Center for Complex Systems and Brain Sciences

About: Center for Complex Systems and Brain Sciences is a based out in . It is known for research contribution in the topics: Hippocampus & Hippocampal formation. The organization has 160 authors who have published 421 publications receiving 31253 citations.

Emerging concepts for the dynamical organization of resting-state activity in the brain

Abstract: A broad body of experimental work has demonstrated that apparently spontaneous brain activity is not random. At the level of large-scale neural systems, as measured with functional MRI (fMRI), this ongoing activity reflects the organization of a series of highly coherent functional networks. These so-called resting-state networks (RSNs) closely relate to the underlying anatomical connectivity but cannot be understood in those terms alone. Here we review three large-scale neural system models of primate neocortex that emphasize the key contributions of local dynamics, signal transmission delays and noise to the emerging RSNs. We propose that the formation and dissolution of resting-state patterns reflects the exploration of possible functional network configurations around a stable anatomical skeleton.

Differential projections of the infralimbic and prelimbic cortex in the rat.

Abstract: The medial prefrontal cortex has been associated with diverse functions including attentional processes, visceromotor activity, decision-making, goal-directed behavior, and working memory. The present report compares and contrasts projections from the infralimbic (IL) and prelimbic (PL) cortices in the rat by using the anterograde anatomical tracer, Phaseolus vulgaris-leucoagglutinin. With the exception of common projections to parts of the orbitomedial prefrontal cortex, olfactory forebrain, and midline thalamus, PL and IL distribute very differently throughout the brain. Main projection sites of IL are: 1) the lateral septum, bed nucleus of stria terminalis, medial and lateral preoptic nuclei, substantia innominata, and endopiriform nuclei of the basal forebrain; 2) the medial, basomedial, central, and cortical nuclei of amygdala; 3) the dorsomedial, lateral, perifornical, posterior, and supramammillary nuclei of hypothalamus; and 4) the parabrachial and solitary nuclei of the brainstem. By contrast, PL projects at best sparingly to each of these structures. Main projection sites of PL are: the agranular insular cortex, claustrum, nucleus accumbens, olfactory tubercle, the paraventricular, mediodorsal, and reuniens nuclei of thalamus, the capsular part of the central nucleus and the basolateral nucleus of amygdala, and the dorsal and median raphe nuclei of the brainstem. As discussed herein, the pattern of IL projections is consistent with a role for IL in the control of visceral/autonomic activity homologous to the orbitomedial prefrontal cortex of primates, whereas those of PL are consistent with a role for PL in limbic-cognitive functions homologous to the dorsolateral prefrontal cortex of primates.

Beta oscillations in a large-scale sensorimotor cortical network: Directional influences revealed by Granger causality

Abstract: Previous studies have shown that synchronized beta frequency (14-30 Hz) oscillations in the primary motor cortex are involved in maintaining steady contractions of contralateral arm and hand muscles. However, little is known about the role of postcentral cortical areas in motor maintenance and their patterns of interaction with motor cortex. We investigated the functional relations of beta-synchronized neuronal assemblies in pre- and postcentral areas of two monkeys as they pressed a hand lever during the wait period of a visual discrimination task. By using power and coherence spectral analysis, we identified a beta-synchronized large-scale network linking pre- and postcentral areas. We then used Granger causality spectra to measure directional influences among recording sites. In both monkeys, strong Granger causal influences were observed from primary somatosensory cortex to both motor cortex and inferior posterior parietal cortex, with the latter area also exerting Granger causal influences on motor cortex. Granger causal influences from motor cortex to postcentral sites, however, were weak in one monkey and not observed in the other. These results are the first, to our knowledge, to demonstrate in awake monkeys that synchronized beta oscillations bind multiple sensorimotor areas into a large-scale network during motor maintenance behavior and carry Granger causal influences from primary somatosensory and inferior posterior parietal cortices to motor cortex.

Evaluating causal relations in neural systems: granger causality, directed transfer function and statistical assessment of significance.

Abstract: We consider the question of evaluating causal relations among neurobiological signals. In particular, we study the relation between the directed transfer function (DTF) and the well-accepted Granger causality, and show that DTF can be interpreted within the framework of Granger causality. In addition, we propose a method to assess the significance of causality measures. Finally, we demonstrate the applications of these measures to simulated data and actual neurobiological recordings.