Long-term potentiation (LTP) is considered a cellular correlate of learning and memory. The presence of G protein-activated inwardly rectifying K(+) (GIRK) channels near excitatory synapses on dendritic spines suggests their possible involvement in synaptic plasticity. However, whether activity-dependent regulation of channels affects excitatory synaptic plasticity is unknown. In a companion article we have reported activity-dependent regulation of GIRK channel density in cultured hippocampal neurons that requires activity oF receptors (NMDAR) and protein phosphatase-1 (PP1) and takes place within 15 min. In this study, we performed whole-cell recordings of cultured hippocampal neurons and found that NMDAR activation increases basal GIRK current and GIRK channel activation mediated by adenosine A(1) receptors, but not GABA(B) receptors. Given the similar involvement of NMDARs, adenosine receptors, and PP1 in depotentiation of LTP caused by low-frequency stimulation that immediately follows LTP-inducing high-frequency stimulation, we wondered whether NMDAR-induced increase in GIRK channel surface density and current may contribute to the molecular mechanisms underlying this specific depotentiation. Remarkably, GIRK2 null mutation or GIRK channel blockade abolishes depotentiation of LTP, demonstrating that GIRK channels are critical for depotentiation, one form of excitatory synaptic plasticity.
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Answer:
The correct answer would be efferent neurons.
Efferent neurons are the motor neurons which communicate information in the opposite direction as compared to the afferent neurons, that is, they communicate information or response impulses from the brain or central nervous system to the muscles or glands.
The response impulses results in the movement of the muscles or activation/deactivation of certain gland
In contrast, afferent neurons are the sensory neurons which carry impulses from the receptors to the central nervous system.
Continuous conduction takes place in unmyelinated axon.
Explanation:
Based on the presence and absence of myelin sheath, the neurons had been classified as myelinated and non-myelinated neurons respectively.
In myelinated neurons the transmission of impulse takes place only at the non myelinated region called nodes of Ranvier. Due to this, the conduction in Myelinated neuron is saltatory.
The conduction in non-myelinated neuron takes place throughout the length of axon and it is continuous.
Saltatory conduction is faster than continuous conduction.
The condition common to protozoa whereby the cell of the organism acts as a gamete is isogamy. It is <span>a condition in which the sexual cells, or gametes, are of the same form and size and are usually indistinguishable from each other. Hope this answers the question.</span>
