Gisele Goddard

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The involvement of new protein and messenger ribonucleic acid synthesis in long-term potentiation was studied in the anaesthetized rat dentate gyrus using several inhibitors of protein synthesis (anisomycin, emetine, cycloheximide and puromycin) and an inhibitor of messenger ribonucleic acid synthesis (actinomycin D). When injected for 1 h just prior to(More)
Evidence is presented that long-lasting enhancement of perforant path synapses following high-frequency activity is a cooperative process requiring coactivity of a considerable number of fibers. This was demonstrated in two ways: (1) A threshold stimulus intensity during high-frequency stimulation was required before any enhancement was observed. This(More)
Brief high-frequency trains of electrical stimulation delivered to the perforant path result in long-term potentiation (l.t.p.) of field potentials recorded extracellularly from granule cells of the dentate gyrus. L.t.p. of the population spike is often disproportionately greater than l.t.p. of the population excitatory post-synaptic potential (e.p.s.p.).(More)
Stimulation of the contralateral hippocampus in the hilar region had a marked effect on granule cell excitability in the fascia dentata. The primary effect was to block the population spike that otherwise occurred in response to perforant path stimulation. In contrast, the size the excitatory post-synaptic potential component of the perforant path-evoked(More)
1. Brief, high-frequency stimulation of the perforant path results in a long-term potentiation (l.t.p.) of the field response evoked in the dentate gyrus by single shocks to the perforant path. We have compared the magnitude and duration of l.t.p. in normal, anaesthetized rats with animals depleted of noradrenaline (NA), 5-hydroxytryptamine (5-HT), or both.(More)
Rats under barbiturate anaesthesia were implanted with stimulating electrodes in the medial septal nucleus and the medial perforant path. A recording electrode and cannula were implanted in the hilus of the dentate gyrus. Electrodes were positioned so that a conditioning pulse to the medial septum, although eliciting no field potential of its own,(More)
Available evidence suggests that a portion of the septohippocampal pathway may form inhibitory synapses on inhibitory interneurons in the dentate gyrus. In contrast, a portion of the commissural input from the contralateral hilus may form excitatory synapses on inhibitory interneurons. To ascertain whether these pathways synapse onto a common population of(More)