T-type calcium channels make your brain smarter
One of the most remarkable features of T-type Calcium channels originates from their low-threshold of activation that makes these channels perfectly suited for regulating neuronal excitability and oscillatory behavior near the resting membrane potential of the cells. They generate a low-threshold burst discharge that occur during diverse forms of neuronal rhythmogenesis, and in some neurons also generate a “window current” that provides a unique opportunity for Calcium entry at rest. In addition, T-type channels also contribute to a low-threshold form of neurotransmitter release provided by the biochemical coupling of the channel with the vesicle release machinery. All of these features of T-type channels are of essential importance for regulating the excitability and electrical responsiveness of nerve cells under physiological conditions near resting states. The implication of T-type channels in the central nervous system is best exemplified by the occurrence of neurological disorders caused by disruption of channel function and includes sleep disorders, absence epilepsy, Parkinson’s disease, neuropathic pain, and possibly neuropsychiatric disorders such as depression and autism spectrum disorders. In addition, and consistent with the abundant expression of T-type channels in brain regions involved in cognitive functions, a role for T-type channels in learning and memory processing has been proposed. Indeed, Cav3.2 T-type channel deficient mice showed altered long-term potentiation in the hippocampal CA1 region and impaired memory. However, the cellular and molecular mechanisms by which T-type channels possibly contribute to memory formation remain largely unknown. In a recent study reported in PLos One, Chung and colleagues have examined the possibility that T-type channels may affect gene expression in cognitive brain areas, which could provide a molecular support for memory formation and long-term consolidation.
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