Mitchell Steinschneider

Professor
Speech processing in auditory cortex; auditory cortex physiology; evoked-potential analysis of cortical processing mechanisms.

Kennedy Center
Room 322
(718) 430-4115

 

The broad objective of this project is to elucidate neural mechanisms associated with complex sound processing relevant for the perception of speech, music and auditory scene analysis by examining electrophysiological responses within monkey auditory cortex. There are many similarities between monkeys and humans in their auditory cortex organization and in their ability to perform phonetic and complex sound discriminations, highlighting the utility of primates as a reasonable electrophysiological model. Direct recordings in monkey auditory cortex offer the opportunity to investigate neural bases of complex sound encoding with a detail that is unobtainable by non-invasive studies in the human. Our studies will clarify normal mechanisms of speech and other complex sound encoding, and serve as a benchmark for evaluating hypotheses regarding dysfunctional processes associated with abnormal speech and hearing development.

Recent speech-related work has focused on the cortical processes involved in the encoding of the voice onset time and place of articulation phonetic parameters. Music-related studies have concentrated on auditory cortical encoding of pitch and timbre, as well as the neural response features associated with consonance and dissonance of musical intervals. Temporal and spectral streaming relevant for auditory scene analysis are also being actively investigated. Cortical responses are described using 4 complementary, concurrently recorded measures of neuronal ensemble activity, (1) multiunit activity (MUA), (2) auditory evoked potentials (AEPs), (3) the derived current source density (CSD), and (4) frequency-specific changes in the EEG, including those in the gamma range (>30 Hz). CSD analysis characterizes the temporal and laminar distributions of current sources and sinks that reflect net synaptic activation and inhibition, whereas phasic MUA patterns determine changes in the net firing rate of neuronal ensembles. Gamma-band activity is envisioned to play a central role in the perceptual binding of sensory attributes crucial for object recognition. These recording procedures yield stable measures of the synchronized neuronal activity required for complex sound encoding. Through their relationship with the AEP, monkey intracortical responses can be directly linked with homologous responses in humans.

 

Selected Publications

Fishman, Y.I., Reser, D.H., Arezzo, J.C. and Steinschneider, M. Neural correlates of auditory stream segregation in primary auditory cortex of the awake monkey. Hearing Res., 151;1-2:167-187, 2001.

Fishman, Y.I., Volkov, I.O., Noh, M.D., Garell, P.C., Bakken, H., Arezzo, J.C., Howard, M.A. and
Steinschneider, M. Consonance and dissonance of musical chords: Neural correlates in auditory
cortex of monkeys and humans. J. Neurophysiol., 86:2761-2788, 2001.


Steinschneider, M. and Dunn, M. Electrophysiology in development neuropsychology. In: Segalowitz, S. and Rapin, I., (Eds.), Handbook of Neuropsychology, Vol. 7, Elsevier Press, 2002, Chapter 5, pp. 91-146.

Steinschneider, M., Fishman, YI, and Arezzo, JC. Representation of the voice onset time (VOT) speech parameter in population responses within primary auditory cortex of the awake monkey. J. Acoust. Soc. Am., 114(1)307-321, 2003.