Previous observations have suggested a role for nitric oxide in the activity of the globus pallidus, but this functional involvement has not yet been tested in vivo. The extracellular activity of single units of the globus pallidus was recorded, and neuronal nitric oxide synthase was inhibited by systemically administering 7-nitro-indazole to a group of anaesthetised rats. Forty-five per cent of cells responded with a decrease in the firing rate. In another group of rats, the microiontophoretic administration of 3-morpholino-sydnonimin-hydrocloride (a nitric oxide donor) induced an increase in neuronal firing rate (24/28 cells), whereas the administration of Nω-nitro-L-arginine methyl ester…

Changes in latency of evoked potentials after caudate nucleus stimulation1

Resume L'activation de la tete du noyau caude de chats qui avaient ete soumis a la section de la moelle epiniere a la hauteur de C 1 produit l'inhibition des potentiels evoques de la zone motrice (region pre-cruciale) et la reduction du temps de latence du maximum de l'onde lente negative. Les resultats de la reduction de latence sont discutes par rapport a la variation d'intensite de la stimulation declenchant l'activite du cortex moteur. On sougline enfin le role joue par le noyau caude dans le controle du systeme moteur.

Accumbens-caudate-septal circuit as a system for hippocampal regulation: involvement of a GABAergic neurotransmission.

Hippocampal-based epileptiform activity may reach the basal ganglia via the nucleus accumbens. Previous data suggested that caudate nucleus is able to influence hippocampal epilepsy, probably sending a projection to the septum. In order to test the hypothesis of a retrograde activation of accumbens-caudate pathway in hippocampal regulation, we electrically stimulated both caudate nucleus and nucleus accumbens and studied modifications of hippocampal EEG in the feline focal epilepsy model. We also performed bilateral electrolytic lesion of nucleus accumbens and repeated caudate stimulation. Results showed that nucleus accumbens stimulation was ineffective in modifying hippocampal epilepsy; o…

Dopaminergic control of feline hippocampal epilepsy: A nigrophippocampal pathway

Abstract Substantia nigra is a mesencephalic structure inserted along several circuits which appear to play a key role in epilepsy. In previous researches we postulated that substantia nigra pars compacta (SNpc) may be the site of a precise control of hippocampal epilepsy while substantia nigra pars reticulata (SNpr) may exert a modulation of both neocortical epilepsy and spreading of hyperactivity toward a motor target. In order to better understand mechanisms subserving nigral action in feline hippocampal epilepsy we electrically stimulated SNpc (dopaminergic), before and after sulpiride (dopamine receptor-antagonist) intravenous injection. Furthermore we compared hippocampal epileptiform…

The role of the substantia nigra in the control of amygdaloid paroxysmal activity.

AbstractBoth in acute and chronic cats, focal paroxysmal activity evoked in the ventro-basal complex of the amygdala has been inhibited by substantia nigra conditioning stimulation, to a greater extent, than by caudate nucleus activation. Injection of kainic acid into substantia nigra resulted in the disappearance of the caudate inhibition. It is suggested that the final control, exerted by the striatum on the amygdaloid seizures, occurs by means of the substantia nigra.

Lateral habenula and hippocampus: A complex interaction raphe cells-mediated

The study has shown an excitatory influence exerted by lateral habenula (LH) on hippocampal pyramidal cells. The modulatory influence is paradoxically serotonine-mediated; in fact all LH stimulation effects were abolished by intrahippocampal iontophoretic methysergide application. The data suggest the involvement of dorsal raphe nucleus. In fact, the dorsal raphe nucleus stimulation caused on hippocampus an expected inhibitory effect antagonized by intrahippocampal iontophoretic methysergide application. In the context of this neural structure we have highlighted a disinhibitory relation between two types of cells: slow serotonergic efferent neurones and fast GABAergic interneurones. The di…

The control of amygdaloid seizures by the globus pallidus.

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.

Modifications of the spontaneous bioelectric activity and of the after discharge evoked in the amygdala after pallidal injection of kainic acid in the cat.

Publisher Summary This chapter explains the modifications of the spontaneous bioelectric activity and of the after discharge (AD) evoked in the amygdala after pallidal injection of kainic acid (KA) in the cat. An experiment was conducted in which injection of KA, a neurotoxic drug analog of glutamate, was made into the entopeduncolar nucleus (EN), the equivalent of the medial globus pallidus of primates, to observe the modifications produced on the spontaneous amygdaloid bioelectric activity and on the evoked AD. An AD was evoked in the amygdala by stimulation of the ipsilateral pyriform cortex. The duration of the amygdaloid AD was related to the stimulus parameters. In the same animal, th…

Study of spindle-spike interactions: Features of basal ganglia control

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 …

The control of amygdaloid and temporal paroxysmal activity by the caudate nucleus

In gatti curarizzati ed in gatti portatori di elettrodi a dimora e liberi di muoversi, la stimolazione ripetitiva ad alta frequenza del nucleo caudato inibisce la comparsa sia dei fenomeni bioelettrici parossistici focalizzati nell'amigdala e nella corteccia temporale sia dei fenomeni comportamentali omologabili all'epilessia psicomotoria.

Modifications in Evoked Activity in the Visual Cortex Induced by the Caudate Nucleus

The visual system, like the other sensorial systems, is subjected to intrinsic, complex control, originating both in the retina (CHANG et al., 1959; ARDUINI and HIRAO, 1960; STERIADE, 1967) and in the visual cortex (BUSER et a/., 1963; JASSIK-GERSCHENFELD and ASCHER, 1963; MEULDERS, 1965), which regulates its input at various levels of the specific pathways. However, the visual system is also influenced by subcortical structures which, though not exerting on it a strictly selective control, determine notable modifications in the level of excitability of the cortical sensorial neurons. It is in fact we11 known that activation of the mesencephalic reticular formation, by increasing the level …

Les Réponses évoquées Du Noyau Caudé A La Suite De Modifications De L'Excitabilité De L'Aire Auditive Primaire

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, pro…

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…

Nigral influence on focal epilepsy.

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…

CCK-8S systemic administration blocks the 7-nitroindazole-induced effects on the EEG of striatum and globus pallidus: a FFT analysis in the rat

Background: Nitric oxide (NO) and cholecystokinin (CCK) are involved in the modulation of several neurotransmitter systems in the basal ganglia, and a functional interaction between their modulatory effects could be hypothesised. Materials and Methods: We studied the effects exerted by the administration of 7-nitroindazole (7-NI) (50 mg kg-1 i.p.), a selective inhibitor of neuronal NO synthase, on the depth EEG activity of the striatum and of the globus pallidus in both not pre-treated and sulphated CCK octapeptide (CCK- 8S)-treated (100 nM kg-1 i.p.) rats. Striatal and pallidal depth EEG power spectra were examined by means of a Fast Fourier Transform analysis. Results: Striatal depth reco…

Evidence of a contralateral motor influence on reciprocal inhibition in man

The role of contralateral movement on both H reflex and reciprocal inhibition was studied. In normal men H reflex was induced by median nerve stimulation. Reciprocal inhibition was achieved through stimulation of the antagonist radial nerve. On this basis the effects of contralateral arm movement were analized. Furthermore the putative influence of exteroceptive origin was also verified by means of digit stimulation. Results showed that contralateral arm movement did not affect H reflex amplitude; on the contrary, it was able to enhance reciprocal inhibition induced by extensors on flexors. Study of cutaneous afferents demonstrated that contralateral digit stimulation failed to elicit modif…

Interrelations between globus pallidus and hippocampal epilepsy in the cat (1)

AbstractElectrically 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.

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

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 Function of the Caudate Nucleus in the Control of Some Paroxystic Activities in the Neuraxis

(1969). The Function of the Caudate Nucleus in the Control of Some Paroxystic Activities in the Neuraxis. Archives Internationales de Physiologie et de Biochimie: Vol. 77, No. 3, pp. 465-484.

Contralateral potentials in the suprasylvian gyrus evoked by pulvinar stimulation.

AbstractIn encephale isole cats the transmission of the bioelectrical activity in the suprasylvian gyrus, evoked by contralateral pulvinar stimulation was explored. Through the excitability increase and decrease of the pulvinar (by strychnine or KCl, respectively), the surgical removal of the ipsilateral suprasylvian gyrus and the electrocoagulation of the posterior commissure it appeared that the transmission of the activity in the suprasylvian gyrus evoked by contralateral pulvinar stimulation occurs through both the callosal and the interthalamic pathway.

A feature of caudate control of focal hippocampal epilepsy: evidence for an anterograde pathway

Previous experimental evidences showed that the caudate nucleus has a modulatory effect on hippocampal epilepsy. The caudate's regulating action might reach the hippocampus either via the septal region or, retrogradely, via the accumbens nucleus. In order to obtain new data about the pathway involved in caudate hippocampal influence the spreading of abnormal activity towards the nucleus accumbens was studied. Furthermore the effects of caudate stimulation in animals with electrolytic lesions of the nucleus accumbens were analyzed. It was observed that abnormal penicillin-induced activity spreaded from the hippocampus to the nucleus accumbens in about 30 minutes. In animals with and without …

Cortical stimulation and reflex excitability of spinal cord neurones in man.

The H reflex technique was used to evaluate the influence exerted by cortical conditioning on the excitability of the alpha-motoneurone pool and on IA interneuronal activity (reciprocal inhibition). In ten subjects at absolute rest electrical and magnetic stimulation of the motor cortex was transcranially applied during flexor carpi radialis H reflex eliciting and in conditions of reciprocal inhibition induced by radial nerve stimulation. The time courses showed that at intensities below motor threshold, electrical brain conditioning induced an increase in the amplitude of the test reflex when the cortical shock was given 4 ms after the test H reflex. On the contrary, reciprocal inhibition …

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.

Effects of iontophoretic 5-hydroxytryptamine on the unitary discharge frequency of caudate nucleus neurons in the rat

AbstractSummaryMicroiontophoretic application of 5-hydroxytryptamine (5-HT) on rat caudate nucleus neurons has both facilitatory and inhibitory effects on the discharge frequency of the neurons; in many cases 5-HT has a two-phase action. An analysis was made of the behaviour of facilitatory and inhibitory responses in time considering the mean firing rate variations during and after 5-HT iontophoretic release. Six types of responses have been described : A : short lasting excitation, B : long lasting excitation, C : short lasting inhibition, D : delayed-onset inhibition, E : inhibition followed by excitation, F : excitation followed by inhibition. Also no topographic localization could be m…

Nitric oxide and glutamate interaction in the control of cortical and hippocampal excitability.

Summary: Purpose: We investigated the role of nitric oxide (NO) as a new neurotransmitter in the control of excitability of the hippocampus and the cerebral cortex, as well as the possible functional interaction between NO and the glutamate systems. Methods: The experiments were performed on anesthetized rats. The bioelectrical activities of the somatosensory cortex and the CA1 region of the hippocampus of these rats were recorded. Pharmacologic inhibition of NO synthase (NOS) through the nonselective and brain-selective inhibitors, N-nitro-L-arginine methyl ester (l-NAME) and 7-nitroindazole (7-NI), was performed. Results: The treatments caused the appearance of an interictal discharge act…

Bilateral reciprocal organisation in man: focus on IA interneurone

The H reflex of flexor carpi radialis and radial-induced reciprocal inhibition were recorded in normal subjects during conditioning stimulation of the contralateral median or radial nerves. It was found that stimulation of the contralateral median nerve enhanced the degree of reciprocal inhibition exerted by the radial nerve on the median nerve, while contralateral radial nerve stimulation reduced the reciprocal inhibition exerted by the extensor on the flexor. In two subjects in which a pure extensor H reflex was recorded specular features were observed following contralateral median and radial stimulation. These findings are considered to be the electrophysiological manifestation of contr…

Les Réponses évoquées Du Noyau Caudé Par Stimulation Du Noyau Cochleaire

Relationship between the caudate nucleus and the dorsal hippocampus, in the cat.

Sintesi di un nuovo derivato dell’acido valproico ed effetti in un modello sperimentale di epilessia ippocampale nel ratto

Functional Relations Between the Caudate Nucleus and the Dorsal Hippocampus in the Cat

Effects of motor cortex removal on circling behaviour.

AbstractChemical stimulation of the dopaminergic nigro-striatal system induces circling behaviour also in animals in which an extensive telencephalic lesion has been performed. In order to avoid the effects linked to chemical stimulation, we have studied the circling behaviour means of electrical stimulation of the caudate nucleus in chronic cats with cortical lesions. The role of the motor cortex on the circling behaviour is emphasized.

Lamotrigine differently modulates 7-Nitroindazole and L-Arginine influence on Rat Maximal Dentate Gyrus Activation

The effects induced on the maximal dentate gyrus activation (MDA) by administering the anticonvulsant lamotrigine (LTG), the selective inhibitor of neuronal nitric oxide synthase 7-nitroindazole (7-NI) and the precursor of nitric oxide (NO) synthesis L-arginine, alone or in combination, were studied in urethane anaesthetized rats. Either 7-NI or LTG alone administration reduced the number of convulsing animals following angular bundle (AB) stimulation; their combined treatment induced a further increase of the anticonvulsant effect as also demonstrated by the decrease of MDA and afterdischarge (AD) durations in the animals still responding to AB stimulation. On the contrary, the injection o…

Habenular effect on hippocampal excitability is not cholinergically-mediated.

m-Chlorophenylpiperazine excites non-dopaminergic neurons in the rat Substantia Nigra and Ventral Tegmental Area by activating serotonin-2c receptors

In vivo electrophysiological techniques were used to study the effect of m-chlorophenylpiperazine, a non-selective serotonin-2C receptor agonist, on the activity of non-dopaminergic neurons in the substantia nigra pars reticulata and the ventral tegmental area of anesthetized rats. Intravenous administration of m-chlorophenylpiperazine (5–320 μg/kg) caused a dose-dependent increase in the basal firing rate of a subpopulation of nigral neurons which do not respond to a footpinch stimulus [P(0) neurons], whereas it did not affect the activity of neurons which are responsive to the footpinch [P(+) neurons]. However, m-chlorophenylpiperazine (5–320 μg/kg) excited all non-dopaminergic neurons sa…

Electrophysiological and microiontophoretic analysis of the habenulo-hippocampal circuit.

In the cat, the effects of lateral habenula stimulation, at different ranges of frequency, on hippocampal units were studied. Habenular stimulation at low frequency excited, while at high frequency inhibited the greater part of hippocampal units. Moreover, in order to clarify the possible pathway involved in the habenulo-hippocampal circuit, the effects of iontophoretic acetylcholine and serotonin on hippocampal units were compared with those of habenular stimulation. Iontophoretic acetylcholine induced both excitatory and inhibitory responses while serotonin induced only inhibitory responses. Iontophoretic atropine blocked the effects of acetylcholine ejection but did not antagonize stimul…