This paper comprehensively explains how allostasis can bring about a paradigm shift in brain structure, psychological phenomena, and neuroscience and mental health research, from the perspective that "the brain's core function is not thinking but predictive bodily regulation (allostasis)." Conclusion: The paper emphasizes that the brain's top priority is predicting and adjusting the body's balance and efficient resource allocation, rather than thinking or emotions, suggesting that this perspective can deepen existing brain-psychology research.

1. Introduction: What Is the Brain's True Mission?

Traditionally, psychology and neuroscience focused on the brain's main functions as thinking, emotion, perception, consciousness and other 'mental activities.' However, this paper flips that view, emphasizing that the brain's true mission is to predictively and proactively coordinate the demands of various bodily systems (resource allocation, waste removal, immunity, environmental sensing, etc.) -- in other words, 'allostasis.'

"The core task of every brain is to anticipate physiological needs and prepare to meet them in advance."

Key Terms Explained Simply

• Allostasis: The ability to 'predict in advance and appropriately adjust' the body's various demands (e.g., nutritional needs, waste removal, stress responses).
• Difference from homeostasis: While homeostasis is reactive regulation that restores balance 'after' a problem occurs, allostasis is 'predictive regulation' that prepares 'before' problems arise.
• Interoception: Sensing internal body states (hunger, heartbeat, etc.) and modeling the corresponding regulatory signals.
• Visceromotor control: The brain's neural control that directly coordinates internal organs (heart, lungs, gastrointestinal tract, etc.).

"All the mental phenomena we think of (thoughts, emotions, attention, etc.) may actually originate from the primary mission of efficient bodily coordination."

2. 'Stress' and Allostasis: A Shift in Definition

Past psychology regarded stress as 'psychological threat perception' or unpleasant affect, but recent approaches take a more biological, energy-based perspective. The authors explain:

"Stress is a state in which the brain and body prepare for substantial energy expenditure (allostatic fluctuation)." They emphasize that this is not necessarily 'bad' or a 'problem,' but rather a value-neutral state where the body is preparing to meet its needs.

In real life and experiments, when prepared metabolic expenditure matches actual demands well, we barely perceive stress. But when predictive signals are 'excessive' or 'insufficient,' we experience it as 'stress' or 'discomfort.'

"Psychological experiences (mood, emotion) can function as a low-dimensional allostatic 'weather map.'"

3. Measuring Allostasis and Its Relationship to Mental Phenomena

(1) How Can Allostatic Regulation Be 'Measured'?

Allostasis cannot be measured with a single number or simple indicator:

• Various bodily processes (ion concentrations, cell division, telomere repair, etc.) are highly intertwined and constantly adjusting
• A key characteristic is maintaining 'stability through change'
• The concept of 'allostatic load' is a product of stress-disease theory, but the authors point out that this concept has limitations in interpreting cause and effect

(2) 'Mind' Is a Byproduct of Brain-Body Regulation

• Cognition, emotion, and conceptualization abilities arise 'incidentally' as the brain predicts bodily needs, prepares responses, and assigns meaning
• Our concepts and beliefs can also impose 'top-down constraints' on bodily organs and regulatory systems Example: Cognitive behavioral therapy reducing cardiovascular disease risk; conditioning influencing immune responses, cardiac responses, and digestive enzyme regulation
• Humans navigate their 'socio-ecosystem' at a highly sophisticated level through concepts and abstraction, which significantly impacts brain function

"Like all animals, we fundamentally live by utilizing 'concepts,' and these concepts don't necessarily have to be conscious or linguistic."

4. Anatomical and Functional Evidence for the Allostatic Brain Architecture

(1) The Brain's Core Is a 'Predictive Body Regulation Network'

• The central autonomic network, limbic system, parts of the frontal lobe, hippocampus, hypothalamus-brainstem, and other regions directly connected to the body's interior are arranged in a 'ring' at the brain's core
• This network exchanges bidirectional signals with organs including the heart, lungs, gastrointestinal tract, cerebral vasculature, and endocrine system
• This is clearly visible in resting state fMRI studies; even at rest, the brain continues monitoring visceral states and making predictive adjustments
• Abundant data and network analyses support that existing 'default mode network,' 'salience network,' etc. are ultimately parts of this body regulation network

"We thought we were studying psychological networks, but what we were really studying was the 'allostatic network.'"

(2) Structure of Signal Flow: The 'Limbic-Sensory' Structural/Functional Gradient

• The brain's structure shows gradual changes in neurons, layers, and connectivity patterns from the limbic system (allostatic core) to sensory/motor regions
• Signals flow from limbic areas (internal cortex, integration/coordination regions) to multidimensional sensory areas (V1, A1, S1, etc.) through 'compression to decompression,' with information flowing in and out as prediction and error signals are compared
• Not all senses occupy the same position: interoception, olfaction, and gustation input already 'compressed' signals directly to limbic areas at a higher hierarchy, while vision, audition, and touch have inherently much more complex raw signals
• This aligns with several innovative theories in modern neuroscience, including 'predictive coding' and low-dimensional waves across the whole brain

"The flow of neural signals in the brain appears to be an optimization system with the overarching goal of predictive bodily regulation, beyond mere mental phenomena."

5. Allostatic Signals and Their Coupling with Behavior and Psychological Phenomena

• Centralized regulation (e.g., metabolic stimulation via vaccination) or pharmacological control of the heart and viscera dramatically changes various psychological indicators including psychological experience, memory retrieval/flexibility, and mood
• Afferent (ascending) signals also coordinate whole-brain signals:
  • Example: Periodic bodily signals such as breathing, heartbeat, and gastrointestinal motility are coupled with brain-wide network (resting/default mode) oscillations, deeply influencing diverse functions including cognition, affect, and memory
  • Involuntary bodily signals (heart, breathing, etc.) serve as the frame ('context for external input') of whole-brain signals that we 'normally don't consciously perceive'

"Breathing is a kind of 'oscillator (vibration coordinator)' that synchronizes neural signals across the entire brain."

• In practice, the timing of heartbeat/breathing clearly affects sensory processing and perceptual accuracy of vision, hearing, and touch
• Involuntary signals interact with the brain's predictive signals to guide the processing of environmental information

"Sensory perception and behavior are not independent processes; they are adjusted to the body's rhythms, and meaning is generated within them."

6. Neurodegeneration (Alzheimer's) and Clinical Issues from an Allostatic Perspective

(1) Alzheimer's Example:

• A decrease in glucose metabolism/uptake in the brain is observed during aging
• Traditional interpretation: Viewed as the cause of 'memory decline and other cognitive function deterioration'
• Allostatic perspective: This decrease may be the brain's self-regulatory process for more 'essential survival' functions such as waste (amyloid, etc.) management and pH stabilization
• In practice, artificially increasing glucose supply improves short-term cognition but can cause more serious metabolic/waste problems in the long term
• The 'core' of the disease may not be thoughts or memory, but the brain's adaptive (allostatic) attempt to maintain bodily balance

"The core symptoms of Alzheimer's (cognitive decline) are ultimately also choices the brain made in pursuit of more fundamental physiological goals (survival)."

(2) Social Factors, Caregiving, and Allostatic Health

• Human survival and health are highly sensitive to social support and attachment; intimate relationships reduce bodily burden (allostatic load) and significantly slow the rate of cognitive decline and behavioral problems
• Social isolation substantively increases related metabolic proteins (GDF-15) and even dementia risk

7. Conclusion and Recommendations

"Separating mind and body is merely an artificial distinction; the brain's essential task is efficient prediction and regulation of the body. Therefore, if we want to know what the mind is and how it arises, we must fundamentally examine how the brain conserves energy and regulates the body."

This paper does not assert that the 'allostasis-first' perspective is definitively correct, but rather presents a new starting point for questions -- "what kinds of progress can psychology and neuroscience make when we change our perspective?"

In Closing

This paper throws down a powerful challenge to the long-held assumption that 'brain = organ of thought/emotion.' It proposes that the brain is, above all, a predictive regulatory organ for keeping the body alive and maintained, and suggests reinterpreting all psychological phenomena, behavior, sociality, and mental illness within this framework. Going forward, neuroscience, clinical practice, and mental health research will find deeper answers from an integrated perspective of 'body-brain-mind.'

Key Keywords: allostasis predictive body regulation brain core network mind-body integration survival-based reinterpretation of cognition metabolic causes of Alzheimer's influence of visceral signals (breathing, heart) on cognition/emotion social support and neural health