The aim of the paper is to first investigate some properties of the hyperspace $theta(X)$, and then in the next article it deals with some detailed study of a special type of subspace $downarrowtheta C(X)$ of the space $theta (Xtimes mathbb I)$.

The theta rhythm is one of the largest and most sinusoidal activity patterns in the brain. Here I survey progress in the field of theta rhythms research. I present arguments supporting the hypothesis that theta rhythms emerge owing to intrinsic cellular properties yet can be entrained by several theta oscillators throughout the brain. I review behavioral correlates of theta rhythms and consider...

Some of the strongest experimental and computational links between oscillations and cognition concern the oscillations in the hippocampal formation supporting spatial and mnemonic processing. We review experimental and theoretical work concerning well-established hippocampal oscillations such as theta, gamma, and high-frequency ripples and how they relate to spatial, mnemonic, and anxietyrelate...

The anterior thalamic nuclei are assumed to support episodic memory with anterior thalamic dysfunction a core feature of diencephalic amnesia. To date, the electrophysiological characterization of this region in behaving rodents has been restricted to the anterodorsal nucleus. Here we compared single-unit spikes with population activity in the anteroventral nucleus (AV) of freely moving rats du...

Intracellular recordings were made in the dorsal hippocampal formation of urethane-anesthetized rats as the local field activity spontaneously cycled between a synchronous condition termed theta and an asynchronous condition termed LIA. All cells reported in this study were labeled with Neurobiotin and classified as theta-related or non-theta-related according to the system of Colom and Bland [...

A regular slow wave theta rhythm can be recorded in the medial entorhinal cortex (MEC) of freely moving rats during voluntary behaviors and paradoxical sleep. Electrode penetrations normal to the cortical layers proceeding from the deeper to the more superficial layers reveal a continuous theta rhythm in layers IV-III (deep MEC theta rhythm) with an amplitude maximum in layer III, a null betwee...

Rhythms with time scales of multiple cycles per second permeate the mammalian brain, yet neuroscientists are not certain of their functional roles. One leading idea is that coherent oscillation between two brain regions facilitates the exchange of information between them. In rats, the hippocampus and the vibrissal sensorimotor system both are characterized by rhythmic oscillation in the theta ...

Theta waves in the amygdala are known to be synchronized with theta waves in the hippocampus. Synchronization between amygdala and hippocampal theta waves is considered important for neuronal communication between these regions during the memory-retrieval process. These theta waves are also observed during rapid eye movement (REM) sleep. However, few studies have examined the mechanisms and fun...

Experiments were carried out in urethane-anesthetized rats in order to evaluate the hypothesis that the red nucleus has functional connections with the hippocampal formation. Depth profiles of electrical stimulation in Experiment 1 confirmed that stimulation administered to the red nucleus elicited theta field activity in the hippocampal formation with a linear relationship between stimulus int...