Year: 2008
Type: dissertation
Abstract: In order to execute cognitive functions the brain must bind features and information which \noccurs at different cortical areas. The most accepted hypothesis to underlie such integration \nof information is the binding by synchrony. Accordingly to it: two brain regions \ninteract with each other whenever they have coherent activity. The mechanism of this \nphenomenon has been subject of controversial debate for many years: how can two distant \ndynamical elements synchronize at zero lag even in the presence of non-negligible \ndelays in the transfer of information between them? So far, complex mechanisms and \nneural architectures have been proposed to answer this question. However, a simple and \nrobust mechanism has been proposed recently. Zero-lag synchronization between two \nelements is achieved by relaying the dynamics via a third mediating element. The synchronization \nthus obtained is robust over a considerable parameter range. In this work we \nstudy the dynamical relay phenomenon in complex networks of chemically coupled neurons, \nspecifically the capacity to provide the basis for the binding by synchrony process. \nWe show that three identical neuronal populations satisfy the minimum conditions to produce \nlag-free synchrony among delayed populations reciprocally connected to a central \nrelay population. We also investigate the dynamical behavior of the thalamocortical circuit \nwhose relay station role is played by the thalamus. We found that the thalamocortical \ncircuit supports the dynamical relay mechanism. More importantly, we report the identification \nof a variable that might be responsible to control the on-off synchronization of the \ncortical populations depending only on the ratio of dorsal over ventral thalamus external \nactivity. The simplicity of the key controlling element in the model also suggests that \nboth bottom-up and top-down incoming stimulus to thalamic region share responsibilities \nin the cortical synchronization phenomenon, in contrast to previous hypothesis. This \nwork supports the binding by synchrony theory and helps to establish solid bases for this \nphenomenon.
Author: Leonardo L. Gollo
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W985378331