Topic: phase transition

The question of the origin of homochirality of living matter, or the dominance of one handedness for all molecules of life across the entire biosphere, is a long-standing puzzle in the research on the Origin of Life. In the fifties, Frank proposed a mechanism to explain homochirality based on the properties of a simple autocatalytic network containing only a few chemical species. Following this work, chemists struggled to find experimental realizations of this model, possibly due to a lack of proper methods to identify autocatalysis [1]. In any case, a model based on a few chemical species see

Brain rhythms in the alpha frequency range [8Hz-12Hz] are present in idling conditions and sleep. They have also an important role in cognition, e.g. they modulate activity of task-irrelevant neural populations, and enhances selective attention among others. A prominent occipital alpha wave emerges in mammals when the subjects close eyes (alpha generation) and it is blocked when opening eyes (alpha blocking). This switch in alpha power is accompanied by an inverse switch in gamma activity [1]. With open eyes, the brain receives strong input from the external world and responds by strong gamma-

Healthy brains exhibit a rich dynamical repertoire with flexible and varied spatiotemporal patterns replays on both microscopic and large scales. Neurodegenerative diseases reduce this functional repertoire. We hypothesize that microscopic dynamics must operate in or near a critical regime for the functional repertoire to be fully explored and for realistic flexible dynamics to emerge. To test this hypothesis, we use a modular Spiking Neuronal Network model, where each group of Leaky Integrate and Fire neurons represents a cortical region. A STDP-based rule is used to learn patterns of activat

Cortical neuronal networks exhibit a rich dynamical repertoire and are capable of performing many different computations, for instance the generation of multiple distinct dynamical patterns in motor cortex. However, we do not know what connectivity structures support this capability, nor the mechanism for selecting among the dynamics required for different tasks. We develop an analytical theory describing a network model capable of multi-task computation, where the connectivity is generated as a sum over a large number of low-rank matrices, each of which is specialized to perform one low-dimen

Brain rhythms in the alpha frequency range [8Hz-12Hz] are present in idling conditions and sleep. For instance, a prominent occipital alpha wave emerges in mammals when the subjects closes eyes (alpha generation) and it is blocked when opening eyes (alpha blocking). This switch in alpha power is accompanied by an inverse switch in gamma activity [1]. Considering input as random input fluctuations, this switch may result from an alteration in exogenous fluctuations. In a first part, the work proposes a mathematical mesoscopic neural mass model for the cortico-thalamic feedback (CTF) loop derive