Cortico-hippocampal interaction during up-down states and memory consolidation.
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Animals↗
Biomedical subjects
Mayank R Mehta
Publications and source records attributed to Mayank R Mehta.
Phase-locking of hippocampal interneurons' membrane potential to neocortical up-down states.
During quiet wakefulness and sleep, and under anesthesia, the membrane potentials of neocortical pyramidal neurons show synchronous, slow oscillations, so-called up-down states (UDS), that can be detected in the local field potential (LFP). The influence of this synchronized, spontaneous neocortical activity on the hippocampus is largely unknown. We performed the first in vivo whole-cell recordings from hippocampal dorsal CA1 interneurons and found that their membrane potentials were phase-locked to neocortical up-down states with a small delay. These results provide strong evidence for cortico-hippocampal interaction and suggest that neocortical activity drives hippocampal interneurons during UDS.
Action Potentials↗
Role of rhythms in facilitating short-term memory.
Working memory tasks have been associated with the appearance of elevated single unit activity (SUA) in primate studies, and oscillatory activity in the EEG or the local field potential (LFP) in humans. The study by Lee et al. in this issue of Neuron provides novel insights regarding the relationship between SUA and LFP rhythmicity in V4 during working memory tasks.
Action Potentials↗
Cooperative LTP can map memory sequences on dendritic branches.
Hebbian synaptic learning requires co-activation of presynaptic and postsynaptic neurons. However, under some conditions, information regarding the postsynaptic action potential, carried by backpropagating action potentials, can be strongly degraded before it reaches the distal exhibit Hebbian long-term potentiation (LTP)? Recent results show that LTP can indeed occur at synapses on distal dendrites of hippocamal CA1 neurons, even in the absence of a postsynaptic somatic spike. Instead. local dendritic spikes contribute to the depolarization required to induce LTP. Here, a dendritically constrained synaptic learning rule is proposed, which suggests that nearby synapses can encode temporally contiguous events.
Action Potentials↗