A Book Review by John Abbondanza
Though Jeffrey Schwartz is a psychiatrist at UCLA School of Medicine, there is a lot for behavioral optometrists to like in 'The Mind and the Brain - Neuroplasticity and the Power of Mental Force'. The book is Schwartz's attempt to explain how he uses what he calls 'mental force', or the willful power of the mind, to help his patients with obsessive compulsive disorder (OCD). Though the story of his discovery is interesting by itself, he blends into it a good summary of some of the best work in neuroplasticity, including his own, to show how the brain changes through experience. Schwartz also discusses some of the political issues faced by neuroscientists when they present their findings which are contrary to the prevailing medical 'wisdom' at the time, which has obvious optometric parallels.
Brain Lock - The book begins with a philosophical discussion on the nature of the mind (which I found fascinating), followed by a discussion of the neurological findings in his patients with OCD. He describes 'Brain Lock', or the neural circuits that become 'locked' in the 'on' position (the orbito-frontal cortex, the caudate nucleus, and the anterior cingulate gyrus) in patients with OCD. He further describes the 'ego-dystonic' nature of OCD, how patients are aware that their anxiety and behavior is irrational, yet are unable to stop those behaviors. It is almost as if the "events of the brain and the state of the mind were, at least partly, separable" (pg 60-61). Schwartz postulated that the very disjointed nature of the disorder in the mind suggested a possible remedy. What if the rational part of the mind could be harnessed to gain control over the irrational part? He felt that if he could help patients to "experience the OCD symptom without reacting to the discomfort it caused, realizing instead that even the most visceral OCD urge is actually no more than the manifestation of a brain wiring defect" (pg 77-78), it might be therapeutically beneficial. Turns out he was right.
Mental Force - Based on these ideas, he developed a four step program to help his patients with OCD. Those steps are: 1) to Re-label the thoughts and feelings as an 'error message', 2) to Reattribute the feeling to the error message produced by the disease 3) to Refocus attention on some adaptive behavior, and 4) to quickly Revalue the disturbing thoughts as senseless. These four steps allowed his patients to overcome their OCD, without the use of drugs and faster than other treatments available. More importantly, he showed that the PET scans of patients with OCD improved through this process (without drugs), through the power of the patient's own mental force. This is an important concept. The physical activity of the brain could change through conscious and willful mental effort.
Learned Nonuse - Schwartz then spends the next few chapters reviewing some fascinating work on neuroplasticity and remodeling of the brain. He devotes an entire chapter to 'The Silver Spring Monkeys', a series of experiments on monkeys who had the afferent nerves from one arm cut so they could not feel anything in their arm. The monkeys are now 'deafferenated', meaning they have no information going back from the arm to the brain. This results in a limp and useless arm. Sherrington (of Sherrington's Law of Equal Innervation) used this as an example of how both afferent and efferent processing was necessary for movement, called Sherringtonian Reflexology. This became the standard concept of the time, and was widely accepted until Edward Taub, a neuropsychologist, came along with his monkeys.
Taub found that although most monkeys did not use their deafferenated arm, if conditions were just right, monkeyscould learn to use that arm. He found that by restraining the 'good' arm and with proper motivation (a shock if they do not move the arm when a light goes on and a reward if they do move it), the monkeys do learn to move the arm. Taub then did a series of experiments to explore this further. For example, if both arms were deafferenated, they soon learned to use both limbs. If they were deafferenated at birth, not only was their no paralysis, but they used the arm almost as good as normal. This lead Taub to conclude "failure to use a deafferenated limb reflected learned helplessness, not a motor incapacity." (pg 147) Taub called this 'learned nonuse'.
Heresy! - Taub recalled the vehement reaction of his ideas at the time:
"The people in control of neuroscience then were all students of Sherrington… They were very upset... These people really despised me. I couldn't imagine where all this emotion was coming from." (pg 143-144)
Does this sound familiar to us as behavioral optometrists?
Neuroplasticity - Schwartz then describes, in great detail, much of the research on neuroplasticity, the original idea of which was described in 1890 by William James. A sampling of findings:
motor areas of the cortex could be mapped to pinpoint which part of the brain corresponded to a body part (called a 'motor map', or homunculus)
each motor map was as individual as a fingerprint
these differences likely reflected individual skills and experiences
these motor maps changed over time for a given individual
the more an animal uses something, the greater the area represented in the cortex
after amputation, the somatosensory cortex reorganizes to process information form other body areas (Ramachandran and others)
"the amount of cortical territory assigned to a given part of the body reflects not the size of that body part, but its sensitivity" (pg 171)
in another series of experiments, after cutting peripheral nerves (which results in nerves sending their information to a different part of the brain), "with enough use of their rewired hands, monkeys could achieve near-total correction of the scrambled brain addresses" (pg 174)
some of the retinal nerves in lab animals were cut. "After a while, the surviving nerves filled in the area in the visual cortex that the damaged nerves had once delivered inputs to so that there were no holes in the visual field" (pg 177)
"The life we live, in other words, shapes the brain we develop." (pg 179)
when two adjacent fingers are sewn together (artificial syndactyly), after a couple of months, the cortex was remapped
conversely, if you surgically cut patients with congenital syndactyly so their fingers can now move independently, the brain quickly differentiates cortical representation (remapping)
small retinal lesions in cats shifted the retinotopic map on the cortex
'Constraint induced movement therapy' was shown to allow stroke patients to regain use of a paralysed limb
When such improvement was noted, it was shown to be due to an increase in activity on the motor cortexipsilateral to the lesion (motor control is normally contralateral).
The actual citations in the book go on and on, but the main point is clear. The brain reorganizes itself based on its use. This is called "use-dependent cortical reorganization", and is thought to be the basis of recovery after brain injury or stroke.
Attention Must Be Paid - Schwartz devotes an entire chapter to the critical role that attention plays in reorganizing the brain, in neuroplasticity. Think about all of the visual information hitting your retina right now. The words on the page, the computer, the desk or table it is on, the environment immediately around the computer, and the entire room. All of this information is hitting the retina, but we do not process all of it equally. We see what we are paying attention to and what we are looking for. Schwartz explains how the focusing of attention on a visual target can increase the neuronal response in two ways: first by increasing the response to that target; and second, by decreasing the response to competing stimuli.
fMRI studies have shown that human subjects who are anticipating a target to appear in a particular area of the visual field have an increased firing rate (activity) in that area even before the target appears. Other studies have found a 13% increase in somatosensory cortical response to vibration when subjects paid attention to the vibration than when they did not. Schwartz states, "Attention, then, is not some fuzzy, ethereal concept. It acts back on the physical structure and activity of the brain." (pg 333) Furthermore, he quotes neuroscientist Ian Robertson of Trinity College Dublin: "Attention…increases cerebral activity in the brain,.. and since we know that firing a set of synapses again and again makes them (the synapses) grow stronger, it follows that attention is an important ingredient for neuroplasticity." (pg 334)
This is not surprising to anyone who does vision therapy. I am reminded of the often quoted phrase in the OEP clinical curriculum courses "to provide the necessary meaningful experience". If it means nothing to us, then we are not paying attention to it. This will limit the effectiveness of VT by limiting the underlying neuroplastic changes that we are striving to achieve. Attention must be paid!
Optometric Implications - This book wonderfully illustrates a possible mechanism of vision therapy. How is it that vision therapy works? What happens in the brain when it does? After reading this book, there is no doubt now. Vision therapy must lead to changes in the brain, changes in organization and function. This must be the case. The challenge for us as a profession is to test our results and clearly demonstrate to others that this reorganization occurs. This is a call to action. Neuroscientists are our natural allies. Behavioral optometrists should actively study neuroscience, in order to gain further understanding of brain function. Brain science is synergistic with optometric science.
I cannot help but ask many questions after reading this book. For example, is 'learned nonuse' a possible mechanism for the development of amblyopia? What about strabismus? Does the power of mental force have a role in vision therapy? Could we harness it to improve our results? What can we do to increase the level of attention being paid to VT activities?
Optometrists have much to learn from the emerging field of neuroscience. I honestly believe if I was not a behavioral optometrist, I would be a neuroscientist. For those interested in a scientific discussion of the brain without all the molecular biology, a discussion that truly goes into brain function, then "The Mind and the Brain - Neuroplasticity and the Power of Mental Force" is a must read.