studying barn owls in the laboratory sound intensity cues sound timing cues
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PART 2: SENSORY WORLDS #08: PREY LOCATION IN BARN OWLS II. studying barn owls in the laboratory sound intensity cues sound timing cues neural pathways for sound location auditory space interaural time differences delay lines & coincidence detectors - PowerPoint PPT PresentationTRANSCRIPT
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studying barn owls in the laboratory sound intensity cues sound timing cues
neural pathways for sound location auditory space interaural time differences delay lines & coincidence detectors
visual calibration of the auditory world summary
PART 2: SENSORY WORLDS#08: PREY LOCATION IN BARN OWLS II
![Page 2: studying barn owls in the laboratory sound intensity cues sound timing cues](https://reader036.vdocuments.net/reader036/viewer/2022081603/56815735550346895dc4d547/html5/thumbnails/2.jpg)
studying barn owls in the laboratory sound intensity cues sound timing cues
neural pathways for sound location auditory space interaural time differences delay lines & coincidence detectors
visual calibration of the auditory world summary
PART 2: SENSORY WORLDS#08: PREY LOCATION IN BARN OWLS II
![Page 3: studying barn owls in the laboratory sound intensity cues sound timing cues](https://reader036.vdocuments.net/reader036/viewer/2022081603/56815735550346895dc4d547/html5/thumbnails/3.jpg)
owls are auditory & visual animals
systems integrated locate source of stimulus
recall experimental set up...
VISUAL CALIBRATION OF THE AUDITORY WORLD
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monitor head orientation behavior
used “search coil” weak electric field
signal magnitude + sign head position
~ sounds
no echoes
total darkness
sound & head positions correlated by computer
p.64 fig.3.2
BARN OWLS IN THE LABORATORY
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monaural occlusion experiments location error elevation azimuth (minor)
2 critical observations...
p.67 fig.3.4
1. correction after weeks ? young owls yes old owls less
2. remove occlusion error persists, but... corrected / time
BEHAVIORAL ANALYSIS
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monaural occlusion experiments location error elevation azimuth (minor)
p.67 fig.3.4
other cues... vision ? prisms correct ~ visual offset
BEHAVIORAL ANALYSIS
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hypothesis: vision guides evaluation of auditory cues raised young (sensitive) owls with prisms do owls adjust auditory targeting ~ visual input ?
results: normal visual shift only ...auditory shift
p.83 fig.3.15
shift remains
VISUAL vs AUDITORY STIMULI
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developmental regulation of shift 7 mo, shift ~ 20° adults, shift only a few °
results: normal visual shift only ...auditory shift
p.83 fig.3.15
shift remains
VISUAL vs AUDITORY STIMULI
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convergence: azimuthal (ITD) & horizontal (ILD) info in ICX auditory & visual information in optic tectum
receptive fields of optic tectum aligned in columns
p.84 fig.3.16
NEURAL CORRELATES OF PLASTICITY
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receptive fields of optic tectum aligned in columns
p.85 fig.3.17
(A) multimodal space map in optic tectum
(B) prisms shift visual receptive field
(C) + 8 wks... auditory receptive field shifts
NEURAL CORRELATES OF PLASTICITY
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azimuthal plane... expect horizontal shift in auditory perceptive fields induced by abnormal visual cues accompanied by ~ shift in ITDs of tectal neurons
p.85 fig.3.17
what causes this shift in alignment ?
NEURAL CORRELATES OF PLASTICITY
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adaptation of ITD map ~ visual experience
p.86 fig.3.18
(A) optic tectum neurons normal visual tuning @ 0 s (center of field) 8 wks of prism visual tuning @ ~ 50 s
(B) optic tectum neuron arrays shifts follow pattern of visual experience
NEURAL CORRELATES OF PLASTICITY
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ITD tuning curves in ICX neurons of prism-reared owls
shaded = normal & learned
2 stages of ITD adjustment
p.87 fig.3.19
(A) initial: az.= 0°, ITD = 0 s(B) transition: az., ITD (C) shift: az.= 23°, ITD = 40 s
NEURAL CORRELATES OF PLASTICITY
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visual experience modification of auditory localization
young < juvenile > adult 60 days 200
monaural occlusion displacement prisms
optic tectum ITD tuning
(A) juveniles: sensitive to prisms
(B) adults: naïve – insensitive to prisms () experienced – sensitive ()
p.88 fig.3.20
SENSITIVE PERIOD FOR CALIBRATION
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visual horizontal displacement auditory space maps optic tectum ITD map
auditory space maps: ICC ICX op.tectum
p.90 fig.3.21
SITES OF ADAPTIVE PLASTICITY
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auditory space maps: ICC ICX op.tectum
prism reared owls: ICC map normal ICX map shifted ~ optic tectum shift anatomy
normal ICC-ICX input additional ICC-ICX input to shifted ITD region accounts for recovery during lifetime normal accounts for rapid readjustment prisms again
p.90 fig.3.21
SITES OF ADAPTIVE PLASTICITY
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cellular mechanisms ?
involves: glutamate - excitatory neurotransmitter glutamate receptor - NMDA receptor
p.90 fig.3.21
SITES OF ADAPTIVE PLASTICITY
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experiments identified 2 critical auditory cues... time info, ITD NM azimuthal information intensity info, ILD NA elevation information parallel processed, cochlear nuclei ICX
ITD & ILD information ICX space-specific neurons each neuron receptive field in auditory space emergent / unique property (not signal addition)
coordinated auditory & visual world visual tuning of auditory space young / juvenile > adult
SUMMARY
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multimodal maps of sensory world in optic tectum auditory maps can shift register with visual young < juvenile > adult realignment by new ICC ICX connections connections persistent
SUMMARY