Oscillations in the dentate gyrus as a tool for the performance of the hippocampal functions: Healthy and epileptic brain.

The dentate gyrus (DG) is part of the hippocampal formation and is essential for important cognitive processes such as navigation and memory. The oscillatory activity of the DG network is believed to play a critical role in cognition. DG circuits generate theta, beta, and gamma rhythms, which participate in the specific information processing performed by DG neurons.

Hippocampal non-theta state: The "Janus face" of information processing.

The vast majority of studies on hippocampal rhythms have been conducted on animals or humans in situations where their attention was focused on external stimuli or solving cognitive tasks. These studies formed the basis for the idea that rhythmical activity coordinates the work of neurons during information processing. However, at rest, when attention is not directed to external stimuli, brain rhythms do not disappear, although the parameters of oscillatory activity change.

From mechanisms to functions: The role of theta and gamma coherence in the intrahippocampal circuits.

Brain rhythms are essential for information processing in neuronal networks. Oscillations recorded in different brain regions can be synchronized and have a constant phase difference, that is, they can be coherent. Coherence between local field potential (LFP) signals from different brain regions may be correlated with the performance of cognitive tasks, indicating that these regions of the brain are jointly involved in the information processing.

The Relationship Between the Rhythmic Components of the Brain Electrical Activity During the Development of Status Epilepticus: An Operational Model of Brain Rhythms Generation.

Despite the fact that brain rhythms are widely studied and officially classified, there is no consensus on their relationship, which can shed light on the genesis of rhythmic activity, its synchronization, functional role, and the formation of pathological reactions. Using the experimental status epilepticus (SE) as a model of brain in a hypersynchronized state with well-defined rhythms, we aimed to study the relationship between the rhythmic components of the brain electrical activity. Local field potentials (LFPs) were recorded simultaneously from the hippocampus, entorhinal cortex, medial septum, and amygdala during normal conditions and after kainic acid (KA) administration in waking guinea pigs.

Nonlinear reactions of limbic structure electrical activity in response to rhythmical photostimulation in guinea pigs.

Photostimulation of the visual analyzer with a periodic signal is widely used in research and clinical practice, as well as in brain-computer interface technologies. In most studies of rhythmic photostimulation in structures of visual system at all its levels, the nonlinear nature of the response reactions is noted. However, the mechanism of formation of the induced electrophysiological reactions remains unclear.

Fatty acid amide hydrolase inhibitor URB597 may protect against kainic acid-induced damage to hippocampal neurons: Dependence on the degree of injury.

Objective: Status epilepticus (SE) provokes changes, which lead to neuronal alterations. Endocannabinoids (eCBs) can affect the neuronal survival during excitotoxicity and brain damage. Using a kainic acid (KA)-induced experimental SE model, we investigated whether cellular changes entail damage to endoplasmic reticulum (ER), mitochondria, and nuclei in hippocampal cells (CA1 field), and whether these alterations can be diminished by treatment with URB597, an inhibitor of eCB enzymatic degradation.

Endocannabinoid-dependent protection against kainic acid-induced long-term alteration of brain oscillations in guinea pigs.

Changes in rhythmic activity can serve as early biomarkers of pathological alterations, but it remains unclear how different types of rhythmic activity are altered during neurodegenerative processes. Glutamatergic neurotoxicity, evoked by kainic acid (KA), causes hyperexcitation and acute seizures that result in delayed brain damage. We employed wide frequency range (0.

Attenuation of kainic acid-induced status epilepticus by inhibition of endocannabinoid transport and degradation in guinea pigs.

Status epilepticus (SE) is a medical emergency associated with a high rate of mortality if not treated promptly. Exogenous and endogenous cannabinoids have been shown to possess anticonvulsant properties both in vivo and in vitro. Here we study the influence of endocannabinoid metabolism on the development of kainic acid-induced SE in guinea pigs.

Disturbances of septohippocampal theta oscillations in the epileptic brain: reasons and consequences.

Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy, characterized by hippocampal sclerosis and memory deficits. It is well-documented that intrinsic neuronal oscillations and provided by them communications between brain structures are of importance for cognition. Epilepsy disturbs these brain rhythms and presumably therefore affects memory.