Thalamic state control of cortical paired-pulse dynamics

Area of Science:

• Neuroscience
• Systems Neuroscience
• Sensory Processing

Background:

• Neural circuits exhibit complex dynamics during sensory information processing.
• The thalamocortical circuit, crucial for sensory perception, shows repeatable neural dynamics in response to stimuli.
• Understanding how thalamic state shapes cortical responses is key to deciphering sensory encoding.

Purpose of the Study:

• To investigate the role of thalamic state in modulating cortical dynamics within the rodent vibrissa pathway.
• To differentiate between sensory-evoked and artificially stimulated thalamocortical responses.
• To determine if thalamic bursting activity underlies observed facilitation dynamics in the cortex.

Main Methods:

• In vivo voltage-sensitive dye (VSD) imaging of the rodent cortex.
• Single-unit recording in the thalamus.
• Optogenetic manipulation of thalamic firing modes (burst vs. tonic).
• Stimulation of the vibrissa pathway via natural whisker input and artificial thalamic input.

Main Results:

• Sensory stimulation of whiskers elicited suppressive cortical dynamics.
• Artificial thalamic stimulation induced a facilitation dynamic in the cortex, absent during sensory stimulation.
• Thalamic neurons exhibited enhanced bursting activity with artificial stimulation.
• Optogenetically shifting thalamus from burst to tonic mode abolished the cortical facilitation dynamic.

Conclusions:

• Thalamic state, particularly bursting activity, significantly shapes stimulus-evoked dynamics in the thalamocortical pathway.
• Thalamic bursting plays a critical role in mediating cortical facilitation.
• This study provides direct evidence for the influence of thalamic firing modes on cortical sensory processing.