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MEDS 371 Auditory system II: hindbrain. Dr. Duck O. Kim. cat brain dissected showing auditory system. cerebellum. auditory cortex. inferior colliculus. cochlear nucleus. medial geniculate. auditory nerve. Oliver. dorsal. anterior. tonotopic organization of CN. cat CN. h.
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MEDS 371 Auditory system II: hindbrain Dr. Duck O. Kim
cat brain dissected showing auditory system cerebellum auditory cortex inferior colliculus cochlear nucleus medial geniculate auditory nerve Oliver
dorsal anterior tonotopic organization of CN cat CN h DCN h AVCN CN: cochlear nucleus DCN: dorsal CN AVCN: anterovent. CN PVCN: posterovent. CN PVCN h Arnesen & Osen, 1978
type I (95%) 1. spherical bushy cell; AVCN 2. stellate cell; VCN 3. globular bushy cell; AVCN 4. octopus cell; PVCN 5. fusiform cell; DCN Kiang, 1975
cells in the cochlear nucleus PST histogram F O PST histogram GB spiral ganglion neuron type I (95%) S SB Kiang, 1975
end bulbs of Held at bushy cells of the AVCN Ryugo, 1999, Fig-10
intrinsic properties EPSPs cochlear nucleus neurons intracellular recording in brain-slice preparation Oertel et al., 1988
The "where-processing" of sound: Neural representation of auditory space requires de novo computation unlike the retinotopic map.
head-related impulse responses & transfer functions of rabbit Kim, Bishop, Kuwada, 2010
Sound localization cues * interaural time difference (ITD) 5 μsec; ~ 1 deg azimuth. * interaural level difference (ILD) * spectral cues *direct/reverberant energy ratio; distance virtual auditory space
cortex thalamus midbrain CN & SOC pons the ascending auditory pathways of the cat binaural & monaural pathways Brodal, 1981
Brodal Fig 9-8 mso: medial sup. olive; lso: lateral sup. olive ntb: nuc. trazepoid body; ic: inf. coll.
LSO LSO MSO MSO MNTB MNTB cat superior olivary complex D M (axons & endings) (somata & dendrites) Tsuchitani, 1978, Fig. 10
ILD processing in LSO Purves Fig 13-14A
ILD processing in LSO Purves Fig 13-14B
model for ITD coding employing neural delay lines & coincidence detectors MSO neurons act as coincidence detectors. best ITD 1 = 0 ms; sound in front best ITD 2 = 50 ms best ITD 3 = 100 ms ... best ITD 7 = 700 ms; sound on opposite side maximum firing when left (acoustic delay + neural delay) = right (acoustic delay + neural delay) Jeffress, 1948; Kuwada
head-related impulse responses & transfer functions of rabbit Kim, Bishop, Kuwada, 2010
Inferior colliculus neurons show azimuth tuning. 10 dB 30 dB 50 dB Kuwada, Bishop, Alex, Condit, Kim, 2011, J. Neurophys.
auditory & somatosen. inputs Sup. coll. contains visual and auditory space maps. Purves Box 20B
cortex thalamus midbrain CN & SOC pons the descending auditory pathways of the cat Brodal, 1981
olivocochlear neurons LOC: lateral olivocochlear MOC: medial olivocochlear Warr et al., 2002
afferent afferent inner hair cell outer hair cell afferent nerve ending afferent nerve ending * afferent nerve fibers efferent nerve ending * efferent nerve fibers Smith, 1975