger. 14.20 – 14.40 Jeroen Granzier – The role of illuminant color perception in color constancy. 14.40 – 15.00 Jos van der Geest - Roles of CYLN2 and GTF2IRD1 in Williams Syndrome. 15.00 – 15.20 Martijn Schonewille – Purkinje cells in awake behaving animals operate in stable

upstate membrane potential. 15.20 – 15.45 Refreshments/coffee & tea Walk on the beach/drinks/whatever you feel like 18.00 – 19.45 Diner Keynote lecture 1 (Moderator: Frans Verstraten) 20.15 – 21.00 Key-note lecuture: “Cognition in Motion” Professor Ian Thornton (University of Wales Swansea) 21.15 Bar & Poster Session 1 (organized by Helmholtz Phd Student Council) Thursday 23 JUNE 06.00 – 07.00 Early bird walk/run/swim 07.00 – 08.45 Breakfast Session 3 – Psychonomics Neuro-imaging (Moderator: Leon Kenemans) 09.00 – 09.20 Bas Neggers – Cortical and subcortical contributions to saccade latency in the

human brain 09.20 – 09.40 Joke Baas – Prefrontal cortex activation during phasic fear and sustained anxiety. 09.40 – 10.00 Hubert Fonteijn – Anatomical evidence for functional networks? A DTI study. 10.00 – 10.20 Mark Rijpkema – Being a forest or a tree is just relative: local and global attention

to hierarchical visual stimuli 10.30 – 11.00 Coffee/tea Session 4 – Physics of Men


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(Moderator: Astrid Kappers ) 11.00 – 11.20 Raymond van Ee – Physics of Man in bird eyes’ view 11.20 – 11.40 Michelle Doumen – The effect of distance, visual angle and context on pointing 11.40 – 12.00 Jeroen van Boxtel – How many motion systems does the human brain possess? 12.00 – 12.20 Wouter Bergmann Tiest – Ecological physics and haptics. 12.30 – 14.00 Lunch & sniff-some-fresh-air-time Session 5 – Behavioral Biology (Moderator: Johan Bolhuis) 14.00 – 14.20 Simon Reader – Social Learning 14.20 – 14.40 Johan Bolhuis – Brain mechanisms of birdsong memory 14.40 – 15.00 Liesbeth Sterck – Testing for episodic memory in primates 15.00 – 15.20 Refreshments/coffee/Tea 15.20 – 16.00 Key-note lecuture 2 : Lightness and Multiple Illumination Levels

Dr. Suncica Zdravkovic (University of Novi Sad) 16.00 – 18.00 EVENT!/walk on the beach/drinks/whatever you want to do 18.00 – 19.45 Diner BBQ (Moderator: Frans Verstraten) 20.00 – 21.00 Forum “To be a Helmholtz School graduate student: mutual expectations” Panelists: Helmholtz AIO-counsel & respresentatives from the Helmholtz School. 21. 15 Bar & Poster Session 2 (organized by Helmholtz Phd Student Council) Friday 24 JUNE 06.00 – 07.00 Beach exercise/walk/Swim 07.00 – 08.45 Breakfast Session 7 - Helmholtz Audio crowd (Amsterdam & Utrecht) (Moderator: Joost Festen) 09.00 – 09.20 Erwin George (VUmc) - Factors affecting speech reception in modulated noise. 09.20 – 09.40 Maarten van Beurden (AMC) - Loudness measuring procedures. 09.40 – 10.00 Martijn Agterberg – Neurotrophins enhance spiral ganglion survival after induced

deafness. 10.00 – 10.20 Sjaak Klis - The Influence of Basilar Membrane Position on the Cochlear

Summating Potential. 10.30 – 11.00 Coffee/Tea Session 8 – Psychonomics Neuropsychology (Moderator: Edward de Haan) 11.00 – 11.20 Gudrun Nys – The neural basis of visual hallucinations in hemianopic patients 11.20 – 11.40 Martine van Zandvoort – Cognitive function after lacunar Infarcts 11.40 – 12.00 Albert Postma – Remembering the where and when of events. On the integration of

spatial and temporal information in memory 12.00 – 12.20 Roy Kessels – Contextual memory and binding 12.30 – 14.00 Lunch & sniff-some-fresh-air-time 14.00 –… Whatever you feel like…!


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Program & Abstracts Wednesday 22 JUNE 9.30 – 10.30 Arrival, coffee/tea & cake 10.45 Opening and History of the Helmholtz School in the fast lane – Prof. Dr. Guido

Smoorenburg (chairman of the board) Session 1 – Functional Neurobiology (Moderator: Bert van den Berg) 11.00 – 11.20 Lonneke Eeuwes – Prey detection in catfish 11.20 – 11.40 Jeanette Lortije – Motion adaptation modulates implied motion processing 11.40 – 12.00 Jan Brascamp – A common standard for measuring motivational and physical

variables in binocular rivalry 12.00 – 12.20 Rogier Bours – Spatio-temporal tuning in macaque area MT 11.00 – 11.20 Lonneke Eeuwes – Prey detection in catfish All aquatic organisms are

surrounded by a very weak bioelectric field, consisting of a direct current (DC) and an alternating current (AC) component. It is assumed that the DC component originates from biochemical processes that take place during osmoregulation, hereby generating transepithelial potentials, whereas the AC component is caused by ventilatory movements. Electrosensitive animals, such as catfish, use these features to localize their prey. Although the electroreceptor organs are insensitive to a pure DC signal, electrosensitive fish can perceive DC stimuli by movement of the source relative to the electroreceptor organs. To discover which features of the bioelectric field are important in prey detection, 2AFC experiments are conducted.

11.20 – 11.40 Jeanette Lortije – Motion adaptation modulates implied motion processing. Photographs of objects in motion evoke a higher BOLD response in human motion sensitive area MT+ than photographs of the same objects at rest. This implied motion activation may imply feedback from temporal object recognition areas onto MT+. To further explore the nature of this feedback response, we recorded evoked potential EEGs from 14 subjects which viewed photographs of human agents, in either running or standing still posture. Differences in evoked potentials between these two conditions can be assigned to an implied motion response. We found significant implied motion responses from 120 to 200 ms and from 400 to 500 ms. Both were visible as a negative potential at posterior, and as a positive potential at frontal electrodes. If it is true that implied and real motion both activate the same neurons in MT+, then the EEG response to one type of motion should be altered after adaptation to the other. Therefore, we studied the implied motion response after adaptation to real motion in the same and the opposite direction as the implied motion. The adapted response showed the same scalp distribution across time as the non-adapted response, but differed in amplitude. The first implied motion response (120 to 200 ms) was still significant for both adaptation directions, though attenuated and temporally shifted. After adaptation in the opposite direction, the response was delayed by 20 ms (140 to 220 ms). In contrast, the response after adaptation in the same direction was not only delayed, but also shorter (140 to 180 ms). The response from 400 to 500 ms was still strong after adaptation in the opposite direction, but much weaker after adaptation in the same direction. These results indicate that implied motion responses in motion sensitive areas are direction selective.

11.40 – 12.00 Jan Brascamp – A common standard for measuring motivational and physical

variables in binocular rivalry. Although we view the world with two eyes, we


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perceive it as singular: the two eye images are fused into a single percept. When the images on the two retinas are too dissimilar however, fusion fails and gives way to binocular rivalry. Under such conditions subjects' perception constantly alternates between the left and the right eye image. In order to characterise and understand this phenomenon many researchers have investigated the dynamics of these alternations, trying to answer questions such as: 'How fast does people's perception alternate?', 'How does this particular percept duration depend on the previous one?', and importantly: 'How do these dynamics depend on stimulus parameters?' Over the years the body of literature on this subject has steadily grown and presently we have a fairly clear view of these dynamics and how they depend on physical parameters such as stimulus contrast, spatial frequency, etc. A question that seems harder to answer in a quantitative way is how these dynamics depend on motivational variables, such as: 'What happens when I try to hold on to the left eye percept?' Nevertheless, there has recently been considerable progress in this direction as well, and it has been shown that such motivational factors have consistent and measurable effects on the dynamics of binocular rivalry. These results provide the background for our present aim: to find a common framework in which both physical and motivational parameters can be measured, i.e. in which they become commensurable. If successful, this would allow us to express such motivational variables in physical terms, rendering them more manageable in a scientific context. In addition, within such a framework we can study interactions between physical and motivational parameters, addressing important questions about the level in the neural system at which these parameters act and possibly interact.

12.00 – 12.20 Rogier Bours – Spatio-temporal tuning in macaque area MT Motion detection in apparent motion of random dot patterns (RDP) requires correlation across space and time. It has been difficult to study the temporal requirements for the initial correlation step because temporal measurements jointly depend on temporal filtering, delay-tuning and successive temporal integration. Moreover, it has been difficult to construct a stimulus containing a single delay only. To measure delay tuning independent of temporal integration, we constructed a motion stimulus containing a single delay value only, and with constant motion energy, irrespective of delay. The stimulus consists of a sparse random dot pattern with a two frame, single step dot lifetime. It is constructed by generating a dynamic random dot pattern on each stimulus frame, and showing this pattern once again at a delay of n frames later, superimposed on the newly generated RDP. Each frame thus consists for 50% of new random dots and 50% displaced random dots. The delay between corresponding dot patterns can be chosen freely, without affecting the number of steps per second, steps in total, and temporal frequency content. We measured the activity of motion-sensitive neurons in area MT in anesthesized monkeys as a function of both step size and delay. The data will be compared to the spatio-temporal characteristics found in human motion perception.

Session 2 – Neurosciences Rotterdam (Moderator: John van den Dobbelsteen) 14.00 – 14.20 Krista Overvliet – Haptic serial search with three fingers is slower than with

one finger. 14.20 – 14.40 Jeroen Granzier – The role of illuminant color perception in color constancy. 14.40 – 15.00 Jos van der Geest - Roles of CYLN2 and GTF2IRD1 in Williams Syndrome. 15.00 – 15.20 Martijn Schonewille – Purkinje cells in awake behaving animals operate in

stable upstate membrane potential. 14.00 – 14.20 Krista Overvliet – Haptic serial search with three fingers is slower than with

one finger. Two haptic serial search tasks were used to investigate whether the distance between items in a haptic display influences search time and search


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strategies. In both tasks subjects had to search for a target (cross) between a fixed number of non-targets (circles). All items were aligned horizontally so that the subject could easily move his fingers from left to right over the display without vision. Two factors were varied: position of the target and item distance. Three different distances were measured: two, four, and six times the width of the fingertip. The items and the distance between them were scaled to fingertip size to keep the relative size constant. In the first experiment subjects used their index finger to scan the items. As expected, search time depended on target position as well as on item distance. Subjects used different strategies to move over the display in the different distance conditions. In the ‘distance six’ condition the movements were like ‘saccades’ and ‘fixations’, while in the ‘distance two’ condition the movement was smooth. When comparing the search times of the ‘distance two’ condition to those of a static haptic search task, with the same stimuli presented to the fingertips simultaneously, search times were the same. Thus, movement did not give any advantage over static exploration. In the second experiment the subjects put three fingers in line and used them together to scan the items. The search times of the ‘distance two’ and the ‘distance four’ condition increased compared to the first experiment. The search times for the ‘distance six’ condition stayed the same. When only considering time in contact with an item, search times were the same for all distance conditions. This suggests that the subjects did not use the time in between the items to process any information about them. However, the search times of the second experiment increased compared to the first experiment. Because in both ‘distance two’ and ‘distance four’ conditions subjects were in contact with at least two items, the increased search times might result from interference between the fingers.

14.20 – 14.40 Jeroen Granzier – The role of illuminant color perception in color constancy. Placing differently coloured backgrounds behind two identical surfaces makes the two surfaces look different from each other. This is a phenomenon known as chromatic induction. One interpretation of chromatic induction is that the visual system attributes part of the difference in background colour to a difference in illumination. If so, chromatic induction is a misdirected attempt to maintain colour constancy. In accordance with this interpretation, chromatic induction appears to be weaker in simple displays, in which it is evident that the surrounding surfaces have different colours, than in more complex displays, in which pictorial depth cues suggest that the illumination rather than the surface of the background is different. If this interpretation of chromatic induction is correct, we may also find strong chromatic induction if the difference in colour and luminance between the two backgrounds in question is rendered in a manner that suggests that it is caused by a difference in illumination. We therefore simulated a surface illuminated by a lamp at the upper left and a differently coloured ambient illumination. We examined whether this results in strong chromatic induction, and whether the kind of background (plain, regularly textured, randomly textured) matters.

14.40 – 15.00 Jos van der Geest - Roles of CYLN2 and GTF2IRD1 in Williams Syndrome.

Williams Syndrome (WS) is a disorder caused by a hemizygous deletion of 25-30 genes on chromosome 7q11.23. Several of these genes including those encoding syntaxin 1A (STX1A), LIM-kinase 1 (LIMK1), cytoplasmic linker protein-115 (CYLN2) and general transcription factors (GTF2I and GTF2IRD1) are expressed in the brain and may contribute to the neurological and cognitive deficits in WS-patients. Recent studies of patients with partial deletions indicate that hemizygosity of GTF2I contributes to mental retardation in WS, while hemizygosity of STX1A probably does not. Here we investigate whether CYLN2 and GTF2IRD1 contribute to the neuropsychological deficits in WS. Behavioral assessment of a new unique patient in which STX1A and LIMK1, but not CYLN2 and GTF2IRD1, are deleted showed that his cognitive and motor coordination functions were better than in typical WS patients. Comparative analyses of gene specific CYLN2 and GTF2IRD1 knock-out mice showed that a reduced size of the corpus callosum as well as deficits


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in motor coordination and hippocampal memory formation can be attributed to a deletion of CYLN2, while increased ventricle volume can be attributed to both CYLN2 and GTF2IRD1. In conjunction these data indicate that CYLN2 is a major gene responsible for neuropsychological deficits in Williams Syndrome.

. 15.00 – 15.20 Martijn Schonewille – Purkinje cells in awake behaving animals operate in

stable upstate membrane potential. Bistability of membrane potentials has been described for various neurons in the brain. Recently, evidence has been provided that complex spikes can alter the state of the membrane potential of Purkinje cells suggesting a mechanism by which somatosensory stimulation can act as a toggle switch to control the triggering of simple spikes and thereby motor behavior. Yet, all forms of bistability have only been demonstrated under anesthesia. Using intracellular and extracellular recordings we show that bistability of Purkinje cell activity as well as the toggle phenomenon are virtually absent in wildtype animals during motor performance or motor learning in the awake state, whereas both are prominently present under anesthetics or following genetic mutations that enhance inhibition. We conclude from our study that the membrane potential of Purkinje cells is effectively constrained to the upstate level under physiological circumstances and that silent states can be evoked by manipulating their intrinsic excitability.

Keynote lecture 1 (Moderator: Frans Verstraten) 20.15 – 21.00 Key-note lecuture: Cognition in Motion Professor Ian Thornton (University of Wales Swansea) Studies of object recognition have traditional used static, pictorial stimuli as a probe into our internal representations of the world. In this talk, I will argue that the use of such stimuli could be imposing serious limits on the way we think about perception, cognition and action. In particular, I will take one domain, face perception, and demonstrate that motion -- typically ignored as a recognition cue -- can play a major role in determining individual identity.


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Thursday 23 JUNE 06.00 – 07.00 Early bird walk/run/swim 07.00 – 08.45 Breakfast Session 3 – Psychonomics Neuro-imaging (Moderator: Leon Kenemans) 09.00 – 09.20 Bas Neggers – Cortical and subcortical contributions to saccade latency in the

human brain 09.20 – 09.40 Joke Baas – Prefrontal cortex activation during phasic fear and sustained

anxiety. 09.40 – 10.00 Hubert Fonteijn – Anatomical evidence for functional networks? A DTI study. 10.00 – 10.20 Mark Rijpkema – Being a forest or a tree is just relative: local and global

attention to hierarchical visual stimuli 09.00 – 09.20 Bas Neggers – Cortical and subcortical contributions to saccade latency in the

human brain An important property of our motor system is the ability to either perform or inhibit an automatic goal-directed reaction. Imagine for example how easily we can catch a ball, while at the same time we would never grasp a stinging insect approaching us. The oculomotor system provides a good model to study this ability. Monkey midbrain superior colliculus (SC) neurons are responsible for automatic visually-evoked saccades, whereas the frontal eye fields (FEF) can prevent reflexive glances. Little is known about human SC or the competition between the midbrain and frontal areas controlling saccades. In the present functional magnetic resonance (fMRI) study we used the GAP paradigm, where a stimulus fixated with the eyes is removed 200ms prior to saccade target onset. Subjects were required to either look at the target or prevent an eye movement. From what is known from non-human primate neurophysiology of the SC, it is expected that the gap will result in enlarged neuronal activity in the human SC, dis-inhibiting the oculomotor system and enhancing automatic reactions. Importantly, we demonstrate that the human homologue of the SC is indeed activated by the removal of a fixation target, in either task. The FEF show a reverse pattern when saccades were suppressed. Furthermore, magnitude of responses in the SC correlated negatively with saccade latency, and in the FEF positively. These findings confirm for the first time in humans that the SC generates automatic goal-directed saccades, whereas the FEF can exert volitional control over automatic orienting.

09.20 – 09.40 Joke Baas – Prefrontal cortex activation during phasic fear and sustained

anxiety. At least two forms of anxiety can be differentiated: A phasic response to a clearly identifiable and imminent threat, and a more sustained response not clearly linked to a specific stimulus. The prefrontal cortex appears to play a modulatory role in aversive states. Some parts of prefrontal cortex are activated during emotional states, but other areas such as medial prefrontal cortex are inversely correlated with intensity of fear or anxiety. Methods: Throughout 2-min conditions, subjects could either receive no shock, predictable shock, or unpredictable shock. Shapes were presented which served as a signal for shock only in the predictable condition. BOLD data was acquired from 18 subjects. Results: Subjective data indicated significant induction of phasic and sustained anxiety. The main test for sustained anxiety indicated higher BOLD signal in the unpredictable shock condition in the right dorsal anterolateral prefrontal cortex, and increased activation during the safe conditions in the orbital sulcus bilaterally. The main test for phasic fear revealed higher BOLD response to the cue predicting the shock in the right inferior frontal gyrus. The subgenual anterior cingulate gyrus showed increased activity during the safe condition. Conclusion: These findings suggest that phasic fear and sustained anxiety are driven by different prefrontal brain systems. The activations during safe conditions are consistent with previous reports of an inverse relationship between prefrontal activity and aversive states. Future work could


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investigate the (lack of) recruitment of these areas in patients with anxiety disorders during states of fear and anxiety.

09.40 – 10.00 Hubert Fonteijn – Anatomical evidence for functional networks? A DTI study.

Diffusion Tensor Imaging (DTI) is a promising tool to reveal the anatomical basis of functional networks. However, several problems exist, which have made the direct application of DTI difficult. The aim of this study is to investigate to what extent DTI can provide extra knowledge about functional networks, as defined by imaging studies. We have done this by taking network nodes from eight effective connectivity studies and studying the connectivity defined by DTI-based fibre tracking between these nodes. We could thus evaluate the fibre tracks found against the connections proposed in the literature. A large number of connections were confirmed with DTI. There was found little evidence for interhemispheric connections from regions other than the most lateral ones. Some asymmetry was observed between left and right-hemispheric networks. Furthermore, a large amount of inter-subject variability was observed.

10.00 – 10.20 Mark Rijpkema – Being a forest or a tree is just relative: local and global

attention to hierarchical visual stimuli. It is widely assumed that local and global levels of hierarchical visual stimuli are being processed predominantly in the left and right hemisphere respectively. Both directed attention to a specific level and attention switching between two levels of such a stimulus may provide insight in the network of brain areas involved in visual attention. To investigate how attention switching is represented in this network we extended the classical Navon figure (a large letter made out of small letters) with an additional level: the middle level is both global with respect to the local level and local with respect to the global level, making processing of the middle level 'jump' between hemispheres. The aim of this study was to characterize the triple level Navon figures psychophysically and to investigate the hemispheric activation differences between attention to the global, middle, and local level of these stimuli by fMRI. The reaction times in the phychophysics study increased significantly from global to middle to local attention. The fMRI results showed clear differential activation of global and local attention. Increased activation during attention to the global level of a stimulus compared to the local level was found mostly in right occipital and parietal areas, whereas the left hemisphere showed preference for local processing, corresponding to the classical theory of local and global processing preference. Attention to the middle level shows activation in both hemispheres. Middle versus local attention shows activation in right BA 18, just as global versus local. Middle versus global attention shows activation in left BA 18, just as local versus global. Being local or global thus seems to be relative. In conclusion, attention to the middle level activates areas involved in global processing and areas involved in local processing, reflecting the local and global properties of the middle level.

Session 4 – Physics of Men (Moderator: Astrid Kappers ) 11.00 – 11.20 Raymond van Ee – Physics of Man in bird eyes’ view 11.20 – 11.40 Michelle Doumen – The effect of distance, visual angle and context on pointing 11.40 – 12.00 Jeroen van Boxtel – How many motion systems does the human brain possess? 12.00 – 12.20 Wouter Bergmann Tiest – Ecological physics and haptics. 11.00 – 11.20 Raymond van Ee – Physics of Man in bird eyes’ view. Physics of Man combines

research that falls into the realm of Perception, Motor Action, Awareness and Physical Properties. A bird eyes' view will be given of several recently developed research directions in our department.

11.20 – 11.40 Michelle Doumen – The effect of distance, visual angle and context on pointing

My research concerns how accurate people perceive positions of objects. Our main


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focus is on extracting parameters that affect the size and direction of errors when judging spatial relations between objects. So far, we have examined (1) spatial effects like the distance between the objects and the observer and the visual angle between two objects, and (2) contextual effects, like a wall parallel to the pointing direction or a frontoparallel arrangement of the objects. The method we have been using is a 3D exocentric pointing task, in which the observer has to direct a pointer towards a target with a remote control. The dependent variables were the deviation of the veridical settings in the horizontal plane (slant) and in the vertical plane (tilt). For the deviations of the slant we found effects of the horizontal visual angle and of a distance-measure (the relative distance); whereas the tilt was only dependent on the visual angle in the vertical direction. Concerning the contextual effects, the data were not consistent over all observers, so we can conclude that observers differ in the degree in which they use the structure that is provided by the scene to make an estimate of the positions of objects.

11.40 – 12.00 Jeroen van Boxtel – How many motion systems does the human brain possess?

Several lines of evidence support the view that the human brain has two (or even more) centers in which visual motion information is processed. One of the proposed divisions is the division in a fast and slow motion system. The literature supporting this specific division is shortly reviewed, and experiments are discussed that cast doubt on the widely accepted view that fast and slow motion systems exist. Instead a single motion system account is proposed.

12.00 – 12.20 Wouter Bergmann Tiest – Ecological physics and haptics. It is very interesting

to study the way we use our sense of touch to explore the physical world around us. This is the domain of ecological physics. Ecological physics can be seen as the counterpart of neurophysiology in the study of perception. An important aspect of the tangible world around us is our interaction with materials. Haptically important physical properties are for instance temperature, thermal conductance, roughness, compressibility and friction. Although these are well-defined quantities in physics, their meaning in the context of perception is less clear. In our research, we have tried to relate physical roughness and compressibility with perceptions by measuring the perceived dissimilarity of a large number (124) of different materials. It turns out that, for instance, the perception of roughness is not just determined by the height profile of a material, but also by other parameters. At present, efforts are underway to measure how well materials can be distinguished by differences in thermal conductance. We will measure the dependence on ambient temperature and the discrimination threshold of transient temperatures.

Session 5 – Behavioral Biology (Moderator: Johan Bolhuis) 14.00 – 14.20 Simon Reader – Social Learning 14.20 – 14.40 Johan Bolhuis – Brain mechanisms of birdsong memory 14.40 – 15.00 Liesbeth Sterck – Testing for episodic memory in primates 14.00 – 14.20 Simon Reader – Social Learning Learning from others – social learning – may

often provide a low-cost solution to information acquisition, and is known to play a role in determining animal foraging patterns, mate choice, habitat selection, learned vocalisations, predator avoidance and in several other contexts important to survival and reproductive success. In many cases of social transmission, a novel behaviour pattern, or innovation, is transmitted. In guppy fish, I find that sex, body size, motivational state, and temperament differences all play a role in determining innovator identity. Such individual differences may have dramatic consequences for the diffusion of information through groups, with information restricted to subsections of the population. Moreover, recent work from other laboratories suggests that individual fish take into account the reliability of their personal information when making the decision between utilising personal versus social


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information. This suggests animals may facultatively switch between information gathering strategies depending on prevailing conditions, a possibility currently under investigation in our laboratory. I conclude by discussing the evolution of social learning and innovation. Comparative analysis of an extensive database of published reports of primate innovation and social learning suggests that these two capacities have evolved together. Furthermore, both these indices of behavioural flexibility correlate with relative neocortex volume, providing evidence for a link between these cognitive capacities and primate brain volume.

14.20 – 14.40 Johan Bolhuis – Brain mechanisms of birdsong memory Song acquisition in

songbird males is a prominent model system for the study of the brain mechanisms of memory. Songbirds, such as zebra finches (Taeniopygia guttata), learn their songs from an adult conspecific tutor during a sensitive period early in life. Exposure of adult males to their tutor song leads to increased expression of immediate early genes (IEGs) in brain regions outside the conventional 'song system', particularly the caudomedial nidopallium (NCM) and the caudomedial mesopallium (CMM). IEG expression in the NCM correlates significantly with the strength of song learning (i.e. the number of elements copied), suggesting that in males, the NCM may be (part of) the neural substrate for the representation of tutor song. There were no significant differences in overall IEG expression in NCM, CMM or hippocampus between males that were exposed to the tutor song, to their own song or to novel song. However, there was a significant positive correlation between IEG expression in the NCM (but not in the other two regions) and strength of song learning in the males that were exposed to the tutor song, but not in the other two groups. Thus, experience-related neuronal activation in the NCM is specific to the tutor song and thus unlikely to be a result of differences in attention. Zebra finch males both learn the characteristics of tutor song and learn to produce a similar own song. Female zebra finches do not sing, but nevertheless they learn the characteristics of a song to which they were exposed when young, and form a preference for it. Adult zebra finch females that were re-exposed to their father’s song showed significantly greater IEG expression than controls that were exposed to a novel song, in the CMM, but not in the NCM or hippocampus. These results suggest that in female zebra finches, the CMM may be (part of) the neural substrate for the representation of the memory of their father’s song.

14.40 – 15.00 Liesbeth Sterck – Testing for episodic memory in primates. The hallmark of

human social cognition is Theory of Mind, the ability to have ideas about the intentions, desires and beliefs of another individual. This cognitive capacity is thought to have a crucial effect on human social behaviour. Theory of Mind may require some fundamental cognitive capacities combined with sufficient executive brainpower. One of these capacities is episodic memory, the ability to recall personal experiences and to use recollections to plan future behaviour. Whether animals possess episodic memory is currently hotly debated. However, some animals can integrate several features of a past event (e.g., when, what, who) and use this recalled event to control their current and future behaviour. This so-called episodic-like memory may be present in monkeys. I will present two paradigms I developed to test for the presence of episodic memory in primates. The first paradigm employs social behaviour to test whether primates recall a past event. It combines observations of social behaviour, indicating general relationship quality, with behavioural tests that vary in the nature of the past interaction (what), the identity of the interaction partner (who) and the time interval (when). The second paradigm tests whether primates plan future behaviour when they can exchange a token for food. These studies will indicate whether primates possess episodic-like memory.


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Keynote lecture 2 (Moderator: Frans Verstraten) 15.20 – 16.00 Key-note lecuture: Lightness and Multiple Illumination Levels

Dr. Suncica Zdravkovic (University of Novi Sad) Lightness, i.e. perceived reflectance of a surface, was as a rule studied on objects under a single illumination level. In such conditions some of the main issues were constancy, contrast and articulation. Differently conceptualized theories were trying to model the data and anchoring models seem to be able to predict the widest range of conditions. New research is concerned with more complex conditions: multiple illumination levels. Illumination levels differences are presented in spatial domain, within a visual scene or on a single object and in temporal domain. The data are discussed within Anchoring model. Forum (Moderator: Frans Verstraten) 20.00 – 21.30 Forum “To be a Helmholtz School graduate student: mutual expectations” Panelists: Helmholtz AIO-counsel & respresentatives from the Helmholtz School.


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Friday 24 JUNE Session 7 - Helmholtz Audio crowd (Amsterdam & Utrecht) (Moderator: Joost Festen) 09.00 – 09.20 Erwin George (VUmc) - Factors affecting speech reception in modulated noise. 09.20 – 09.40 Maarten van Beurden (AMC) - Loudness measuring procedures. 09.40 – 10.00 Martijn Agterberg – Neurotrophins enhance spiral ganglion survival after

induced deafness. 10.00 – 10.20 Sjaak Klis - The Influence of Basilar Membrane Position on the Cochlear

Summating Potential. 09.00 – 09.20 Erwin George - Factors affecting speech reception in modulated noise" A

common complaint among hearing-impaired listeners is that speech in background noise, although audible, may not be understood, especially when the noise level changes rapidly over time. Hearing-impaired listeners seem to benefit less from the relatively silent periods or gaps in this type of noise. Understanding the processes behind this effect is important, since fluctuating backgrounds are very common in everyday situations. The speech reception threshold (SRT) for sentences in steady-state noise and in several amplitude-modulated noises was measured for 8 normal-hearing listeners (NHR), 29 sensorineural hearing-impaired listeners (HI), and 16 normal-hearing listeners with simulated hearing loss (SIM). The Speech Intelligibility Index (SII) was calculated for each listener to determine the amount of available speech information. A raised SII indicates less efficient handling of the information due to supra-threshold deficits. Results show that reduced speech understanding in noise can only partly be accounted for by reduced audibility. Temporal resolution and age are shown to be the main factors governing speech understanding for speech in modulated noise, accounting for more than half of the inter-subject variance. Their influence appears to be related to the processing of mainly higher signal frequencies.

09.20 – 09.40 Maarten van Beurden (AMC) - Loudness measuring procedures. Loudness is a

psychophysical property that can be described as the subjective perception of sound intensity. Besides intensity it is influenced by the bandwidth, the duration, the (center) frequency and the dynamic behavior of the signal. In my research I am especially interested in the influences of bandwidth and duration on loudness perception and the ways that they interact. Loudness measurements, as all subjective measurements, are however very sensitive to biases. Therefore the measurement procedure is very important. In this presentation I will focus on this important issue and I will present the results of a comparative study between a conventional measuring procedure and a new measuring procedure. Both are adaptive, two-interval, two-alternative forced-choice loudness-matching procedures, but the task is modified in the new procedure. Instead of estimating which signal is louder, the new task is estimating which loudness difference is larger. Besides I will briefly compare these two matching procedures with a loudness scaling procedure.

09.40 – 10.00 Martijn Agterberg – Neurotrophins enhance spiral ganglion survival after

induced deafness. Since the introduction of the cochlear implant in the 80s, deaf people have an opportunity to hear. The implant stimulates the auditory nerve directly with electrical currents, resulting in an auditory experience. There is a large variability in the performance of speech perception in cochlear implant users. One of the sources of this large variability might be degeneration of spiral ganglion cells (SGCs). The SGCs of the auditory nerve degenerate because of the missing input from the auditory sensory cells. We are interested in enhancing SGC survival in animals which have been deaf for a clinically relevant period. We investigated the remaining cochlear function and degeneration pattern of SGCs in deafened guinea pigs treated with brain derived neurotrophic factor (BDNF). In the control group, guinea pigs were implanted with an extracochlear electrode (placed on the round


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window) and deafened by co-administration of kanamycin and furosemide. Animals were sacrificed for histology after 1-8 weeks. In the treated group, 2 weeks after the deafening procedure, the right cochleas were implanted with an electrode and cannula. The cannula was attached to a mini-osmotic pump (flow rate: 0.25 µl/h) filled with brain derived neurotrophic factor (BDNF). BDNF (100 µg/ml) was administered to the cochlea for 4 weeks. Animals were sacrificed for histology after these 4 weeks. In all animals compound action potentials (CAPs) and auditory brainstem responses (ABRs) were recorded before and at various times after deafening. Acoustical stimuli were broadband clicks and tone pips of various frequencies (2-16 kHz). In the control group, SGC densities started to decrease significantly between 2 and 4 weeks and reached a 70% loss 8 weeks after treatment. We found a significant effect of BDNF treatment: treated (right) cochleas showed 2 to 3 times higher SGC densities than untreated (left) cochleas.

10.00 – 10.20 Sjaak Klis - The Influence of Basilar Membrane Position on the Cochlear

Summating Potential. Stimulation with sound evokes three kinds of far-field potentials that can be recorded in and around the cochlea. One of these three, the summating potential (SP), is a DC receptor potential with size and polarity dependent on recording location and stimulus attributes. Cochlear potentials in general are useful for the characterisation of the cochlear transduction process in normal and pathological situations, e.g., Meniere’s disease. A typical enlargement of the endolymphatic space is pathognomic for Meniere’s disease. If this enlargement is accompanied by endolymphatic overpressure, the basilar membrane and the organ of Corti, essential in cochlear transduction, will get displaced. This displacement is thought to change the operating point of the cochlear transducer, thereby altering the nonlinear SP, making the SP a potential indicator of endolymphatic hydrops. We aimed to characterize the SP in several artificial conditions of basilar membrane displacement. Previously, we have studied the SP in 2 situations of basilar membrane displacement in guinea pigs: low-frequency biasing of the basilar membrane and perfusion of the perilymphatic spaces with low- and high-osmolality perilymph. Recently, we used various perilymphatic perfusion rates to alter the position of the basilar membrane. The three experiments showed a mutually consistent relation between basilar membrane position and SP magnitude and polarity, which is remarkable because the duration of the displacement varied from milliseconds (biasing) to hours (osmotic manipulations). The SP consistently increases with displacement towards scala tympani. Thus, SP magnitude could be a reliable indicator of basilar membrane displacement with endolymphatic hydrops because displacement towards scala tympani is what we expect with endolymphatic hydrops. Our results suggest that an enhanced SP could be a direct reflection of endolymphatic hydrops, provided that the hydrops is accompanied by endolymphatic overpressure. However, in Meniere patients, there are other phenomena that may affect the SP. The SP may be affected by rupture of Reissner’s membrane accompanied by potassium intoxication and there may be hair cell damage of sufficient magnitude to reduce all cochlear potentials, including

Session 8 – Psychonomics Neuropsychology (Moderator: Edward de Haan) 11.00 – 11.20 Gudrun Nys – The neural basis of visual hallucinations in hemianopic patients 11.20 – 11.40 Martine van Zandvoort – Cognitive function after lacunar Infarcts 11.40 – 12.00 Albert Postma – Remembering the where and when of events. On the

integration of spatial and temporal information in memory 12.00 – 12.20 Roy Kessels – Contextual memory and binding 11.00 – 11.20 Gudrun Nys – The neural basis of visual hallucinations in hemianopic patients

Hallucinatory experiences are found in a broad range of psychiatric patients, neurological patients, and even in healthy subjects. The most prominent neurological conditions involving visual hallucinations are Lewy body dementia,


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Charles Bonnet syndrome (visual hallucinations of the blind), and “peduncular hallucinosis” after brain stem or thalamic lesions. In hemianopic patients who suffer from an occipital stroke, hallucinations are frequently localised to the affected part of the visual field. According to fMRI studies in patients with Charles Bonnet syndrome and Lewy Body dementia, the neural basis of visual hallucinations is in V1 and/or higher-level visual areas depending on the nature of the hallucinations. The neural basis of visual hallucinations in patients with an infarction in occipital cortex remains unclear. A case study is presented in which we examined the neural correlates of visual hallucinations in a hemianopic patient by means of functional neuro-imaging. Some potential underlying mechanisms and the significance of hallucinations with respect to recovery from visual field defects will be discussed.

11.20 – 11.40 Martine van Zandvoort – Cognitive function after lacunar Infarcts. To date,

stroke is one of the most invalidating diseases in the western world and these invalidation is mostly caused by cognitive deficits due to the stroke. In 25% of the strokes it concerns a lacunar infarction caused by an obstruction in a penetrating small artery in the brain. 1 Despite the presumed ‘innocence’ of these minor strokes, cognitive functioning is often decreased in these patients.2 This appears to be the result of neuronal metabolic derangement in the brain and not of the lesion itself.3 It is under debate to what extent these metabolic derangements are inherent to vascular risk factor present in most of these patient or that the derangement must be seen as a side-effect of an ischemic event. A decrease in cognitive function due to neuronal metabolic derangement might be an early sign of a brain at risk for vascular dementia even before structural damage is apparent. Recent research findings will be discussed in the light of relatively imaging techniques like magnetic resonance imaging and perfusion imaging.

11.40 – 12.00 Albert Postma – Remembering the where and when of events. On the

integration of spatial and temporal information in memory Remembering events typically requires recalling the core elements of an event in their proper spatiotemporal context, or, in other words, the where and when of events. This presentation will address the question of how spatial and temporal context information are integrated. One possibility is that integration is obligatory and automatic (that is effort to remember where something happened will also automatically result in remembering when it happened). Alternatively, it might depend on directed attention and effort. Relevant data will be discussed from a study examining whether Korsakoff patients can process spatial and temporal order information in memory under conditions which included presentation of only a single feature (i.e. temporal or spatial information), combined spatiotemporal presentation, and combined spatiotemporal order recall. Korsakoff patients were found to suffer comparable spatial and temporal order recall deficits. Interestingly, recall of a single feature was the same when only spatial or temporal information was presented compared to conditions which included combined spatiotemporal presentation and recall. In contrast, control subjects performed worse when they have to recall both spatial and temporal order compared to when they have to recall only one of these features. These findings together indicate that spatial and temporal information are not automatically integrated. Korsakoff patients have marked problems in coding the feature at hand. Moreover, their lower recall of both features at the same time suggests that Korsakoff patients are impaired in binding different contextual attributes together in memory. The neurocognitive implications of these results are discussed.

12.00 – 12.20 Roy Kessels – Contextual memory and binding. There is abundant evidence that

the hippocampus is involved in the consolidation of memory, specifically when a relational component must be processed. That is, patients with lesions in the hippocampus typically show difficulties in associative memory (e.g., paired-associate learning). More recently, it has been postulated that the hippocampus might act as a general memory binding device which is not only involved in the formation of associations between arbitrary elements (e.g., 2 words) but also


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integrates and holds together features of information that intrinsically belong together, such as object and location or item content and color. A previous study in patients with unilateral lesions in the hippocampal formation has shown that object-location binding was indeed impaired in this group (Kessels et al., 2004). However, in this study we did not directly compare memory for single items to memory for combined information. The current presentation will focus on the binding hypothesis in relation to the development of contextual memory dysfunction in normal cognitive ageing (Kessels et al., submitted). Furthermore, data will be presented on the underlying neurocognitive basis of memory binding using fMRI showing that especially the right hippocampus is involved in the binding of spatial information to items, but that it is not involved in the binding of color and item (Piekema et al., submitted).

proceedings of the 3 helmholtz retreat · 5 anema, helen grad. stud psn utrecht 6 baas, daan grad....

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