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The discharge patterns and layer distribution of entorhinal cortex (EC) units were investigated in paralysed and locally anesthetized rats injected with physostigmine in order to induce theta (theta) rhythm. Entorhinal unit activity and field potentials were recorded simultaneously with the same micropipette. Hippocampal CA1 theta rhythm was used as(More)
Dorsal hippocampal theta rhythm (theta) and extracellular unit activity from CA1 pyramidal layer were recorded in awake guinea pigs, both during standing and during walking on a conveyor belt at increasing speeds. Amplitude, frequency and rhythmicity of theta increased linearly with the movement speed. In this preparation we found the same three types of(More)
The laminar distribution of theta (theta) field potentials in the entorhinal cortex (EC) was investigated in paralysed and locally anesthetized rats injected with physostigmine in order to induce theta rhythm. Electrode penetrations through the medial, intermediate and lateral subdivisions of the EC showed in all cases: 1. the presence of theta rhythm from(More)
The hippocampal EEG and the transmembrane potential of CA1-CA3 hippocampal pyramids were recorded in curarized and urethanized rats. Pyramids were identified by antidromic driving and intracellular staining with Lucifer yellow. During theta-rhythm most pyramids showed 10-20 mV sustained depolarizations and potential oscillations either consisting of 5-10 mV(More)
The lateral septum receives the most important afferents from the hippocampus, has been proposed to contribute to theta (theta) rhythm generation. Our aim was to study the membrane and circuital properties of lateral septum neurons and their relationship with hippocampal rhythms. Extra- and intracellular recordings (n=81) were obtained in(More)
Transmembrane potentials from medial septal and diagonal band of Broca (MS-DBB) neurons and hippocampal field activity were recorded in curarized and urethanized rats. MS-DBB cells were studied during large amplitude irregular activity and during hippocampal theta rhythm, elicited by either sensory (i.e. stroking the fur on the animal's back) or electrical(More)
To compare the ongoing electrical activity in possibly homologous structures of reptiles and mammals, the electrographic activity (micro-EEG) from major parts of the cortex of unanesthetized turtles (Pseudemys) and geckos (Gekko) was recorded with and without acute and chronic stimuli, physostigmine and atropine. Electrodes were placed in the medial cortex(More)
The effects of intracellular Cl- diffusion and hyperpolarizing current pulses on inhibitory postsynaptic potentials (IPSPs) and the transmembrane theta rhythm of CA1-CA3 pyramidal neurons were tested in urethanized and curarized rats. Cl- diffusion and hyperpolarizing currents decreased the amplitude of IPSPs evoked by fornix stimulation without modifying(More)
An experimental stable model of an in vitro turtle brain (Chrysemys d'orbigny) was developed in order to compare electrographic activity (EEG) with transmembrane potentials. Two preparations were used: a whole intact hemisphere and a whole open hemisphere. The latter permitted easier impalement of cortical neurons through the ependymal surface. The EEG(More)
The activity of 72 neurons recorded in the reticularis pontis oralis nucleus (RPO) was examined in anesthetized and curarized rats during hippocampal theta (theta) rhythm elicited by either sensory stimulation or carbachol microinjections. During hippocampal theta rhythm evoked by sensory stimulation, 63.9% of RPO neurons increased their discharge rate(More)