The brain weighs about three pounds and has a consistency something like tofu. It has 1.1 trillion cells — considerably more cells than stars in the Milky Way (estimated at somewhere between 100 and 400 billion). Signals cross our brain through neural networks in a tenth of a second, and a typical neuron makes 5,000 connections with other neurons, establishing a network of 500 trillion synapses — a system more complex than almost anything we can conceive of. The brain is always on. It operates 24 hours per day, 7 days a week, 365 days per year fueled by glucose and oxygen. Like a data bank, it stores things. Some of these things entertain us, some comfort us, some bore us, and others torture us. To employ a common metaphor, our habitual thoughts and behaviors create a road map in the brain — a system of frequently traversed highways and byways that become very much like well-worn, physiological pathways or even ruts. The popular expression I’m stuck in a rut says it all.

The Triune Theory

Although out of favor with many scientists working today, Paul MacLean’s triune brain theory is an intuitively sensible model for understanding more about our brain and its relationship to our behaviors. MacLean, a physician and neuroscientist, theorized that the brain has three basic structures related to our evolutionary development: a reptilian complex, a paleo-mammalian mid brain structure, and the neo-mammalian neocortex. Per MacLean, the reptilian brain includes the brain stem and the basal ganglia. It’s primarily involved with instinctual survival behaviors like aggression, dominance, territoriality, and ritual displays. By contrast, the paleo-mammalian brain (or mid-brain) was described as being composed of the limbic system, which includes the septum, amygdalae, hippocampus, and cingulate cortex. It is mostly concerned with emotional processing, the motivations that drive feeding and reproductive behaviors, maternal and parental instincts, relational bonding, and the emotional component involved in making decisions. Finally, the neo-mammalian brain in MacLean’s model includes the cerebral neocortex, which is responsible for higher cognitive functions like abstract thought, planning, reasoning, and decision-making, as well as our capacity for complex social interactions.

For the purposes of this book (and the Radical Responsibility path in general), I use the terms reptilian, limbic, and neocortex as a kind of shorthand to refer to these three functional areas of the brain. All of these activities actually involve complex, integrated interactions within the whole system of the brain, so please understand this somewhat oversimplified breakdown for what it is — a helpful rubric of sorts. That being said:

  • The reptilian complex (the survival brain) regulates hormones and supervises fear-based avoidance behaviors intended to promote survival.
  • The limbic system (the feeling brain) processes emotions; generates behaviors to meet our needs for food, warmth, shelter, and procreation; and informs our decision-making process with emotional intelligence.
  • The neocortex (the thinking brain) plans, reasons, makes most decisions, and manages social interactions.

There are two more concepts in common use today that will be important for our exploration of brain science as it applies to Radical Responsibility: execution function and amygdala hijack.

Executive Function

The executive function, located primarily within the neocortex, or thinking brain, plays a critical organizing role in the brain, operating much like a CEO making overall decisions about resource allocation within an organization. The executive function decides where to place our mental and physical resources, how to organize and prioritize brain activity, where to direct our attention in each moment, as well as the degree of focus. Specifically, executive function refers to a set of cognitive processes necessary for:

  • planning
  • correcting errors
  • trouble-shooting
  • problem solving
  • moral reasoning
  • effective decision making
  • resisting strong habitual tendencies
  • and controlling cognitive processes in order to achieve outcomes (for example, attention control, reappraisal, and working memory)

These processes primarily involve neural structures in the pre-frontal regions of the brains frontal lobes (the dorsolateral pre-frontal cortex, the anterior cingulate cortex, and the orbital frontal cortex), but they also involve connections to other areas of the neocortex in addition to the basal ganglia and the brain stem. However, for the sake of simplicity, I’ll generally refer to executive function as residing in the neocortex.

Amygdala Hijack

“When we are emotionally triggered we generally don’t make the best decisions.”

Coined by Daniel Goleman, this expression refers to a sudden emotional flooding that is disproportionate to the actual stimulus. In other words, it imputes a much greater perceived emotional or physical threat based on past memories. The amygdalae are emotional processing centers, part of the limbic system in the midbrain (paleo-mammalian brain) that function like a warning system. They alert the reptilian brain to activate the HPA (hypothalamus-pituitary-adrenal) axis, releasing adrenalin and cortisol into the bloodstream and triggering the fight, flight, or freeze response to perceived threats. To put it more simply, the feeling brain hijacks the thinking brain, causing emotional flooding and reactivity disproportionate to whatever is actually occurring in the moment. And when our locus of control shifts to the fight, flight, or freeze response (under the control of the reptilian brain), we have less access to our executive function and our ability to make rational, objective, or wise decisions.

Amygdala hijack can also refer to the rush of positive emotions like sudden, uproarious laughter in response to a funny joke, or intense joy brought on by a sense of heartfelt connection. So if you find yourself fortunate enough to experience some kind of ecstasy, enjoy it! But wait until you come back down to earth before making any major life decisions.

This is a modified excerpt from Radical Responsibility: How to Move Beyond Blame, Fearlessly Live Your Highest Purpose, and Become an Unstoppable Force for Good by Fleet Maull, Ph.D.

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