Order in Time: How the Cooperation Between the Hands Informs the Design of the Brain

Abstract

Our interest is in identifying the laws or principles that govern how the nervous system produces coordinated activity. To find these laws, we do not think it so useful to treat the brain as a general purpose machine, capable of producing arbitrary outputs to arbitrary inputs. Rather, our strategy is to place the organism in particular contexts, viewing the brain more as a special purpose device, that is temporarily self-organized for specific behavioral functions. Just as the boundary conditions must be carefully chosen for studies of other physical systems (‘the system must be prepared’) so too it is important to select a class of tasks that affords insights into the relationship between brain and behavior. When this is done we believe it is possible to see how surface simplicity-in the form of laws-may arise from deep complexity. Along with new data presented here, the evidence draws us to the following inescapable conclusion: In tasks-that involve ordering in time, the highdimensional nervous system (approximately 50 neurotransmitters, 10³ cell types, 10¹⁴ neurons and neuronal connections) restricts its effective degrees of freedom to the phase- and frequency-locking phenomena of coupled nonlinear oscillators. It lives, in other words, on a low dimensional manifold and is governed by low-dimensional, dynamical laws. This design may be seen at multiple levels of description [1,2] and appear in a variety of functional behavioral patterns including coordination, learning, memory, perception-action patterns and even intentional behavior (see e.g., [3,4]). In the next section we briefly summarize previous and recent results on temporal patterns and our theoretical understanding of them. Then we extend the treatment to an important case, namely forms of temporal organization in which the intrinsic frequencies in the system are not the same. Overall, our results-in addition to supporting the main hypothesis mentioned above-serve to unify a number of physical, biological and psychological phenomena. By definition, the laws of temporal order are abstract,though realizable (and hence measurable), on many different scales of observation.