Abstract
Previous studies have shown that the auditory cortex can enhance the perception of behaviorally important sounds in the presence of background noise, but the mechanisms by which it does this are not yet elucidated. Rapid plasticity of spectrotemporal receptive fields (STRFs) in the primary (A1) cortical neurons is observed during behavioral tasks that require discrimination of particular sounds. This rapid task-related change is believed to be one of the processing strategies utilized by the auditory cortex to selectively attend to one stream of sound in the presence of mixed sounds. However, the mechanism by which the brain evokes this rapid plasticity in the auditory cortex remains unclear. This paper uses a neural network model to investigate how synaptic transmission within the cortical neuron network can change the receptive fields of individual neurons. A sound signal was used as input to a model of the cochlea and auditory periphery, which activated or inhibited integrate-and-fire neuron models to represent networks in the primary auditory cortex. Each neuron in the network was tuned to a different frequency. All neurons were interconnected with excitatory or inhibitory synapses of varying strengths. Action potentials in one of the model neurons were used to calculate the receptive field using reverse correlation. The results were directly compared to previously recorded electrophysiological data from ferrets performing behavioral tasks that require discrimination of particular sounds. The neural network model could reproduce complex STRFs observed experimentally through optimizing the synaptic weights in the model. The model predicts that altering synaptic drive between cortical neurons and/or bottom-up synaptic drive from the cochlear model to the cortical neurons can account for rapid task-related changes observed experimentally in A1 neurons. By identifying changes in the synaptic drive during behavioral tasks, the model provides insights into the neural mechanisms utilized by the auditory cortex to enhance the perception of behaviorally salient sounds.
Highlights
The auditory cortex utilizes a variety of processing strategies to enhance the perception of behaviorally-meaningful sounds in the presence of background noise
A genetic algorithm was used to optimize the synaptic drive between neurons to produce spectrotemporal receptive fields (STRFs) and the behavioral changes in STRFs that matched experimentally recorded data
To ensure the overall model structure was producing expected results, the cortical neural network model was reduced in complexity by removing synaptic connections between cortical neurons
Summary
The auditory cortex utilizes a variety of processing strategies to enhance the perception of behaviorally-meaningful sounds in the presence of background noise. Rapid plasticity of receptive fields in primary (A1) cortical neurons is observed during behavioral tasks that require discrimination of particular sounds (Fritz et al, 2003, 2005a,b; Elhilali et al, 2004, 2007). This rapid, task-related change may enhance the ability to selectively attend to one acoustic feature or to one stream of sound in the presence of mixed sounds. It is important to consider a sound’s spectral and temporal features together
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