Neurons in the songbird forebrain area HVc are sensitive to the
temporal structure of the bird's own song and are capable of
integrating auditory information over a period of several hundred
milliseconds. Extracellular studies have shown that the responses of
some HVc neurons depend on the combination and temporal order of
syllables from the bird's own song, but little is known about the
mechanisms underlying these response properties. To investigate these
mechanisms, we recorded intracellular responses to a set of auditory
stimuli designed to assess the degree of dependence of the responses
on temporal context. This report provides evidence that HVc neurons
encode information about temporal structure using a variety of
mechanisms including syllable-specific inhibition, excitatory
post-synaptic potentials with a range of different time courses, and
burst-firing non-linearity. The data suggest that the sensitivity of
HVc neurons to temporal combinations of syllables results from the
interactions of several cells and does not arise in a single step from
afferent inputs alone.
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