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Science. 2013 Jun 28;340(6140):1591-4. doi: 10.1126/science.1236425.

Deep cortical layers are activated directly by thalamus.

Author information

1
Department of Neuroscience and Kavli Institute for Brain Science, Columbia University, New York, NY 10032, USA.

Abstract

The thalamocortical (TC) projection to layer 4 (L4) is thought to be the main route by which sensory organs communicate with cortex. Sensory information is believed to then propagate through the cortical column along the L4→L2/3→L5/6 pathway. Here, we show that sensory-evoked responses of L5/6 neurons in rats derive instead from direct TC synapses. Many L5/6 neurons exhibited sensory-evoked postsynaptic potentials with the same latencies as L4. Paired in vivo recordings from L5/6 neurons and thalamic neurons revealed substantial convergence of direct TC synapses onto diverse types of infragranular neurons, particularly in L5B. Pharmacological inactivation of L4 had no effect on sensory-evoked synaptic input to L5/6 neurons. L4 is thus not an obligatory distribution hub for cortical activity, and thalamus activates two separate, independent "strata" of cortex in parallel.

PMID:
23812718
PMCID:
PMC4203320
DOI:
10.1126/science.1236425
[Indexed for MEDLINE]
Free PMC Article

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