Behavioral engagement facilitates auditory neuron responses beyond their receptive fields.

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Sensory Processing

Background:

• Neural responses in the auditory cortex are modulated by behavioral demands, like spatial attention.
• The influence of off-receptive field (RF) stimuli on neural responses and task contribution is less understood.
• Previous work suggested location-specific facilitation from off-RF stimulation, indicating behavioral modulation of spatial RFs.

Purpose of the Study:

• To investigate how behavioral tasks modulate neural responses to stimuli both inside and outside neuronal receptive fields (RFs) in the auditory cortex.
• To explore the extent and characteristics of task-related off-RF facilitation.
• To determine the neural mechanisms underlying this phenomenon.

Main Methods:

• Marmosets were trained to attend to auditory stimuli at locations inside or outside the RFs of auditory cortical neurons.
• Neural firing rates and membrane potentials were recorded.
• A normalization model was used to simulate and explain the observed neural modulations.

Main Results:

• Most neurons showed increased firing rates for attended targets inside their RFs.
• Significant task-related facilitation was also observed for stimuli outside RFs, sometimes surpassing responses to RF-center stimuli during passive listening.
• Off-RF facilitation was more prevalent in caudal auditory cortex areas compared to rostral areas and the primary auditory cortex.
• Neural recordings confirmed widespread suppression and hyperpolarized membrane potentials for off-RF stimuli, consistent with the normalization model.

Conclusions:

• Behavioral task demands recruit a wider network of auditory cortical neurons than those responsive to a target sound during passive listening.
• Task-specific attention can dynamically expand the effective spatial receptive fields of auditory neurons.
• Widespread suppression mechanisms play a crucial role in mediating task-related off-RF facilitation.