Layer V pyramidal neuron

From Lübke et al 1996

- Dendrites sample the entire cortical column.

- Axons project locally, and distally to basal ganglia, brainstem, & spinal cord.

- Receives local inputs (from the same cortical column) and distal inputs (other cortical areas and thalamus).

Excitatory connections between layer V pyramidal cells

Kalisman et al 2005

Full connectivity predicted from morphology vs. Sparse (10 %) functional connectivity

Bouton

Touch

The solution: All-to-All Potential Connectivity

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Whole-cell recordings &Confocal connection analysis

Connections between interneurons & pyramidal neurons

Summary

- An inhibitory feedback loop is described for layer V pyramidal cells.

- The loop is frequency dependent, and is more prevalent than monosynaptic excitation.

- It is mediated by a facilitating excitatory connection onto GABAergic inhibitory neurons.

- The inhibition is targeted to the dendrites of pyramidal neurons (low reversal & dendritic patch experiments).

- Multi-patch recordings of PCs and Interneurons revealed that the loop was mediated by dendritic-targeting Martinotti cells.