Autism, Brain Evolution, and the Get Set Response

By Robert DePaolo

 Abstract

 This article discusses the hyper-inhibitory and spiked movement fluctuations that typify autism in the context of human brain evolution; specifically the origin of a dualistic integrating/sequencing (“get-set”) mental capacity that otherwise facilitates internal cognition, self- regulation and language processing.
While many diagnostic aspects of autism have been well documented, some remain fairly obscure yet meaningful in considering the cause of the disorder. For example, the well-respected Gilliam Autism Rating scale includes questions about various aspects of autism such as stereotypy, inappropriate social behaviors, sensory behaviors and language deficiencies.  Only one item on the questionnaire refers to “darting behavior” yet this autistic movement pattern might ultimately explain a great deal about the origin and nature of the disorder.
As McFabe (2009) and Redlich, Cueli et. al. (2002) have noted, autistic individuals tend to display particular movement anomalies. Actually since it pertains to more than motor functions it might be called a functional anomaly. It is characterized by abrupt alternations extreme inhibition and “drift” similar to the waxy flexibility seen in catatonia, and abrupt, spiked activation like the “darting” behavior mentioned in the GARS. Much of the duress experienced by autistic individuals results from having to go from states of non-responsiveness to hyper-activation  in rapid time frames in the course of every behavioral or cognitive effort. Such a tendency would seem to indicate that autism is typified by, among other things, lack of a preparatory mechanism within the central nervous system that would otherwise modulate between low-inhibitory and high-excitatory states. If so, that would make virtually all experiences potentially aversive and it might explain why many autistic individuals lack motivation to engage in social activities, (Schultz, Kohl et al 2012) are prone to physical fatigue (Shoffner 2008 ), have low task endurance (Koldewyn, Swallow 2011) and find high stimulus interactions such as eye contact aversive ( Doherty-Sneddon (2012), (Burns, 2012)..
In that context, one might surmise that the behavior patterns associated with autism, for example stereotyped movements, preference for stimulus monotony, vocalization patterns and social avoidance are adaptations to duress; specifically a life of endless surprises and abrupt arousal/somatic shifts. It might also explain why some autistic individuals exhibit pockets of brilliance. Perhaps in some instances there is enough predictability over their environment to preclude the need for ‘preparatory activities” …here used in place of “sensory” or “stereotyped” behaviors. When able to focus on the external world they can take self-regulation for granted and learn more efficiently.
In that sense this would imply that autism can be defined as a condition within the central nervous system involving a pan-resistance to experience that blocks the capacity to process information from the outside world.
There isn’t necessarily anything new in that statement. The research results of Belmonte and Yurgelun (2003) which point to shifts between under inclusive and over-inclusive perceptual processing would predict the same. The difference is that the massive shifts in arousal can be viewed as more than perceptual. Indeed they can be said to influence movement, perception, memory, emotion and all faculties. Whether feeling, sensing, behaving or communicating the autistic individual is forced to undergo discomforting accelerations in all psycho-physiological functions. Yet while that paradigm might help explain some aspects of the “what” in autism. The “why’ is a bit more complex.
In the Beginning  
It is interesting to note that upon initial referral to evaluators or physicians, many parents express the greatest concern about lack of language development and social awareness. As discussed above, many diagnostic tests revolve around such topics and the presence of those traits in autism is well documented. Yet upon deeper questioning, specifically; what was the very first thing you noticed about your child that led you to think something might be wrong; the parent frequently refers to a state of lethargy. They might assert that their child seems to be in a sleepy state, is non responsive to stimuli, displays an excessively flexible head carriage, body and sitting posture. As with speech and cognition, the soma seems un-stabilized by a modulating mechanism.  In such cases it is the lack of energy that first stands out as a sign of atypical development. These parents often compare the behavior of their child with that of other children. They recall that other babies sitting in a shopping cart at the supermarket always look at strangers, often make faces, smile, seem enchanted by the external world. More to the point, these children are energized and have the ergonomic capacity and efficiency to interact and take pleasure from the interaction, whereas their child exhibits a certain limpness.
Using the initial stags of child development as a guide it might make sense to presume the natural/pathogenic state of autism lies in that trend toward limpness, or in less colloquial terms, extreme mind-body lethargy. Yet abrupt arousal and movement fluctuations and lethargy are in many ways, opposites. Thus the question becomes, is the relatively non-responsive state a result of lethargy or is it due to input flooding that serves to block response selection and attention? In other words is the autistic child extremely tired or extremely uncertain?
Some research has shown that energy deficiencies are indeed one component of autism. For example Rudacile (2011) has implicated mitochondrial dysfunction as a possible factor in the onset of the disorder – mitochondria being the engines within cells enabling them to process and metabolize sugars and other nutrients in converting them to energy and behavior. On the other hand behavior cannot occur unless there is some capacity for stimulus discrimination and flooding would prevent that. Energy depletion is involved in some way but the chicken-egg model applies here. Does energy enable the person to control overload or is it a byproduct of the sensory work involved in trying to parse flooded inputs without adequate parsing capacities to begin with?
Beyond that is the question of how this all pertains to human brain function in general. To address that question it might be interesting to take a look back at human brain evolution to see how our perceptions, language, movement style and general psychology became quintessentially human.
A Tale of Ancestral Integration
If, as most paleo-anthropologists assume, human evolution derives from primate origins then we are the descendants of tree-dwellers. All arboreal primates have eyes situated in front, i.e have stereoscopic vision, enabling them to utilize depth perception – a most important faculty in leaping among branches high up in the forest canopy. Thus in the most basic sense the primate brain is a centralizing structure, able and inclined to take disparate neuronal inputs and collate them into a core perceptual-motor skill. For early primates that facilitated not only efficient branch-swinging but also set the stage for inter-group acoustical communications by which to issue warnings about approaching predators like snakes and eagles. Group communication is inherently integrative because in order for the signals to be recognizable to all members they had to be rule-governed. Thus the social-interactive prowess of the primate conceivably resulted from the same neural tendency toward integration that facilitated stereoscopic vision. It seems to have been a classic example of what Darwin called a “conversion”
Integration is essentially synonymous with “aiming.” Thus primate brain evolution ran parallel to the enhancement of various “aiming” faculties.. Aiming is a good thing, but like all other adaptations it comes with a cost. Aiming entails such a recruitment of neural inputs that it has the potential to a flood the brain – like a terminal with too many trains arriving at the same time. Flooding can produce confusion, but since arboreal primates use this function successfully it is hard to describe such a brain model as a liability. In fact, for arboreal primates it is not.
On the other hand that might be because while their brains are large compared to most other creatures, they are much smaller than the human brain. Flooding in a smallish brain is not nearly as confusing as it is in a large brain. Once the early human brain reached its current size and structure other internecine, systemic and neurological adaptations had to occur to prevent mass neural confusion. As if to solve the problem of integration-induced overload, the human brain began to erect parsing barriers. Hemispheric differentiation was one such mechanism. It separated experience into a linguistic and sequential (left-hemisphere) vs. holistic (right hemisphere) take on things. But even more was involved. In order to utilize integration skills (which give us language rules, hunting/aiming skills, social cohesion and other centralized experiential phenomena) yet keep from experiencing flooding, required what neurologist William Calvin has referred to as a “get-set” response. (1990) This is essentially a pause function designed to hold inputs in abeyance, brace the person prior to aiming, interpreting, interacting socially or for that matter engaging in any behavior until response refinement can occur. It is the precursor to what we now refer to as attention span. In human evolution a bipedal movement style helped that process along because having to shift from the left to right leg (something our more centralized primate cousins cannot do) forced a sequential behavioral and movement style. Thus upright walking required a pause between alternating limbs so the left and right side would not be activated simultaneously. The same sequential function within the brain likely set the stage for step-by-step cognition, including language grammar, logic, mathematical operations, analytical thought, extended attention span and other cognitive skills.

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