Activity In Right Ventrolateral Prefrontal Cortex Research Articles

Brain functional activation and first mood episode in youth at risk for bipolar disorder

BackgroundIn order to identify biomarkers of prodromal mood disorders, we examined functional brain activation in children and adolescent at familial risk for bipolar disorder. MethodsOffspring of parents with bipolar I disorder (at-risk youth; N = 115, mean ± SD age: 13.6 ± 2.7; 54 % girls) and group-matched offspring of healthy parents (healthy controls; N = 58, mean ± SD age: 14.2 ± 3.0; 53 % girls) underwent functional magnetic resonance imaging while performing a continuous performance task with emotional and neutral distracters. At baseline, at-risk youth had no history of mood episodes or psychotic disorders. Subjects were followed longitudinally until developing their first mood episode or being lost to follow-up. Standard event-related region-of-interest (ROI) analyses were performed to compare brain activation at baseline between groups and in survival analyses. ResultsAt baseline, at-risk youth exhibited reduced activation to emotional distracters in the right ventrolateral prefrontal cortex (VLPFC) (p = 0.04). Activation was not significantly altered in additional ROIs, including left VLPFC, bilateral amygdala, caudate, or putamen. In those at-risk youth who developed their first mood episode during follow-up (n = 17), baseline increased activation in right VLPFC, right caudate, and right putamen activation predicted the development of a mood episode. LimitationsSample size of converters, loss to follow-up, and number of statistical comparisons. ConclusionsWe found preliminary evidence that a reduced activation in right VLPFC might be a marker of risk for or resilience to mood disorders in at-risk youth. Conversely, an increased activation in the right VLPFC, caudate, and putamen might indicate an increased risk for the later development of their first mood episode.

Effects of aging on true and false memory formation: An fMRI study

Compared to young, older adults are more likely to forget events that occurred in the past as well as remember events that never happened. Previous studies examining false memories and aging have shown that these memories are more likely to occur when new items share perceptual or semantic similarities with those presented during encoding. It is theorized that decreased item-specific encoding and increased gist encoding contribute to these age differences in memory performance. The current study used a modified version of the Deese–Roediger–McDermott (DRM) paradigm to investigate the neural correlates of true and false memory encoding. Results indicated that, compared to young, older adults showed reduced activity in medial temporal lobes (MTL), left ventrolateral prefrontal cortex (VLPFC), and visual cortices associated with subsequent true memories. Despite these decreases older adults showed increased activity in right VLPFC and left superior temporal gyrus (STG) for subsequent true memories. Age-related increases in STG were also associated with subsequent false memories. Results support the theory that older adults engage in less item-specific encoding and greater gist encoding, and that these increases in gist encoding support both subsequent true and false memories. Furthermore, results extend findings of reduced frontal asymmetry in aging, often found in block designs, to the subsequent memory paradigm. Results suggest that greater bilateral frontal activity during encoding in aging are not just task-related, but may be associated with subsequent successful memory performance.

Neural Responses to Emotional Stimuli Are Associated with Childhood Family Stress

An early family environment marked by harsh parenting has been related to risk for multiple mental disorders in adulthood, risks that may be mediated, in part, by deficits in emotion regulation skills. This study examined neural mechanisms underlying these consequences of "risky" families (RF) by exploring neural activity to tasks involving responses to emotional stimuli. Participants completed an assessment of RF and participated in a functional magnetic resonance imaging (fMRI) investigation that examined 1) amygdala reactivity to observation of fearful/angry faces; 2) amygdala and right ventrolateral prefrontal cortex (RVLPFC) reactivity to labeling emotions displayed in these faces; and 3) the relation between RVLPFC and amygdala activity during the labeling task. Offspring from nonrisky families showed expected amygdala reactivity to observing fearful/angry faces and expected activation of RVLPFC while labeling the emotions, which was significantly negatively correlated (-.44) with amygdala activation. Offspring from risky families showed little amygdala activation during the observation task and a strong positive correlation (+.66) between RVLPFC and amygdala activation in the labeling task, suggesting a possible dysregulation in the neural systems involved in responses to emotional stimuli. Offspring from risky families exhibit atypical responses to emotional stimuli that are evident at the neural level.

Working memory for complex figures: An fMRI comparison of letter and fractal n-back tasks.

n-back letter and fractal tasks were administered to 11 participants during functional magnetic resonance imaging to test process specificity theories of prefrontal cortex (PFC) function and assess task validity. Tasks were matched on accuracy, but fractal n-back responses were slower and more conservative. Maintenance (1-back minus 0-back) activated inferior parietal and dorsolateral PFC, with additional activation in right ventrolateral PFC during letter n-back and left lingual gyrus during fractal n-back. Maintenance plus manipulation (2-back minus 0-back) activated inferior parietal, Broca's area, insula, and dorsolateral and ventral PFC, with greater right dorsolateral PFC activation for letter n-back. Manipulation only (2-back minus 1-back) produced additional and equivalent dorsolateral PFC and anterior cingulate activation in both tasks. Results support fractal n-back validity and indicate substantial overlap in working memory functions of dorsal and ventral PFC.