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Although the improvement in WM performance with cholinergic enhancement was a nonsignificant trend in the current study (P ϭ 0.07), in a previous study (9) with a larger sample (n ϭ 13) the effect was highly significant (P Ͻ 0.001). In the current study, we analyzed RT data for six of our seven subjects because the behavioral data for one subject were(More)
Various subsets of brain neurons express a hyperpolarization-activated inward current (I(h)) that has been shown to be instrumental in pacing oscillatory activity at both a single-cell and a network level. A characteristic feature of the stellate cells (SCs) of entorhinal cortex (EC) layer II, those neurons giving rise to the main component of the perforant(More)
BACKGROUND Although the induction of behavioural unconsciousness during sleep and general anaesthesia has been shown to involve overlapping brain mechanisms, sleep involves cyclic fluctuations between different brain states known as active (paradoxical or rapid eye movement: REM) and quiet (slow-wave or non-REM: nREM) stages whereas commonly used general(More)
A multicompartmental biophysical model of entorhinal cortex layer II stellate cells was developed to analyze the ionic basis of physiological properties, such as subthreshold membrane potential oscillations, action potential clustering, and the medium afterhyperpolarization. In particular, the simulation illustrates the interaction of the persistent sodium(More)
Layers II and V of the entorhinal cortex (EC) occupy a privileged anatomical position in the temporal lobe memory system that allows them to gate the main flow of information in and out of the hippocampus, respectively. In vivo studies have shown that layer II of the EC is a robust generator of theta as well as gamma activity. Theta may also be present in(More)
Evidence has accumulated suggesting that the median raphe (MR) mediates hippocampal theta desynchronization. However, few studies have evaluated theta-related neural circuitry during MR manipulation. In urethane-anesthetized rats, we investigated the effects of MR stimulation on hippocampal field and cell activity using high-frequency (100 Hz), theta burst(More)
The entorhinal cortex funnels sensory information from the entire cortical mantle into the hippocampal formation via the perforant path. A major component of this pathway originates from the stellate cells in layer II and terminates on the dentate granule cells to activate the hippocampal trisynaptic circuit. In addition, there is also a significant, albeit(More)
Oscillation and synchronization of neural activity is important in normal brain function but is also relevant to epileptogenesis. One of the most frequent forms of epilepsy originates in temporal lobe circuitry of which the entorhinal cortex (EC) is crucial. Because muscarinic receptor activation promotes oscillatory dynamics in EC neurons, we investigated(More)
1. Single-unit discharge patterns of cells in specific nuclei of the caudal diencephalon were characterized in relation to simultaneously recorded field activity from the stratum moleculare of the dentate gyrus according to the criteria that have been used previously to classify cells in the hippocampal formation (including entorhinal cortex), medial(More)
Hippocampal theta rhythms have been associated with a number of behavioural processes, including learning, memory and arousal. Recently it has been argued that the suppression of hippocampal theta is a valid indicator of anxiolytic drug action. Like all such models, however, it has relied almost exclusively on the experimental effects of well-known,(More)