Depression and temporal lobe epilepsy represent an epiphenomenon sharing similar neural networks: clinical and brain structural evidences / Depressão e epilepsia de lobo temporal representam um epifenômeno compartilhando redes neurais similares: evidências clínicas e de neuroimagem estrutural

The relationship between depression and epilepsy has been known since ancient times, however, to date, it is not fully understood. The prevalence of psychiatric disorders in persons with epilepsy is high compared to general population. It is assumed that the rate of depression ranges from 20 to 55% in patients with refractory epilepsy, especially considering those with temporal lobe epilepsy caused by mesial temporal sclerosis. Temporal lobe epilepsy is a good biological model to understand the common structural basis between depression and epilepsy. Interestingly, mesial temporal lobe epilepsy and depression share a similar neurocircuitry involving: temporal lobes with hippocampus, amygdala and entorhinal and neocortical cortex; the frontal lobes with cingulate gyrus; subcortical structures, such as basal ganglia and thalamus; and the connecting pathways. We provide clinical and brain structural evidences that depression and epilepsy represent an epiphenomenon sharing similar neural networks.

A relação entre depressão e epilepsia é conhecida desde a antiguidade; entretanto, até o momento, não é completamente compreendida. A prevalência de transtornos psiquiátricos nas pessoas com epilepsia é elevada quando comparada à população em geral. A taxa de depressão varia de 20 a 55% nos pacientes com epilepsia refratária, especialmente considerando-se aqueles com epilepsia do lobo temporal causada por esclerose mesial temporal. A epilepsia do lobo temporal é um bom modelo biológico para compreender as bases estruturais comuns entre a epilepsia e a depressão. É relevante ressaltar que a epilepsia do lobo mesial e a depressão apresentam circuitos similares envolvendo: os lobos temporais com o hipocampo, a amigdala, o córtex entorrinal e o neocortex; os lobos frontais com o giro cíngulo; estruturas subcorticais, como os núcleos da base e o tálamo, e suas vias de conexão. Postulamos por meio de evidências clínicas e estruturais que a depressão e a epilepsia representam um epifenômeno com redes neuronais similares.

Red neural por defecto y enfermedad de Alzheimer / Default mode network and Alzheimer's disease

Brainfunctioning is mainly intrinsic, notprimarily reflexive. This is supported by the high energy requirements ofthe resting brain (20% ofall the energy consumed) which only marginally increases with changes in brain activity. Modern neuroimaging and neurophysiological techniques have led to the discovery of the so called brain default mode network (DMN), a constellation of brain regions which support brain activity at rest and whose discharges decrease during task-induced activities. Another characteristic ofthe DMN are the elevated levéis of aerobic glycolysis (Warburg effect), that is, metabolism ofglucose to lactic acid in thepresence ofsufficient levéis ofoxygen. In Alzheimer's disease there is amyloid deposition and metabolic disruption at the DMN regions. Changes in connectivity among the different nodes ofthe DMN and its connections with the hippocampus have been reported. The characteristics ofthe DMN and its relation to Alzheimer's disease are discussed. This issue is ofinterest in the pathogenesis and possibly for its usefulness as a biomarker ofthe disease.

Learning about brain physiology and complexity from the study of the epilepsies

The brain is a complex system, which produces emergent properties such as those associated with activity-dependent plasticity in processes of learning and memory. Therefore, understanding the integrated structures and functions of the brain is well beyond the scope of either superficial or extremely reductionistic approaches. Although a combination of zoom-in and zoom-out strategies is desirable when the brain is studied, constructing the appropriate interfaces to connect all levels of analysis is one of the most difficult challenges of contemporary neuroscience. Is it possible to build appropriate models of brain function and dysfunctions with computational tools? Among the best-known brain dysfunctions, epilepsies are neurological syndromes that reach a variety of networks, from widespread anatomical brain circuits to local molecular environments. One logical question would be: are those complex brain networks always producing maladaptive emergent properties compatible with epileptogenic substrates? The present review will deal with this question and will try to answer it by illustrating several points from the literature and from our laboratory data, with examples at the behavioral, electrophysiological, cellular and molecular levels. We conclude that, because the brain is a complex system compatible with the production of emergent properties, including plasticity, its functions should be approached using an integrated view. Concepts such as brain networks, graphics theory, neuroinformatics, and e-neuroscience are discussed as new transdisciplinary approaches dealing with the continuous growth of information about brain physiology and its dysfunctions. The epilepsies are discussed as neurobiological models of complex systems displaying maladaptive plasticity.

SNDDDE: sistema neuro-difuso para auxiliar no diagnóstico de doenças epilépticas / NFSDED: neuro-fuzzy system to support the diagnosis of epileptic diseases

Introdução: Esta pesquisa aborda o desenvolvimento de um sistema neurodifuso para auxiliar no diagnóstico de doenças epilépticas (SNDDDE). Sistemas neurodifusos representam o tipo mais comum de inteligência artificial na medicina. O sistema neurodifuso contém conhecimento médico representado na forma de regras, unindo a força de dois paradigmas: redes neurais artificiais e lógica difusa. Objetivo: O maior interesse da pesquisa é examinar a aplicabilidade das operações aritméticas difusas t-normas e tconormas, implementadas através de neurônios difusos. Resultados: Os resultados mostram que as operações aritméticas difusas Soma/Produto de Einstein E/OU implementadas com o neurônio difuso proposto por Kwan-Cai obtiveram os melhores índices de acertos do sistema quando comparadas com as operações aritméticas padrões máx/mín.

Background: This research approaches the development of a neuro-fuzzy system to support the diagnosis of epileptic diseases (NFSDED). Neuro-fuzzy systems are the most common type of artificial intelligence in medicine. The neuro-fuzzy system contains medical knowledge represented by rules, gathering the strength of two paradigms: artificial neural networks and fuzzy logic. Objective: The main interest of the research is to examine the applicability of the t-norms and t-conorms fuzzy arithmetical operations, implemented by fuzzy neurons. Results: Show that the arithmetical operations of Einstein's Sum/Product AND/OR implemented with the fuzzy neuron proposed by Kwan-Cai obtained the highest rates of system hits, when compared to the min/max arithmetical operations.

BrainTV: a novel approach for online mapping of human brain functions

Our understanding of the brain's functional organisation has greatly benefited from occasional exploratory sessions during electrophysiological studies, trying various manipulations of an animal's environment to trigger responses in particular neurons. Famous examples of such exploration have unveiled various unexpected response properties, such as those of mirror neurons. This approach, which relies on the possibility to test online the reactivity of precise neural populations has no equivalent so far in humans. The present study proposes and applies a radically novel framework for mapping human brain functions in ecological situations based on a combination of a) exploratory sessions, using real-time electrophysiology to formulate hypotheses about the functional role of precise cortical regions and b) controlled experimental protocols specifically adapted to test these hypotheses. Using this two-stage approach with an epileptic patient candidate for surgery and implanted with intracerebral electrodes, we were able to precisely map high-level auditory functions in the patients' superior temporal lobe. We propose that this procedure constitutes at the least a useful complement of electrical cortical stimulations to map eloquent brain areas in epileptic patients before their surgery, but also a path of discovery for human functional brain mapping.