Anterior Medial Prefrontal Cortex Exhibits Activation during Task Preparation but Deactivation during Task Execution

BACKGROUND: The anterior prefrontal cortex (PFC) exhibits activation during some cognitive tasks, including episodic memory, reasoning, attention, multitasking, task sets, decision making, mentalizing, and processing of self-referenced information. However, the medial part of anterior PFC is part of the default mode network (DMN), which shows deactivation during various goal-directed cognitive tasks compared to a resting baseline. One possible factor for this pattern is that activity in the anterior medial PFC (MPFC) is affected by dynamic allocation of attentional resources depending on task demands. We investigated this possibility using an event related fMRI with a face working memory task. METHODOLOGY/PRINCIPAL FINDINGS: Sixteen students participated in a single fMRI session. They were asked to form a task set to remember the faces (Face memory condition) or to ignore them (No face memory condition), then they were given 6 seconds of preparation period before the onset of the face stimuli. During this 6-second period, four single digits were presented one at a time at the center of the display, and participants were asked to add them and to remember the final answer. When participants formed a task set to remember faces, the anterior MPFC exhibited activation during a task preparation period but deactivation during a task execution period within a single trial. CONCLUSIONS/SIGNIFICANCE: The results suggest that the anterior MPFC plays a role in task set formation but is not involved in execution of the face working memory task. Therefore, when attentional resources are allocated to other brain regions during task execution, the anterior MPFC shows deactivation. The results suggest that activation and deactivation in the anterior MPFC are affected by dynamic allocation of processing resources across different phases of processing

Breath Counting as a Measure of Sustained Attention in Mindfulness Meditation and its Effect on Mood

A great deal of research is currently being carried out on mindfulness meditation, but most of this research suffers from obvious problems and shortcomings. Particularly lacking are objective, observable measures of mindfulness performance that would make it possible to track long-term improvement while at the same time assuring experimental control during individual sessions. One promising method is the so-called breath counting task (BCT) devised by Levinson et al. (2014), which pairs a button-pressing response with each breath during a meditation-like cognitive task. This study involves two experiments investigating the effects of individual-difference variables such as depression, anxiety, personality (Big 5), and working memory capacity on BCT performance, mind wandering, and changes in positive and negative mood. We found that BCT performance correlated with self-reported mind wandering, and tended to decline over the course of the 15-minute training session. Mood, particularly negative mood, decreased in intensity following the BCT, and this effect appeared stronger for participants higher in depression and anxiety. Overall, these results provide further evidence of the BCT’s potential usefulness in investigating the cognitive processes that underlie mindfulness meditation

The Framing Effect and Risky Decisions: Examining Cognitive Functions with fMRI

The ‘‘framing effect’’ is observed when the description of options in terms of gains (positive frame) rather than losses (negative frame) elicits systematically different choices. Few theories explain the framing effect by using cognitive information-processing principles. In this paper we present an explanatory theory based on the cost–benefit tradeoffs described in contingent behavior. This theory proposes that individuals examining various alternatives try to determine how to make a good decision while expending minimal cognitive effort. For this study, we used brain activation functional magnetic resonance imaging (fMRI) to evaluate individuals that we asked to choose between one certain alternative and one risky alternative in response to problems framed as gains or losses. Our results indicate that the cognitive effort required to select a sure gain was considerably lower than the cognitive effort required to choose a risky gain. Conversely,the cognitive effort expended in choosing a sure loss was equal to the cognitive effort expended in choosing a risky loss. fMRI revealed that the cognitive functions used by the decision makers in this study were localized in the prefrontal and parietal cortices of the brain,a finding that suggests the involvement of working memory and imagery in the selection process