Topic: theta oscillations

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

Knowing where we are, where we have been, and where we are going is critical to many behaviors, including navigation and memory. One potential neuronal mechanism underlying this ability is phase precession, in which spatially tuned neurons represent sequences of positions by activating at progressively 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

Neurological disorders share common high-level alterations, such as cognitive deficits, anxiety, and depression. This raises the possibility of fundamental alterations in the way information conveyed by neural firing is maintained and dispatched in the diseased brain. Using experimental epilepsy as a model of neurological disorder we tested the hypothesis of altered information processing, analyzing how neurons in the hippocampus and the entorhinal cortex store and exchange information during slow and theta oscillations. We equate the storage and sharing of information to low level, or primiti

The hippocampus and the amygdala are two structures required for emotional memory. While the hippocampus encodes the contextual part of the memory, the amygdala processes its emotional valence. During Non-REM sleep, the 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,

Temporal lobe epilepsy is associated with memory deficits but the circuit mechanisms underlying these cognitive disabilities are not understood. We used electrophysiological recordings, open-source wire-free miniaturized microscopy and computational modeling to probe these deficits in a model of temporal lobe epilepsy. We find desynchronization of dentate gyrus interneurons 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.

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

A prominent theory proposes that maintaining sequential information in memory is reflected in ordered firing 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

The hippocampus plays a central role in memory processing. In order to avoid deleterious interference between stored and ongoing experience, theoretical considerations require a separation between phases of memory encoding and recall within the same neural circuit, 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

Sustained attention is the focusing attention process on the selected stimulus for a long time, which can be measured with sustained attention to response task (SART). Our research group aimed to investigate the age-related changes in inhibitory functions 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