Achala H. Rodrigo

A problem-solving task specialized for functional neuroimaging: validation of the Scarborough adaptation of the Tower of London (S-TOL) using near-infrared spectroscopy

Problem-solving is an executive function subserved by a network of neural structures of which the dorsolateral prefrontal cortex (DLPFC) is central. Whereas several studies have evaluated the role of the DLPFC in problem-solving, few standardized tasks have been developed specifically for use with functional neuroimaging. The current study adapted a measure with established validity for the assessment of problem-solving abilities to design a test more suitable for functional neuroimaging protocols. The Scarborough adaptation of the Tower of London (S-TOL) was administered to 38 healthy adults while hemodynamic oxygenation of the PFC was measured using 16-channel continuous-wave functional near-infrared spectroscopy (fNIRS). Compared to a baseline condition, problems that required two or three steps to achieve a goal configuration were associated with higher activation in the left DLPFC and deactivation in the medial PFC. Individuals scoring higher in trait deliberation showed consistently higher activation in the left DLPFC regardless of task difficulty, whereas individuals lower in this trait displayed less activation when solving simple problems. Based on these results, the S-TOL may serve as a standardized task to evaluate problem-solving abilities in functional neuroimaging studies.

Differentiating functions of the lateral and medial prefrontal cortex in motor response inhibition

The right inferior frontal gyrus is generally considered a critical region for motor response inhibition. Recent studies, however, suggest that the role of this cortical area in response inhibition may be overstated and that the contributions of other aspects of the prefrontal cortex are often overlooked. The current study used optical imaging to identify regions of the prefrontal cortex beyond the right inferior frontal gyrus which may serve to support motor response inhibition. Forty-three right-handed healthy adults completed a manual Go/No-Go task while evoked oxygenation of the prefrontal cortex was measured using 16-channel functional near-infrared spectroscopy. During motor response inhibition, the right inferior frontal gyrus, and to a lesser extent the homologous contralateral region, showed increased activation relative to a baseline task. Conversely, the medial prefrontal cortex was significantly deactivated, and the extent of reduced activity in this region was associated with fewer errors on the response inhibition task. These findings suggest a more substantial role of the left inferior frontal gyrus in response inhibition and possibly a distinct function of the middle frontal gyrus subserving error detection on manual motor control tasks.

Mindful awareness of feelings increases neural performance monitoring

Mindfulness has been associated with enhanced performance monitoring; however, little is known about the processes driving this apparent neurocognitive benefit. Here, we tested whether focusing present-moment awareness toward the nonjudgmental experience of emotion facilitates rapid neural responses to negative performance outcomes (i.e., mistakes). In particular, we compared whether directing present-moment awareness toward emotions or thoughts would enhance the neurophysiological correlates of performance monitoring: the error-related negativity (ERN) and the error positivity (Pe). Participants were randomly assigned to either a thought-focused or an emotion-focused group, and first they completed a preinduction go/no-go task. Subsequently, the groups followed inductions that promoted mindful attention toward either thoughts or emotions, before completing a final postinduction go/no-go session. The results indicated that emotion-focused participants demonstrated higher neural sensitivity to errors in the time course of the ERN, whereas focusing on thoughts had no effect on performance monitoring. In contrast, neither induction procedure altered the amplitude of the later Pe component. Although our manipulations also induced changes in behavior, the ERN effects remained significant after controlling for performance. Thus, our results suggest that mindfulness meditation boosts early neural performance monitoring (ERN amplitude), specifically through meditation’s influence on affective processing.

Linking trait-based phenotypes to prefrontal cortex activation during inhibitory control

Inhibitory control is subserved in part by discrete regions of the prefrontal cortex whose functionality may be altered according to specific trait-based phenotypes. Using a unified model of normal range personality traits, we examined activation within lateral and medial aspects of the prefrontal cortex during a manual go/no-go task. Evoked hemodynamic oxygenation within the prefrontal cortex was measured in 106 adults using a 16-channel continuous-wave functional near-infrared spectroscopy system. Within lateral regions of the prefrontal cortex, greater activation was associated with higher trait levels of extraversion, agreeableness and conscientiousness, and lower neuroticism. Higher agreeableness was also related to more activation in the medial prefrontal cortex during inhibitory control. These results suggest that personality traits reflecting greater emotional stability, extraversion, agreeableness and conscientiousness may be associated with more efficient recruitment of control processes subserved by lateral regions of the prefrontal cortex. These findings highlight key links between trait-based phenotypes and neural activation patterns in the prefrontal cortex underlying inhibitory control.

Predicting Treatment Outcomes from Prefrontal Cortex Activation for Self-Harming Patients with Borderline Personality Disorder: A Preliminary Study

Self-harm is a potentially lethal symptom of borderline personality disorder (BPD) that often improves with dialectical behavior therapy (DBT). While DBT is effective for reducing self-harm in many patients with BPD, a small but significant number of patients either does not improve in treatment or ends treatment prematurely. Accordingly, it is crucial to identify factors that may prospectively predict which patients are most likely to benefit from and remain in treatment. In the present preliminary study, 29 actively self-harming patients with BPD completed brain-imaging procedures probing activation of the prefrontal cortex (PFC) during impulse control prior to beginning DBT and after 7 months of treatment. Patients that reduced their frequency of self-harm the most over treatment displayed lower levels of neural activation in the bilateral dorsolateral prefrontal cortex (DLPFC) prior to beginning treatment, and they showed the greatest increases in activity within this region after 7 months of treatment. Prior to starting DBT, treatment non-completers demonstrated greater activation than treatment-completers in the medial PFC and right inferior frontal gyrus. Reductions in self-harm over the treatment period were associated with increases in activity in right DLPFC even after accounting for improvements in depression, mania, and BPD symptom severity. These findings suggest that pre-treatment patterns of activation in the PFC underlying impulse control may be prospectively associated with improvements in self-harm and treatment attrition for patients with BPD treated with DBT.

Examining the Neural Correlates of Incidental Facial Emotion Encoding Within the Prefrontal Cortex Using Functional Near-Infrared Spectroscopy

Previous neuroimaging research has implicated the prefrontal cortex PFC as a region of the brain that is vital for various aspects of emotion processing. The present study sought to examine the neural correlates of incidental facial emotion encoding, with regard to neutral and fearful faces, within the PFC. Thirty-nine healthy adults were presented briefly with neutral and fearful faces and the evoked hemodynamic oxygenation within the PFC was measured using 16-channel continuous-wave functional near-infrared spectroscopy. When viewing fearful as compared to neutral faces, participants demonstrated higher levels of activation within the right medial PFC. On the other hand, participants demonstrated lower levels of activation within the left medial PFC and left lateral PFC when viewing fearful faces, as compared to neutral faces.These findings are consistent with previous fMRI research, and suggest that fearful faces are linked to a neural response within the right medial PFC, whereas neutral faces appear to elicit a neural response within left medial and lateral areas of the PFC.

Tryptophan hydroxylase 1 gene polymorphisms alter prefrontal cortex activation during response inhibition.

OBJECTIVE The tryptophan hydroxylase 1 gene (TPH1) catalyzes the formation of 5-hydroxytryptophan, a precursor to the neurotransmitter serotonin. Variations in the gene encoding this enzyme may underlie difficulties in impulse control; however, the proximate relationship between risk alleles for polymorphisms in the TPH1 gene and the neural correlates of response inhibition remain poorly understood. The present study examined the relationship of 2 single nucleotide polymorphisms in the TPH1 gene (rs1799913 and rs4537731) to prefrontal cortex (PFC) activation on a response inhibition task. METHOD Evoked hemodynamic oxygenation in the PFC was measured in 30 unrelated healthy adult women using 16-channel continuous-wave functional near-infrared spectroscopy while they completed a manual go/no-go task. RESULTS TPH1 alleles showed no association with demographic characteristics, general intelligence, impulsive personality traits, or accuracy and response latency indices on the go/no-go task. Participants carrying the risk alleles, however, showed less activity primarily in bilateral inferior frontal gyri and medial PFC under conditions of response inhibition. CONCLUSIONS Polymorphisms in the TPH1 gene may be represented by diminished activity in lateral areas of the PFC underlying response inhibition. Reduced activity in medial PFC might represent altered self-monitoring of performances on the response inhibition task.

Need fulfillment and the modulation of medial prefrontal activity when judging remembered past, perceived present, and imagined future identities

Abstract People’s abilities to integrate temporally distant identities are known to be facilitated by the fulfillment of basic psychological needs. However, the neural systems that support the integrative functions of need fulfillment are not well understood. Neuroimaging studies indicate that the medial prefrontal cortex (MPFC) differentiates remembered past, perceived present, and imagined future identities, possibly on the basis of the self-relevance attributed to specific identity representations. Using optical neuroimaging, we examined the relationship between need fulfillment and activity within the MPFC when young adults (N = 110) made trait judgments about their past, present, and future identities. Participants reporting higher need fulfillment evidenced similarly high levels of activity in the right-MPFC across the conditions; in contrast, those reporting lower need fulfillment evidenced markedly reduced activity when judging past and future identities. Results thus suggest that, among people who experience higher need fulfillment, the MPFC processes temporally distant identities in a similarly self-relevant manner. These findings provide a new type of evidence of the relationship between need fulfillment and identity integration and provide future studies with a point of entry for further examining the neural basis of identity integration.

Cognitive Reappraisal of Negative Emotional Images in Borderline Personality Disorder: Content Analysis, Perceived Effectiveness, and Diagnostic Specificity

Individuals with borderline personality disorder (BPD) report using cognitive reappraisal less often than healthy individuals despite the long-term benefits of the emotion regulation strategy on emotional stability. Individuals with BPD, mixed anxiety and/or depressive disorders (MAD), and healthy controls (HC) completed an experimental task to investigate the tactics contained in cognitive reappraisal statements vocalized for high and low emotional intensity photographs. Self-reported effectiveness after using cognitive reappraisal to decrease negative emotions was also evaluated. Although BPD and MAD used a similar number of cognitive reappraisal tactics, they perceived themselves as less effective at reducing their negative emotions compared to HC. During cognitive reappraisal, BPD and MAD uttered fewer words versus HC, while BPD uttered fewer words versus MAD. Results suggest that individuals with BPD and MAD are less fluent and perceive themselves as less effective than HC when using cognitive reappraisal to lower negative emotions regardless of stimulus intensity.