Stochasticity Versus Determinacy in Neurobiology: From Ion Channels to the Question of the “Free Will”

Abstract

If one accepts that decisions are made by the brain and that neuronal mechanisms obey deterministic physical laws, it is hard to deny what some brain researchers postulate, such as “We do not do what we want, but we want what we do” and “We should stop talking about freedom. Our actions are determined by physical laws.” This point of view has been substantially supported by spectacular neurophysiological experiments demonstrating action-related brain activity (readiness potentials, blood oxygen level–dependent signals) occurring up to several seconds before an individual becomes aware of his/her decision to perform the action. This report aims to counter the deterministic argument for the absence of free will by using experimental data, supplemented by computer simulations, to demonstrate that biological systems, specifically brain functions, are built on principle randomness, which is introduced already at the lowest level of neuronal information processing, the opening and closing of ion channels. Switching between open and closed states follows physiological laws but also makes use of randomness, which is apparently introduced by Brownian motion – principally unavoidable under all life-compatible conditions. Ion-channel stochasticity, manifested as noise, function is not smoothed out toward higher functional levels but can even be amplified by appropriate adjustment of the system’s non-linearities. Examples shall be given to illustrate how stochasticity can propagate from ion channels to single neuron action potentials to neuronal network dynamics to the interactions between different brain nuclei up to the control of autonomic functions. It is proposed that this intrinsic stochasticity helps to keep the brain in a flexible state to explore diverse alternatives as a prerequisite of free decision-making.

Harnessing stochasticity for superconductive multi-layer spike-rate-coded neuromorphic networks

“…Inspired by the stochasticity in biological systems [19,[21][22][23], the proposed synapse stochastically gates incoming spikes, encoding the synaptic weight in the probability that the synapse will propagate an incoming fluxon to the output, implementing the first SFQ 'blank-out' [19,20,25] synapse in the literature. Stochastically dropping spikes at synapses is a well-known phenomenon in biology [19,[21][22][23], and biomimetic hardware will likely lead to efficient hardware.…”

“…Synapses in SNNs mimic biology by modulating the strengths of the connections between upstream and downstream neurons. While most SNNs employ synapses that modulate the amplitude of spiking events, this work utilizes an alternative approach wherein synapses modulate spike rate by-inspired by the prevalent stochasticity observed in biological systems [19,[21][22][23] -stochastically gating individual synaptic spiking events.…”

“…SFQ synapses emulating the stochasticity in the brain [19,[21][22][23] are described along with SFQ leaky-integrate-and-fire (LIF) neurons. These primitive synaptic and neuronal circuits directly cascade with each other, permitting the construction of deep neuromorphic networks.…”

Understanding as explaining: how motives can become causes

“…This stochasticity of elementary processes is even increased in organisms, because they are open, farfrom-equilibrium systems (Nobel & Nobel 2021). Within the brain, this has been shown to lead to labile neural networks whose indeterminacy can be harnessed by higher-level selection and causation, including the person's desires and intentions (Noble & Noble, 2021;Braun, 2021). 5 Circular causality, as we can see, means neither external causation nor mind-body interaction; rather, we can consider it as a relation of implication, as de Haan ( 2020) has aptly put it.…”

“…Freedom of will should not be regarded as a purely mental feat, however, but rather as an 'embodied freedom', which integrates the person's entire bodily, affective and cognitive situation in the decision and its execution (see Fuchs 2018: 236-243 for further explanation). The concept of embodied freedom is thus based on circular causality as well; it regards decisions as superordinate, intentionally directed acts that are enabled by the stochasticity or indeterminacy of the neuronal micro-processes involved (Braun, 2021;Noble & Noble, 2021). 6 4 The role of phenomenology for explanation I have advanced a specific interpretation to the concept of conditional linkage provided by Husserl.…”