PDF《Enlarging炉he爏cope：爂rasping?》

1? ? Enlarging?the?scope:?grasping?brain?complexity?? ? Emmanuelle Tognoli1 *, J.

A. Scott Kelso1,2

1 The Human Brain and Behavior Laboratory, Center for Complex Systems and Brain Sciences, Florida Atlantic University, Boca Raton, FL, USA

2 Intelligent System Research Centre, University of Ulster, Derry, N. Ireland Correspondence: Emmanuelle Tognoli Center for Complex Systems and Brain Sciences Florida Atlantic University

777 Glades Road Boca Raton, FL-33431, USA [email protected] Abstract: To further advance our understanding of the brain, new concepts and theories are needed. In particular, the ability of the brain to create information flows must be reconciled with its propensity for synchronization and mass action. The framework of Coordination Dynamics and the theory of metastability are presented as a starting point to study the interplay of integrative and segregative tendencies that are expressed in space and time during the normal course of brain function. Some recent shifts in perspective are emphasized, that may ultimately lead to a better understanding of brain complexity. Theories of the brain: a concise history How does the brain work? This nagging question is an habitué from the top ten lists of enduring problems in Science'

s grand challenges. Grasp this paradox: how is one human brain Ca chef d'

oeuvre of complexity honed by NatureC ever to reach such a feast as to understand itself? Where one brain may fail at this notorious philosophical riddle, maybe a strong and diversely-skilled army of brains may come closer. Understanding of the local principles at play has emerged due to the combined efforts of many scientists: neurons talk to their partners by teasing them with charged particles of either excitatory or inhibitory effect, as Nobel laureate Sir John Eccles demonstrated [1]. Targeted release of ions was later shown at sites that seem designed for the exchange of information: typically the axonal termination of the emitting neuron facing the dendrites of a receiving partner [2]. Many of those two-some neural interlocutors build into a reticulum with remarkable emergent properties. A booming network science followed, generalizing microscale principles on a large-scale. David Rumelhart and James McClelland and many others pursued this connectionist endeavor [3,4]. Putting function first, they aimed to model specific aspects of human cognition and behavior such as visual perception or language. Others, such as Olaf Sporns devoted much effort to the neurobiological fidelity of their inquiries, conceiving behavior as emergent phenomenon from the appropriate connectional design [5], which they probed either with theoretical connectivity models where brain complexity is carefully thought of [6];

or complementarily with empirically-derived models that borrow their connectional blueprints from images of real brains [7]. Neuronal relays and the propagation of information The principle of synaptic transmission proved to be picture-perfect for a theory of communication, boosted by the influential work published in

1948 by Claude Shannon [8]. Transfer of information became a principal tenet of brain function, and theories went so far as to conceive of centers as final destinations for information to be communicated (the concept has now retreated, although it remains perniciously present in neuroscientists'

2? ? conceptions of brain hierarchies;

an alternate view is that it is the journey, but not an elusive final destination, that really matters). This theory of information processing in the brain raises a question that may not have received enough attention: can we readily transpose findings from the smallest synaptic level Cfindings that speak of only a pair of neurons-- to larger spatial scales such as neural areas or the whole brain? In all justice, countless emergent phenomena were discovered through this extrapolation, both in empirical and theoretical work. But it remains an uneasy feeling that so much of Brain Science is built upon the foundation of a pair of neurons, outside the context of their networks, and with two open-ended areas of darkness at either of their extremities that must be thought of as the entire remainder of the organism'