Of Marshmallows, Brain Plasticity and Attachment (part II)

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Even a cursory glance reveals that the topic of brain plasticity is both scientifically and politically complex. As mentioned in part I, the concept of brain plasticity attempts to capture the brain’s apparent ability to change in response to new experiences such as therapy, cognitive exercises, and even certain religious practices (i.e., meditation and mindfulness). Suffice it to say that brain plasticity has been used to support myriad scientific and political positions.

In his 2003 review article entitled Limits on Plasticity, Michael S. C. Thomas points out that evolutionary psychologists tend to frame brain plasticity as being limited. The limited evolutionary model goes something like this: there’s an innate blueprint (e.g., no so-called blank slate), there are certain critical periods during development of the brain, a closing off of flexibility as the brain matures, ending with limited plasticity in the adult years. In contrast, post evolutionists (for lack of a better term) frame brain plasticity as being permanently plastic. According to Thomas, their model goes something like this: some initial biases toward specialized brain centers exist, however, biases are weak (e.g., no innate blueprints), across development the overall brain system “retains hidden reserves available at any age to learn new skills or to compensate for damage, so long as the correct behavioral interventions are used” (quoting Thomas). Thomas spends the rest of his review article trying to tease out the correct way to frame brain plasticity. As you would expect, the appropriate frame depends on what brain process you are looking at, the stage of development, and the amount of damage the brain has sustained. The following quote by Thomas (sans references) captures the shifting nature of brain plasticity:

Different [brain] functions may emerge or come online at different times. For instance, frontal areas [home to the executive functions], although offering some early limited function in infants, are nevertheless much later in maturing to their adult function than many other cognitive abilities. As a consequence of developing at different rates, different brain systems may then vary in the extent to which their structure is open to shaping by the environment.

I found the following hierarchy of brain systems and their relative level of adaptability to be illuminating. The list is from least adaptable to most adaptable. As Thomas puts it, “[C]hanges in plasticity are region specific”:

  • motor systems
  • visual systems
  • language systems
  • reasoning systems
  • sensory map systems

Thomas reveals that as a brain center becomes modularized, processing efficiency goes up as plasticity goes down. For instance, when tasks are relatively symmetrical, such as face and limb movements, Thomas observes, “One motor cortex is sufficient to control both sides of the body.” As tasks become asymmetrical, such as voluntary hand movements, the picture changes. “A single motor cortex does not have sufficient developmental plasticity,” writes Thomas, “to take on such a complex function [as voluntary hand movements].” Here’s Thomas’ “bottom line”: “There is likely no single thing as the brain’s plasticity.”

If you look at a relatively simple, modularized brain system, it may appear to fit within the evolutionary frame. Look at a complex distributed brain system and you may find support for the post evolutionary frame. But as Thomas makes clear, there is no way to “cut the brain at the joints” so that one frame or the other can be used wholesale. The overall brain system has simple parts and complex parts, and they all depend on each other.

As I read Thomas’ article I could not help but think about Newtonian physics versus quantum physics. Clearly both areas of physics are interrelated, however, both areas need their own separate frames in order to achieve understanding. I would argue that the brain should be approached in the same way. The conceptual framework of brain plasticity certainly allows us to gain an understanding of certain brain processes, but I would not use it wholesale to frame all brain processes and functions. Knowing the limits of any conceptual framework is key. For more on this topic see Ernest Keen’s 2000 book entitled Chemicals for the Mind. Personally I enjoyed Thomas’ systems approach to brain development and function. I’m not sure you can successfully study the brain without taking an organic systems approach. In my opinion, Mischel’s book on the Marshmallow Test (see part I) would have benefited greatly from a systems approach to the subject of mastering self-control.

Thomas has a great section that talks about the myriad developmental problems often facing children from Romanian orphanages. Attachment researchers have spent a lot of time studying these children (i.e., see the work of Charles H. Zeanah). Many of these children have suffered deprivation in the areas of social contact and interaction. Using research conducted on children from Romanian orphanages as a backdrop, Thomas makes the following summary statement (again, sans references):

Many accounts of developmental plasticity have argued that plasticity diminishes in systems subserving lower level cognitive functions before it does so in systems subserving higher level functions. Indeed, the high-level frontal executive systems are thought to retain their plasticity the longest [which agrees with Mischel’s position as talked about in part I]. The longer the plasticity of a system, the more opportunity the environment has to determine its structure and overcome initial disruptions. Yet evidence from these unfortunately deprived children paints a different picture. If plasticity is measured by recovery after early deprivation, high-level executive systems appear to demonstrate a swifter reduction in plasticity than do the more basic sensorimotor and cognitive abilities. If we appeal to the theoretical framework of acquired brain damage in children, these data suggest that we should view the development of executive functions less in terms of plasticity and more in terms of early vulnerability.

If you must acquire brain damage, here’s Thomas’ list of so-called ideal conditions:

  • have as little as possible
  • have it early
  • have it on only one side of the brain
  • be a girl (yes, the hormonal milieu tends to give girls a certain level of protection against brain damage)
  • come from a supportive family
  • hope that your supportive family lives near a good hospital

Three quick points from Thomas’ article. First, brain plasticity can cut both ways. Simply, the effects of brain plasticity can be maladaptive. For instance Thomas draws our attention to “phantom limb pain in amputees and loss of digit function in violinists” (quoting Thomas) as examples of maladaptive brain plasticity.

Second, lower, more simple brain centers may become damaged in such a way that the damage only presents itself as higher, more complex brain centers come online. According to Thomas, for the higher brain centers to develop properly, the lower brain centers have to contribute their part. Early damage may result in lower brain centers still able to perform their localized functions but unable to perform their globalized functions, that is to say, pass needed information along to the upper brain centers. This is why a child may appear to develop normally until such a time as the higher brain functions come online. As an example, this is why it is often difficult to make a diagnosis of autism in very young children. According to Thomas, early cognitive abilities, such as attention, memory, and learning skills, are vulnerable to early disruption. “Without these capacities,” writes Thomas, “the child does not have the tools to efficiently acquire new abilities and cannot progress along the normal pathway of cognitive development.”

Third, Thomas touches on the topic of the brain’s “chicken and egg” dilemma. Which comes first? brain use or brain development? Well, they both go hand-in-hand. The brain develops as it is used, and how the brain is used affects development. But Thomas offers up one caveat: “[I]t is currently unclear how much the inherent plasticity of the brain is actually reducing over time, and how much the adult brain simply has many more functions established within it that are now unwilling to give up their circuits and synapses while they are still being used.” Pulling from the work of cognitive scientist George Lakoff, once cognitive models (i.e., the liberal and conservative political cognitive models) are set up, they are very hard if not impossible to change. Using a computer metaphor, it’s hard to take brain centers offline so that their programming (i.e., Bowlby’s Inner Working Models) could be upgraded.

Our society today tends to “poo poo” kids running, jumping, and playing as so much fluff. On last night’s news there was a report that school systems across the country are considering giving up recess time so kids can study up on tests now required by Common Core. If there is one central message to be gained from Thomas’ article it is the following: the brain is a complex system and all brain centers must be given their due for there to be overall successful brain development. Ignoring some areas while focusing on others is a perilous plan. If you wish for good executive functioning, get kids running, jumping, and playing. Skipping over physical activities and jumping right to behavioral tasks designed to increase EF ignores the brain’s position as a complex system. Just saying.

Thomas closes his summary article with a quote that nicely takes us into the realm of the politics of brain plasticity. Thomas writes:

Cognitive development itself is crucially dependent on the right sort of interactions with the environment. Discussions of brain plasticity should not narrow our focus to neural processes alone. If people want to recover, if people want to change, then they need to rely on the world and other people as much as the properties of their own brains.

Probably without realizing it, Thomas ends by supporting a liberal frame of brain plasticity. Thomas suggests that we not view our neuronal selves as existing within the individual (the conservative position), but as extending out into the world and held by our relationships with others (the liberal view). Back when I attended attachment conferences, I often heard about how the mother (and later father) acts as a surrogate frontal, executive function brain for the developing infant/child. Suffice it to say that the notion of a surrogate executive function brain expresses a liberal ideology. As an observation, one way to take brain systems offline so that change can happen is to use a surrogate brain, like a mother or father or even therapist. At times like these I tend to come back to one overarching philosophical question: If the brain is infinitely plastic, then where does our sense of self reside?

In the next part we will look at a 2010 article by Victoria Pitts-Taylor entitled The Plastic Brain: Neoliberalism and the Neuronal Self. According to Pitts-Taylor, brain plasticity has been used to support many different political ideologies. Here’s a partial list to get you thinking:

  • liberalism
  • conservatism
  • neoliberalism
  • social constructionism
  • postmodernism
  • poststructuralism

We’ll pick back up in the next part by looking at political framings of brain plasticity. Just remember that if you hear about any intervention, an ideology frames that intervention. Recall from above that the permanently plastic ideology prescribes “correct behavioral interventions.” Again, I have mentioned Midgley’s continuum many times before, and I’ll mention it one more time:

Worldview <==> Ideology <==> Methodology <==> Intervention