The limits of brain determinacy

Abstract

The genes do not control everything that happens in a cell or an organism, because thermally induced molecular movements and conformation changes are beyond genetic control. The importance of uncontrolled events has been argued from the differences between isogenic organisms reared in virtually identical environments, but these might alternatively be attributed to subtle, undetected differences in the environment. The present review focuses on the uncontrolled events themselves in the context of the developing brain. These are considered at cellular and circuit levels because even if cellular physiology was perfectly controlled by the genes (which it is not), the interactions between different cells might still be uncoordinated. A further complication is that the brain contains mechanisms that buffer noise and others that amplify it. The final resultant of the battle between these contrary mechanisms is that developmental stochasticity is sufficiently low to make neurobehavioural defects uncommon, but a chance component of neural development remains. Thus, our brains and behaviour are not entirely determined by a combination of genes-plus-environment.

Beyond Molecular Codes: Simple Rules to Wire Complex Brains

“…An important lesson from these example is the use of stochastic processes as an integral and necessary part of developmental algorithms, which contrasts with the view of noise as something that development just has to cope with or minimize in order to create a robust outcome (Clarke, 2012; Mele et al, 2015). Recent work in several fields has highlighted the importance of understanding both stochastic processes and heterogeneity of cellular behavior.…”

Neural computing: the metaphorical, cultural roots of brain models

“…Such a network causes system-wide repercussions of local disturbances in the developing brain (Payne 1999). In addition it was pointed out that the network is intrinsically undetermined, i.e., the outcome of neural development cannot be predicted solely from the interaction of genes and environment (Clarke 2012). The third is the neural networks responsible for behavior.…”

Patterned Brain Stimulation, What a Framework with Rhythmic and Noisy Components Might Tell Us about Recovery Maximization

“…The better question might be: “could we afford to exclude it”? To address these questions we have to define what exactly is meant by the term “neural noise,” which: (i) sums up all neural activity which could not directly be associated with a specific function but may be part of the signal instead of random noise (Stein et al, 2005), (ii) is not constant, i.e., the level of noise differs with respect to brain-states (Misic et al, 2010) and extrinsic input (Harris and Wolpert, 1998), and (iii) is always present, throughout all systems in the whole brain (Shadlen and Newsome, 1994; Ermentrout et al, 2008; Clarke, 2012). It is therefore important to understand if the brain is just robust against noise – which is undisputed – or if it utilizes noise, meaning that neural noise is an important and necessary system ingredient (Shadlen and Newsome, 1994; Friston, 1997; Lindner, 2004; Stein et al, 2005; Sejnowski and Paulsen, 2006; Ermentrout et al, 2008; McDonnell and Ward, 2011).…”