The Mental Maxwell Relations: A Thermodynamic Allegory for Higher Brain Functions

Abstract

The theoretical framework of classical thermodynamics unifies vastly diverse natural phenomena and captures once-elusive effects in concrete terms. Neuroscience confronts equally varied, equally ineffable phenomena in the mental realm, but has yet to unite or to apprehend them rigorously, perhaps due to an insufficient theoretical framework. The terms for mental phenomena, the mental variables, typically used in neuroscience are overly numerous and imprecise. Unlike in thermodynamics or other branches of physics, in neuroscience, there are no core mental variables from which all others formally derive and it is unclear which variables are distinct and which overlap. This may be due to the nature of mental variables themselves. Unlike the variables of physics, perhaps they cannot be interpreted as composites of a small number of axioms. However, it is well worth exploring if they can, as that would allow more parsimonious theories of higher brain function. Here we offer a theoretical exercise in the spirit of the National Institutes of Health Research Domain Criteria (NIH RDoC) Initiative and the Cognitive Atlas Project, which aim to remedy this state of affairs. Imitating classical thermodynamics, we construct a formal framework for mental variables, an extended analogy – an allegory – between mental and thermodynamic quantities. Starting with mental correlates of the physical indefinables length, time, mass or force, and charge, we pursue the allegory up to mental versions of the thermodynamic Maxwell Relations. The Maxwell Relations interrelate the thermodynamic quantities volume, pressure, temperature, and entropy and were chosen since they are easy to derive, yet capable of generating nontrivial, nonobvious predictions. Our “Mental Maxwell Relations” interlink the mental variables consciousness, salience, arousal, and distraction and make nontrivial, nonobvious statements about mental phenomena. The mental system thus constructed is internally consistent, in harmony with introspection, and respects the RDoC criteria of employing only psychologically valid constructs with some evidence of a brain basis. We briefly apply these concepts to the problem of decision-making and sketch how some of them might be tested empirically.

How the Brain Becomes the Mind: Can Thermodynamics Explain the Emergence and Nature of Emotions?

“…The thermodynamic insight of the neural system is an increasingly pursued goal in consciousness science [ 7 , 8 , 23 , 24 , 26 , 80 ]. The brain’s intelligent computation is based on the sensory system’s information gathering.…”

“…There is a computational equivalence of operational noise levels (information), therefore arousal [ 13 ], with temperature [ 26 ]. For example, irritability is accompanied by increased breath, heart rate, skin conductance, shivers, and hot or cold chills, which exert a measurable metabolic burden [ 86 ].…”

“…Conversely, relaxation depends on reduced amygdala activity [ 109 ]. The brain’s memory storage embeds motivation, a state vector, within a multidimensional state or information space [ 26 , 88 ], generating a realistic emotional cinema. The cycle’s energetic consequences arise from the brain’s spatio-temporal orientation [ 43 , 46 ].…”

“…The following discussion will deduce emotions and the thermodynamic consequences of awareness. In this, we follow earlier insightful work on the free energy principle and the thermodynamic analysis of cognition [ 22 , 23 , 24 , 25 , 26 ].…”

What Is Psychological Spin? A Thermodynamic Framework for Emotions and Social Behavior

“…In our discussion, we will use a narrower definition, as deviations from the psychological balance of the mind. In this definition, emotions represent the homeostatic regulators, which aid in the recovery of the resting state [14,15]. The above conclusion gains more significance by understanding that the autonomic nervous system, responsible for encoding the novelty and significance of stimuli, operates involuntarily and regulates arousal, thus influencing the intensity and nature of emotional responses [15,16].…”