Tag Archives: supplemental motor area

Response Inhibition in the 21st Century (EF Skills Series)

If there is a human condition that is written most about second to human emotions, it would be that of impulse. Motivation powered by Dopamine and sped by Acetylcholine (AcH) is not necessarily supported by the higher-order skills that the Frontal Cortex is known for when impulse gets in the way. For example, when a choice is made by a person to eat what is body assistive or eat what is fast and palatable, chances are impulses drive the attention toward the sensory appealing choice.

It is by responding with delayed gratification, to not take the most convenient method to an end goal, that we can assess the process of each step toward the goal. How then can pacing be valued equitably when it is the efficiency of speed and productivity that pays higher dividends? What was pioneered by the Marshmallow test conducted by Walter Mischel in 1972 on preschoolers continues to be replicated, and bottom-line conclusions are the better a person redirects and controls his or her impulses, the clearer the direction of the path toward the end goal/s. Though not entirely specified, the original test was an exercise of concretizing “waiting” into something that had a “reward” in the end, and that the Marshmallow itself was not the real goal.

The ultimate reward of response inhibition is to process the game of waiting. Waiting on public transportation with a throng of people. Waiting and completing the morning routine despite sleep deprivation. Sticking to the regimen that is pro-health (physical, mental, emotional). To play the game of waiting efficiently, strategies that are at the person’s disposal are in the Inhibitory control toolkit, including scenario playing such as Stimulus–Stimulus- and Stimulus–Response-conflict with the many selves and environments a person interacts with.

The Waiting Game can be very difficult for those who have challenges attending to simple steps. The hippocampus is unable to maintain bridges with the Pre-Frontal Cortex (PFC) when the thoughts are not in sync, where working memory is affected since inhibiting responses allow memories to be processed clearly. Mindfulness exercises do increase the strengthening of neural pathways from the parietal cortex to the frontal cortex as it supports the just ‘being’ state without conclusions. However, as with attention, mindfulness requires a push-pull of one’s attentional inhibition, which means the decision to let some things just pass by like clouds while maintaining focus on the journey of the mind during the session is multilayered. Do I respond to the thought cloud of the ding of the phone, maybe that was an email…or do I cut this short, dinner time is close and I have friends coming later…wait, what was I supposed to be concentrating on…?

The yin-yang of inhibitory control behavior has many names in the field of behavioral science. Response Inhibition is also referred to as ‘Behavioral Inhibition,’ ‘Motor Inhibition,’ ‘Prepotent Response Inhibition,’ and ‘(Attention) Restraint’; while Attentional Inhibition is also referred to as ‘Interference Control,’ ‘Interference Suppression,’ ‘Resistance to (Distracter) Interference,’ and ‘Attention Constraint.’ Think of the two as the demonstration of Newton’s third law is: For every action, there is an equal and opposite reaction. This means response and attention in every interaction are the pair of forces acting on the two interacting choice objects.

Both these inhibition rubrics are necessary when interacting with general life situations that require working memory (both in verbal and auditory means), visual memory (stop and analyze then respond), reflexive responses (go/no-go tasks and responses), word spatial recognition, and figure grounding contrast and comparative analysis. In short, in every single aspect of living that requires a decision between options, it is the brain’s processes that attach to memories and emotions that decide between the choice to stay the course and inhibit or choose the one that interferes with the course and give in to the attentional distracter.

According to Verbruggen, et al (2014) in their study, The Inhibitory Control Reflex, performance in response inhibition paradigms can be modeled as an independent “horse race” between a go process, which is triggered by the presentation of a go stimulus, and a stop process, which is triggered by the presentation of the no-go stimulus or the stop signal. When the stop process finishes before the go process, response inhibition is successful and no response is emitted (signal-inhibit); when the go process finishes before the stop process, response inhibition is unsuccessful and the response is incorrectly emitted (signal-respond). The latency of the stop process (stop-signal reaction time or SSRT) is covert, but it can be estimated in the stop-signal task. SSRT has proven to be an important measure of the cognitive control processes that are involved in stopping.

Yet it is the weight of the end goal that determines the type of inhibitory control that one ultimately uses more of. And as mentioned earlier, the more concrete the process of inhibition by the fruition of an actual marked goal, the more likely one stays the course and avoids attentional constraints. In order to facilitate goal-directed behavior, the proper motor actions in a given context need to be selected and then executed. Regions within the medial wall of the
frontal cortex, in particular, the supplementary motor area (SMA), have been implicated in response preparation, selection, and execution. Single-cell recordings in monkeys performing a delayed reaction task reveal a distinction between the rostral portion of the SMA (‘‘pre-SMA’’) and the caudal portion of the SMA (‘‘SMA proper’’); neuronal activity is seen in the SMA proper only during the response; activity in the pre-SMA, however, is associated with both the delay period and the response, suggesting that the pre-SMA is involved in both preparation and selection of the response. This means that inhibitory responses are best strengthened when paired with a visual spatial or perceptual motor component prior to perceiving and selecting what the response selection is.

This could also support the idea that the younger the developmental age, the more multi-modal means are necessary to train the inhibitory models of the PFC. Competing with the gadgets that provide instant gratification however is much more prevalent since coming out of the lockdown, making the responses less precise and more impatient. Also part of the multi-modal means is to create a fruitful digital diet, one that is realistic and supportive of the ‘school or home work’ that still needs to be done in the platform while being able to segregate the ‘fun work’ that is embedded in the devices. One possibility is that increased functional segregation of neural networks during development results in greater differentiation of individual inhibitory control mechanisms at the behavioral level. Evidence for this is suggested by findings from the study done by Mostofsky, et. al (May 2021) Response Inhibition and Response Selection: Two Sides of the Same Coin) have found that tasks related to executive control tend to coalesce as a single factor in young children, but form a multi-factor construct in adults. This does not mean however that the addictive properties of smart devices do not affect adults the way they do children; response inhibition is key for moderation and for caudate nucleus sustainability, one of the social centers of the brain.