studying barn owls in the laboratory sound intensity cues sound timing cues
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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 & PART 2: SENSORY WORLDS #08: PREY LOCATION IN BARN OWLS II
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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 Presentation
Transcript of studying barn owls in the laboratory sound intensity cues sound timing cues
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
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
owls are auditory & visual animals
systems integrated locate source of stimulus
recall experimental set up...
VISUAL CALIBRATION OF THE AUDITORY WORLD
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
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
monaural occlusion experiments location error elevation azimuth (minor)
p.67 fig.3.4
other cues... vision ? prisms correct ~ visual offset
BEHAVIORAL ANALYSIS
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
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
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
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
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
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
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
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
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
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
cellular mechanisms ?
involves: glutamate - excitatory neurotransmitter glutamate receptor - NMDA receptor
p.90 fig.3.21
SITES OF ADAPTIVE PLASTICITY
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
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
