Volume of left amygdala subregion predicted temperamental trait of harm avoidance in female young subjects. A voxel-based morphometry study

Voxel-based morphometry studies of personality: issue of statistical model specification--effect of nuisance covariates

There are an increasing number of studies on the localization of personality using voxel-based morphometry. Due to the complex analytic challenge in volumetric studies, the specification and treatment of the nuisance covariate (such as age, gender, and global measures) is currently not consistent. Here, we present a study in which we conducted voxel-based morphometry with Five-Factor Model (FFM) of personality traits (extraversion, neuroticism, openness to experience, agreeableness, and conscientiousness) that aimed to test the influence of NC specification in the determination of the results. In this study, 62 healthy subjects underwent MRI investigation and completed a German version of the FFM personality questionnaire. Voxel-based morphometry was used to investigate the correlation between the FFM personality traits and subtle brain structure. Different NC combinations were used during the model specification. Significant clusters were found only under the condition of some of the NC combinations but not under the others. In addition, we use the structure equation modeling (automated specification search from AMOS) to narrow down the possible choices of NC combinations according to a set of goodness-of-fit indices to identify well-fitted statistic models. As a final step, theoretical implications of the results are discussed, before accepting the selected model.

Individual sensitivity to pain expectancy is related to differential activation of the hippocampus and amygdala

Anxiety arising during pain expectancy can modulate the subjective experience of pain. However, individuals differ in their sensitivity to pain expectancy. The amygdale and hippocampus were proposed to mediate the behavioral response to aversive stimuli. However, their differential role in mediating anxiety-related individual differences is not clear. Using fMRI, we investigated brain activity during expectancy to cued or uncued thermal pain applied to the wrist. Following each stimulation participants rated the intensity of the painful experience. Activations in the amygdala and hippocampus were examined with respect to individual differences in harm avoidance (HA) personality trait, and individual sensitivity to expectancy, (i.e. response to cued vs. uncued painful stimuli). Only half of the subjects reported on cued pain as being more painful than uncued pain. In addition, we found a different activation profile for the amygdala and hippocampus during pain expectancy and experience. The amygdala was more active during expectancy and this activity was correlated with HA scores. The hippocampal activity was equally increased during both pain expectancy and experience, and correlated with the individual's sensitivity to expectancy. Our findings suggest that the amygdala supports an innate tendency to approach or avoid pain as reflected in HA trait, whereas the hippocampus mediates the effect of context possibly via appraisal of the stimulus value.

The BDNF Val66Met polymorphism impacts parahippocampal and amygdala volume in healthy humans: incremental support for a genetic risk factor for depression

BACKGROUND

The role of the brain-derived neurotrophic factor (BDNF) in the pathogenesis of affective disorders such as depression has been controversial. Mounting evidence comes from structural imaging, that the functional BDNF Val66Met polymorphism influences the hippocampal volume with carriers of the 66Met allele (Val/Met and Met/Met group) having smaller hippocampi. Given that stress-induced atrophy of the hippocampus is associated with the pathogenesis of affective disorders, the functional BDNF Val66Met polymorphism could be an incremental risk factor.

METHOD

Eighty-seven healthy Caucasian participants underwent structural imaging and were genotyped for the BDNF Val66Met polymorphism. Data were analysed by means of voxel-based morphometry (VBM).

RESULTS

Region of interest (ROI) analyses revealed an association between the 66Met allele and smaller parahippocampal volumes and a smaller right amygdala. In addition, the whole-brain analysis showed that the thalamus, fusiformus gyrus and several parts of the frontal gyrus were smaller in 66Met allele carriers.

CONCLUSIONS

This study demonstrates that the impact of the BDNF Val66Met polymorphism is not confined to the hippocampus but also extends to the parahippocampal gyrus and the amygdala.

The brain structural disposition to social interaction

Social reward dependence (RD) in humans is a stable pattern of attitudes and behaviour hypothesized to represent a favourable disposition towards social relationships and attachment as a personality dimension. It has been theorized that this long-term disposition to openness is linked to the capacity to process primary reward. Using brain structure measures from magnetic resonance imaging, and a measure of RD from Cloninger's temperament and character inventory, a self-reported questionnaire, in 41 male subjects sampled from a general population birth cohort, we investigated the neuro-anatomical basis of social RD. We found that higher social RD in men was significantly associated with increased gray matter density in the orbitofrontal cortex, basal ganglia and temporal lobes, regions that have been previously shown to be involved in processing of primary rewards. These findings provide evidence for a brain structural disposition to social interaction, and that sensitivity to social reward shares a common neural basis with systems for processing primary reward information.

The anatomy of the mesolimbic reward system: a link between personality and the placebo analgesic response

The anticipation of clinical benefit, a crucial component of placebo analgesia, has been suggested to be a special case of reward anticipation. Since reward processing is closely linked to the ventral striatum and the neurotransmitter dopamine, we examined the relationships between brain gray matter, placebo analgesic response, and personality traits associated with dopaminergic neurotransmission. We report that dopamine-related traits predict a substantial portion of the pain relief an individual gains from a sham treatment. Voxel-based morphometry of magnetic resonance images shows that the magnitude of placebo analgesia is related to gray matter density (GMD) in several brain regions, including the ventral striatum, insula, and prefrontal cortex. Similarly, GMD in ventral striatum and prefrontal cortex is related to dopamine-related personality traits. Our findings highlight the relationship between placebo and reward and potentially offer ways of identifying subjects who are likely to show large placebo analgesic responses.

Neuroanatomical correlates of temperament in early adolescents

OBJECTIVE

Temperament refers to enduring behavioral characteristics that underpin individual differences in human behavior, including risk for psychopathology. Research attempting to investigate the neurobiological basis of temperament represents an important step toward elucidating the biological mechanisms underlying these individual differences. In the present study, we examined the relation between four core temperament dimensions and anatomically defined regions of the limbic and prefrontal cortices.

METHOD

We used a cross-sectional design to examine a large sample (N = 153; mean age 12.6 years, SD 0.4, range 11.4-13.7) of healthy early adolescents who were selected from a larger sample to maximize variation in temperament. The main outcome measures were psychometric measures of temperament (four factors: effortful control, negative affectivity, surgency, and affiliativeness) based on the Early Adolescent Temperament Questionnaire-Revised, and volumetric measures of a priori brain regions of interest (anterior cingulate cortex [ACC], orbitofrontal cortex, amygdala, and hippocampus).

RESULTS

We found regional brain volumes to account for small but significant amounts of the variance in self-reported temperament scores. Specifically, higher effortful control was associated with larger volume of the left orbitofrontal cortex and hippocampus. Higher negative affectivity was associated with smaller volume of the left dorsal paralimbic relative to limbic portion of the ACC. Higher affiliativeness was associated with larger volume of the right rostral/ventral limbic portion of the ACC. Affiliativeness and surgency also showed a number of female-specific associations, primarily involving the rostral/ventral ACC.

CONCLUSIONS

Our results provide support for a neuroanatomical basis for individual differences in temperament and have implications for understanding the neurobiological mechanisms underlying the development of a number of psychiatric disorders.

The association of anxiety disorders and obsessive compulsive personality disorder with anorexia nervosa: evidence from a family study with discussion of nosological and neurodevelopmental implications

BACKGROUND

To investigate the association of anorexia nervosa with anxiety disorders through use of a case-control family study design.

METHOD

Lifetime prevalence of anxiety disorders and obsessive compulsive personality disorder was determined among 574 first-degree relatives of 152 probands with anorexia nervosa and compared to rates observed among 647 first-degree relatives of 181 never-ill control probands.

RESULTS

Adjusting for comorbidity of the same illness in the proband, relatives of probands with anorexia nervosa, had a significantly higher prevalence of generalized anxiety, obsessive compulsive disorder, separation anxiety disorder, social phobia, panic disorder, and obsessive compulsive personality disorder compared to relatives of never-ill control probands.

CONCLUSION

Anorexia nervosa may share familial liability factors in common with various anxiety phenotypes. In suggesting that a transmitted propensity for anxiety is a key aspect of vulnerability in anorexia nervosa, the findings point to research developments in the affective neurosciences, specifically the neurocircuitry of fear and anxiety, as a heuristic framework in which to interpret aspects of premorbid temperamental anxieties and clinical symptoms.