Functional Logic of Layer 2/3 Inhibitory Connectivity in the Ferret Visual Cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Understanding cortical inhibition is key to deciphering circuit function.
• Identifying connectivity rules between inhibitory interneurons and targets is crucial.

Purpose of the Study:

• To investigate the orientation tuning of layer 2/3 inhibitory inputs in the ferret visual cortex.
• To determine the relationship between inhibitory interneuron responses and their postsynaptic targets.

Main Methods:

• In vivo axon imaging
• Functional input mapping
• Physiology
• Patterned optogenetic stimulation
• Intracellular recordings
• Synaptic conductance measurements

Main Results:

• Inhibitory boutons show robust orientation tuning, with preferences potentially differing from their cortical column.
• Inhibitory input fields originate from diverse orientation domains, challenging co-tuned inhibition/excitation models.
• Individual neurons deviate from a co-tuned regime, confirmed by synaptic conductance measurements.

Conclusions:

• Simple rules do not govern inhibitory input arrangement in layer 2/3 circuits.
• Heterogeneity within presynaptic inhibitory networks influences neural response properties.