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Biomedical subjects

M Sabatino

Publications and source records attributed to M Sabatino.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effects of substantia nigra and pallidum stimulation on hippocampal interictal activity in the cat.

In the present work the role played by substantia nigra pars compacta and globus pallidus pars interna on hippocampal bioelectrical activity is studied. Injections of sodium penicillin (i.v.) produce 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, proceeding to generalized seizure activity. The results are discussed in the light of the interrelationships between basal ganglia and hippocampus, hypothesizing a putative feedback loop from striatal to limbic centers.

Action Potentials↗
PubMed1986

Relations between basal ganglia and hippocampus: action of substantia nigra and pallidum.

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, proceeding to generalised seizure activity. The results are discussed in the light of a putative feedback loop from basal ganglia to hippocampus, probably underlying co-participation of the two subcortical structures in the control of motor behaviour.

Animals↗
PubMed1986

Negative occurrence between hippocampal rhythmic slow activity and epileptiform spikes: influence of the striatum.

The effects of caudate and septal stimulation on hippocampal activity were studied. Sodium penicillin was intravenously injected in order to induce a steady rate of interictal 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 RSA genesis in the striato-hippocampal pathway or in the reciprocal septo-hippocampal connections.

Animals↗
PubMed1986

Effect of acetylcholine and dopamine iontophoretically applied on the sensory responsive caudate unit.

A putative integrative function of the striatum was evaluated through the study of the electrical activity of sensory responsive caudate neurones. Both nervous (radial nerve) and auditory stimulations were delivered in order to characterize populations of neurones affected by peripheral stimuli; the units were previously activated by iontophoretic glutamate. On these units the iontophoretic ejection of ACh and DA was tested. Experimental results demonstrated a prevalent excitatory effect of ACh, while DA appeared to exert a drastic decrease on firing rate. A comparison between peripheral stimuli and chemical substances was made. The result of such study showed a most important action of the neurotransmitters employed. The activity of caudate units following single shock activation was also explored. This investigation underlined a certain degree of facilitatory influence of ACh; DA, on the contrary, had the tendency to exert a marked inhibitory action. The results are interpreted in view of the striatal peculiar position on cortico-striato-thalamo-cortical circuit. An integrative function of basal ganglia on sensori-motor activity of the cortex is postulated and the importance of ACh and DA is emphasized.

Acetylcholine↗
PubMed1985

Striatal and septal influence on hippocampal theta and spikes in the cat.

The experiments studied the modulation exerted by the septum and the caudate nucleus on hippocampal activity in the cat. Injections (i.v.) of sodium penicillin were performed in order to obtain a steady interictal epileptic activity. Hippocampal slow rhythmic activity showed a marked decrease either in duration or in frequency following penicillin activation. Both septal and caudate electrical stimulation inhibited spike frequency through a theta eliciting mechanism. Caudate stimulation failed to determine any sort of effect after medial septum lesions. The importance of the septum as modulation station between basal ganglia and hippocampus is emphasized.

Animals↗
PubMed1985

[Feeding behavior of the cat in response to stimulation of the caudate nucleus].

In chronic free-moving cats unilateral, low frequency, long duration stimulation of the caudate nucleus causes a significant reduction of food intake. The effects are greatest at the beginning of the stimulation. On cessation of stimulation the animals take enough food to compensate for that lost during the time of stimulation. Results are discussed either considering interrelationships between striatum and lateral hypothalamus, either regarding recent viewpoints distinguishing two striatal compartments: dorsal or "non limbic" striatal region and ventral or "limbic" striatal region.

Animals↗
PubMed1985

[Effect of the globus pallidus on hippocampal epilepsy in the cat].

The action of the pallidum on electrically induced afterdischarge of the hippocampus (HAD) was studied. Significant facilitatory influences on HAD duration were observed when pallidal conditional stimulation immediately preceded hippocampal test stimulation. The phenomenon appeared to be into correlation with the interval between conditioning and test stimulation. Experimental data are discussed as strongly presumptive of a functional interrelationship between the inhibitory role played by the caudate on both pallidum and hippocampus; facilitatory influence of the pallidum on HAD duration is discussed too.

Action Potentials↗
PubMed1985

[Contrasting effects of stimulation of the caudate nucleus and globus pallidus on paroxysmal hippocampal activity in the cat].

The different actions exerted by pallidum and caudate nucleus on electrically induced epileptic activity of hippocampus were analyzed. Caudate appeared to inhibit hippocampal after discharges duration (HAD) while the globus pallidus exerted a facilitatory effect on HAD duration. Both effects were maximal when conditioning stimulation immediately preceded hippocampal test stimulation. The results are discussed considering reciprocal functional connections of the two striatal structures.

Animals↗
PubMed1985

Effects of caudate nucleus on paroxysmal activity in hippocampus of cat.

Electrically induced afterdischarges (ADs) were evoked in cat's dorsal hippocampus. The effect of the conditioning prestimulation of the caudate head on AD duration was tested. A strong inhibitory action was observed when conditioning caudate stimulation immediately preceded hippocampal test stimulation. An increase in threshold values following caudate stimulation was also noted. The time course of the inhibitory phenomenon showed a decrease of the caudate conditioning effect when the interval between the two stimuli increased: complete disappearance of such effect was found to occur at about 600 msec. When caudate head stimulation followed the onset of hippocampal AD, this was inhibited only during caudate stimulation while presenting facilitation after caudate stimulation terminated. The results are discussed in terms of a possible explanation of the contrasting action of the pallidum, while previous findings attesting the facilitatory role of these structures are considered, as are the effects of caudate stimulation on hippocampal AD.

Animals↗
PubMed1985

Striatal influence on ingestive behaviour in the cat.

In freely moving cats with chronically implanted electrodes an analysis was made of the effects on feeding behaviour of low-frequency long-duration stimulation of the caudate nucleus, the substantia nigra and the globus pallidus. In all 3 structures a significant reduction of food intake was observed and in the pallidus this reached the point of a complete block of feeding. The effects were always limited to the period of stimulation. At the end of stimulation the animals recovered and took in food quantities equal to those of controls. The results are interpreted on the basis of reciprocal connections between the basal ganglia and the hypothalamus; the role of the striatum on the selection of certain movements and its possible involvement in behaviour is also discussed.

Animals↗
PubMed1985

Effects of substantia nigra stimulation on electrical and mechanical activities of the duodeno-jejunal loop, in the cat.

The effect of substantia nigra stimulation on duodeno-jejunal intraluminal pressure and electrical activity was analysed in the cat. An inhibitory influence was noted to occur on both the intestinal pressure and the electrical response activity (ERA): the effect seemed to be in correlation with the stimulus parameters employed. After bilateral vagotomy, the inhibition remained substantially unchanged. The possibility of the existence of a sympathetic pathway mediating the effect is emphasized.

Animals↗
PubMed1984

Interrelations between globus pallidus and hippocampal epilepsy in the cat.

Electrically induced afterdischarge (ADs) were evoked in the cats' dorsal hippocampus. The action of the conditioning prestimulation of the pallidus nucleus on AD duration was studied. A significant facilitatory influence was observed when pallidal conditioning stimulation immediately preceded hippocampal test stimulation. The time course of the phenomenon showed a decrease of the conditioning action when the interval between the two stimulations increased : complete disappearance of the effect occurred after about 800 ms. Results are discussed as far as functional relationships between basal ganglia and rhinencephalic system are concerned.

Action Potentials↗
PubMedDate not supplied

Neuropsychology of selective attention and magnetic cortical stimulation.

Informed volunteers were asked to perform different neuropsychological tests involving selective attention under control conditions and during transcranial magnetic cortical stimulation. The tests chosen involved the recognition of a specific letter among different letters (verbal test) and the search for three different spatial orientations of an appendage to a square (visuo-spatial test). For each test the total time taken and the error rate were calculated. Results showed that cortical stimulation did not cause a worsening in performance. Moreover, magnetic stimulation of the temporal lobe neither modified completion time in both verbal and visuo-spatial tests nor changed error rate. In contrast, magnetic stimulation of the pre-frontal area induced a significant reduction in the performance time of both the verbal and visuo-spatial tests always without an increase in the number of errors. The experimental findings underline the importance of the pre-frontal area in performing tasks requiring a high level of controlled attention and suggest the need to adopt an interdisciplinary approach towards the study of neurone/mind interface mechanisms.

Adult↗