Publisher Correction: Two dynamically distinct circuits drive inhibition in the sensory thalamus.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Two dynamically distinct circuits drive inhibition in the sensory thalamus.

Most sensory information destined for the neocortex is relayed through the thalamus, where considerable transformation occurs. One means of transformation involves interactions between excitatory thalamocortical neurons that carry data to the cortex and inhibitory neurons of the thalamic reticular nucleus (TRN) that regulate the flow of those data. Although the importance of the TRN has long been recognised, understanding of its cell types, their organization and their functional properties has lagged behind that of the thalamocortical systems they control.

Contributions of diverse excitatory and inhibitory neurons to recurrent network activity in cerebral cortex.

The recurrent synaptic architecture of neocortex allows for self-generated network activity. One form of such activity is the Up state, in which neurons transiently receive barrages of excitatory and inhibitory synaptic inputs that depolarize many neurons to spike threshold before returning to a relatively quiescent Down state. The extent to which different cell types participate in Up states is still unclear.

Two functionally distinct networks of gap junction-coupled inhibitory neurons in the thalamic reticular nucleus.

Gap junctions (GJs) electrically couple GABAergic neurons of the forebrain. The spatial organization of neuron clusters coupled by GJs is an important determinant of network function, yet it is poorly described for nearly all mammalian brain regions. Here we used a novel dye-coupling technique to show that GABAergic neurons in the thalamic reticular nucleus (TRN) of mice and rats form two types of GJ-coupled clusters with distinctive patterns and axonal projections.

Thalamic control of layer 1 circuits in prefrontal cortex.

Knowledge of thalamocortical (TC) processing comes mainly from studying core thalamic systems that project to middle layers of primary sensory cortices. However, most thalamic relay neurons comprise a matrix of cells that are densest in the "nonspecific" thalamic nuclei and usually target layer 1 (L1) of multiple cortical areas. A longstanding hypothesis is that matrix TC systems are crucial for regulating neocortical excitability during changing behavioral states, yet we know almost nothing about the mechanisms of such regulation.

Developmental changes in somatostatin-positive interneurons in a freeze-lesion model of epilepsy.

Somatostatin-expressing (SS) cells are inhibitory interneurons critical to the regulation of excitability in the cerebral cortex. It has been suggested in several animal models of epilepsy that the activity of these neurons reduces the occurrence and strength of epileptiform activity. The physiological properties of SS cells further support these hypotheses.

Initiation, propagation, and termination of epileptiform activity in rodent neocortex in vitro involve distinct mechanisms.

Waves of epileptiform activity in neocortex have three phenomenological stages: initiation, propagation, and termination. We use a well studied model of epileptiform activity in vitro to investigate directly the hypothesis that each stage is governed by an independent mechanism within the underlying cortical circuit. Using the partially disinhibited neocortical slice preparation, activity is induced and modulated using neurotransmitter receptor antagonists and is measured using both intracellular recordings and a linear array of extracellular electrodes.

Inhibitory effect of mouse neocortex layer I on the underlying cellular network.

The mammalian cortical layer I is a convergence site for axons of sub- and intracortical origin, and the apical dendritic tufts of pyramidal neurons. A prominent feature of layer I is an extensive plexus of inhibitory axons, which originate from stellate cells in all cortical laminae. The role of this inhibitory projection in the activity of cortical networks has yet to be determined.

The spatial dimensions of electrically coupled networks of interneurons in the neocortex.

Inhibitory interneurons of the neocortex are electrically coupled to cells of the same type through gap junctions. We studied the spatial organization of two types of interneurons in the rat somatosensory cortex: fast-spiking (FS) parvalbumin-immunoreactive (PV+) cells, and low threshold-spiking (LTS) somatostatin-immunoreactive (SS+) cells. Paired recordings in layer 4 demonstrated that both the probability of coupling and the coupling coefficient drop steeply with intersomatic distance, reaching zero beyond 200 microm.