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Fast-Spike Interneurons in Visual Cortical Layer 5: Heterogeneous Response Properties Are Related to Thalamocortical
Chuyi Su1, Rosangela F Mendes-Platt1, Jose-Manuel Alonso1,2
1Department of Psychological Sciences, University of Connecticut, Storrs, Connecticut.
Summary
Fast-spiking inhibitory interneurons in rabbit Layer 5 visual cortex receive direct input from the LGN, exhibiting properties similar to Layer 4 cells. Others show distinct tuning, suggesting indirect pathways influence their function.
Area of Science:
- Neuroscience
- Visual Cortex Research
- Cellular Electrophysiology
Background:
- Layer 4 (L4) of rabbit V1 hosts fast-spiking GABAergic interneurons (SINs) with potent LGN input and specific response properties.
- Layer 5 (L5) also contains SINs, but their properties and thalamocortical connections are less understood.
Purpose of the Study:
- To investigate the response properties and thalamocortical connectivity of L5 SINs in awake rabbits.
- To compare L5 SINs with previously characterized L4 SINs.
- To elucidate the pathways influencing L5 SIN function.
Main Methods:
- Electrophysiological recordings in awake rabbits (both sexes).
- Assessment of L5 SIN response properties to visual stimuli.
- Analysis of thalamocortical connectivity via LGN stimulation and cross-correlation of spike trains.
Main Results:
- Many L5 SINs receive strong, fast monosynaptic input from the LGN, sharing response properties with L4 SINs and located in upper L5.
- L5 SINs with longer LGN synaptic latencies showed sharper orientation tuning, longer response latencies, and lower firing rates, residing in deeper L5.
- These differences suggest distinct functional pathways (direct LGN vs. indirect intracortical) for L5 SINs.
Conclusions:
- L5 SINs exhibit heterogeneous response properties linked to their thalamocortical input.
- Direct LGN input shapes L5 SINs similarly to L4 SINs.
- Multisynaptic intracortical pathways contribute to the distinct properties of deeper L5 SINs.
Keywords:
Layer 5cannonical cortical circuitfast-spike interneuronsfeedforward inhibitionthalamocorticalMore Related Videos
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