Modelling the Slope Sensitivity of Primary Auditory Cortex Neurons in Awake Cats

K. Ozawa, Y. Koike, H. Wakagi, Y. Sato, and S. Chimoto (Japan)


Functional model, primary auditory cortex, phasic neuron,slope sensitivity, awake cat, and brain–machine interface


Measurements of single-spike responses to tone-burst stimuli have revealed heterogenic response types among the primary auditory cortex (A1) neurons in awake cats. These neurons include phasic neurons that are sensitive to the rise in the stimulus amplitude (stimulus slope) at stimulus onset, and sustained cells that are sensitive to the stimulus slope and the steady-state sound level at a later period during the stimuli presentation. To explain the behavior of the slope-sensitive phasic cells, we have developed an auditory model, consisting of six stages: the inner hair cell (IHC), the primary auditory nerve (AN), the ventral cochlear nucleus (VCN), the inferior colliculus (IC), the medial geniculate body (MGB), and the A1 neuron. The model was constructed as a MATLAB program. The IHC, AN, VCN, and IC models are based on previous studies, whereas we have newly developed the models of the MGB and A1 neurons. The model output successfully replicated physiological data in terms of the response rise time, maximum driven rate, and onset latency corresponding to the slope of the input stimulus. This model can be used to convert acoustical signals into electrical stimuli as part of an auditory brain–machine interface for individuals with severe hearing impairments.

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