Mental Energy – an fMRI study of the core control network for goal-oriented behavior

Our research plans address the mental energy concept, by which we mean the mental resources an individual can recruit in order to perform optimally. We propose that a common resource pool is available in the human brain for any task that requires mental effort, or focused awareness and willful action. Several recent reports identified the anterior insula and the anterior cingulate cortices (AIC and ACC) as a core control network for goal-oriented behavior, and it has recently been proposed that the AIC engenders awareness and the ACC engenders volitional action. Our central hypothesis is that this core neural network provides the “mental energy” needed for any effortful task.

• Staff:

Maria Engström , Assoc. Prof.		fMRI analysis		CMIV + IMH/Radiology
Thomas Karlsson , Assoc. Prof.		Behavioral studies		CMIV + IBL
Bud Craig , Prof.		Senior scientist		Barrow Neurological Institute, Phoenix,
Anne-Marie Landtblom , Assoc. Prof.		Mentor		CMIV + IKE/Neuro Science
Mathias Hällgren , PhD		Behavioral studies		IKE/Technical Audiology
Kenny Skagerlund , Stud.		Behavioral studies

• Former Staff:

• Project Description:

Background

This hypothesis is an outgrowth of recent fMRI work  at CMIV. In a study that was just published, higher performance in language tasks correlated strongly with increased activity in the right AIC during a verbal sentence completion task (van Ettinger-Veenstra et al. 2009); in a study that has not been reported yet, increased difficulty in a working memory span task correlated strongly with increased activation in the AIC and ACC bilaterally (Engström and Karlsson, in preparation). These observations are consistent with those of others on auditory comprehension in a noisy background (Giraud et al. 2004) and “mental effort” in a different memory task (Jansma et al. 2007). Increased performance on these simple tasks is also known to correlate highly with increased performance on written intelligence tests, such as the conventional Wechsler test. The inspection time task is another simple visual or auditory psychophysiological test that essentially measures mental speed, and it uniquely has a significant correlation (r ~ 0.5) with psychometric intelligence, as documented by a meta-analysis of over 90 studies (Grudnik and Kranzler 2001). The fMRI study by Deary et al. reported that in a population of 20 subjects difficulty in the inspection time task correlated strongly and selectively with activation of the AIC and the ACC bilaterally. In other words, the brain activity observed during the inspection time task suggests the hypothesis that individual psychometric intelligence is moderated by recruitment of the AIC / ACC core control network. In addition, we will expand this work to address the broader concept of “mental energy” by including the working memory span (“effort”) task and also the finger-tapping task, which the literature suggests will produce parallel correlations with intelligence that have both fundamental and clinical significance (O’Boyle et al 1994; Prigatano et al 2004, 2008). In the proposed experiments, we will study normal, healthy subjects; if these experiments verify our central hypothesis regarding “mental energy”, then we can extend this work in the future to several important patient populations (e.g., autism, dementia, traumatic brain injury, ADHD) for which declines in general intelligence or in finger-tapping have clinical significance.


Methods

We will perform psychophysical, psychometric, behavioral, and functional imaging (fMRI) experiments in each subject.  As described above, we will recruit individual volunteers from local high schools (Gymnasium) between 18 and 20 years of age who are right-handed, healthy, have satisfactory visual acuity, and can be placed in an MRI scanner.   Each subject will participate in two sessions of approximately one and a half hour. The first session will include behavioral tests of e.g. working memory span, verbal ability, and general intelligence as well as the inspection time task. The participants will also perform a dichotic listening test and a finger-tapping experiment at the first session. At the second session, the fMRI session, the subjects will perform inspection-time, verbal working memory, sentence reading, and finger-tapping.