Long-term potentiation of synaptic responses in the hippocampus is a unique form of physiological plasticity which can be induced by brief episodes of repetitive afferent activity and which can persist for days or months. The present study describes cooperative (or associative) interactions among afferents to the stratum radiatum of CA1 for the induction and maintenance of this phenomenon. A gr...

The activity of single neurons recorded from rabbit hippocampus during classical conditioning of the nictitating membrane reflex was studied. All cells were first categorized according to their responses after fornix stimulation--i.i., antidromic activation, orthodromic activation, or no activation. The majority of cells that were antidromically activated--pyramidal cells--showed a highly posit...

We report a 26-year-old woman with frequent episodes of palpitation and dizziness. Resting electrocardiography showed no evidence of ventricular preexcitation. During electrophysiologic study, a concealed right posteroseptal accessory pathway was detected and orthodromic atrioventricular reentrant tachycardia incorporating this pathway as a retrograde limb was reproducibly induced. After succes...

The spontaneous activity of hypothalamic units was studied in chronic awake and ketamine-anesthetized rats. Ketamine appeared to decrease significantly the spontaneous firing of neurons in the ventromedial hypothalamic nucleus (VMH) but did not influence the activity in either the dorsomedial hypothalamic nucleus (DMH) or the lateral hypothalamic area (LHA). The responses obtained in the medial...

The form and time sequence of spikes generated by orthodromic, antidromic, and direct stimulation and during spontaneous activity have been studied with intracellular electrodes simultaneously introduced in the soma and in different parts of the axon of the giant nerve cell of Aplysia. Evidence was obtained that under normal conditions of excitability, the spike originates at some distance from...

Recovery of orthodromic and antidromic population spikes in CA1 hippocampal slices of 30-day-old Wistar rats has been studied in the reperfusion period after prolonged (90 min) decapitation ischemia with and without preceding 15 min long non-voluntary motor activity of intact animals. The preconditioning motor activity significantly enhances the resistance of pyramidal neurons to ischemia at a ...

Electrophysiological studies were performed to elucidate the mechanism underlying the antivertigo action of eperisone, an antispastic drug, using cats anesthetized with alpha-chloralose. Iontophoretic application of eperisone up to 100 nA produced a dose-dependent inhibition of spike generation upon vestibular nerve stimulation in monosynaptic and polysynaptic neurons of the medial vestibular n...

The approach to successful ablation of arrhythmias is based on elucidating the underlying mechanism and relative dimensions of the tachycardia circuit. Activation mapping readily distinguishes macroreentry from focal arrhythmias, the latter of which have centrifugal spread. When macroreentrant atrial tachycardia is suspected, entrainment maneuvers with atrial overdrive pacing at various anatomi...

Abstract The paper presents a coherent, original theory and an effective algorithm to calculate the surface area of geodesic polygon, i.e. on ellipsoid revolution limited by geodesics, connecting pairs subsequent vertices known geographical coordinates. Using cylindrical coordinate system introducing equatorial triangle, novel strict recursive formulas were derived for longitude distance along ...