Abigail A. Baird

An FMRI investigation of the impact of interracial contact on executive function

We investigated whether individual differences in racial bias among white participants predict the recruitment, and potential depletion, of executive attentional resources during contact with black individuals. White individuals completed an unobtrusive measure of racial bias, then interacted with a black individual, and finally completed an ostensibly unrelated Stroop color-naming test. In a separate functional magnetic resonance imaging (fMRI) session, subjects were presented with unfamiliar black male faces, and the activity of brain regions thought to be critical to executive control was assessed. We found that racial bias predicted activity in right dorsolateral prefrontal cortex (DLPFC) in response to black faces. Furthermore, activity in this region predicted Stroop interference after an actual interracial interaction, and it statistically mediated the relation between racial bias and Stroop interference. These results are consistent with a resource depletion account of the temporary executive dysfunction seen in racially biased individuals after interracial contact.

Differential role of the orbital frontal lobe in emotional versus cognitive perspective-taking

Lesions of the orbital frontal lobe, particularly its medial sectors, are known to cause deficits in empathic ability, whereas the role of this region in theory of mind processing is the subject of some controversy. In a functional magnetic resonance imaging study with healthy participants, emotional perspective-taking was contrasted with cognitive perspective-taking in order to examine the role of the orbital frontal lobe in subcomponents of theory of mind processing. Subjects responded to a series of scenarios presented visually in three conditions: emotional perspective-taking, cognitive perspective-taking and a control condition that required inferential reasoning, but not perspective-taking. Group results demonstrated that the medial orbitofrontal lobe, defined as Brodmanns areas 11 and 25, was preferentially involved in emotional as compared to cognitive perspective-taking. This finding is both consistent with the lesion literature, and resolves the inconsistency of orbital frontal findings in the theory of mind literature.

Functional Magnetic Resonance Imaging of Facial Affect Recognition in Children and Adolescents

OBJECTIVE To examine further the role of the amygdala in the recognition of facial expression in adolescents. METHOD Twelve healthy adolescents were studied using functional magnetic resonance imaging technology during a task of facial affect recognition and a visual control task. RESULTS All subjects demonstrated a significant increase in signal intensity in the amygdala for the facial expression recognition task. CONCLUSIONS The data are consistent with previous work in healthy adult subjects implicating the amygdala as essential for the recognition of fearful facial expression.

Functional Differences Among Those High and Low on a Trait Measure of Psychopathy

BACKGROUND It has been established that individuals who score high on measures of psychopathy demonstrate difficulty when performing tasks requiring the interpretation of others emotional states. The aim of this study was to elucidate the relation of emotion and cognition to individual differences on a standard psychopathy personality inventory (PPI) among a nonpsychiatric population. METHODS Twenty participants completed the PPI. Following survey completion, a mean split of their scores on the emotional-interpersonal factor was performed, and participants were placed into a high or low group. Functional magnetic resonance imaging data were collected while participants performed a recognition task that required attention be given to either the affect or identity of target stimuli. RESULTS No significant behavioral differences were found. In response to the affect recognition task, significant differences between high- and low-scoring subjects were observed in several subregions of the frontal cortex, as well as the amygdala. No significant differences were found between the groups in response to the identity recognition condition. CONCLUSIONS Results indicate that participants scoring high on the PPI, although not behaviorally distinct, demonstrate a significantly different pattern of neural activity (as measured by blood oxygen level-dependent contrast)in response to tasks that require affective processing. The results suggest a unique neural signature associated with personality differences in a nonpsychiatric population.

Frontal Lobe Activation during Object Permanence: Data from Near-Infrared Spectroscopy

The ability to create and hold a mental schema of an object is one of the milestones in cognitive development. Developmental scientists have named the behavioral manifestation of this competence object permanence. Convergent evidence indicates that frontal lobe maturation plays a critical role in the display of object permanence, but methodological and ethical constrains have made it difficult to collect neurophysiological evidence from awake, behaving infants. Near-infrared spectroscopy provides a noninvasive assessment of changes in oxy- and deoxyhemoglobin and total hemoglobin concentration within a prescribed region. The evidence described in this report reveals that the emergence of object permanence is related to an increase in hemoglobin concentration in frontal cortex.

Overt propositional speech in chronic nonfluent aphasia studied with the dynamic susceptibility contrast fMRI method.

This study examined activation levels in the left (L) supplementary motor area (SMA) and the right (R) SMA (separately), and activation in nine R perisylvian language homologues during overt, propositional speech in chronic nonfluent aphasia patients. Previous functional imaging studies with a variety of chronic aphasia patients have reported activation in these regions during different language tasks, however, overt propositional speech has not been examined. In the present research, four nonfluent aphasia patients were studied during overt elicited propositional speech at 4-9 years post-single L hemisphere stroke, which spared the SMA. The dynamic susceptibility contrast (DSC) method of functional MRI was used to calculate relative cerebral blood volume (relCBV) for cortical regions of interest (ROIs) during the first-pass bolus of gadolinium during two conditions: (1) pattern (silent viewing of checkerboard patterns) and (2) story (overt, elicited propositional speech describing sequential pictures, which formed a story). During the story condition, controls had significantly higher relCBV in L SMA than in R SMA; aphasics, however, had significantly higher relCBV in R SMA than in L SMA. During the pattern condition, no significant differences were observed between the L SMA and the R SMA for either controls or aphasics. In addition, aphasics had significantly higher relCBV in the R sensorimotor mouth during story than pattern. This R sensorimotor mouth relCBV was also significantly higher in aphasics than controls during story, and the two groups did not differ during pattern. The overall mean relCBV for the nine R perisylvian ROIs was significantly higher for aphasics than controls during both story and pattern. These results suggest that poor modulation, including possible over-activation of R sensorimotor mouth and other R perisylvian language homologues may underlie in part, the hesitant, poorly articulated, agrammatic speech associated with nonfluent aphasia.

Anatomical Changes in the Emerging Adult Brain: A Voxel-Based Morphometry Study

Research has consistently confirmed changes occur in brain morphometry between adolescence and adulthood. The purpose of the present study was to explore anatomical change during a specific environmental transition. High‐resolution T1‐weighted structural magnetic resonance imaging (MRI) scans were acquired from 19 participants (mean age at initial scan = 18.6 years) during their freshman year. Scans were completed during the fall term and 6 months later before the conclusion of the school year. Voxel‐based morphometry was used to assess within‐subject change. Significant intensity increases were observed along the right midcingulate, inferior anterior cingulate gyrus, right caudate head, right posterior insula, and bilateral claustrum. Regional changes were not observed in two control groups; one controlling for method and another controlling for age‐specific change over time. The results suggest that significant age‐related changes in brain structure continue after the age of 18 and may represent dynamic changes related to new environmental challenges. Findings from the regions of change are discussed in the context of specific environmental demands during a period of normative maturation. Hum Brain Mapp, 2005.

Functional Connectivity: Integrating Behavioral, Diffusion Tensor Imaging, and Functional Magnetic Resonance Imaging Data Sets

In the present study, we combined 2 types of magnetic resonance technology to explore individual differences on a task that required the recognition of objects presented from unusual viewpoints. This task was chosen based on previous work that has established the necessity of information transfer from the right parietal cortex to the left inferior cortex for its successful completion. We used reaction times (RTs) to localize regions of cortical activity in the superior parietal and inferior frontal regions (blood oxygen level-dependent [BOLD] response) that were more active with longer response times. These regions were then sampled, and their signal change used to predict individual differences in structural integrity of white matter in the corpus callosum (using diffusion tensor imaging). Results show that shorter RTs (and associated increases in BOLD response) are associated with increased organization in the splenium of the corpus callosum, whereas longer RTs are associated with increased organization in the genu.

Eye-Gaze Direction Modulates Race-Related Amygdala Activity

Although previous research has found greater activity in the human amygdala in response to Black male compared with White male targets, the basis of this effect remains unclear. For example, is it race alone that triggers amygdala activity, or do other stimulus cues, in conjunction with racial group membership, also play a critical role in this regard? To address this issue, we used functional magnetic resonance imaging to measure amygdala activity in response to Black and White male targets displaying different eye-gaze directions (i.e. direct or averted gaze), as gaze cues have been shown to influence the socio-emotional aspects of person construal. The results revealed that eye-gaze direction significantly moderates race-related amygdala activity. Specifically, Black targets only generated greater amygdala activity than White targets when the faces bore direct gaze. This finding is noteworthy as it demonstrates the importance of compound stimulus cues in the appraisal of social targets.

Obeessive-compulsive disorder among schizophrenic patients: An exploratory study using functional magnetic resonance imaging data

Despite the growing research on the etiology of obsessive-compulsive disorder (OCD), and schizophrenia, the clinical distinction between the two disorders is not clearly understood. In the present investigation, we sought to better understand the relationship between OCD and psychotic disorders by examining functional magnetic resonance imaging (fMRI) data from a group of schizophrenic patients with varying degrees of OCD symptomatology, based on results of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the National Institute of Mental Health (NIMH) rating scales of OCD. While subjects performed a cognitive challenge paradigm that included a verbal fluency task, activation data from the left dorsolateral prefrontal cortex were collected and analyzed. We hypothesized that the fMRI signal patterns in schizophrenic patients with high levels of OCD symptomatology would differ from that of schizophrenic patients with a low level of OCD. For the group as a whole, no significant relationship was found for scores of either rating scale and fMRI signal change; however, a significant association was found for a subgroup of patients. For these schizophrenics, there was a negative relationship between OCD symptomatology and activation of the left dorsolateral prefrontal cortex. These results support the suggestion of several researchers that a relationship between OCD severity and neurophysiological activity exists in schizophrenia.