studying barn owls in the laboratory sound intensity cues sound timing cues
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PART 2: SENSORY WORLDS #07: PREY LOCATION IN BARN OWLS I. 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#07: PREY LOCATION IN BARN OWLS I
![Page 2: studying barn owls in the laboratory sound intensity cues sound timing cues](https://reader035.vdocuments.net/reader035/viewer/2022070407/56814388550346895db003cf/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#07: PREY LOCATION IN BARN OWLS I
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Intensity differences
Timing differences
high frequency ...
short wavelength
low frequency ...
long wavelength
AUDITORY CUES
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Tyto alba, hunt using auditory cues height: 1-1.5 ft wing span: 3 ft velocity: 4-8 m/s forms pair bonds hunting nocturnal
& crepuscular small rodents > other
small animals prey of great horned
owls restricts barn owl hunting to deep night
BARN OWL BIOLOGY
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Tyto alba, hunt using auditory cues locates prey in space
horizontal vertical relative to self
prey capture... FIG 1
how to determine the cues? not visual (test in dark) heat, olfactory, auditory ? early mouse/paper expt.
p.63 fig.3.1
BARN OWL BIOLOGY
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1st important behavioral observation...
owls turn their heads rapidly toward sound
bring source to center
tested experimentally...
p.63 fig.3.1
BARN OWLS IN THE LABORATORY
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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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features of barn owl auditory system
face covered with rows of stiff feathers... facial ruff
sound-collecting surface auditory canals
ears asymmetrical right ear & opening directed , sensitivity head left ear & opening directed , sensitivity head
BARN OWLS IN THE LABORATORY
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2D mapping of sound dimensions
azimuth horizontal
elevation vertical
can target soundwithin 1°-2°
3x human accuracyin vertical dimension
p.65 fig.3.3
BARN OWLS IN THE LABORATORY
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2D mapping of sound dimensions
most sensitive tosound in front
frequency range100 Hz - 12 kHz
azimuth: accurate within 1 - 9 kHz
elevation: accuratewithin 3 - 10 kHz p.65 fig.3.3
BARN OWLS IN THE LABORATORY
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experiments identified 2 critical auditory cues...
sound intensity cues elevation dimension
sound timing cues azimuth dimension
BARN OWLS IN THE LABORATORY
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attenuated sound, blocking ears with 2 types of plugs soft modest hard severe
sound location... recall that the ears are asymmetrical...
right ear & opening directed , sensitivity head left ear & opening directed , sensitivity head
interaural intensity differences to target elevation, also called interaural level differences (ILD)
SOUND INTENSITY CUES
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attenuated sound, blocking ears with 2 types of plugs soft modest hard severe
sound location error... elevation some azimuth
not sufficient to explain accuracy
p.67 fig.3.4
SOUND INTENSITY CUES
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removed facial ruff
sound location error... mostly elevation (head oriented @ horizontal plane) azimuth OK ruff amplifies directional asymmetry of ears
SOUND INTENSITY CUES
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sounds arrive @ different times to each ear difference in time = temporal disparity
barn owls can distinguish 10 ms temporal disparity interaural time difference (ITD) use ITD for azimuthal sound source determinations
p.68 fig.3.5a
SOUND TIMING CUES
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sounds arrive @ different times to each ear 2 types of temporal disparity
transient (onset / offset) ongoing
can use both which is used ?
p.68 fig.3.5b
SOUND TIMING CUES
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implanted miniature speakers decouple disparities
measured orientation ~ ongoing temporal disparity range of 10 - 80 s head movement to target represented by disparity
orientation not ~ transientdisparity
p.69 fig.3.6
SOUND TIMING CUES
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anatomical structures
basilar mem. / inner ear frequency coding phase locking intensity coding
cranial nerve VIII
cochlear nuclei NA NM p.71 fig.3.7
NEURAL PATHWAYS FOR SOUND LOCALIZATION
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anatomical structures
cochlear nuclei NA NM
NL
LL
higher auditory centers ICC (~ mam. IC) ICX p.71 fig.3.7
NEURAL PATHWAYS FOR SOUND LOCALIZATION
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p.72 fig.3.8a
external nucleus (ICX) neuron response
frontal sound
ICX space-specificneurons
AUDITORY SPACE
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p.72 fig.3.8b
external nucleus (ICX) neuron response
frontal sound
ICX space-specificneurons
map
AUDITORY SPACE
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p.73 fig.3.9
external nucleus (ICX) neuron response
frontal sound
ICX space-specific neurons
map
2nd roving speaker
excitatory (peaks) & inhibitory (trough) regions
AUDITORY SPACE
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p.74 fig.3.10
2D field
space-specific neurons are binaural
driven by bilateral stimuli
eg, neuron peak response...
response ILD & ITD specific
ILD ~ 11 dB
ITD ~ 32 s
AUDITORY SPACE
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cochlear nuclei ICX
NM time info ITD azimuth phase sensitive intensity sensitive
NA intensity info ILD elevation intensity sensitive
p.71 fig.3.7
AUDITORY SPACE
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cochlear nuclei ICX... parallel pathways ?
inject reversible local anesthetics, record from space-specific ICX neuron, sound target stimuli
NM disruption selectivity for time disparity no effect on level disparity
NA disruption selectivity for level disparity no effect on time disparity
AUDITORY SPACE
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Jeffress’s neuronal circuit model for encoding time
coincidence detector C fires best with L & R coincident signals
delay line L (eg) codes R delay
p.77 fig.3.11
INTERAURAL TIME DIFFERENCES
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Konishi model built on Jeffress for encoding ITD
coincidence detector neuron arrays variable delays
features encodes ITD neurons encode different ITDs but... = output ITD place code p.78 fig.3.12
INTERAURAL TIME DIFFERENCES
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does the owl use this mechanism ? ... evidence
anatomy... NM NL (putative neural substrate for model) ipsilateral & contralateral innervation of NL innervation parallel
p.79 fig.3.13
DELAY LINES & COINCIDENCE DETECTORS
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does the owl use this mechanism ? ... evidence
physiology... NL neurons phase-lock to binaural stimuli delay asymmetry delay ~ temp. disparity NL neurons = coincidence detectors p.79 fig.3.13
DELAY LINES & COINCIDENCE DETECTORS
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does the owl use this mechanism ? ... evidence
anatomy + physiology... each ITD encoded by different delays space-specific neurons NL position info ICX
p.80 fig.3.14
DELAY LINES & COINCIDENCE DETECTORS
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does the owl use this mechanism ? ... evidence
anatomy + physiology... each ITD encoded by different delays space-specific neurons NL position info ICX
p.71 fig.3.7
DELAY LINES & COINCIDENCE DETECTORS
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ILD (intensity) processing ? ...
poorly understood
v. nuc. lat. lemniscus
spatial organization ~ ICX
bicoordinate signatures not yet elucidated
p.71 fig.3.7
DELAY LINES & COINCIDENCE DETECTORS
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integration with other sensory input
ICX optic tectum sensory space maps
optic tectum brain stem
p.84 fig.3.16
sens
orymoto
r
sensory motor
br stem tegmentum 3D map of head position distinct circuits
AUDITORY SPACE