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7_melcher_handot - Neuroimaging Correlates of Human...

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Unformatted text preview: Neuroimaging Correlates of Human Auditory Behavior HST 722 Brain Mechanisms for Hearing and Speech October 27, 2005 Jennifer Melcher Harvard-MIT Division of Health Sciences and Technology HST.722J: Brain Mechanisms for Hearing and Speech Course Instructor: Jennifer R. Melcher "The Problem" "The Problem" Figure by MIT OCW. Sound Perception Noninvasive Physiologic Measures Neural Activity Figure above illustrates how auditory evoked potentials are measured. Potential shown was evoked by a click stimulus and was recorded in a human subject. Waveform is the averaged response to many click presentations. (AEP record from R.A. Levine) (Courtesy of Robert Aaron Levine. Used with permission.) Furst et al. (1985) Click lateralization is related to the component of the dichotic brainstem auditory evoked potentials of human subjects For binaural clicks with different ITDs and ILDs, quantied perception binaural difference potential Attributes of the binaural difference are correlated with the perception of binaural sound. Binaural difference (BD) is derived from BAEPs evoked by monaural and binaural stimuli (above). BAEP: brainstem auditory evoked potential The BD reFects an interaction between converging signals from the two ears at the level of the brainstem. Binaural Difference Potential ig. 9. Binaural, sum of the monaurals, and binaural difference waveforms for both species. The binaural (solid lines) and sum of the monaural waveforms (dotted lines) are superimposed. The difference between these two waveforms, the binaural difference (BD) waveform, is plotted below. The recording electrodes were vertex to nape for both species. Stimuli were 10/sec; rarefaction clicks at 40 dB SL for the cat and 38 dB HL for the human. (from ullerton et al., 1987) 4 8 12 4 8 12 msec msec CAT 24 SU 44 b d a c 7.0 V 0.2 V CAT HUMAN MON BIN BD P4 P5 Figures by MIT OCW. Cellular Generators of the Binaural Difference Potential Cellular generators of the binaural difference potential in cat. Diagonal line shadings indicate the generators of the Frst peak (b; white on black) and possible generators of the second peak (d; black on white). The schematic of the lower auditory system (at bottom) shows the generators relationship to other cells. NLL, nuclei of the lateral lemniscus; IC, inferior colliculus. (rom Melcher, 1996) LEFT SOC Midline Trapezoid body Auditory nerve Lateral lemniscus NLL/IC ? MSO LSO Principal cell COCHLEAR NUCLEUS Cellular generators of the binaural difference potential in cat. Green color indicate the generators of the first peak ('b'; white on black) and possible generators of the second peak ('d'; black on white). The schematic of the lower auditory system (at bottom) shows the generators' relationship to other cells....
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This note was uploaded on 11/11/2011 for the course BIO 9.07 taught by Professor Ruthrosenholtz during the Spring '04 term at MIT.

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7_melcher_handot - Neuroimaging Correlates of Human...

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