Corticothalamic layer 6 controls cortical activity and thalamic firing mode in a bidirectional manner
Ross Folkard1, Emilio Ulises Isaías-Camacho1, Alexander Groh1
1Medical Biophysics, Institute for Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany.
Cerebral Cortex (New York, N.Y. : 1991)
|March 24, 2026
Summary
Corticothalamic layer 6 neurons in the somatosensory cortex can switch from inhibiting to exciting cortical circuits. Their activity also influences thalamic firing modes, revealing a complex role in sensory processing.
Area of Science:
- Neuroscience
- Computational Neuroscience
Background:
- Corticothalamic layer 6 (CTX L6) plays a crucial role in information flow between the cortex and thalamus.
- Prior studies show conflicting inhibitory or excitatory effects of CTX L6 on cortical dynamics, necessitating further investigation.
Purpose of the Study:
- To elucidate the nuanced function of CTX L6 in sensory processing.
- To resolve discrepancies regarding the modulatory effects of CTX L6 on cortical and thalamic circuits.
Main Methods:
- In vivo electrophysiology in the primary somatosensory cortex of anesthetized mice.
- Optogenetic stimulation to manipulate CTX L6 firing rate and spiking statistics.
- Translaminar, multi-channel recordings to assess circuit-level effects.
Main Results:
- Increasing CTX L6 firing rates induced a transition from inhibition to excitation across cortical layers.
- CTX L6 activity promoted population synchrony in cortical subpopulations independently of overall activity levels.
- CTX L6 bidirectionally modulated thalamic bursting in a frequency-dependent manner.
Conclusions:
- CTX L6 in the somatosensory cortex exhibits bidirectional control over cortical firing modes.
- CTX L6 influences thalamic firing modes, demonstrating a complex role in thalamocortical signaling.
- These findings provide a more nuanced understanding of CTX L6 function in sensory information processing.
Keywords:
corticothalamic feedbackfiring-mode switching (burst → tonic)frequency-dependent modulationpopulation synchronysensory gain controlMore Related Videos
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