Pattern changes of EEG oscillations and BOLD signals associated with temporal lobe epilepsy as revealed by a working memory task.

BACKGROUND: It is known that the abnormal neural activity in epilepsy may be associated to the reorganization of neural circuits and brain plasticity in various ways. On that basis, we hypothesized that changes in neuronal circuitry due to epilepsy could lead to measurable variations in patterns of both EEG and BOLD signals in patients performing some cognitive task as compared to what would be obtained in normal condition. Thus, the aim of this study was to compare the cerebral areas involved in EEG oscillations versus fMRI signal patterns during a working memory (WM) task in normal controls and patients with refractory mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS). The study included six patients with left MTLE-HS (left-HS group) and seven normal controls (control group) matched to the patients by age and educational level, both groups undergoing a blocked design paradigm based on Sternberg test during separated EEG and fMRI sessions. This test consisted of encoding and maintenance of a variable number of consonant letters on WM. RESULTS: EEG analysis for the encoding period revealed the presence of theta and alpha oscillations in the frontal and parietal areas, respectively. Likewise, fMRI showed the co-occurrence of positive and negative BOLD signals in both brain regions. As for the maintenance period, whereas EEG analysis revealed disappearance of theta oscillation, fMRI showed decrease of positive BOLD in frontal area and increase of negative BOLD in the posterior part of the brain. CONCLUSIONS: Generally speaking, these patterns of electrophysiological and hemodynamic signals were observed for both control and left-HS groups. However, the data also revealed remarkable differences between these groups that are consistent with the hypothesis of reorganization of brain circuitry associated with epilepsy.

Neuropsychiatric symptoms in Alzheimer's disease are related to functional connectivity alterations in the salience network.

Neuropsychiatric syndromes are highly prevalent in Alzheimer's disease (AD), but their neurobiology is not completely understood. New methods in functional magnetic resonance imaging, such as intrinsic functional connectivity or "resting-state" analysis, may help to clarify this issue. Using such approaches, alterations in the default-mode and salience networks (SNs) have been described in Alzheimer's, although their relationship with specific symptoms remains unclear. We therefore carried out resting-state functional connectivity analysis with 20 patients with mild to moderate AD, and correlated their scores on neuropsychiatric inventory syndromes (apathy, hyperactivity, affective syndrome, and psychosis) with maps of connectivity in the default mode network and SN. In addition, we compared network connectivity in these patients with that in 17 healthy elderly control subjects. All analyses were controlled for gray matter density and other potential confounds. Alzheimer's patients showed increased functional connectivity within the SN compared with controls (right anterior cingulate cortex and left medial frontal gyrus), along with reduced functional connectivity in the default-mode network (bilateral precuneus). A correlation between increased connectivity in anterior cingulate cortex and right insula areas of the SN and hyperactivity syndrome (agitation, irritability, aberrant motor behavior, euphoria, and disinhibition) was found. These findings demonstrate an association between specific network changes in AD and particular neuropsychiatric symptom types. This underlines the potential clinical significance of resting state alterations in future diagnosis and therapy.

Brain plasticity for verbal and visual memories in patients with mesial temporal lobe epilepsy and hippocampal sclerosis: an fMRI study.

We aimed to identify the brain areas involved in verbal and visual memory processing in normal controls and patients with unilateral mesial temporal lobe epilepsy (MTLE) associated with unilateral hippocampal sclerosis (HS) by means of functional magnetic resonance imaging (fMRI). The sample comprised nine normal controls, eight patients with right MTLE, and nine patients with left MTLE. All subjects underwent fMRI with verbal and visual memory paradigms, consisting of encoding and immediate recall of 17 abstract words and 17 abstract drawings. A complex network including parietal, temporal, and frontal cortices seems to be involved in verbal memory encoding and retrieval in normal controls. Although similar areas of activation were identified in both patient groups, the extension of such activations was larger in the left-HS group. Patients with left HS also tended to exhibit more bilateral or right lateralized encoding related activations. This finding suggests a functional reorganization of verbal memory processing areas in these patients due to the failure of left MTL system. As regards visual memory encoding and retrieval, our findings support the hypothesis of a more diffuse and bilateral representation of this cognitive function in the brain. Compared to normal controls, encoding in the left-HS group recruited more widespread cortical areas, which were even more widespread in the right-HS group probably to compensate for their right mesial temporal dysfunction. In contrast, the right-HS group exhibited fewer activated areas during immediate recall than the other two groups, probably related to their greater difficulty in dealing with visual memory content.

DTI voxelwise analysis did not differentiate older depressed patients from older subjects without depression.

INTRODUCTION: Neuroimaging has been widely used in studies to investigate depression in the elderly because it is a noninvasive technique, and it allows the detection of structural and functional brain alterations. Fractional anisotropy (FA) and mean diffusivity (MD) are neuroimaging indexes of the microstructural integrity of white matter, which are measured using diffusion tensor imaging (DTI). The aim of this study was to investigate differences in FA or MD in the entire brain without a previously determined region of interest (ROI) between depressed and non-depressed elderly patients. METHOD: Brain magnetic resonance imaging scans were obtained from 47 depressed elderly patients, diagnosed according to DSM-IV criteria, and 36 healthy elderly patients as controls. Voxelwise statistical analysis of FA data was performed using tract-based spatial statistics (TBSS). RESULTS: After controlling for age, no significant differences among FA and MD parameters were observed in the depressed elderly patients. No significant correlations were found between cognitive performance and FA or MD parameters. CONCLUSION: There were no significant differences among FA or MD values between mildly or moderately depressed and non-depressed elderly patients when the brain was analyzed without a previously determined ROI.

White and grey matter abnormalities in patients with SPG11 mutations.

BACKGROUND: Mutations in SPG11 are the most frequent known cause of autosomal recessive hereditary spastic paraplegia. Corpus callosum thinning is a hallmark of the condition but little is known about damage to other structures in the CNS. OBJECTIVE: To evaluate in vivo cerebral damage in patients with SPG11 mutations. METHODS: 5 patients and 15 age and sex matched healthy controls underwent high resolution diffusion tensor imaging (32 directions) and a T1 volumetric (1 mm slices) acquisition protocol in a 3 T scanner (Philips Achieva). These sequences were then analysed through voxel based morphometry (VBM) and tract based spatial statistics (TBSS). RESULTS: Mean age of the patients was 23.6±4.5 years (range 14-45) and mean duration of disease was 12 years (range 5-15). All patients presented with progressive spastic paraplegia and three were already wheelchair bound when first evaluated. Mutations found were: c.529_533delATATT, c.704_705delAT, c.733_734delAT, c.118C>T and c.7256A>G. VBM identified significant grey matter atrophy in both the thalamus and lentiform nuclei. TBSS analyses revealed reduced fractional anisotropy involving symmetrically subcortical white matter of the temporal and frontal lobes, the cingulated gyrus, cuneus, striatum, corpus callosum and brainstem. CONCLUSIONS: Widespread white matter damage in patients with SPG11 mutations has been demonstrated. Grey matter atrophy was prominent in both the thalamus and basal ganglia but not in the cerebral cortex. These findings suggest that neuronal damage/dysfunction is more widespread than previously recognised in this condition.

Partial reversibility of hypothalamic dysfunction and changes in brain activity after body mass reduction in obese subjects.

OBJECTIVE: Inflammation and dysfunction of the hypothalamus are common features of experimental obesity. However, it is unknown whether obesity and massive loss of body mass can modify the immunologic status or the functional activity of the human brain. Therefore, the aim of this study was to determine the effect of body mass reduction on brain functionality. RESEARCH DESIGN AND METHODS: In humans, changes in hypothalamic activity after a meal or glucose intake can be detected by functional magnetic resonance imaging (fMRI). Distinct fMRI analytic methods have been developed to explore changes in the brain's activity in several physiologic and pathologic conditions. We used two analytic methods of fMRI to explore the changes in the brain activity after body mass reduction. RESULTS: Obese patients present distinct functional activity patterns in selected brain regions compared with lean subjects. On massive loss of body mass, after bariatric surgery, increases in the cerebrospinal fluid (CSF) concentrations of interleukin (IL)-10 and IL-6 are accompanied by changes in fMRI patterns, particularly in the hypothalamus. CONCLUSIONS: Massive reduction of body mass promotes a partial reversal of hypothalamic dysfunction and increases anti-inflammatory activity in the CSF.

Neural correlates of lexical-semantic memory: A voxel-based morphometry study in mild AD, aMCI and normal aging.

Neuroanatomical correlations of naming and lexical-semantic memory are not yet fully understood. The most influential approaches share the view that semantic representations reflect the manner in which information has been acquired through perception and action, and that each brain area processes different modalities of semantic representations. Despite these anatomical differences in semantic processing, generalization across different features that have similar semantic significance is one of the main characteristics of human cognition. METHODS: We evaluated the brain regions related to naming, and to the semantic generalization, of visually presented drawings of objects from the Boston Naming Test (BNT), which comprises different categories, such as animals, vegetables, tools, food, and furniture. In order to create a model of lesion method, a sample of 48 subjects presenting with a continuous decline both in cognitive functions, including naming skills, and in grey matter density (GMD) was compared to normal young adults with normal aging, amnestic mild cognitive impairment (aMCI) and mild Alzheimer's disease (AD). Semantic errors on the BNT, as well as naming performance, were correlated with whole brain GMD as measured by voxel-based morphometry (VBM). RESULTS: The areas most strongly related to naming and to semantic errors were the medial temporal structures, thalami, superior and inferior temporal gyri, especially their anterior parts, as well as prefrontal cortices (inferior and superior frontal gyri). CONCLUSION: The possible role of each of these areas in the lexical-semantic networks was discussed, along with their contribution to the models of semantic memory organization.

As correlações neuroanatômicas de nomeação e memória lexical-semântica não são totalmente entendidas. As abordagens mais influentes compartilham a idéia de que representações refletem a maneira na qual a informação foi adquirida por meio da percepção e ação e que cada área do cérebro processa diferentes modalidades de representações semânticas. Apesar destas diferenças anatômicas no processamento semântico, a generalização de diferentes aspectos que tem significância semântica análoga é uma das principais características da cognição humana. MÉTODOS: Nós avaliamos as regiões cerebrais relacionadas à nomeação e à generalização semântica de desenhos de objetos visualmente apresentados do Teste de Nomeação de Boston (TNB), que compreende diferentes categorias, como animais, vegetais, utensílios, comida e móveis. Para criar um modelo de método de lesão, nós investigamos uma amostra de 48 pessoas que demonstraram um declínio contínuo em funções cognitivas, incluindo habilidades de nomeação e em densidade de substância cinzenta (DSC) em relação a adultos jovens: envelhecimento normal, comprometimento cognitivo leve amnéstico (CCLa) e doença de Alzheimer (DA). Nós correlacionamos seus erros semânticos no TNB, assim como seus desempenhos de nomeação, com a DSC de todo o cérebro que foi medido por morfometria baseada em vóxel (MBV). RESULTADOS: As áreas que mais se relacionaram à nomeação e aos erros semânticos foram as estruturas mediais temporais, tálamo, giro temporal superior e inferior, especialmente em suas partes anteriores e os córtices pré-frontais (giro frontal inferior e superior). CONCLUSÃO: Discutimos o provável papel de cada uma dessas áreas na rede lexical-semântica e sua contribuição para os modelos de organização semântica.

Asymmetrical hippocampal connectivity in mesial temporal lobe epilepsy: evidence from resting state fMRI.

BACKGROUND: Mesial temporal lobe epilepsy (MTLE), the most common type of focal epilepsy in adults, is often caused by hippocampal sclerosis (HS). Patients with HS usually present memory dysfunction, which is material-specific according to the hemisphere involved and has been correlated to the degree of HS as measured by postoperative histopathology as well as by the degree of hippocampal atrophy on magnetic resonance imaging (MRI). Verbal memory is mostly affected by left-sided HS, whereas visuo-spatial memory is more affected by right HS. Some of these impairments may be related to abnormalities of the network in which individual hippocampus takes part. Functional connectivity can play an important role to understand how the hippocampi interact with other brain areas. It can be estimated via functional Magnetic Resonance Imaging (fMRI) resting state experiments by evaluating patterns of functional networks. In this study, we investigated the functional connectivity patterns of 9 control subjects, 9 patients with right MTLE and 9 patients with left MTLE. RESULTS: We detected differences in functional connectivity within and between hippocampi in patients with unilateral MTLE associated with ipsilateral HS by resting state fMRI. Functional connectivity resulted to be more impaired ipsilateral to the seizure focus in both patient groups when compared to control subjects. This effect was even more pronounced for the left MTLE group. CONCLUSIONS: The findings presented here suggest that left HS causes more reduction of functional connectivity than right HS in subjects with left hemisphere dominance for language.

Long term follow up of familial mesial temporal lobe epilepsy / Evolução da epilepsia de lobo temporal mesial familiar

OBJECTIVE: To analyze seizure outcome in individuals with familial mesial temporal lobe epilepsy (FMTLE). METHOD: We followed prospectively 64 individuals with FMTLE and 37 asymptomatic individuals belonging to 28 families. RESULTS: Patients with FMTLE had a mean follow up was 93.4 ± 15.8 months. At baseline they were divided in benign (n = 29), remission (n = 28) and refractory (n = 7). At last follow up visit 41.4 percent patients with benign FMTLE remained classified as benign, 20.7 percent became refractory and 37.9 percent were in remission. In the subgroup of FMTLE in remission 21 75 percent remained without seizures; 21.4 percent were classified as benign FMTLE, and one died (3.6 percent) from cause unrelated to epilepsy. All refractory patients remained refractory. From the asymptomatic group, 10.8 percent became symptomatic (FMTLE). The mean follow up was 76.0 ± 21.2 months. CONCLUSION: Prospective follow up of more than 7 years in patients with FMTLE revealed that it is unlikely to achieve seizure control in those with refractory seizures. Patients with diagnose of more benign forms of FMTLE for more than one year are likely to either remit or remain under well controlled seizures. The majority of patients who had achieved seizure remission remained seizure-free and none became refractory. Asymptomatic individuals had a greater probability to have seizures compared to the general population in a 6 year period of follow up.

OBJETIVOS: Analisar a evolução de famílias com epilepsia de lobo temporal mesial familiar (ELTMF). METODOLOGIA: Seguimento prospectivo de 64 pacientes com ELTMF e 37 membros assintomáticos pertencente a 28 famílias. RESULTADOS: A média de seguimento dos pacientes com ELTMF foi de 93,4 ± 15,8 meses. Na avaliação inicial os pacientes foram divididos em benignos (n = 29), remissão (n = 28) e refratários (n = 7). Na última visita disponível, 41,4 por cento dos pacientes com ELTMF benigna permaneceram classificados como benignos, 20,7 por cento tornaram-se refratários e 37,9 por cento entraram em remissão. No grupo em remissão, 75 por cento permaneceram livres de crise, 21,4 por cento foram classificados como benignos e um faleceu (3,6 por cento) de causa não relacionada à epilepsia. Todos pacientes refratários permaneceram refratários. Em relação aos assintomáticos 10,8 por cento evoluíram com crises. A média de seguimento dos assintomáticos foi de 76,0 ± 21,2 meses. CONCLUSÃO: O seguimento prospectivo de mais de 7 anos de pacientes com ELTMF revelou que é improvável ocorrer controle de crises no grupo refratário. No grupo benigno é muito provável que estes indivíduos entrem em remissão ou permaneçam com evolução benigna. A maioria dos pacientes do grupo em remissão permaneceu em remissão e nenhum se tornou refratário. Em relação aos assintomáticos a probabilidade de apresentar uma crise no decorrer de aproximadamente 6 anos foi maior que o observado na população geral.

Transcription of succinate dehydrogenase subunit 4 (sdh4) gene in potato: detection of extensive RNA editing and co-transcription with cytochrome oxidase subunit III (cox3) gene.

The potato (Solanum tuberosum L.) mitochondrial cox3/ sdh4 gene cluster was previously identified by heterologous hybridization using a Marchantia polymorpha sdh4 probe. In this work, this potato gene cluster was cloned, sequenced and its expression was evaluated. The gene sequence and gene locus organization were found to be similar to the corresponding gene cluster in other dicot species, where known. Northern hybridizations with potato and cauliflower (Brassica oleraceae) mtRNA and RT-PCR analyses using potato mtRNA indicated that cox3 and sdh4 are co-transcribed in both species, generating a complex transcription pattern, where several transcripts from 1.1 kb to 4.4 kb are found. The potato transcript from this cluster displayed 14 and 13 RNA-editing sites, in the cox3 and sdh4 genes respectively, which changed the codon identity to amino acids and created a sdh4 partially edited stop codon. Forty-three cDNA clones were analyzed for editing process and revealed different partial-editing with no apparent sequential processing in the sdh4 gene.