Francisco Estrada-Villanueva

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.

Alumina cream-induced Focal Motor Epilepsy in Cats Part 1. Lesion Size and Temporal Course

The epileptogenic effect of known amounts of alumina cream injected 3 mm below the pial surface of the right sensori‐motor cortex was investigated systematically in 16 cats observed for 80 days.

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 MUA 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 those observed in intact animals.

Alumina cream induced focal motor epilepsy in cats. II. Wakefulness--sleep modulation of pyramidal tract multiple unit activity.

Abstract Quantitative changes in tonic and phasic multiple unit activities of the pyramidal tract (PT MUA) were determined during wakefulness-sleep state shifts of a group of cats with alumina cream induced focal motor epilepsy. In addition, tonic multiple unit activity from neck muscles (EMG MUA) was recorded as an indicator of peripheral neuromuscular tonic excitability. Changes in PT MUA and EMG MUA were related to other EEG and clinical epileptogenic events. 1. [1] During wakefulness (W), animals showed both EEG spikes and clinical convulsions. Tonic PT MUA and EMG MUA were high and phasic PT MUA showed a pronounced and significant transient increase time locked to the EEG spike. During slow wave sleep (SWS), animals showed EEG spikes with no (or discrete) clinical convulsions. Tonic PT MUA and EMG MUA were low and phasic PT MUA showed a slight although significant transient increase time locked to the EEG spike. During paradoxical sleep (PS) animals showed EEG spikes with no clinical convulsions. Tonic PT MUA was high while EMG MUA was low and phasic PT MUA showed a pronounced and significant trandient increase time locked to the EEG spikes. 2. [2] A significant decrease in tonic and phasic PT MUA and tonic EMG MUA was found when animals shifted from W to SWS. A significant increase in tonic and phasic PT MUA and decrease in tonic EMG MUA were found when animals shifted from SWS to PS. No significant changes in tonic and phasic PT MUA and a significant decrease in EMG MUA were found when animals indirectly shifted from W to PS. These data suggest that wakefulness-sleep states modulate initiation and propagation of epileptic impulses at two different levels of the CNS: cortical and spinal. Accordingly, W activates both, SWS deactivates both and PS activates the cortical while deactivates the spinal one.

Alumina cream induced focal motor epilepsy in cats. I. Wakefulness-sleep modulation of cortical paroxysmal EEG spikes

Abstract Quantitative changes in amplitude, density and temporal distribution of cortical paroxysmal EEG spikes from motor cortex (spikes) during wakefulness-sleep state shifts were studied in a group of cats with alumina cream induced focal motor epilepsy. Special care was taken in analyzing various types of spikes and in operationally defining wakefulness-sleep states. Main results and conclusions referred to type B spikes since it was present in all cats during the convulsive stage and in all wakefulness-sleep states within the same cat. 1. (1) During wakefulness (W), individual type B spikes showed a mean amplitude of 215 ± 28 μV, density of 60 ± 13/min and interval of 462 ± 36 msec. Correlation coefficient between individual spike and EMG clonic contractions (convulsions) was equal to one. 2. (2) There was a significant increase spike density (decreased interval) when cats shifted from W to slow wave sleep (SWS) and significant decrease spike density (increase interval) when cats shifted from SWS to paradoxical sleep (PS). In contrast, no significant changes in spike density and interval were found in cats between W and PS. 3. (3) No significant differences in spike amplitude and interval variance were found during wakefulness-sleep shifts. 4. (4) Arousal shifted cats from SWS to W and produced changes in amplitude density and interval similar to those spontaneously observed in shifts from SWS to PS. 5. (5) Spike/convulsion correlation coefficient was reduced from one to zero (or near zero) when cats spontaneously shifted from W to SWS and PS, and it was increased from zero (or near zero) to one when cats shifted from SWS to W by means of an arousal stimulus presentation.

Carbachol “push-pull” perfusion in the reticular formation: Effect on the contiguous multiple-unit activity and other sleep-waking parameters in cats

Abstract The effects of carbachol perfusion in the pontine (PRF) and mesencephalic (MRF) reticular formation on contiguous multiple-unit activity (MUA) and other sleep-waking parameters of cats were determined. Perfusion of carbachol into the PRF significantly increased the number of contiguous MUA neuronal spikes. There was a linear relationship between the number of minutes of perfusion and MUA neuronal spikes from the 1st to the 8th minute (estimated 1 to 8 μg), followed by a plateau of maximal MUA activation from the 8th to the 10th minute (estimated 8 to 10 μg), and a subsequent decrease in number of MUA cellular spikes from the 10th to the 11th minute (estimated 10 to 11μg) when the perfusion was discontinued. Concomitantly, the perfusion significantly decreased electromyographic MUA (hypotonia) but it did not systematically modify the mesencephalic reticular formation and other electrophysiologic and behavioral sleep-waking parameters. Perfusion of carbachol into the MRF significantly increased the number of contiguous MUA neuronal spikes. There was a linear relationship between the number of minutes of perfusion and the number of MUA neuronal spikes from the 1st to the 11th minute (estimated 1 to 11 μg) when the perfusion was discontinued. Concomitantly, the perfusion significantly increased electromyographic MUA (hypertonia) and produced a systematic electrophysiologic and behavioral arousal response.

Alumina Cream-Induced Focal Motor Epilepsy in Cat. Part 5. Excision and Transplant of the Epileptogenic Granuloma

Summary: 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 (|xg/ml) in granuloma and perile‐sional 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. In addition, there was a significant positive correlation between MSD of all recipients and the aluminum content in perilesional cortex of control epileptic cats (r = 0.719, p <0.001). There was a negative correlation between MSD of latent P, convulsive, and remission donors and the aluminum content in perilesional cortex of control epileptic cats (r = 0.650, p <0.01). In contrast, the antiepileptogenic effect of AC granuloma excision in donors during the latent M stage was not larger than in the convulsive stage. MSD of these donors did not correlate with the aluminum content of granulomas in epileptic controls.

Specific and Nonspecific Multiple Unit Activities during the Onset of Pentylenététrazol Seizures. III. Animals with Ablations of the Cerebral Cortex

Summary: The effects of cortical ablations on behavior, wakefulness‐sleep states, and PTZ‐induced seizures were studied in a group of cats. Animals were divided in two groups: group I, animals with ablations of primary sensory cortices, including the primary somatosensory, visual, and auditory cortices; group II, animals with ablations of association cortices, including the parietal, cingulate, and orbitofrontal cortices. Animals of group I showed apathy, decreased visual and auditory reactivity, and postural defects. They showed no significant changes in wakefulness‐sleep states. Threshold doses of PTZ failed to induce EEG tonic‐clonic discharges but did increase multiple unit activity (MUA) of the motor cortex and the mesencephalic and pontine reticular formations, as has been reported for intact animals. In contrast, animals of group II showed variable degrees of hyperactivity, significant increase in the amount of wakefulness, and decrease in slow‐wave sleep, with no changes in paradoxical sleep. Threshold doses of PTZ induced EEG tonic‐clonic seizures that lasted 10 to 100 times as long as those seen in intact animals, and MUA increments of the motor cortex and mesencephalic and pontine reticular formations were significantly larger than those observed in group I and intact animals. These findings support the idea that association cortices modulate the wakefulness‐sleep states and exert an important inhibitory effect on the development of PTZ‐induced seizure activity at cortical and subcortical levels.

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.

Alumina cream-induced epilepsy in cats. III. Wakefulness-sleep modulation of multiple unit activity in the reticular formation

Abstract Quantitative changes in tonic and phasic multiple unit activities (MUA) of the mesencephalic (MRF) and pontine reticular formations (PRF), pyramidal tract (PT) and neck muscles (EMG) during wakefulness (W), slow wave sleep (SWS) and paradoxical sleep (PS) were determined in alumina cream-induced epileptic cats showing two types of EEG/EMG seizures: type B characterized by continuous isolated EEG spikes and EMG jerks (epilepsia partialis continua) and type C characterized by episodic tonic-clonic EEG spikes and EMG jerks (adversive seizures). 1. (1) Tonic PT, MRF and PRF MUA were large during W and PS and low during SWS while EMG MUA was large during W, low during SWS and almost abolished during PS. PT and EMG MUA significantly decreased while MRF and PRF MUA did not change when cats shifted from W to SWS. PT, MRF and PRF MUA significantly increased while EMG MUA decreased from SWS to PS. PRF MUA significantly increased and EMG MUA significantly decreased while PT and MRF MUA did not change from W to PS. 2. (2) During W, type B phasic PT, MRF, PRF and EMG MUA significantly increased time-locked to the onset of isolated EEG spikes. During SWS and PS, PT, MRF and PRF MUA significantly increased while EMG MUA remained unchanged at the onset of EEG spikes. Type B phasic PT MUA significantly decreased when cats shifted from W and PS to SWS, EMG MUA decreased from W to SWS and PS while MRF and PRF did not change systematically through different wakefulness-sleep state shifts. 3. (3) During W, type C phasic PT, MRF and PRF MUA significantly increased 1 sec before while EMG MUA increased 1 sec after the onset of EEG tonic-clonic discharges. During PS, PT, MRF and PRF MUA significantly increased 5-4 sec before, decreased 2–3 sec after and increased 5–6 sec after while EMG MUA remained low and unchanged until it significantly increased 4 sec after the onset of tonic-clonic EEG discharges. PT MUA significantly increased 3 sec before, PRF MUA decreased 3 sec after and EMG MUA decreased 1–4 sec after the onset of tonic-clonic EEG discharges when cats shifted from W and SWS to PS.