Activation of Corticothalamic Layer 6 Cells Decreases Angular Tuning in Mouse Barrel Cortex
François Philippe Pauzin1, Nadja Schwarz1, Patrik Krieger1
1Department of Systems Neuroscience, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.
Frontiers in Neural Circuits
|November 19, 2019
Summary
L6 corticothalamic (L6 CT) cells modulate whisker direction processing by altering cortical inhibition, not thalamic output. This specific circuit primes the neocortex for complex tactile tasks like texture discrimination.
Area of Science:
- Neuroscience
- Sensory Processing
- Computational Neuroscience
Background:
- The mouse whisker system is a model for studying sensory processing.
- L6 corticothalamic (L6 CT) cells play a role in sensory information flow.
- Understanding the precise circuits involved in tactile processing is crucial.
Purpose of the Study:
- To investigate the contribution of L6 CT cells to whisker deflection direction processing.
- To determine whether L6 CT cell effects on cortical processing originate from thalamic output or cortical circuits.
- To explore the role of L6 CT-driven inhibition in adapting sensory responses.
Main Methods:
- Optogenetic activation of genetically defined L6 CT cells in mice.
- Electrophysiological recordings in the somatosensory barrel cortex (BC).
- Comparison with general optogenetic activation of GABAergic interneurons (Gad2-expressing cells).
Main Results:
- Activation of L6 CT cells induced an adapted mode in BC, reducing angular tuning of excitatory neurons.
- This loss of tuning was due to changes in cortical inhibition, not thalamic output.
- L6 CT-driven cortical inhibition, unlike general GABAergic activation, abolished adaptation to whisker responses.
- Evidence suggests a subpopulation of L6 CT cells activates specific GABAergic interneurons.
Conclusions:
- L6 CT cells selectively modulate cortical processing of whisker direction.
- A specific L6 CT-to-GABAergic interneuron circuit predisposes the neocortex for complex tactile tasks.
- This circuit is critical for processing information requiring multiple whisker touches, such as texture discrimination.
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