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Single axon fast inhibitory postsynaptic potentials elicited by a sparsely spiny interneuron in rat neocortex
1Department of Physiology, Royal Free Hospital School of Medicine, London, U.K.
Neuroscience
|April 1, 1995
Summary
Researchers identified a specific type of inhibitory neuron in the rat neocortex. This study provides functional data on sparsely spiny, burst-firing interneurons inhibiting pyramidal neurons via GABA-A receptors.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Mammalian Neocortex Research
Background:
- The inhibitory role of various neocortical interneuron subtypes remains largely unconfirmed functionally.
- Conclusive data linking specific interneuron morphologies to inhibitory functions are scarce.
Purpose of the Study:
- To provide functional data on a specific interneuron subtype in the mammalian neocortex.
- To characterize the inhibitory postsynaptic potential (IPSP) elicited by a sparsely spiny, burst-firing interneuron on a pyramidal neuron.
Main Methods:
- Paired intracellular recordings in adult rat somatosensory cortex slices.
- Electrophysiological analysis of inhibitory postsynaptic potentials (IPSPs).
- Morphological and ultrastructural examination of identified interneurons and their synaptic contacts.
Main Results:
- A sparsely spiny, burst-firing interneuron was shown to evoke fast IPSPs in a layer II pyramidal neuron.
- The IPSPs were mediated by GABA-A receptors, as indicated by lack of effect from GABAB antagonist.
- Extracellular calcium concentration modulated IPSP amplitude and paired-pulse depression, suggesting presynaptic mechanisms.
Conclusions:
- This study presents the first functional characterization of a single axon IPSP from an identified neocortical interneuron.
- Sparsely spiny, burst-firing interneurons are confirmed to inhibit pyramidal neurons, likely through GABA-A receptors.