Neocortical inhibitory interneuron subtypes are differentially attuned to synchrony- and rate-coded information

Area of Science:

• Neuroscience
• Computational Neuroscience
• Cortical Circuitry

Background:

• Neurons transmit information via spike timing (synchrony) and firing frequency (rate).
• The differential sensitivity of distinct neuronal subtypes to these coding schemes remains largely unexplored in the neocortex.

Purpose of the Study:

• To investigate whether fast-spiking (FS) and regular-spiking (RS) interneurons exhibit distinct sensitivities to synchrony-based versus rate-based neural information encoding.
• To elucidate the role of interneuron subtypes in processing information conveyed by different neural coding strategies.

Main Methods:

• Utilized patterned optical stimulation in mouse somatosensory cortex slices to selectively activate FS and RS interneurons.
• Encoded a binary signal using either spike synchrony or firing rate patterns.
• Quantified the mutual information between the encoded signal and interneuron responses to assess information transmission.

Main Results:

• FS interneurons showed higher information transmission for synchrony encoding within the initial 5 milliseconds.
• Both FS and RS interneurons carried more information than excitatory neurons in later responses to synchrony encoding.
• RS interneurons demonstrated superior information transmission for rate encoding after several milliseconds.

Conclusions:

• Neocortical interneuron subtypes possess distinct sensitivities to synchrony and rate coding mechanisms.
• FS interneurons are more attuned to rapid, synchronous events, whereas RS interneurons are more responsive to sustained firing rates.
• These findings highlight the specialized roles of interneuron subtypes in neural information processing within cortical circuits.