Sleep regulation of the distribution of cortical firing rates

Abstract

Sleep is thought to mediate mnemonic and homeostatic functions. However, the mechanism by which this brain state can implement both the “selective” plasticity needed to consolidate novel memory traces as well as the “general” plasticity necessary to maintain a well-functioning neuronal system is unclear. Recent findings show that both of these functions differentially affect neurons based on their intrinsic firing rate, a ubiquitous neuronal heterogeneity. Furthermore, they are both implemented by the NREM slow oscillation, which also distinguishes neurons based on firing rate during sequential activity at the DOWN->UP transition. These findings suggest a mechanism by which spiking activity during the slow oscillation acts to maintain network statistics that promote a skewed distribution of neuronal firing rates, and “perturbation” of that activity by hippocampal replay acts to integrate new memory traces into the existing cortical network.

Memory corticalization triggered by REM sleep: mechanisms of cellular and systems consolidation

“…Since REM sleep is related to spine elimination during development [114], the increased firing rate during waking towards the set-point showed by [243] may be sustained by sleep-dependent structural changes, since they do not return to the previous firing pattern after complete sleep epochs. Although other homeostatic processes may participate as neuronal regulation of intrinsic excitability [246], they may be also sleep-dependent [247].…”

Impaired state-dependent potentiation of GABAergic synaptic currents triggers seizures in an idiopathic generalized epilepsy model

“…Simultaneous EEG (two channels, band filtered at 0.1-100 Hz) and multi-unit recordings (one-channel, band filtered 300-2000 Hz) (both in current-clamp mode) data along with one channel EMG recordings(400 Hz) were collected by using two multiClamp 700B amplifiers (total 4 channels, Molecular devices Inc., Union City, CA) and Clampex 10 software (Molecular Devices Inc., Union City, CA), and digitized at 20 kHz using a Digidata 1440A. (Kandel & Buzsaki, 1997;Levenstein et al, 2017)) were applied]. The injected current amplitudes(pA) and duration were chosen to avoid kindling effect which needs larger currents within uA amplitude range (Lothman et al, 1990;Racine, 1972aRacine, , 1972b.…”

Network resonance during slow-wave sleep facilitates memory consolidation through phase-coding

“…A series of recent studies have demonstrated that sleep has heterogeneous effects on neuronal firing rates within neural circuits. Specifically, initially highly active neurons reduce their firing rates across a period of sleep, while sparsely firing neurons simultaneously increase their firing rate (4,5,30). Sleep is essential for this redistribution of firing rates, as firing rate changes do not occur in animals that are experimentally sleep deprived (5).…”

“…While certain features of information storage may be localized to specific cell populations (e.g., location information encoded in hippocampal place cell activity), in general, localizing memory traces to specific neural circuits has been an elusive task (2). Furthermore, recent data indicate that engrams are formed from neuronal populations which are vastly heterogeneous in terms of their firing patterns, with log-normal distributions of firing rates ranging over many orders of magnitude (4,5). These populations appear to encode different aspects of experience (5)(6)(7) and may exhibit different dynamics during memory consolidation processes.…”

“…It remains unclear what activity-dependent mechanisms could mediate consolidation leading to such an attractor formation. However, oscillatory patterning, such as that occurring during sleep, has been implicated in promoting synaptic plasticity (4,5,(12)(13)(14). Various network oscillations appear preferentially in specific brain circuits (e.g., hippocampal and thalamocortical circuits) during particular behavioral states (i.e.…”