Leibniz MMS Days 2022 - Abstract

Hajizadeh, Aida

Auditory cortex modelled as a dynamical network of oscillators: understanding event-related fields and their adaptation

Sensitivity of neuronal responses to the temporal pattern of auditory stimuli is an ubiquitous phenomenon in the auditory cortex (AC). This sensitivity is reflected, for example, in adaptation, the reduction of the response magnitude of auditory neurons to repetitive stimulation. Short-term synaptic depression (STSD) is considered to be a potential candidate underlying adaptation. We examined this hypothesis by using a mechanistic model based on AC anatomy. The model replicates the event-related field (ERF) of the magnetoencephalogram as well as ERF adaptation. The model dynamics are described by excitatory and inhibitory state variables of cell populations characterized by nonlinear firing rates. We analysed the system dynamics by linearizing the firing rates and solving the STSD equation using time-scale separation. This allows for characterization of AC dynamics as a superposition of damped harmonic oscillators, so-called normal modes. We show that adaptation can be accounted for as modulations of these normal modes. In this view, adaptation results from a complete reorganization of AC dynamics rather than a reduction of activity in discrete sources.