Hind limb motoneurons activity during fictive locomotion or scratching induced by pinna stimulation, serotonin, or glutamic acid in brain cortex-ablated cats.

In brain cortex-ablated cats (BCAC), hind limb motoneurons activity patterns were studied during fictive locomotion (FL) or fictive scratching (FS) induced by pinna stimulation. In order to study motoneurons excitability: heteronymous monosynaptic reflex (HeMR), intracellular recording, and individual Ia afferent fiber antidromic activity (AA) were analyzed. The intraspinal cord microinjections of serotonin or glutamic acid effects were made to study their influence in FL or FS During FS, HeMR amplitude in extensor and bifunctional motoneurons increased prior to or during the respective electroneurogram (ENG). In soleus (SOL) motoneurons were reduced during the scratch cycle (SC). AA in medial gastrocnemius (MG) Ia afferent individual fibers of L6-L7 dorsal roots did not occur during FS Flexor digitorum longus (FDL) and MG motoneurons fired with doublets during the FS bursting activity, motoneuron membrane potential from some posterior biceps (PB) motoneurons exhibits a depolarization in relation to the PB (ENG). It changed to a locomotor drive potential in relation to one of the double ENG, PB bursts. In FDL and semitendinosus (ST) motoneurons, the membrane potential was depolarized during FS, but it did not change during FL Glutamic acid injected in the L3-L4 spinal cord segment favored the transition from FS to FL During FL, glutamic acid produces a duration increase of extensors ENGs. Serotonin increases the ENG amplitude in extensor motoneurons, as well as the duration of scratching episodes. It did not change the SC duration. Segregation and motoneurons excitability could be regulated by the rhythmic generator and the pattern generator of the central pattern generator.

La Insulectomía podría ser un abordaje ideal para crisis insulares y peri-insulares? / Insulectomy for insular and peri-insular seizures could be an ideal and safe approach?

La insulectomía es una técnica microquirúrgica establecida para el tratamiento de la epilepsia refractaria al tratamiento farmacológico. El origen insular de la epilepsia es inusual, sin embargo, con la investigación a través de electrodos híbridos este tipo de epilepsia ha incrementado su diagnóstico. Los autores hacen hincapié en las funciones insulares, así como los puntos de referencia anatómicos para la cirugía. Se discuten las principales complicaciones y las bases fisiológicas para las indicaciones de cirugía.

Insulectomy is an established microsurgical technique for treatment of insular epilepsy refractory to clinical management. The insular origin of epilepsy is unusual, however with depth investigation through hybrids electrodes such kind of epilepsy is increasing its diagnosis. The authors emphasizes the insular functions as well as the anatomical landmarks for surgery. The main complications are discussed and physiological basis for indications.

Possible roles of COX-1 in learning and memory impairment induced by traumatic brain injury in mice

People who suffer from traumatic brain injury (TBI) often experience cognitive deficits in spatial reference and working memory. The possible roles of cyclooxygenase-1 (COX-1) in learning and memory impairment in mice with TBI are far from well known. Adult mice subjected to TBI were treated with the COX-1 selective inhibitor SC560. Performance in the open field and on the beam walk was then used to assess motor and behavioral function 1, 3, 7, 14, and 21 days following injury. Acquisition of spatial learning and memory retention was assessed using the Morris water maze on day 15 post-TBI. The expressions of COX-1, prostaglandin E2 (PGE2), interleukin (IL)-6, brain-derived neurotrophic factor (BDNF), platelet-derived growth factor BB (PDGF-BB), synapsin-I, and synaptophysin were detected in TBI mice. Administration of SC560 improved performance of beam walk tasks as well as spatial learning and memory after TBI. SC560 also reduced expressions of inflammatory markers IL-6 and PGE2, and reversed the expressions of COX-1, BDNF, PDGF-BB, synapsin-I, and synaptophysin in TBI mice. The present findings demonstrated that COX-1 might play an important role in cognitive deficits after TBI and that selective COX-1 inhibition should be further investigated as a potential therapeutic approach for TBI.

Possible roles of COX-1 in learning and memory impairment induced by traumatic brain injury in mice.

People who suffer from traumatic brain injury (TBI) often experience cognitive deficits in spatial reference and working memory. The possible roles of cyclooxygenase-1 (COX-1) in learning and memory impairment in mice with TBI are far from well known. Adult mice subjected to TBI were treated with the COX-1 selective inhibitor SC560. Performance in the open field and on the beam walk was then used to assess motor and behavioral function 1, 3, 7, 14, and 21 days following injury. Acquisition of spatial learning and memory retention was assessed using the Morris water maze on day 15 post-TBI. The expressions of COX-1, prostaglandin E2 (PGE2), interleukin (IL)-6, brain-derived neurotrophic factor (BDNF), platelet-derived growth factor BB (PDGF-BB), synapsin-I, and synaptophysin were detected in TBI mice. Administration of SC560 improved performance of beam walk tasks as well as spatial learning and memory after TBI. SC560 also reduced expressions of inflammatory markers IL-6 and PGE2, and reversed the expressions of COX-1, BDNF, PDGF-BB, synapsin-I, and synaptophysin in TBI mice. The present findings demonstrated that COX-1 might play an important role in cognitive deficits after TBI and that selective COX-1 inhibition should be further investigated as a potential therapeutic approach for TBI.

Role of the superior colliculus in the expression of acute and kindled audiogenic seizures in Wistar audiogenic rats.

PURPOSE: The role of the superior colliculus (SC) in seizure expression is controversial and appears to be dependent upon the epilepsy model. This study shows the effect of disconnection between SC deep layers and adjacent tissues in the expression of acute and kindling seizures. METHODS: Subcollicular transections, ablation of SC superficial and deep layers, and ablation of only the cerebral cortex were evaluated in the Wistar audiogenic rat (WAR) strain during acute and kindled audiogenic seizures. The audiogenic seizure kindling protocol started 4 days after surgeries, with two acoustic stimuli per day for 10 days. Acute audiogenic seizures were evaluated by a categorized seizure severity midbrain index (cSI) and kindled seizures by a severity limbic index (LI). RESULTS: All subcollicular transections reaching the deep layers of the SC abolished audiogenic seizures or significantly decreased cSI. In the unlesioned kindled group, a reciprocal relationship between limbic and brainstem pattern of seizures was seen. The increased number of stimuli provoked an audiogenic kindling phenomenon. Ablation of the entire SC (ablation group) or of the cerebral cortex only (ctx-operated group) hampered the acquisition of limbic behaviors. There was no difference in cSI and LI between the ctx-operated and ablation groups, but there was a difference between ctx-operated and the unlesioned kindled group. There was also no difference in cSI between SC deep layer transection and ablation groups. Results of histologic analyses were similar for acute and kindled audiogenic seizure groups. CONCLUSIONS: SC deep layers are involved in the expression of acute and kindled audiogenic seizure, and the cerebral cortex is essential for audiogenic kindling development.

Functional hemispherectomy variant a report of twenty one cases / Functional hemispherectomy variant a report of twenty one cases

Objective and importance: Although Rasmussen´s hemispherectomy is a proven effective technique, the reduction in surgical time and in blood volume los during its performance is crucial. This is achieved by means of the tecnichal variant intended to disconnect instead of to remove the temporal lobe. Clinical representation: We present 21 children operated between 1997 and 2004 in whom a functional hemisfactory (FH) variant was performed. The clinical manifestations included the following crises: hemianopsia, versive crises, abscences, CPC and tonic crises, with secondary generalization in some of the children. Intervention: The proposed variant is a sort of combination of Rasmussen´s hemispherectomy and Delalande´s hemispherectomy, involving disconnection and isolation of the temporal lobe. This is achieved at cortical level by prolonging the incision of the mesial aspect of the occipital lobe by intraventricular route is extended towards the fornix to reach the free border of the cerebellar tentorium. The juncture of both incisions disconnects the neocortex from the temporal lobe, as well as the parahippocampal gyrus and the hippocampus itself. Since aprevious complete callosotomy, a temporal stem section and amigdala suction had been performed, the temporal lobe remains in situ, but nonfunctional. Conclusion: It is the autor conviction that Rasmussen´s hemipherectomy is a valid procedure given its proven efficacy. We believe that the proposed technical variant is particularly useful for neurosurgeons that are in training in the field of epilepsy surgery, as a priori stage to the use of more restricted disconnecting techniques

Functional hemispherectomy variant a report of twenty one cases / Functional hemispherectomy variant a report of twenty one cases

Objective and importance: Although Rasmussen s hemispherectomy is a proven effective technique, the reduction in surgical time and in blood volume los during its performance is crucial. This is achieved by means of the tecnichal variant intended to disconnect instead of to remove the temporal lobe. Clinical representation: We present 21 children operated between 1997 and 2004 in whom a functional hemisfactory (FH) variant was performed. The clinical manifestations included the following crises: hemianopsia, versive crises, abscences, CPC and tonic crises, with secondary generalization in some of the children. Intervention: The proposed variant is a sort of combination of Rasmussen s hemispherectomy and Delalande s hemispherectomy, involving disconnection and isolation of the temporal lobe. This is achieved at cortical level by prolonging the incision of the mesial aspect of the occipital lobe by intraventricular route is extended towards the fornix to reach the free border of the cerebellar tentorium. The juncture of both incisions disconnects the neocortex from the temporal lobe, as well as the parahippocampal gyrus and the hippocampus itself. Since aprevious complete callosotomy, a temporal stem section and amigdala suction had been performed, the temporal lobe remains in situ, but nonfunctional. Conclusion: It is the autor conviction that Rasmussen s hemipherectomy is a valid procedure given its proven efficacy. We believe that the proposed technical variant is particularly useful for neurosurgeons that are in training in the field of epilepsy surgery, as a priori stage to the use of more restricted disconnecting techniques (AU)

Effects of bilateral ablation or 6-OHDA lesion of the frontal cortex upon the behaviors induced by apomorphine and amphetamine in adult cats.

The main aim of this study was to compare the effects of bilateral 6-OHDA lesion of the prefrontal, frontal and media cerebral cortex, with those of suction ablation of the same areas, upon apomorphine and amphetamine evoked behaviors. Twenty five cats were distributed in four groups: 1) 8 cats received bilateral, injection of 6-OHDA (32 micrograms per hemisphere), and the behaviors elicited by separate injection of apomorphine (2.0 mg/kg s.c.) and amphetamine (2.5 mg/kg s.c.) before and after the lesion were compared; 2) 3 cats received a unilateral injection of 6-OHDA into the cited areas and dopamine concentration on the lesioned site and the contralateral non-lesioned side were compared; 3) 8 cats had bilateral suction ablation of the cited cortical areas and the results of apomorphine and amphetamine evoked behaviors before and after ablation were compared, and 4) the effects of solvent injections and sham operations were studied in 6 additional cats. 6-OHDA lesion had scanty effects on the behaviors evoked by apomorphine and amphetamine. Only two (fear like behavior and lack of food motivation) out of 9 behaviors elicited by apomorphine were modified, while two of five behaviors elicited by amphetamine (immobility and food motivation) showed a change. On the other hand, the ablation procedure had a much wider effect on the behaviors elicited by the dopaminergic agonist drugs. All 5 behaviors evoked by amphetamine were modified, while only 4 of nine behaviors induced by apomorphine did change. These results show the importance of the interplay between dopamine and the target tissue that receive the dopaminergic fibers in the production of the behaviors evoked by parenteral injection of apomorphine and amphetamine.

Neuroplasticidad y adaptación funcional del sistema nervioso: aproximación a la anatomía funcional del tronco cerebral / Neuroplasticity and funcional supply of nervous system: aproximation to brain stem funcional anatomy

Se revisa las últimas investigaciones sobre plasticidad neuronal, en relación con el crecimiento dendrítico y la regeneración de los cilindroejes en la suplencia funcional de la corteza cerebral y el sistema estriado en la reorganización de las funciones superiores. Se recuerda la importancia de las funciones del tronco cerebral en el hombre y se propone una nueva sistematización: el Arqui-tronco, en relación a sus funciones vegetativas, el Paleo-tronco, en relación con el hombre y su medio ambiente y el Neo-tronco, cuyas funciones aún desconocemos. En fin, se presenta la observación de una paciente decorticada mediante la evaluación clínica y la resonancia magnética que, sin embargo, mantiene sus funciones de percepción y elaboración de juicios y criterios; la expresión de estos la ejecuta mediante gritos.

Ether and immobilization stress effects on pituitary adrenal function in hemidecorticate rats

Hemidecortication (HD) (left cerebral hemisphere) performed in rats with the aim of analyzing the modulating effect of the cerebral cortex on the hypothalamic-pituitary-adrenal axis. Corticosterone release induced either by or immobilization stress was evaluated in control (C) and HD rats. The percentage increase in corticosterone was greater in HD than in C rats after 15 min of ether stress (HD = 142%, C = 50%) and after 60 min of immobilization stress (HD = 197%, C = 126%). An in vitro test showed that the release of ACTH induced by corticotropin releasing hormone (CRH) from hemipituitary fragments from HD rats was not different from that in control rats. These results suggest an inhibitory effect of the cerebral cortex on the hypothalamus which may modulate the secretion of corticoptropin releasing peptides

Increased susceptibility of detelencephalated rats to audiogenic seizures induced by microinjection of bicuculline into the inferior colliculus.

1. The participation of telencephalic forebrain structures in the induction of audiogenic seizure (AGS) susceptibility and in the behavioral expression of AGS was investigated in rats. 2. Rats that were initially susceptible (N = 12) or non-susceptible (N = 28) to audiogenic seizure were surgically detelencephalated. 3. A unilateral microinjection of a low dose (30 pmol) of the GABA antagonist bicuculline methiodide (BM) was applied to the inferior colliculus (IC) before the animals were exposed to a 120-dB acoustic stimulus. 4. All susceptible rats still exhibited all components of audiogenic seizure after removal of the telencephalon. 5. After BM microinjection, a higher incidence (66% vs 41%) and shorter latencies (6-20 s vs 9-55 s) of occurrence of tonic seizures were observed in the detelencephalated non-susceptible rats when compared to non-operated non-susceptible rats (N = 12). 6. These results suggest that the induction of the behavioural expression of audiogenic seizures is subserved by brain stem neuronal networks but does not require the telencephalon and that telencephalic structures may exert control over audiogenic seizures by inhibiting IC cells through GABAergic neurons.

Ether and immobilization stress effects on pituitary adrenal function in hemidecorticate rats.

Hemidecortication (HD) (left cerebral hemisphere) was performed in rats with the aim of analyzing the modulating effect of the cerebral cortex on the hypothalamic-pituitary-adrenal axis. Corticosterone release induced either by ether or immobilization stress was evaluated in control (C) and HD rats. The percentage increase in corticosterone was greater in HD than in C rats after 15 min of ether stress (HD = 142%, C = 50%) and after 60 min of immobilization stress (HD = 197%, C = 126%). An in vitro test showed that the release of ACTH induced by corticotropin releasing hormone (CRH) from hemipituitary fragments from HD rats was not different from that in control rats. These results suggest an inhibitory effect of the cerebral cortex on the hypothalamus which may modulate the secretion of corticotropin releasing peptides.

Swimming escape learning in rats with telencephalic lesions.

Experiments were conducted to determine whether rats having unilateral or bilateral ablation of either the neocortex or telencephalon can learn to escape from a tank of water by climbing a platform. Hemi- or bilaterally decorticated rats were able to learn the swimming escape task, the same being observed for hemidetelencephalated rats. Fully detelencephalated rats, however, did not exhibit this capability. These results show that integrity of one of the cerebral hemispheres is necessary in order to allow swimming escape learning.

Swimming escape learning in rats with telencephalic lesions

Experiments were conducted to determine whether rats having unilateral or bilateral ablation of either the neocortex or telencephalon can learn to escape from a tank of water by climbing a platform. Hemi - or bilaterally decorticated rats were able to learn the swimming escape task, the same being observed for hemidetelencephalated rats. Fully detelencephalated rats, however, did not exhibit this capability. These results show that integrity of one the cerebral hemispheres is necessary in order to allow swimming escape learning

Increased susceptibility of detelencephalated rats to audiogenic seizures induced by microinjection of bicuculline into the inferior colliculus

The participation of telencephalic forebrain structures in the induction of audiogenic seizure (AGS) susceptibility and in the behavioral expression of AGS was investigated in rats. Rats that were initially susceptible (N = 12) or non-susceptible (N = 28) to audiogenic seizure were surgically detelencephalated. A unilateral microinjection of a low dose (30 pmol) of the GABA antagonist bicuculline methiodide (BM) was applied to the inferior colliculus (IC) before the animals were exposed to a 120-dB acoustic stimulus. All susceptible rats still exhibited all components of audiogenic seizure after removal of the telencephalon. After BM microinjection, a higher incidence (66% vs 41%) and shorter latencies (6-20 s vs 9-55) s) of occurrence of tonic seizures were observed in the detelencephalated non-susceptible rats when compared to non-operated non-susceptible rats(N = 12). These results suggest that the induction of the behavioral expression of audiogenic seizures issubserved by brain stem neuronal networks but does not require the telencephalon and that telencephalic structures may exert control over audiogenic seizures by inhibiting IC cells through GABAergic neurons

Hemisferectomia: modificaçäo técnica / Hemisferectomy: a techinical modification

Os autores relatam uma modificaçäo técnica nas hemisferectomias totais, com intuito de prevenir os sangramentos tardios e distorçöes cerebrais

Thyroid function in hemidecorticate rats.

1. Thyroid function was evaluated in hemidecorticate (HD) and control (C) rats by determining serum T3 and T4 levels and the development of incisors and mandibles and through analysis of various histological features of the thyroid such as follicle size, colloid droplet content and [3H]-glycine uptake by follicular cells. 2. HD animals presented normal levels of circulating T3 but significantly lower T4 levels. 3. There was slight atrophy of the gland in HD animals and fewer colloid droplets were present in the cytoplasm of the follicular cells in this group, indicating a reduction in the breakdown of thyroglobulin. [3H]-glycine uptake by HD indicated that the rate of thyroglobulin biosynthesis was not altered in the experimental animals. 4. The growth of mandibles (weight) and incisors (weight and length) was reduced in HD compared to the control animals. 5. These results suggest that hemidecortication causes mild hypothyroidism (trophoprivic type) probably by affecting hypothalamic function.

Thyroid function in hemidecorticate rats

1. Throid function was evaluated in hemidecorticate (HD) and control (C) rats by determining serum T3 and T4 levels and the development of incisors and mandibles and through analysis of various histological features of the thyroid such as follicle size, colloid droplet content and [3H] - glycine uptake by follicular cells. 2. HD animals presented normal levels of circulating T3 but significantly lower T4 levels. 3. There was slight atrophy of the gland in HD animals and fewer colloid droplets were present in the cytoplasm of the follicular cells in this group, indicating a reduction in the breakdown of thyroglobulin. [3H] - glycine uptake by HD indicated that rate of thyroglobulin biosynthesis was not altered in the experimental animals. 4. the growth of mandibles (weight) and incisors (weight and lenght) was reduced in HD compared to the control animals. 5. These results suggest that hemidecortication causes mild hypothyroidism (trophoprivic type) probably by affecting hypothalamic function