Theta oscillations

The dorsal anterior cingulate cortex (dACC) has been studied extensively using effort-based decision-making (EBDM) paradigms and has been shown to track effort costs. However, it remains unclear whether the dACC encodes objective measures of effort, such as energy expenditure, or subjective perceptions of effort. Further, prior EBDM research in humans has focused on artificial, seated tasks like gripping hand dynamometers, which 1) do not accurately reflect real-world effort demands and 2) are limited by fMRI's temporal resolution, making it difficult to link neural activity to behavior. To

…Theta oscillations in the hippocampal CA1 region are prominent during movement and are thought to organize network computations during active exploration, such as the virtual spatial paths formed by the sequential activity of CA1 spatial-tuning neurons, or 'place cells,' known as theta sequences. However, it remains unclear how theta supports memory during periods of immobility, when CA1 theta oscillations dissipate. To address this, we recorded laminar neural activity using

Coherent oscillations of neuronal activity are ubiquitous across brain spatial and temporal scales. Gamma oscillations (30-120Hz), detectable with Local Field Potentials (LFPs), are classically analyzed through massive trial averages. This approach leaves us with one average oscillation shape, one mean power and a view based on rigid frequency bands. Consistently, mechanisms based on biophysical models of neural networks typically predict periodic oscillations (e.g. PING models [1]). The functional role of oscillations have been largely investigated in the hippocampus, where, different gamma-f

…of neurons at different phases of theta oscillations (1). One study has recently challenged this view using single-unit and LFP recordings from epilepsy patients in the human medial temporal lobe (MTL, 2). In addition to predicting a specific temporal relationship between spiking and theta oscillations related to temporal order, the theory also assumes that 1. gamma-frequency activity encodes stimulus-relevant information that is maintained within memory and temporally aligned to spikin

…putatively controlled by hippocampal theta oscillations [1]. However, the neural mechanisms subserving this separation remain unknown. Classical models either remain moot about these mechanisms [2], or assume purpose-built neuromodulatory interactions that are in conflict with biologically realistic timescales of synaptic modulation

…with electroencephalography (EEG) in theta oscillations. The EEG of 19 healthy individuals (young, 18-25 years old, M = 21.71, SD = 2.06; elderly 55-70 years old, M = 62.43 , SD = 6.33) was recorded at the F3, Fz, F4, C3, Cz, C4, P3, Pz, P4, O1, Oz, and O2 locations during the auditory SART. The maximum power of the target stimuli was calcula

…spindle (SO), and REM sleep-related theta oscillations (ThO). Based on the polarity of the down-states (DS) recorded along with the cell firing, we divided Pyrs as superficial (negative DS, layer 2 – L2, n=35) or deep (positive DS, layer 3 – L3, n=35). Most of the Pyrs showed very sporadic firing behavior, with a lower ave

Theta oscillations (4-12 Hz) in the hippocampus are caused by the synchronous bursting activity of neuronal populations. They are critical for grouping and selecting neuronal ensembles in the context of spatial navigation, memory, and learning, but the reason why this frequency band is particularly effective for adjusting neuronal ensembles remains speculative. Here we show that burst activity at the CA3-CA1 synapse of the mouse hippocampus leads to a rapid activation of astrocytic leaflets possibly via the retrograde release of endocannabinoids that activate transient receptor potential chann

…cell spiking is sparsely paced by theta oscillations during active exploration but tightly synchronised by sharp-wave/ripples (SWRs) during sleep/rest. Notably, previous studies have related SWRs to a current sink in the stratum radiatum, reporting CA3 inputs that serve memory consolidation. Here, we explore whether individual SWRs deviate from t

Alzheimer's disease (AD) is a progressive neurodegenerative condition characterized by a significant decline in episodic memory. More recent research indicates that impairments in spatial navigation may serve as a more sensitive biomarker for AD compared to episodic memory alterations. To study the cellular mechanisms behind spatial memory and navigation deficits in AD we used the APP/PS1 mouse model of amyloidosis. To assess spatial memory updating, a non-stressful paradigm called Objects in Updated Locations (OUL) was employed. This task allows the quantification of the different times of ex

…Theta oscillations in the hippocampus, which have been hypothesised to support learning and memory, may provide a read out of memory relevant neural activity. Supporting this, optogenetic stimulation of the hippoc

Rodents show pronounced local field potential (LFP) oscillations in the theta frequency range (7-12Hz in rodents) during exploration. Theta frequencies are thought to take part in memory processing by ensuring accurate sequences of neuron firing to facilitate plasticity processes. Many principal neurons in the parahippocampal areas, such as grid cells and place cells, show pronounced theta modulation. Grid cells in the medial entorhinal cortex (MEC) are theta modulated during active wakefulness, with power and frequency correlating to e.g. running speed or environmental familiarity. Suppressin

Hippocampal representations that underlie spatial memory undergo continuous refinement following formation during exploration. Understanding the role of sleep in this process has been challenging because of the inaccessibility of place fields when animals are not actively exploring a maze. Here, we devised a novel Bayesian learning approach based on the spike-triggered average decoded position in ensemble recordings to track dynamically the spatial tuning of individual neurons during offline states in freely moving rats. Measuring these dynamic tunings, we found spatial representations within

Theta oscillations in dorsomedial frontal cortex (DMFC) are prominent signatures of cognitive control and error monitoring (Cavanagh and Frank, Trends Cogn. Sci., 2014; Cohen, Trends Neurosci., 2014). Yet, the neuronal mechanisms generating these signals remain uncertain. Here, we study whether neocortical pyramidal neurons alone can induce frontal theta during error monitoring by combining electrophysiological data and biophysical modeling. We recorded neuronal spiking and local field potentials (LFPs) across all layers of DMFC from two macaque monkeys performing a saccade countermanding stop

Brain stimulation is a fundamental therapy for neurological diseases including Parkinson’s disease, essential tremor, and epilepsy. One key challenge in delivering effective brain stimulation is identifying the stimulation parameters (e.g. amplitude, frequency, and pulse width) that optimally change symptoms, behavior, or neural activity. Most clinical and translational studies use constant-frequency pulses of stimulation, but irregular pulse patterns or non-pulsatile waveforms may induce unique neural effects that could enable better therapy. Here, we comprehensively evaluate several optogene

…exclusively assigns occurrences of theta-frequency (4–12 Hz) oscillations to exploratory behavior and rapid eye movement (REM) sleep, and of ripple-frequency (120–250 Hz) oscillations to wakeful rest and non-REM sleep. However, due to their differential expression across hippocampal strata, reports of such exclusivity demand validation through simultaneous multi-strata recordings. Here, we assessed co-occurrence of the two oscillations in multi-channel recording

Spike timing relative to theta phase has been shown to mediate spatial and non-spatial information processing in medial temporal lobe (MTL) regions including hippocampus [1,2,3]. A prominent theory suggests that neural activity at different phases of theta oscillations encodes the serial order of items within short-term memory [4]. Based on recordings of spiking activity and local field potentials (LFPs) of epilepsy patients performing a multi-item sequential memory task, we show phase-dependent spiking during the delay, with preferred phases that were related to stimulus position within the s

…earlier phases of local network theta oscillations. Based on studies in rodents, researchers have hypothesized that phase precession may be a general neural pattern for representing sequential events for learning and memory. By recording human single-neuron activity during spatial navigation, we

…exchange information during slow and theta oscillations. We equate the storage and sharing of information to low level, or primiti

…hippocampus displays high frequency oscillations called “ripples”. Our early work shows that the suppression of ripples during sleep impairs performance on a spatial task, underlying their crucial role in memory consolidation. We more recently showed that the joint amygdala-hippocampus activity linked to aversive learning is reinstated during the following Non-REM sleep epochs,

…with CA1 interneurons during theta oscillations and a loss of precision and stability of place fields. We also find that emergence of place cell dysfunction is delayed, providing a potential temporal window for treatments.