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F Estrada-Villanueva

Publications and source records attributed to F Estrada-Villanueva.

13 recordsLinked to original sources
PubMed1986

Alumina cream-induced focal motor seizures in cats: bilateral lesions of the mesencephalic reticular formation.

The effect of bilateral lesions of the mesencephalic reticular formation on the EEG-EMG patterns of types B and C alumina cream-induced focal motor seizures was studied in cats with chronically implanted electrode and cannula lesion systems. EEG patterns included number, amplitude, and contralateral propagation of type B spikes and occurrence and duration of type C tonic-clonic discharges. EMG patterns included changes in muscular multiple-unit activity time locked to the onset of type B spikes and to the onset and end of type C tonic-clonic EEG paroxysmal discharges. The lesions persistently blocked the orienting response to visual, auditory, and tactile stimuli to both sides in all cats and produced other neurologic symptoms partially or totally recovered in some cats. The lesions significantly increased the number, amplitude, and contralateral propagation of type B EEG spikes and the occurrence, but not the duration, of type C EEG tonic-clonic discharges. Ipsi- and contralateral adversion of the tonic phase were completely blocked and the muscular contractions of the clonic phase were reduced and delayed. These facts suggest that in intact epileptic cats, the mesencephalic reticular formation has an ascending suppressive influence on the mechanism related to EEG spike generation and precipitation of seizures but also a descending facilitatory control on the corticospinal epileptic impulses mediated through pyramidal and extrapyramidal pathways.

Aluminum Oxide↗
PubMed1985

Alumina cream induced focal motor epilepsy in cats. VI. Excision of the perilesional cortex.

The effect of surgical excision of dorsolateral, ventromedial and combined (dorsolateral-ventromedial) perilesional cortices on EMG-EEG patterns of alumina cream induced focal motor seizures was studied in cats with chronically implanted electrodes. EMG patterns included clinical convulsions and related EMG-multiple unit activity. EEG patterns included number, amplitude, polarity and contralateral propagation of type B isolated spikes and type C tonic-clonic paroxysmal discharges. (1) Dorsolateral decortications abolished isolated jerks and related EMG-multiple unit activity and blocked propagation with no effect on number, amplitude and polarity of EEG spikes of type B seizures (epilepsia partialis continua). Dorsolateral decortications reduced contraversion and repetitive jerks and related EMG-multiple unit activity with no changes in number, amplitude, polarity and propagation of EEG tonic-clonic paroxysmal discharges of type C seizures (adversive epilepsy). (2) Ventromedial decortications decreased the number but neither changed jerks and related EMG-multiple unit activity nor amplitude, polarity, propagation of EEG spikes of type B seizures. Ventromedial decortications abolished contraversion and jerks and related EMG-multiple unit activity and reduced number, amplitude and duration with no changes in polarity and propagation of EEG paroxysmal discharges of type C seizures. (3) Combined decortications abolished jerks, contraversion and related EMG-multiple unit activity with a variable effect on EEG patterns of type B and C seizures. In 4 cats, combined decortications abolished while in other 2 cats decreased the amplitude and reversed the polarity of type B spikes and reversed the polarity and blocked the propagation of type C paroxysmal discharges.

Aluminum Oxide↗
PubMed1984

Alumina cream-induced focal motor epilepsy in cats. Part 5. Excision and transplant of the epileptogenic granuloma.

The role of alumina cream (AC) epileptic granulomas in producing clinical convulsions and EEG spikes was evaluated by excising and transplanting such granulomas from donors to recipient cats. In donors, granulomas were produced by single microinjections of AC into the right motor cortex and were subsequently excised during latent premature (P), mature (M), convulsive, and remission stages. The excised granulomas from donors were homogenized and injected into the homologous cortices of the recipient cats. The epileptogenic effect of the AC granuloma transplant in the recipients and the antiepileptogenic effect of the AC granuloma excision in the donors were evaluated by the presence or absence of clinical convulsions and the maximal EEG spike density at the right motor cortex (MSD) after lesion excision and transplant. In addition, a correlation between MSD (spikes/10 min) of donors and recipients and the aluminum content (microgram/ml) in granuloma and perilesional cortex of control epileptic cats (neither excised nor transplanted) was established during latent P, M, convulsive, and remission stages. The epileptogenic effect of AC granulomas transplanted into recipients was significantly larger when they were excised from donors in latent P and M than in convulsive, and in convulsive than in remission. The antiepileptogenic effect of AC granuloma excision in donors was significantly larger in latent P than in latent M and convulsive, and in convulsive than in remission. The aluminum content of AC granuloma and perilesional and contralateral cortices in controls was significantly larger in latent P and M than in convulsive and in convulsive than in remission.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1983

Alumina cream-induced focal motor epilepsy in cats. IV. Peduncular and midline tegmental lesions.

The effect of peduncular and midline tegmental lesions on EEG-EMG patterns of type B and C alumina cream-induced focal motor seizures was studied on cats with chronically implanted electrodes and cannula lesion systems. EEG patterns included number, amplitude and contralateral propagation of type B spikes and occurrence and duration of type C tonic-clonic discharges. EMG patterns included phasic multiple unit activity (EMG MUA) time locked to the onset of type B EEG spikes and time locked to the onset (contradversive OTCD) and end (clonic ETCD) of type C tonic-clonic EEG paroxysmal discharges. (1) Lesions of the middle third of the cerebral peduncle, ipsilateral to the cortical epileptogenic focus, blocked type B muscular convulsions and significantly decreased phasic EMG MUA at contralateral face, neck and limbs. (2) Bilateral peduncular lesions blocked clonic type C muscular convulsions and significantly decreased phasic clonic ETCD EMG MUA at the same body regions. (3) Midline tegmental lesions blocked phasic type C muscular convulsions and significantly decreased phasic contradversive OTCD EMG MUA at neck muscles. (4) Bilateral peduncular lesions significantly increased and midline tegmental lesions significantly decreased (below the previous interictal) contradversive OTCD EMG MUA. (5) Neither peduncular nor midline tegmental lesions significantly changed EEG patterns of type B and C seizures.

Aluminum Oxide↗
PubMed1976

Specific and nonspecific multiple unit activities during the onset of pentylenetetrazol seizures. II. Acute lesions interrupting nonspecific system connections.

Nonspecific cortical, thalamic, mesencephalic, and pontine multiple unit activities (MUA) and changes in EEG and MUS of the sciatic nerve after threshold pentylenetetrazol activation were studied in three groups of animals in which neuronal connections were interrupted at three different levels of the central nervous system: spinal, mesencephalic, and prethalamic. Maximal increments of nonspecific MUA and maximal increments and maximal decrements of sciatic MUA after pentylenetetrazol from each group of lesioned animals were statistically compared with tose observed in intact animals. 1. Pentylenetetrazol threshold for producing cortical tonic-clonic EEG discharges was increased in animals with nesencephaic and prethalamic lesions but was not modified in animals with spinal transection. 2. Cortical MUA maximal increment was significantly decreased in mesencephalic and prethalamic lesioned animals, whereas thalamic MUA maximal increment was significantly decreased in mesencephalic and significantly increased in prethalamic lesioned animals. Pontine MUA maximal increment was significantly increased in spinal, mesencephalic, and prethalamic lesioned animals, and mesencephalic M-A maximal increment was not significantly modified in either prethalamic lesioned or in spinal transected animals. 3. Sciatic MUA maximal increment and maximal decrement were significatly decreased in spinal transected animals, whereas only maximal increment was significantly decreased in mesencephalic and only maximal decrement was significantly decreased in prethalamic lesioned animals. These results based on lesion experiments permit us to infer than under normal cinditions the development of generalized seizures induced by threshold pentylenetetrazol injection is highly dependent upon the neuronal interactions between nonspecific structures at different levels of the central nervous system. The possible nature of these neuronal interactions in the intact animals is discussed.

Animals↗
PubMed1975

Specific and nonspecific multiple unit activities during the onset of pentylentetrazol seizures. I. Intact animals.

A quantitative evaluation of specific and nonspecific multiple unit activity (MUA) before and during pentylenetetrazol-induced EEG tonic-clonic discharges (OTCD) was made at four levels of the CNS: cortical, thalamic, mesencephalic, and pontine. In addition, MUA of sciatic nerve was recorded to detect possible spinal cord efferent discharges. At all levels, sustained increase in specific and nonspecific multiple unit activity preceded EEG and sciatic nerve discharges induced by pentylenetetrazol. Increments in nonspecific MUA occurred sooner and were larger than those of specific MUA, and increments in mesencephalic nonspecific MUA occurred sooner and were larger than those of other cortical, thalamic, and pontine nonspecific MUAs. This sequence of neuronal activation suggests that pentylenetetrazol seizures are initiated in nonspecific structures at the mesencephalic level.

Animals↗