What the cognitive neurosciences mean to me

Cognitive Neuroscience is an interdisciplinary area of research that combines measurement of brain activity (mostly by means of neuroimaging) with a simultaneous performance of cognitive tasks by human subjects. These investigations have been successful in the task of connecting the sciences of the brain (Neurosciences) and the sciences of the mind (Cognitive Sciences). Advances on this kind of research provide a map of localization of cognitive functions in the human brain. Do these results help us to understand how mind relates to the brain? In my view, the results obtained by the Cognitive Neurosciences lead to new investigations in the domain of Molecular Neurobiology, aimed at discovering biophysical mechanisms that generate the activity measured by neuroimaging instruments. In this context, I argue that the understanding of how ionic/molecular processes support cognition and consciousness cannot be made by means of the standard reductionist explanations. Knowledge of ionic/molecular meclianisms can contribute to our understanding of the human mind as long as we assume an alternative form of explanation, based on psycho-physical similarities, together with an ontological view of mentality and spirituality as embedded in physical nature (and not outside nature, as frequently assumed in western culture).

Biomolecular information, brain activity and cognitive functions

Molecular neurobiology has provided an explanation of mechanisms supporting mental functions as learning, memory, emotion and consciousness. However, an explanatory gap remains between two levels of description: molecular mechanisms determining cellular and tissue functions, and cognitive functions. In this paper we review molecular and cellular mechanisms that determine brain activity, and then hypothetize about their relation with cognition and consciousness. The brain is conceived of as a dynamic system that exchanges information with the whole body and the environment. Three explanatory hypotheses are presented, stating that: a) brain tissue function is coordinated by macromolecules controlling ion movements, b) structured (amplitude, frequency and phase-modulated) local field potentials generated by organized ionic movement embody cognitive information patterns, and c) conscious episodes are constructed by a large-scale mechanism that uses oscillatory synchrony to integrate local field patterns. © by São Paulo State University.

Efeitos de relevância versus repetição de estímulo lingüístico na indução da memória declarativa

In the LTP (Long-Term Potentiation) model of learning and memory formation, elaborated in the context of molecular neurobiology, the opening of NMDA (N-Metyl-D-Aspartate) channels to entry of calcium ions into the post-synaptic neuron depends on two excitatory events: the repeated activation of the post-synaptic neuron by only one pre-synaptic neuron (Alternative 1), or its concomitant activation by two or more pre-synaptic neurons (Alternative 2). With the purpose of testing these alternatives, in the context of Cognitive Psychology, we presented to 73 university students a sequence of slides, with the duration of 6 seconds each, containing sentences (one for each slide) considered as being relevant or irrelevant for the subjects. Relevant sentences (R1) were presented only one time, while irrelevant ones were divided in three groups: the first one with sentences presented only one time (I1), the second with sentences presented three times (I3) and the third with sentences presented five times (I5). We conjectured that relevant sentences presented only one time would mobilize two or more brain excitatory pathways (corresponding to Alternative 2 above), while repeated irrelevant sentences would progressively activate the same sensory pathway. After the presentation of the sentences, the subjects answered a written questionnaire with questions about each presented sentence. The results indicate a prevalence of correct answers to R1 over I1, I3 and I5, suggesting that the relevance factor has greater weight than repetition in the induction of declarative memories

Molecular and Cytogenetic Analyses on Brazilian Youths with Pervasive Developmental Disorders

The Pervasive Developmental Disorders (PDDs) constitute a group of behavioral and neurobiological impairment conditions whose main features are delayed communicative and cognitive development. Genetic factors are reportedly associated with PDDs and particular genetic abnormalities are frequently found in specific diagnostic subgroups such as the autism spectrum disorders. This study evaluated cytogenetic and molecular parameters in 30 youths with autism or other PDDs. The fragile X syndrome was the most common genetic abnormality detected, presented by 1 patient with autism and 1 patient with PPD not-otherwise specified (PPD-NOS). One girl with PDD-NOS was found to have tetrasomy for the 15q11-q13 region, and one patient with autism exhibited in 2/100 metaphases an inv(7)(p15q36), thus suggesting a mosaicism 46,XX/46,XX,inv(7)(p15q36) or representing a coincidental finding. The high frequency of chromosomopathies support the hypothesis that PDDs may develop as a consequence to chromosomal abnormalities and justify the cytogenetic and molecular assessment in all patients with PDDs for establishment of diagnosis.

Astrocytes and human cognition: Modeling information integration and modulation of neuronal activity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Recent advances in brain physiology and cognitive processing

The discovery of participation of astrocytes as active elements in glutamatergic tripartite synapses (composed by functional units of two neurons and one astrocyte) has led to the construction of models of cognitive functioning in the human brain, focusing on associative learning, sensory integration, conscious processing and memory formation/retrieval. We have modelled human cognitive functions by means of an ensemble of functional units (tripartite synapses) connected by gap junctions that link distributed astrocytes, allowing the formation of intra- and intercellular calcium waves that putatively mediate large-scale cognitive information processing. The model contains a diagram of molecular mechanisms present in tripartite synapses and contributes to explain the physiological bases of cognitive functions. It can be potentially expanded to explain emotional functions and psychiatric phenomena. © MSM 2011.