Regeneration II: Role for self-direction?
In response to my recent regeneration post, my brother-in-law writes: “The brain IS cool – and so are your articles! Might functional recovery be self-directed? – have you read the research on neuroplasticity?”
I have to confess before I forge ahead that the forebrain is a Johnny-come-lately topic for me. I have lived my professional life immersed in the wonders of the brainstem and spinal cord. I feel a great affinity for these structures, which along with the peripheral nervous system are as impactful as they are underestimated.
My standoffish attitude toward the forebrain has a couple of sources. First, the forebrain tells lies on a regular basis. It is even difficult to figure out when the forebrain is acting duplicitously. On the other hand, the brainstem-spinal cord has no ability for deception or subterfuge. As a case in point, consider a person who swears up and down that they are not _____ (fill in the blank: depressed, delusional, addicted to alcohol and so on) or that they really, really like the dish of food that you just served. Lies abound in such instances. These lies include lies directed to the self as well as toward others. But a look at posture and facial expression and other outputs of the brainstem tell the true story.
Another reason that I have resisted the allure of the forebrain is that it is the antithesis of an underdog, all glitzy and commonly accepted as top dog so to speak. In other words, I like the brainstem because of my natural inclination to root for the less obvious and less glamorous underdog.
When I wrote my textbook, Medical Neurobiology, I had to learn about everything that I had hitherto ignored and this included the forebrain. My own research on empathy has also required that I pay the forebrain more heed.
With that background, let’s return to the question of self-directed functional recovery. I will give you my opinion and encourage readers to make up their own minds on the topic. First, let’s consider functional recovery that works really, really well: regeneration of limbs in octopi and amphibians. I think it’s exceedingly unlikely that self-direction plays any role here. Similarly, in the mammal, the vast majority of anatomical and physiological recovery is dictated by the facts of the situation. A chunk of brain does not re-make itself, no matter how much you want it to, any more than an amputated limb remakes itself in mammals. A cut peripheral nerve may re-connect, not perfectly but enough for recovery.
Now let’s imagine that we are in a gray zone where some recovery is possible but not at all a sure things. A cerebral stroke is just such a gray zone. Most strokes produce a core region of dead neurons surrounded by a penumbra, an area containing neurons that are at risk for dying but are not necessarily doomed. Will penumbral neurons live or will they die? Is there a role for personality, drive, and social connectedness in biasing the direction that events take? I think there may be in an indirect way. People that are socially connected, excited about life, and want to live to see ______[their favorite team win; their first grandchild; and so on] have better health outcomes than socially isolated, depressed individuals who have “given up” on life. We don’t know the mechanisms of this connection between social and psychological health on one hand and physiological health on the other but we do know that the connection exists. Since this connection improves outcomes in diseases such as cancer, it is not far-fetched to imagine that it could also improve recovery from stroke.
I will close by re-emphasizing that the impact of social and psychological health on physiological health is small and is dwarfed by the facts of the injury. Remember this and have compassion for those who fall victim to brain injuries from stroke, tumor, disease, or traumatic injury. People with brain injuries did not want or ask for their illness and in the end, they succumb to illness because of the power of the illness, not because of any lack in the effort to live.