Final Report Summary - NBC-EFFORT (Neural and behavioral correlates of mental effort)
Project objectives
This project was aimed at investigating the neural substrates underlying the voluntary investment of graded effort during a challenging mental task, as well as the central circuitry associated with the perception of effort in the same task. The effect on task performance of different levels of applied effort was also of interest. The study involved the collection of fMRI, behavioural, and psychometric data for a planned sample of 36 healthy volunteers, to yield a projected usable cohort of 30 subjects.
Project results
We were able to recruit a total of 35 volunteers for the experiment in the period between November 2010 and December 2011. The data collection phase lasted somewhat longer than planned due to the fact that critical resources, namely MRI scanner time slots and the local pool of volunteers eligible for MRI experiments, had to be shared with other researchers at the host institution conducting a number of other brain-imaging studies. The recruitment of the volunteers was performed in complete accord with the ethical committee guidelines and all the volunteers signed the informed consent form approved by the ethical committee.
Although all the data collection as well as the essential pre-processing has been completed, due to concurrent teaching duties of the researcher at the host institution and some difficulties in recruiting project assistants with the required level of expertise in brain imaging, we were able to perform only preliminary analyses at the present time. These analyses have so far indicated:
- A large heterogeneity in the neural correlates of the graded voluntary application of mental effort to the experimental task. In other words, it appears that different individuals implement quite different "neural strategies" when instructed to put maximum or minimum effort in a cognitively demanding task. This finding, although not completely unexpected, does warrant the employment of more sophisticated approaches to data analysis.
- A positive correlation between the individual degree of right insular cortex activation and the self-reported level of "frustration" experienced while performing the task. Given the central role of the right insula in the interoceptive processes related to the monitoring of the current bodily state, this result is in agreement with Damasio's "somatic marker" hypothesis that sees emotional states ("frustration" in our case, a dimension related to the negative valence of effort perception) as representations of variations in the body's internal state.
It should be noted that, due simply to time constraints, the analyses conducted so far were strictly preliminary and of an exploratory nature. In order to reveal the full spectrum of potential effects embedded in the data, a number of more tailored approaches need to be employed. We estimate we will be able to complete all the analyses by the end of the current year.
Potential impact
Although we cannot foresee the precise nature of the findings that will be uncovered, the identification of specific brain circuits implicated in the active engagement of mental exertion and in the subjective perception of the aversive feeling of effort - along with the assessment of their modulatory influence on actual task performance - may have a number of important implications. Several clinical conditions are characterised by the presence of an increased sense of mental effort and apathy, which significantly degrades the patients' quality of life and negatively affects mood. Identifying the neural substrates of the executive and the affective dimension of effort may help in devising appropriate strategies for remediation of these symptoms and improving patients' quality of life (e.g. behavioural-cognitive therapy or transcranial magnetic stimulation).
Furthermore, this research may also provide important information outside of the clinical settings, especially in the fields of education (where cognitive effort is a crucial element), and human factors in specific work typologies characterised by a high level of executive demand (e.g. air-traffic controllers).
This project was aimed at investigating the neural substrates underlying the voluntary investment of graded effort during a challenging mental task, as well as the central circuitry associated with the perception of effort in the same task. The effect on task performance of different levels of applied effort was also of interest. The study involved the collection of fMRI, behavioural, and psychometric data for a planned sample of 36 healthy volunteers, to yield a projected usable cohort of 30 subjects.
Project results
We were able to recruit a total of 35 volunteers for the experiment in the period between November 2010 and December 2011. The data collection phase lasted somewhat longer than planned due to the fact that critical resources, namely MRI scanner time slots and the local pool of volunteers eligible for MRI experiments, had to be shared with other researchers at the host institution conducting a number of other brain-imaging studies. The recruitment of the volunteers was performed in complete accord with the ethical committee guidelines and all the volunteers signed the informed consent form approved by the ethical committee.
Although all the data collection as well as the essential pre-processing has been completed, due to concurrent teaching duties of the researcher at the host institution and some difficulties in recruiting project assistants with the required level of expertise in brain imaging, we were able to perform only preliminary analyses at the present time. These analyses have so far indicated:
- A large heterogeneity in the neural correlates of the graded voluntary application of mental effort to the experimental task. In other words, it appears that different individuals implement quite different "neural strategies" when instructed to put maximum or minimum effort in a cognitively demanding task. This finding, although not completely unexpected, does warrant the employment of more sophisticated approaches to data analysis.
- A positive correlation between the individual degree of right insular cortex activation and the self-reported level of "frustration" experienced while performing the task. Given the central role of the right insula in the interoceptive processes related to the monitoring of the current bodily state, this result is in agreement with Damasio's "somatic marker" hypothesis that sees emotional states ("frustration" in our case, a dimension related to the negative valence of effort perception) as representations of variations in the body's internal state.
It should be noted that, due simply to time constraints, the analyses conducted so far were strictly preliminary and of an exploratory nature. In order to reveal the full spectrum of potential effects embedded in the data, a number of more tailored approaches need to be employed. We estimate we will be able to complete all the analyses by the end of the current year.
Potential impact
Although we cannot foresee the precise nature of the findings that will be uncovered, the identification of specific brain circuits implicated in the active engagement of mental exertion and in the subjective perception of the aversive feeling of effort - along with the assessment of their modulatory influence on actual task performance - may have a number of important implications. Several clinical conditions are characterised by the presence of an increased sense of mental effort and apathy, which significantly degrades the patients' quality of life and negatively affects mood. Identifying the neural substrates of the executive and the affective dimension of effort may help in devising appropriate strategies for remediation of these symptoms and improving patients' quality of life (e.g. behavioural-cognitive therapy or transcranial magnetic stimulation).
Furthermore, this research may also provide important information outside of the clinical settings, especially in the fields of education (where cognitive effort is a crucial element), and human factors in specific work typologies characterised by a high level of executive demand (e.g. air-traffic controllers).
