Abstract
Birdsong is a complex vocal communication signal, and like humans, birds need to discriminate between similar sequences of sound with different meanings. The caudal mesopallium (CM) is a cortical-level auditory area implicated in song discrimination. CM neurons respond sparsely to conspecific song and are tolerant of production variability. Intracellular recordings in CM have identified a diversity of intrinsic membrane dynamics, which could contribute to the emergence of these higher-order functional properties. We investigated this hypothesis using a novel linear-dynamical cascade model that incorporated detailed biophysical dynamics to simulate auditory responses to birdsong. Neuron models that included a low-threshold potassium current present in a subset of CM neurons showed increased selectivity and coding efficiency relative to models without this current. These results demonstrate the impact of intrinsic dynamics on sensory coding and the importance of including the biophysical characteristics of neural populations in simulation studies.
Highlights
Vocal communication requires an auditory system that can reliably classify signals
The intrinsic dynamics of the neurons themselves, which determine how these inputs are transformed into spiking outputs, may contribute to the neural computations underlying object recognition
To understand how intrinsic dynamics contribute to sensory coding, we constructed a computational model capable of simulating a neural response to an auditory stimulus using a detailed description of different intrinsic dynamics in a higher-order avian auditory area
Summary
In human speech, phonemes produced by different speakers and in different contexts vary broadly in acoustic structure. They are perceived as discrete, invariant categories [1], even when boundaries between phonemes are exceptionally sharp, as with the approximately 10 ms difference in voice-onset time that separates the English phonemes /d/ and /t/ [2]. As in other sensory systems, categorical responses to auditory objects emerge in higherorder areas of the cortex [7,8,9,10,11,12]. In spite of a substantial body of theoretical work [19,20,21], the circuit and cellular mechanisms underlying the emergence of categorical responses remains poorly understood
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