Information Coding through Adaptive Gating of Synchronized Thalamic Bursting

• Bottom-up adaptation continuously modulates thalamic burst/tonic firing
• Adaptation modulates the degree of stimulus-evoked synchronized bursting
• Adapting stimuli shift thalamic encoding from detection to discrimination mode
• Proposed adaptive mechanism of action is sustained depolarization of thalamic neurons

SummaryIt has been posited that the regulation of burst/tonic firing in the thalamus could function as a mechanism for controlling not only how much but what kind of information is conveyed to downstream cortical targets. Yet how this gating mechanism is adaptively modulated on fast timescales by ongoing sensory inputs in rich sensory environments remains unknown. Using single-unit recordings in the rat vibrissa thalamus (VPm), we found that the degree of bottom-up adaptation modulated thalamic burst/tonic firing as well as the synchronization of bursting across the thalamic population along a continuum for which the extremes facilitate detection or discrimination of sensory inputs. Optogenetic control of baseline membrane potential in thalamus further suggests that this regulation may result from an interplay between adaptive changes in thalamic membrane potential and synaptic drive from inputs to thalamus, setting the stage for an intricate control strategy upon which cortical computation is built.

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