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PURPOSE In limbic or mesial temporal lobe epilepsy, much attention has been given to specific regions or cell populations (e.g., the hippocampus or dentate granule cells). Epileptic seizures may involve broader changes in neural circuits, and evidence suggests that subcortical regions may play a role. In this study we examined the midline thalamic regions(More)
An ovarian steroid-dependent cycle of synaptogenesis and synapse shedding occurs naturally in the hippocampus of the adult female rat. The newly formed axospinous synapses in CA1 may differ functionally from extant axospinous synapses, e.g., in terms of their modifiability. Here we assess whether estradiol alters the induction of homosynaptic long-term(More)
1. Changes in extracellular K+ activity were measured with ion-selective microelectrodes in the grey matter of the isolated hemisected frog spinal cord. The magnitude of the elevation of [K+]o (delta[K+]o) produced by repetitive stimulation (25 Hz, 10 s) of afferent fibres in the sciatic nerve was monotonically related to the strength of the electrical(More)
The midline thalamus has a role in memory formation and has well described projections to multiple limbic sites including the hippocampus, amygdala, and entorhinal cortex. Stimulation of this region evokes excitatory responses in the CA1 region of the hippocampus, but nothing is known about the nature of thalamic influence on other limbic sites such as the(More)
The limbic/mesial temporal lobe epilepsy syndrome has been defined as a focal epilepsy, with the implication that there is a well defined focus of onset, traditionally centered around the hippocampus. The pathology of the hippocampus in this syndrome has been well described and a number of physiological abnormalities have been defined in this structure in(More)
CA1 is the major output area for the hippocampus, and current evidence shows that it is excited primarily from ipsilateral and contralateral CA3 pyramidal cells in the rat. Direct connections from the midline thalamic nuclei to the hippocampus have been described anatomically, but the physiological role of these connections has not been reported until the(More)
In one computational model of hippocampal function, the entorhinal cortical input to CA1 is hypothesized to play a key role in the ability of CA1 to decode CA3 recodings. Here, we develop a modification of this CA1 decoder hypothesis that is applicable to several computational theories of hippocampal function, and then we electrophysiologically investigate(More)
Collateral projections are an important feature of the organization of ascending projections from the spinal cord to the brain. Primate spinothalamic tract (STT) neurons with collaterals to the periaqueductal gray (PAG) were studied by means of a fluorescent double-labeling method. Granular Blue and rhodamine-labeled latex microspheres were placed in the(More)
Gamma-aminobutyric acid (GABA) is a putative inhibitory neurotransmitter in the vertebrate nervous system. Several lines of evidence suggest that GABA plays an important role in the processing and modulation of sensory input in the spinal cord dorsal horn. In the present study, the relationship between GABA-immunoreactive (GABA-IR) terminals and(More)
The present study tested the effect of two non-competitive NMDA receptor antagonists, ketamine and phencyclidine, on the induction of long-term depression (LTD) in the dentate gyrus of urethane-anesthetized rats. Both drugs blocked the induction of LTD as well as long-term potentiation (LTP). NMDA receptor activation thus seems to be required for the(More)