Temporal Lobe Epileptic Patients Research Articles

Performance Assessment of Presurgical Tests in Temporal Lobe Epileptic Patients

Performance Assessment of Presurgical Tests in Temporal Lobe Epileptic Patients

Focal Epileptic Area Recognition Employing Cross EEG Rhythm Spectrum Images and Convolutional Neural Network

Accurate detection of focal seizure area through EEG screening is important to remove the affected regions of human brain, prior to surgery. Considering the aforesaid fact, in this paper, we propose a novel approach for automated detection and classification of focal electroencephalography (EEG) signals. In this contribution, we procured the focal and non focal EEG signals recorded from the temporal lobe epileptic patients and decomposed the recorded EEG data into several brain rhythms to obtain their time variation of different neural oscillations. Then, we selected a random EEG signal from each rhythm as a reference and performed cross wavelet transform (XWT) of the rest of the EEG rhythms with their respective chosen reference rhythms to examine their nature of correlation in both time scale and time-frequency frame. Finally, the obtained cross-rhythm spectrum time-frequency image plots were fed to a customized CNN model for the purpose of automated feature extraction and classification of EEG signals. The performance of the proposed CNN model was also compared with two pre-trained benchmark CNN models namely AlexNet and VGGNet16, respectively. We observed that the proposed EEG signal classification framework has delivered 100% accuracy for the delta ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\delta$ </tex-math></inline-formula> ) rhythm and that too at a significantly reduced training time compared to the existing state-of-the-art CNN models. Interestingly, the detection accuracy was also found to be the highest for a particular EEG rhythm, which can be proven useful in real time analysis for accurate diagnosis of focal epilepsy.

Quantitative electrocorticographic biomarkers of clinical outcomes in mesial temporal lobe epileptic patients treated with the RNS® system

ObjectivesFind interictal electrocorticographic (ECoG) biomarkers of clinical outcomes in mesiotemporal lobe (MTL) epilepsy patients. MethodsIn the NeuroPace® RNS® System clinical trials with 256 patients, 20 MTL patients with the most reduction in clinical seizures at Year 7 compared to baseline (upper response quartile; −96.5% median change) and 20 with the least reduction in clinical seizures (lower response quartile; −17.4% median change) were evaluated. Clinical and interictal ECoG features from the two response quartiles were compared. ResultsDemographic and clinical features were similar in the upper and lower response quartiles. Interictal spike rate (ISR) was substantially lower (p < 0.0001) in the upper quartile patients, while normalized theta (4–8 Hz) and normalized gamma (>25 Hz) were also different (p < 0.05) between the two response quartiles. ISR was positively correlated (p < 0.05) with clinical seizure rates in 71% of the channels analyzed. ECoG records captured during months with no clinical seizures had the lowest ISR. ConclusionsISR is a strong differentiator of clinical response in MTL patients. Normalized theta and gamma also differentiates clinical response. SignificanceIn MTL patients, the interictal spike rate along with spectral power computed from chronic ambulatory baseline ECoGs may serve as biomarkers of clinical outcomes and maybe used as treatment endpoints.

Hippocampal neuron loss and astrogliosis in medial temporal lobe epileptic patients with mental disorders.

Hippocampal neuron loss and reactive astrogliosis are pathological features of medial temporal lobe epilepsy. Here, the expression of hippocampal astrogliosis-associated genes are studied in subjects with medial temporal lobe epilepsy and mental disorders (such as depression, anxiety and psychiatric comorbidities). The relationship between functional changes in hippocampus astrocytes and concurrent mental disorders are discussed. Nissl staining identified medial temporal lobe epilepsy-induced neuronal loss in the CA1 region of hippocampus. Quantitative real-time polymerase chain reaction and immunofluorescence technology were used to detect hippocampus glial fibrillary acidic protein, metallothionein, and aquaporin-4. The hippocampus area of subjects with medial temporal lobe epilepsy (with or without mental disorders) were smaller than the control group. Hippocampal neuronal loss and astrogliosis were more obvious in groups of medial temporal lobe epileptic patients with mental disorders. Relative protein levels of glial fibrillary acidic protein, metallothionein-I/II, and aquaporin-4 were significantly higher in subjects with medial temporal lobe epilepsy than seen in controls. Medial temporal lobe epileptic patients with mental disorder or depression had elevated metallothionein-I/II protein level when compared to controls and medial temporal lobe epileptic patients without mental disorder. Protein levels of glial fibrillary acidic protein and aquaporin-4 in medial temporal lobe epileptic patients with mental disorders were significantly lower than that in medial temporal lobe epileptic patients with no mental disorder. It is concluded that functional changes in hippocampus astrocytes are associated with mental disorders in medial temporal lobe epileptic patients and the astrogliosis-related genes of glial fibrillary acidic protein, metallothionein-I/II and aquaporin-4, are involved in this process.

Seizure evolution can be characterized as path through synaptic gain space of a neural mass model.

Physiologically based models could facilitate better understanding of mechanisms underlying epileptic seizures. In this paper, we attempt to reveal the dynamic evolution of intracranial EEG activity during epileptic seizures based on synaptic gain identification procedure of a neural mass model. The distribution of average excitatory, slow and fast inhibitory synaptic gain in the parameter space and their temporal evolution, i.e., the path through the model parameter space, were analyzed in thirty seizures from ten temporal lobe epileptic patients. Results showed that the synaptic gain values located roughly on a plane before seizure onset, dispersed during seizure and returned to the plane when seizure terminated. Cluster analysis was performed on seizure paths and demonstrated consistency in synaptic gain evolution across different seizures from the individual patient. Furthermore, two patient groups were identified, each one corresponding to a specific synaptic gain evolution in the parameter space during a seizure. Results were validated by a bootstrapping approach based on comparison with random paths. The differences in the path revealed variations in EEG dynamics for patients despite showing identical seizure onset pattern. Our approach may have the potential to classify the epileptic patients into subgroups based on different mechanisms revealed by subtle changes in synaptic gains and further enable more robust decisions regarding treatment strategy.

Follow-Up of Peripheral IL-1β and IL-6 and Relation with Apoptotic Death in Drug-Resistant Temporal Lobe Epilepsy Patients Submitted to Surgery.

Increasing amounts of evidence support the role of inflammation in epilepsy. This study was done to evaluate serum follow-up of IL-1β and IL-6 levels, as well as their concentration in the neocortex, and the relationship of central inflammation with NF-κB and annexin V in drug-resistant temporal lobe epileptic (DRTLE) patients submitted to surgical treatment. Peripheral and central levels of IL-1β and IL-6were measured by ELISA in 10 DRTLE patients. The sera from patients were taken before surgery, and 12 and 24 months after surgical treatment. The neocortical expression of NF-κB was evaluated by western blotting and annexin V co-localization with synaptophysin by immunohistochemistry. The neocortical tissues from five patients who died by non-neurological causes were used as control. Decreased serum levels of IL-1 and IL-6 were observed after surgery; at this time, 70% of patients were seizure-free. No values of IL-1 and IL-6 were detected in neocortical control tissue, whereas cytokine levels were evidenced in DRTLE. Increased NF-κB neocortex expression was found and the positive annexin V neurons were more obvious in the DRTLE tissue, correlating with IL-6 levels. The follow-up study confirmed that the inflammatory alterations disappeared one year after surgery, when the majority of patients were seizure-free, and the apoptotic death process correlated with inflammation.

Unraveling the Role of the Hippocampus in Reversal Learning.

Research in reversal learning has mainly focused on the functional role of dopamine and striatal structures in driving behavior on the basis of classic reinforcement learning mechanisms. However, recent evidence indicates that, beyond classic reinforcement learning adaptations, individuals may also learn the inherent task structure and anticipate the occurrence of reversals. A candidate structure to support such task representation is the hippocampus, which might create a flexible representation of the environment that can be adaptively applied to goal-directed behavior. To investigate the functional role of the hippocampus in the implementation of anticipatory strategies in reversal learning, we first studied, in 20 healthy individuals (11 women), whether the gray matter anatomy and volume of the hippocampus were related to anticipatory strategies in a reversal learning task. Second, we tested 20 refractory temporal lobe epileptic patients (11 women) with unilateral hippocampal sclerosis, who served as a hippocampal lesion model. Our results indicate that healthy participants were able to learn the task structure and use it to guide their behavior and optimize their performance. Participants' ability to adopt anticipatory strategies correlated with the gray matter volume of the hippocampus. In contrast, hippocampal patients were unable to grasp the higher-order structure of the task with the same success than controls. Present results indicate that the hippocampus is necessary to respond in an appropriately flexible manner to high-order environments, and disruptions in this structure can render behavior habitual and inflexible.SIGNIFICANCE STATEMENT Understanding the neural substrates involved in reversal learning has provoked a great deal of interest in the last years. Studies with nonhuman primates have shown that, through repetition, individuals are able to anticipate the occurrence of reversals and, thus, adjust their behavior accordingly. The present investigation is devoted to know the role of the hippocampus in such strategies. Importantly, our findings evidence that the hippocampus is necessary to anticipate the occurrence of reversals, and disruptions in this structure can render behavior habitual and inflexible.

Synaptic Reorganization of the Perisomatic Inhibitory Network in Hippocampi of Temporal Lobe Epileptic Patients

GABAergic inhibition and particularly perisomatic inhibition play a crucial role in controlling the firing properties of large principal cell populations. Furthermore, GABAergic network is a key element in the therapy attempting to reduce epileptic activity. Here, we present a review showing the synaptic changes of perisomatic inhibitory neuronal subtypes in the hippocampus of temporal lobe epileptic patients, including parvalbumin- (PV-) containing and cannabinoid Type 1 (CB1) receptor-expressing (and mainly cholecystokinin-positive) perisomatic inhibitory cells, known to control hippocampal synchronies. We have examined the synaptic input of principal cells in the dentate gyrus and Cornu Ammonis region in human control and epileptic hippocampi. Perisomatic inhibitory terminals establishing symmetric synapses were found to be sprouted in the dentate gyrus. Preservation of perisomatic input was found in the Cornu Ammonis 1 and Cornu Ammonis 2 regions, as long as pyramidal cells are present. Higher density of CB1-immunostained terminals was found in the epileptic hippocampus of sclerotic patients, especially in the dentate gyrus. We concluded that both types of (PV- and GABAergic CB1-containing) perisomatic inhibitory cells are mainly preserved or showed sprouting in epileptic samples. The enhanced perisomatic inhibitory signaling may increase principal cell synchronization and contribute to generation of epileptic seizures and interictal spikes.

Preserved anterograde and remote memory in drug-responsive temporal lobe epileptic patients

PurposeTo investigate cognition, particularly anterograde and remote memory, in patients suffering from unilateral drug-responsive mesial temporal lobe epilepsy (mTLE) patients and to compare their performance with that observed in drug-resistant mTLE patients. MethodsSixteen drug-responsive mTLE patients, with only infrequent seizures in their lifetime, were matched for demographic and clinical variables to 18 patients suffering from drug-resistant unilateral mTLE. A comprehensive neuropsychological examination, including baseline, anterograde memory tasks, and a large range of remote memory tests was carried out. ResultsPatients with drug-responsive epilepsy obtained average scores on every anterograde memory test. Although in general, they obtained lower scores than the healthy controls on remote memory tests, the differences failed to reach significance. Moreover, the drug-responsive group performed significantly better than the drug-resistant group on anterograde recall tests and an episodic autobiographical memory test. Performance was not significantly different between the patient groups in personal semantics or memory for public events. ConclusionOur results show that a mild clinical course of mTLE with no cognitive deficits can occur notwithstanding hippocampal sclerosis. The differences in cognitive function between the two groups are likely due to distinct pathophysiology of the underlying cause of epilepsy. Drug-resistant seizures and cognitive deficits may be the consequence of a more severe underlying cerebral process. Better understanding of the variety of pathogenesis of mTLE could help to answer this open question.

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4-Aminopyridine (4AP, 50 μM) induces interictal- and ictal-like discharges in brain slices including parahippocampal areas such as the entorhinal cortex (EC) but the relation between these two types of epileptiform activity remains undifined. Here, by employing field potential recordings in rat EC slices during 4AP application, we found that: (i) interictal events have a wide range of duration (0.4–3.3 s) and interval of occurrence (1.4–84 s); (ii) ictal discharges are either preceded by an isolated “slow” interictal discharge (ISID; duration = 1.5 ± 0.1 s, interval of occurrence = 33.8 ± 1.8 s) or suddenly initiate from a pattern of frequent polispike interictal discharge (FPID; duration = 0.8 ± 0.1 s; interval of occurrence = 2.7 ± 0.2 s); and (iii) ISID-triggered ictal events have longer duration (116 ± 7.3 s) and interval of occurrence (425.8 ± 42.3 s) than those initiating suddenly during FPID (58.3 ± 7.8 s and 202.1 ± 21.8 s, respectively). Glutamatergic receptor antagonists abolished ictal discharges in all experiments, markedly reduced FPIDs but did not influence ISIDs. We also discovered that high-frequency oscillations (HFOs, 80–500 Hz) occur more frequently during ISIDs as compared to FPIDs, and mainly coincide with the onset of ISID-triggered ictal discharges. These findings indicate that interictal events may define ictal onset features resembling those seen in vivo in low-voltage fast activity onset seizures. We propose a similar condition to occur in vivo in temporal lobe epileptic patients and animal models.

Hippocampus-Dependent Strengthening of Targeted Memories via Reactivation during Sleep in Humans

Recent accumulating evidence in animals and humans has shown that memory strengthening occurs, at least partially, during sleep and relies on the covert reactivation of individual memory episodes. However, it remains to be determined whether the hippocampus critically promotes memory consolidation via the reactivation of individual memories during sleep. To investigate the hippocampal-dependent nature of this phenomenon in humans, we selected two groups of chronic temporal lobe epileptic (TLE) patients with selective unilateral (TLE+UHS) or bilateral (TLE+BHS) hippocampal sclerosis and a group of matched healthy controls, and we requested them to learn the association of sounds cueing the appearance of words. On the basis of other similar behavioral paradigms in healthy populations, sounds that cued only half of the learned memories were presented again during the slow-wave sleep stage (SWS) at night, thus promoting memory reactivation of a select set of encoded episodes. A memory test administered on the subsequent day showed that the strengthening of reactivated memories was observed only in the control subjects and TLE+UHS patients. Importantly, the amount of memory strengthening was predicted by the volume of spared hippocampus. Thus, the greater the structural integrity of the hippocampus, the higher the degree of memory benefit driven by memory reactivation. Finally, sleep-specific neurophysiological responses, such as spindles and slow waves, differed between the sample groups, and the spindle density during SWS predicted the degree of memory benefit observed on day 2. Taken together, these findings demonstrate that the hippocampus plays a crucial role in the consolidation of memories via covert reactivation during sleep.

Tenidap, an agonist of the inwardly rectifying K+ channel Kir2·3, delays the onset of cortical epileptiform activity in a model of chronic temporal lobe epilepsy

Objective: Inwardly rectifying K+ (Kir) channel, Kir2·3, has been found down-regulated in the hippocampus of chronic temporal lobe epileptic (cTLE) patients which may underline the mechanism of epilepsy. Tenidap is an agonist of Kir2·3. However, the effect of tenidap on cTLE remains obscure. The aim of the present study was to observe the relationship between Kir2·3 and the pathogenesis of cTLE, and to explore the potential effect of Kir agonists as anti-epileptic drugs.Methods: The pilocarpine temporal lobe epilepsy (TLE) rat model was established and status epilepticus (SE) was induced in rats. The rats were divided into four groups based on time points (0 hours, 6 hours, 72 hours, and two weeks) after SE termination. The dynamic changes in Kir2·3 mRNA and protein expression in the hippocampus were detected at each time point by reverse transcription polymerase chain reaction (RT-PCR) and western blotting to determine an appropriate time for further intervention and observation. Then, tenidap was administered and its effect on the expression of Kir2·3 mRNA/protein and the electroencephalogram (EEG) wave was documented at predetermined time points.Results: The pattern of Kir2·3 mRNA and protein expression was bimodal, as it increased immediately after SE and declined at two weeks, when compared with the control group. Down-regulation of the Kir channels may lead to an impaired clearance of K+ ions from the extracellular space and result in a stronger neuronal depolarisation. Two weeks after SE may be a reversal point. Spontaneous recurrent seizures (SRS) appeared at the two-week point, indicating that chronic epilepsy had occurred. Tenidap up-regulated expressions of both Kir2·3 channel mRNA and protein, which may help to maintain the resting membrane potential (RMP) and hyperpolarisation of the cells.Conclusions: Our results suggest that the down-regulation of the Kir2·3 channel expression might contribute to the pathogenesis of TLE, which may be ameliorated by the administration of tenidap.

Two different interictal spike patterns anticipate ictal activity in vitro

4-Aminopyridine (4AP, 50μM) induces interictal- and ictal-like discharges in brain slices including parahippocampal areas such as the entorhinal cortex (EC) but the relation between these two types of epileptiform activity remains undifined. Here, by employing field potential recordings in rat EC slices during 4AP application, we found that: (i) interictal events have a wide range of duration (0.4–3.3s) and interval of occurrence (1.4–84s); (ii) ictal discharges are either preceded by an isolated “slow” interictal discharge (ISID; duration=1.5±0.1s, interval of occurrence=33.8±1.8s) or suddenly initiate from a pattern of frequent polispike interictal discharge (FPID; duration=0.8±0.1s; interval of occurrence=2.7±0.2s); and (iii) ISID-triggered ictal events have longer duration (116±7.3s) and interval of occurrence (425.8±42.3s) than those initiating suddenly during FPID (58.3±7.8s and 202.1±21.8s, respectively). Glutamatergic receptor antagonists abolished ictal discharges in all experiments, markedly reduced FPIDs but did not influence ISIDs. We also discovered that high-frequency oscillations (HFOs, 80–500Hz) occur more frequently during ISIDs as compared to FPIDs, and mainly coincide with the onset of ISID-triggered ictal discharges. These findings indicate that interictal events may define ictal onset features resembling those seen in vivo in low-voltage fast activity onset seizures. We propose a similar condition to occur in vivo in temporal lobe epileptic patients and animal models.

Impaired mesial synchronization in temporal lobe epilepsy

Objective Temporal lobe epilepsy is commonly associated with synchronous, hyper-synchronous and des-synchronous activity. The aim of the present work is to explore synchronization activity in both mesial areas in temporal lobe epileptic patients during the interictal state. Methods Using a cluster technique, we analyzed 17 temporal lobe epilepsy patients’ records of foramen ovale electrodes activity during the inter-ictal state. Results There exists a clear tendency in the mesial area of the epileptic side to be organized as isolated clusters of electrical activity as compared with the contra-lateral side, which is organized in the form of large clusters of synchronous activity. The number of desynchronized areas is larger in the epileptic side than in the contra-lateral side in 16 out of 17 temporal lobe epileptic patients. Conclusions The mesial area responsible for the seizures is less synchronous than the contra-lateral; the different kind of synchronous organization accounts for a lower synchronization activity at the epileptic side, suggesting that this lack of synchronous cluster organization would favour the appearance of seizures. Significance Our results shed new light regarding synchronization issues in temporal lobe epilepsy and also it would help in reducing drastically the time of study.

Comparison between two scoring systems of the Rey–Osterrieth Complex Figure in left and right temporal lobe epileptic patients

The Rey–Osterrieth Complex Figure (ROCF) is probably one of the most popular measurement instruments of visuoconstructional abilities and nonverbal memory. It is frequently part of neuropsychological test protocols in epilepsy surgery centers. In this study we compared the traditional scoring system of the ROCF developed by Taylor (1998) with a qualitative system that assesses spatial-relational errors devised by Loring et al. [Loring, D. W., Lee, G. P., & Meador, K. J. (1988). Revising the Rey–Osterrieth: Rating right hemisphere recall. Archives of Clinical Neuropsychology, 3, 239–247] in a sample of left and right temporal lobe epilepsy patients undergoing pre-surgical evaluation. We investigated whether the relational-spatial scoring system would be more sensitive to right-sided memory deficits than the traditional Taylor version. There was no difference in the copy phase of the ROCF between the clinical and control groups. There was a significant difference between the control and the clinical groups when the 30-min delayed recall drawings were scored with the Taylor system. However, this system failed to find differences between left and right temporal lobe epileptic patients. On the other hand, comparisons with the qualitative scoring criteria used by Loring et al. [Loring, D. W., Lee, G. P., & Meador, K. J. (1988). Revising the Rey–Osterrieth: Rating right hemisphere recall. Archives of Clinical Neuropsychology, 3, 239–247] revealed that right temporal lobe patients made more spatial-relational errors than patients with left-sided foci. Frequency distribution of these scores for all the three groups and sensitivity and specificity to correctly classify right temporal lobe patients are presented. This investigation demonstrated that applying qualitative, material-specific scoring criteria improves temporal lobe epilepsy presurgical protocols.

Morphology and synaptic input of substance P receptor-immunoreactive interneurons in control and epileptic human hippocampus

Substance P (SP) is known to be a peptide that facilitates epileptic activity of principal cells in the hippocampus. Paradoxically, in other models, it was found to be protective against seizures by activating substance P receptor (SPR)-expressing interneurons. Thus, these cells appear to play an important role in the generation and regulation of epileptic seizures. The number, distribution, morphological features and input characteristics of SPR-immunoreactive cells were analyzed in surgically removed hippocampi of 28 temporal lobe epileptic patients and eight control hippocampi in order to examine their changes in epileptic tissues. SPR is expressed in a subset of inhibitory cells in the control human hippocampus, they are multipolar interneurons with smooth dendrites, present in all hippocampal subfields. This cell population is considerably different from SPR-positive cells of the rat hippocampus. The CA1 (cornu Ammonis subfield 1) region was chosen for the detailed morphological analysis of the SPR-immunoreactive cells because of its extreme vulnerability in epilepsy. The presence of various neurochemical markers identifies functionally distinct interneuron types, such as those responsible for perisomatic, dendritic or interneuron-selective inhibition. We found considerable colocalization of SPR with calbindin but not with parvalbumin, calretinin, cholecystokinin and somatostatin, therefore we suppose that SPR-positive cells participate mainly in dendritic inhibition. In the non-sclerotic CA1 region they are mainly preserved, whereas their number is decreased in the sclerotic cases. In the epileptic samples their morphology is considerably altered, they possessed more dendritic branches, which often became beaded. Analyses of synaptic coverage revealed that the ratio of symmetric synaptic input of SPR-immunoreactive cells has increased in epileptic samples. Our results suggest that SPR-positive cells are preserved while principal cells are present in the CA1 region, but show reactive changes in epilepsy including intense branching and growth of their dendritic arborization.

Association between the M129V variant allele of PRNP gene and mild temporal lobe epilepsy in women

Specific variations in the prion protein gene (PRNP) are associated with, and prevalent in patients with intractable temporal lobe epilepsy (TLE) and influence the surgical outcome. We investigated whether or not the PRNP gene is a susceptibility gene in temporal lobe epileptic patients with mild epilepsy. We systematically screened the entire open reading frame of the PRNP gene and evaluated the genetic contribution of the functional PRNP M129V polymorphism in 289 patients with mild TLE compared with a neurologically unaffected age and sex matched control group (n=272). Statistical analysis revealed a moderate difference in the distribution at codon 129 of the PRNP gene between sporadic mild TLE patients and healthy controls (p=0.036; OR=1.30; 95% CI=1.01-1.68). Although, there was no statistically significant difference in the genotype distribution within the study groups (p=0.101), a further analysis showed that the 129V allele was highly represented only in women with TLE compared with control group (p=0.006, OR=1.632; 95%CI=1.15-2.31). This is the first publication of data that support the hypothesis that the common methionine/valine polymorphism at codon 129 of the PRNP gene may modify the susceptibility of women to mild TLE.

Verbal memory compensation: Application to left and right temporal lobe epileptic patients

This study investigates the compensatory impact of cognitive aids on left and right temporal lobe epileptic patients suffering from verbal memory disorders, who were candidates for surgery. Cognitive aids are defined in the levels-of-processing framework and deal with the depth of encoding, the elaboration of information, and the use of retrieval cues. Results indicate differential compensatory impact for left and right epileptic patients and are discussed according to the HERA model and the compensation framework.

Effects of gap junction blockers on human neocortical synchronization

Field potentials and intracellular recordings were obtained from human neocortical slices to study the role of gap junctions (GJ) in neuronal network synchronization. First, we examined the effects of GJ blockers (i.e., carbenoxolone, octanol, quinine, and quinidine) on the spontaneous synchronous events (duration = 0.2-1.1 s; intervals of occurrence = 3-27 s) generated by neocortical slices obtained from temporal lobe epileptic patients during application of 4-aminopyridine (4AP, 50 muM) and glutamatergic receptor antagonists. The synchronicity of these potentials (recorded at distances up to 5 mm) was decreased by GJ blockers within 20 min of application, while prolonged GJ blockers treatment at higher doses made them disappear with different time courses. Second, we found that slices from patients with focal cortical dysplasia (FCD) could generate in normal medium spontaneous synchronous discharges (duration = 0.4-8 s; intervals of occurrence = 0.5-90 s) that were (i) abolished by NMDA receptor antagonists and (ii) slowed down by carbenoxolone. Finally, octanol or carbenoxolone blocked 4AP-induced ictal-like discharges (duration = up to 35 s) in FCD slices. These data indicate that GJ play a role in synchronizing human neocortical networks and may implement epileptiform activity in FCD.

Efecto diferencial de la lobectomía temporal izquierda y derecha sobre el reconocimiento y la experiencia emocional en pacientes con epilepsia

Temporal lobe and amygdala are structures that participate in emotional processing. The purpose of this study was to determine the differential effect of left (LTL) and right (RTL) temporal lobectomy on emotional recognition and experience as well as mood in treatment resistant epileptics who were evaluated pre and post-surgically. Five temporal lobe epileptic patients participated in the study (two from the right and three from the left hemisphere) who were evaluated before and after three months of the surgery. Emotional and prosodic recognition were evaluated, inside and outside of a social context, with and without time limit. Besides, subjective emotional experience while seeing movie fragments was evaluated as well as positive and negative emotional states, anxiety and depression. After the surgery, patients with RTL had lower number of correct responses in fear facial and prosodic recognition, while patients with LTL did not show deterioration or they even improved. There were not differences as a function of the intervened hemisphere neither in the intensity of emotions perceived in the scenes, nor in the emotional experience, however, both groups experienced a decrease of negative emotions and anxiety. The results suggest that RTL had a greater effect on emotional recognition outside of a context and with limited time than LTL, while in the emotional experience there were not differences between groups. Lobectomy induced an improvement on affective states.