It has often been noted that one of the signs of truly comprehending a complex issue is the ability to express the key concepts in a simple, easily accessible format.  This is certainly true of the Hand Model, developed by Dr. Daniel Siegel to demonstrate the central concepts of brain functioning and the impact of contemplative ‘mindfulness’ practice to help regulate emotional reactivity. As Dr. Siegel explains in his book, Mindsight: The New Science of Personal Transformation (2010),

“If you put your thumb in the middle of your palm and then curl your fingers over the top, you’ll have a pretty handy model of the brain. (My kids can’t stand that pun, either.) The face of the person is in front of the knuckles, the back of the head toward the back of your hand. Your wrist represents the spinal cord, rising from your backbone, upon which the brain sits. If you lift up your fingers and raise your thumb, you’ll see the inner brainstem represented in your palm. Place your thumb back down and you’ll see the approximate location of the limbic area (ideally we’d have two thumbs, left and right, to make this a symmetric model). Now curl your fingers back over the top, and your cortex is in place.”

The brainstem (‘reptilian brain’) is the oldest component of the brain, formed hundreds of millions of years ago.  It regulates the automatic functions (heart and lungs, controls the energy level of the body, and determines the states of arousal (hunger, sexual drives, wakefulness).  It also controls the fight/flight/freeze/faint responses responsible for our survival at times of danger.  In this state, as Dr. Siegel points out, “when we are in survival mode our reactivity makes it quite challenging, if not outright impossible, to be open and receptive to others. So part of the process of developing mindsight involves reducing reactivity when it’s not actually necessary”.

The limbic area (‘old mammalian brain’), evolved around two hundred million years ago, works closely with the brainstem and body to create basic drives and emotional responses.  As Dr. Siegel notes, ”‘Is this good or is this bad?’ is the most basic question the limbic area addresses. We move toward the good and withdraw from the bad. In this way the limbic regions help create the ‘e- motions’ that “evoke motion,” that motivate us to act in response to the meaning we assign to whatever is happening to us in that moment.”  This is the area of the brain required for the development of attachment.  It is also the area of the brain that regulates our stress responses and cortisol levels.  “Finding a way to soothe excessively reactive limbic firing is crucial to rebalancing emotions and diminishing the harmful effects of chronic stress. … mindsight can help us recruit the higher areas of the brain to create a “cortical override” of these limbic reactivities.”  The limbic area “also helps us create several different forms of memory – of facts, of specific experiences, of the emotions that gave color and texture to those experiences.”  It is the area of the brain that house the amygdala, which has the capacity to prompt an instantaneous survival response.  As Dr. Siegel notes, “Here we see that emotional states can be created without consciousness, and we may act on them without awareness.  This may save our lives – or it can cause us to do things we later regret deeply.  In order for us to become aware of the feeling inside us – to consciously attend to and understand them – we need to link these subcortically created emotional states to our cortex.”

The hippocampus (‘sea horse’) acts as the link between widely separated areas of the brain and converts our moment-to-moment experiences into memories.  Dr. Siegel stresses, “The hippocampus develops gradually during our early years and continues to grow new connections and even new neurons throughout our lives. As we mature, the hippocampus weaves the basic forms of emotional and perceptual memory into factual and auto – biographical recollections, laying the foundation for my ability to tell you about that long- ago snake encounter in the Sierras. However, this uniquely human storytelling ability also depends upon the development of the highest part of the brain, the cortex.”

The cortex (‘new mammalian brain’), the youngest part of the brain which expanded greatly with the appearance of primates and then the emergence of human beings, forms the outer layer (‘bark’) of the brain.  “In humans, the more elaborate frontal portion of the cortex allows us to have ideas and concepts and to develop the mindsight maps that give us insight into the inner world. The frontal cortex actually makes neural firing patterns that represent its own representations. In other words, it allows us to think about thinking. The good news is that this gives us humans new capacities to think— to imagine, to recombine facts and experiences, to create. The burden is that at times these new capacities allow us to think too much. As far as we know, no other species represents its own neural representations— probably one reason why we sometimes call ourselves ‘neurotic.’”

Dr. Siegel explains:

On your hand model, the back or posterior cortex extends from your second knuckle (counting from the fingertips) to the back of your hand …The posterior cortex is the master mapmaker of our physical experience, generating our perceptions of the outer world— through the five senses— and also keeping track of the location and movement of our physical body through touch and motion perception. If you’ve learned to use a tool— whether it was a hammer, a baseball bat, or even a car— you may remember the magical moment when your initial awkwardness dropped away. The amazingly adaptive perceptual functions of the back of the cortex have embedded that object into your body- maps so that it is neurally experienced like an extension of your body. This is how we can drive rapidly on a freeway or park a car in a tight space, use a scalpel with precision, or attain a .300 batting average.

Looking again at your hand model, the front of the cortex, or frontal lobe, extends from your fingertips to the second knuckle. This region evolved during our primate history and is most developed in our human species. As we move from the back toward the front, we first encounter a “motor strip” that controls our voluntary muscles. Distinct groups of neurons control our legs, arms, hands, fingers, and facial muscles. These neural groups extend to the spinal cord, where they cross over, so that we make our right- side muscles work by activating our left motor area. (The same crossover is true for our sense of touch, which is represented farther back in the brain, in a zone of the parietal lobe called the “somatosensory strip.”) Coming back to the frontal area and moving a bit more forward, we find a region called the “premotor” strip, which allows us to plan our motor actions. You can see that this part of the frontal lobe is still deeply connected to the physical world, enabling us to interact with our external environment.

THE PREFRONTAL CORTEX

As we move higher and more forward in the brain, we finally come to the area from your first knuckles to your fingertips on the hand model. Here, just behind the forehead, is the prefrontal cortex, which has evolved to this extent only in human beings. …

Look again at your hand model. The outer two fingertips represent the side prefrontal cortex, which participates in generating the conscious focus of attention. When you put something in the “front of your mind” you are linking activity in this region to activity from other areas of the brain, such as the ongoing visual perceptions from the occipital lobe….

Now focus on the middle two fingernail areas…. As I described earlier in this chapter, this area has important regulatory functions that range from shaping bodily processes—through overseeing brainstem activity— to enabling us to pause before we act, have insight and empathy, and enact moral judgments.

What makes this middle prefrontal region so crucial to carrying out these essential functions of a healthy life? If you lift your fingers up and put them back down, you’ll get a sense of the anatomical uniqueness of this region: It connects everything. Notice how your two middle fingertips rest on top of the limbic- thumb and touch the brainstem- palm, and are also linked directly to the cortex- fingers. So the middle prefrontal area is literally one synapse away from neurons in the cortex, the limbic area, and the brainstem. And, as I’ll discuss later, it even has functional pathways that connect us to the social world of other brains.

The middle prefrontal region creates links among the following widely separated and differentiated neural regions: the cortex, limbic areas, and brainstem within the skull, and the internally distributed nervous system of the body proper. It also links signals from all those areas to the signals we send and receive in our social world. As the prefrontal cortex helps coordinate and balance the firing patterns from these many regions, it is profoundly integrative…Lift up your fingers and you’ll have an image of how we “flip our lids” and head down the “low road” in our interactions with others.

It is this prefrontal area, as Dr. Siegel demonstrates in the video, which can be developed through practice to act as an emotional response regulator.  This is the area impacted by the regular contemplative practices of ‘mindfulness’.