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1. We have developed a 19-compartment cable model of a guinea pig CA3 pyramidal neuron. Each compartment is allowed to contain six active ionic conductances: gNa, gCa, gK(DR) (where DR stands for delayed rectifier), gK(A), gK(AHP), and gK(C). THe conductance gCa is of the high-voltage activated type. The model kinetics for the first five of these(More)
1. Mechanisms underlying the propagation of synchronous epileptiform activity in disinhibited hippocampal slices were examined in experimental and computer simulation studies. 2. Experiments were performed with longitudinal slices of the CA3 region. Synchronous firing was initiated by stimulating stratum radiatum fibers in the presence of picrotoxin. It(More)
Excitatory synaptic interactions between CA3 neurones in slices from guinea-pig hippocampus were examined. Recurrent excitatory post-synaptic potentials (e.p.s.p.s) were evoked by action potentials in a single presynaptic neurone or by the antidromic activation of part of the CA3 pyramidal cell population. The peak amplitude of unitary e.p.s.p.s was 1-2 mV(More)
The synchronized firing of neuronal populations is frequently observed in the mammalian central nervous system. The generation of motor activities such as locomotion and respiration requires the simultaneous activation of many neurones and synchronous firing also underlies the cortical alpha rhythm and the hippocampal theta rhythm. However the influence(More)
1. Exposure to the gamma-aminobutyric acid antagonist, picrotoxin, causes the discharge of hippocampal pyramidal cells to become synchronized. Synaptic mechanisms underlying the development of synchrony were investigated by recording from pairs of cells in the CA3 region of guinea-pig hippocampal slices. 2. Picrotoxin suppressed unitary inhibitory synaptic(More)
A method is described for the isolation of neurons from defined regions of the mammalian central nervous system, by a combination of mechanical and enzymatic means. The procedure liberates neurons free of cellular debris and glial investments, allowing the formation of giga-ohm seals with patch clamp electrodes. The characteristic morphology of neurons is(More)
1. Current mediated by GABAA receptors was examined in pyramidal cells acutely dissociated from the hippocampus of mature guinea-pigs. Current responses were measured using whole-cell voltage-clamp recordings. An internal perfusion technique was used to change the intracellular contents during recording. 2. Application of GABA (100-300 microM) by short(More)
1. Neurones were isolated from the CA1 region of the guinea-pig hippocampus and subjected to the whole-cell mode of voltage clamping, to determine the kinetics of voltage-gated Ca2+ channel activation. 2. Isolated neurones had an abbreviated morphology, having lost most of the distal dendritic tree during the isolation procedure. The electrical compactness(More)
1. Intracellular recordings were obtained from pyramidal, granule and hilar cells in transverse slices of guinea-pig hippocampus to examine synaptic interactions between GABAergic neurones. 2. In the presence of the convulsant compound 4-aminopyridine (4-AP), after fast excitatory amino acid (EAA) neurotransmission was blocked pharmacologically, large(More)
Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the cortex. Activation of postsynaptic GABAA receptors hyperpolarizes cells and inhibits neuronal activity. Synaptic responses mediated by GABAA receptors also strongly excited hippocampal neurons. This excitatory response was recorded in morphologically identified interneurons in the(More)