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The neuronal and synaptic organisation of the cerebral cortex appears exceedingly complex, and the definition of a basic cortical circuit in terms of defined classes of cells and connections is necessary to facilitate progress of its analysis. During the last two decades quantitative studies of the synaptic connectivity of identified cortical neurones and(More)
1. The effects of synapses established by smooth dendritic neurones on pyramidal and spiny stellate cells were studied in areas 17 and 18 of the cat visual cortex in vitro. Paired intracellular recordings with biocytin-filled electrodes and subsequent light and electron microscopic analysis were used to determine the sites of synaptic interaction. 2. All(More)
Networks of GABAergic interneurons are implicated in synchronizing cortical activity at gamma frequencies (30-70 Hz). Here we demonstrate that the combined electrical and GABAergic synaptic coupling of basket cells instantaneously entrained gamma-frequency postsynaptic firing in layers 2/3 of rat somatosensory cortex. This entrainment was mediated by rapid(More)
Axons in the cerebral cortex receive synaptic input at the axon initial segment almost exclusively from gamma-aminobutyric acid-releasing (GABAergic) axo-axonic cells (AACs). The axon has the lowest threshold for action potential generation in neurons; thus, AACs are considered to be strategically placed inhibitory neurons controlling neuronal output.(More)
There are two types of inhibitory postsynaptic potentials in the cerebral cortex. Fast inhibition is mediated by ionotropic gamma-aminobutyric acid type A (GABA(A)) receptors, and slow inhibition is due to metabotropic GABA(B) receptors. Several neuron classes elicit inhibitory postsynaptic potentials through GABA(A) receptors, but possible distinct sources(More)
Neuroscience produces a vast amount of data from an enormous diversity of neurons. A neuronal classification system is essential to organize such data and the knowledge that is derived from them. Classification depends on the unequivocal identification of the features that distinguish one type of neuron from another. The problems inherent in this are(More)
Phasic (synaptic) and tonic (extrasynaptic) inhibition represent the two most fundamental forms of GABA(A) receptor-mediated transmission. Inhibitory postsynaptic currents (IPSCs) generated by GABA(A) receptors are typically extremely rapid synaptic events that do not last beyond a few milliseconds. Although unusually slow GABA(A) IPSCs, lasting for tens of(More)
GABA (gamma-aminobutyric acid) is predominantly released by local interneurons in the cerebral cortex to particular subcellular domains of the target cells. This suggests that compartmentalized, synapse-specific action of GABA is required in cortical networks for phasic inhibition. However, GABA released at the synaptic cleft diffuses to receptors outside(More)
Networks of GABAergic neurons have been implicated in neuronal population synchronization. To define the extent of cellular interconnections, we determined the effect, number, and subcellular distribution of synapses between putative GABAergic neurons in layers II-IV of the cat visual cortex using paired intracellular recordings in vitro followed by(More)
1. Dual intracellular recordings were made from synaptically coupled pyramidal cell-to-interneurone pairs (n = 5) of the cat visual cortex in vitro. Pre- and postsynaptic neurones were labelled with biocytin, followed by correlated light and electron microscopic analysis to determine all sites of synaptic interaction. 2. Pyramidal neurones in layers II-III(More)