The lateral and ventromedial prefrontal cortex work as a dynamic integrated system:evidence from FMRI connectivity analysis

Recent functional magnetic resonance imaging (fMRI) investigations of the interaction between cognition and reward processing have found that the lateral prefrontal cortex (PFC) areas are preferentially activated to both increasing cognitive demand and reward level. Conversely, ventromedial PFC (VMPFC) areas show decreased activation to the same conditions, indicating a possible reciprocal relationship between cognitive and emotional processing regions. We report an fMRI study of a rewarded working memory task, in which we further explore how the relationship between reward and cognitive processing is mediated. We not only assess the integrity of reciprocal neural connections between the lateral PFC and VMPFC brain regions in different experimental contexts but also test whether additional cortical and subcortical regions influence this relationship. Psychophysiological interaction analyses were used as a measure of functional connectivity in order to characterize the influence of both cognitive and motivational variables on connectivity between the lateral PFC and the VMPFC. Psychophysiological interactions revealed negative functional connectivity between the lateral PFC and the VMPFC in the context of high memory load, and high memory load in tandem with a highly motivating context, but not in the context of reward alone. Physiophysiological interactions further indicated that the dorsal anterior cingulate and the caudate nucleus modulate this pathway. These findings provide evidence for a dynamic interplay between lateral PFC and VMPFC regions and are consistent with an emotional gating role for the VMPFC during cognitively demanding tasks. Our findings also support neuropsychological theories of mood disorders, which have long emphasized a dysfunctional relationship between emotion/motivational and cognitive processes in depression.

Using a combined motivational and volitional intervention to promote exercise and healthy dietary behaviour among undergraduates

Aims: This study tested the impact of combining a motivational intervention based on protection motivation theory (PMT, Rogers, 1983 [18]) plus a volitional intervention based on action planning and coping planning, as a way to promote the prevention of type 2 diabetes among UK undergraduates. Methods: Eighty-four participants were randomly assigned to either a control group or one of three experimental conditions: motivational intervention (PMT), volitional intervention (APCP), or combined motivational and volitional intervention (PMT&APCP). PMT variables, dietary and exercise behaviours were measured at three time-points over a four-week period. Results: The motivational intervention significantly changed PMT variables. The combined motivational and volitional intervention significantly decreased fat intake and increased the frequency of exercise relative to all other groups, and significantly increased the amount of fruit and vegetables consumed relative to control and volitional intervention groups. Conclusions: These results suggest that motivational intervention is effective at changing cognitions but changing behaviour requires an intervention based on both motivation and volition.