Search results for "Decerebrate State"
showing 9 items of 9 documents
Nigral influence on focal epilepsy.
1990
The substantia nigra (SN) has been proposed as a structure involved in epileptiform phenomena. Previous investigations demonstrated that SN is able to elicit hippocampal rhythmic slow activity (RSA) as well as to inhibit hippocampal interictal spikes induced by parenteral administration of penicillin. The present series of experiments was carried out in order to characterize the action of SN on a focal model of hippocampal epilepsy. Experiments were performed on encephale isole cats in which steady epileptiform activity was induced by locally applied penicillin. Electrical stimulation of SN pars reticulata (pr) caused a statistically significant decrease of hippocampal spike frequency and a…
A study of caudate inhibition on an epileptic focus in the cat hippocampus
1988
The mechanisms whereby the caudate nucleus modifies hippocampal spiking activity have been studied. Epileptiform activity was induced in the cat hippocampus by topical application of sodium penicillin in different concentrations. The frequency of induced spikes appeared to be directly correlated to the two doses of epileptogenic agent. The inhibitory effect of 10 Hz caudate stimulation on spike frequency was present even when stimulation lasted for 180 s. Likewise 25 Hz caudate stimulation brought about an inhibition which was maintained by stimulus trains lasting up to 90 s, while the degree of inhibition was reduced by trains of longer duration (120, 150 and 180 s); similar results were a…
Negative occurrence between hippocampal rhythmic slow activity and epileptiform spikes: Influence of the striatum
1986
AbstractThe effects of caudate and septal stimulation on hippocampal activity were studied. Sodium penicillin was intravenously injected in order to induce a steady rate of in-terictal epileptic activity. Penicillin injection caused significant reduction of the rate of occurrence and duration of hippocampal rhythmic slow activity (RSA). Spontaneous RSA as well as RSA-eliciting caudate and septal stimulation induced a marked inhibition on frequency of epileptiform complexes. Lesions of the medial septal nucleus made it impossible to record RSA or to observe any sort of influence on hippocampal epileptiform activity by caudate stimulation. This result suggests that the septum is important for…
The control of amygdaloid seizures by the globus pallidus.
1981
Both in acute and chronic cats entopeduncular stimulation inhibits, to a greater extent than caudate activation, focal paroxysmal activity in the ventro-basal complex of the amygdala. Lesion of entopeduncular neurons, by means of kainic acid injection, induces a decrease of the caudate inhibitory effect. It is suggested that neostriatal control of the amygdaloid seizures occurs partly through the globus pallidus.
Study of spindle-spike interactions: Features of basal ganglia control
1987
Summary Changes in cortical spindle distribution following penicillin (PCN) injections were studied in feline generalized PCN epilepsy. PCN activation caused no substantial changes in spindle duration, frequency and intraburst frequency, while significant reductions in the amplitude of the negative waves were noted. At the same time combinations of spindle waves and epileptic complexes were recorded with one or more spikes randomly occurring at the beginning, in the middle, or at the end of a spindle envelope. Low frequency stimulation of the caudate nucleus induced a certain degree of enhancement in cortical precruciate spike frequency while high frequency activation of the entopeduncular …
Effect of Intraperitoneal Sterile Urine Injection on Abdominal Myoelectrical Activity in the Spinal Rat Model
1991
The abdominal muscle reflex contractions in response to intraperitoneal injection of homologous sterile urine and acid, alkaline, hypo- and hyperosmolar solutions are studied in an acute spinal rat model by conventional and integrated electromyographic techniques. Intraperitoneal injection of homologous sterile urine causes a powerful and almost immediate abdominal muscle contracture of relative short duration. This response seems not to be related to urine pH or osmolarity, since only when solutions with extreme variations in these parameters are injected intraperitoneally are significant abdominal muscle contractions observed.
Mechanism of the cardiovascular activity of laudanosine: comparison with papaverine and other benzylisoquinolines.
1994
1. The activity of (+/-)-laudanosine, a benzyltetrahydroisoquinoline alkaloid, was investigated in pithed rats and rat isolated aorta. Its effects on [3H]-(+)-cis-diltiazem and [3H]-nitrendipine binding to rat cerebral cortical membranes, and on the different molecular forms of cyclic nucleotide phosphodiesterases (PDE) isolated from bovine aorta were investigated. 2. The dose-response curve to methoxamine (3-300 micrograms kg-1, i.v.) in normotensive pithed rats was shifted to the right by (+/-)-laudanosine, 3 and 6 mg kg-1. 3. (+/-)-Laudanosine inhibited in a concentration-dependent manner the contractile responses evoked by noradrenaline (NA 1 microM), depolarizing solution (KCl 80 mM) o…
Relations between basal ganglia and hippocampus: Action of substantia nigra and pallidum
1986
Several interrelationships exist between basal ganglia and hippocampus. The ventral striatum appears to be involved in the control of the dopaminergic nigro-striatal pathway. The caudate, in turn, seems to influence the hippocampal theta rhythm and to inhibit hippocampal spikes. In the present work the role played by globus pallidus pars interna and substantia nigra pars compacta on hippocampal bioelectrical activity is studied. Injection of sodium penicillin i.v. produces steady interictal spikes in the hippocampus. Substantia nigra stimulation induces regular theta rhythm and inhibits the spikes. Pallidal stimulation, on the contrary, appears to strongly enhance epileptiform activity, pro…
Modifications induced on the amygdaloid paroxysmal activity by entopeduncolar or nigral injection of kainic acid, in the cat.
1983
Entopeduncolar or nigral injection of kainic acid determines an early decrease of the evoked amygdaloid paroxysmal activity and a later increase of the after discharge duration. This biphasic effect is likely due to the structural analogy of the drug with monosodium glutamate, a neuroexcitant amino acid. The data suggest that the basal ganglia exert a tonic control on the amygdaloid activity.