A pilot study of quantitative MRI measurements of ventricular volume and cortical atrophy for the differential diagnosis of normal pressure hydrocephalus.

Current radiologic diagnosis of normal pressure hydrocephalus (NPH) requires a subjective judgment of whether lateral ventricular enlargement is disproportionate to cerebral atrophy based on visual inspection of brain images. We investigated whether quantitative measurements of lateral ventricular volume and total cortical thickness (a correlate of cerebral atrophy) could be used to more objectively distinguish NPH from normal controls (NC), Alzheimer's (AD), and Parkinson's disease (PD). Volumetric MRIs were obtained prospectively from patients with NPH (n = 5), PD (n = 5), and NC (5). Additional NC (n = 5) and AD patients (n = 10) from the ADNI cohort were examined. Although mean ventricular volume was significantly greater in the NPH group than all others, the range of values overlapped those of the AD group. Individuals with NPH could be better distinguished when ventricular volume and total cortical thickness were considered in combination. This pilot study suggests that volumetric MRI measurements hold promise for improving NPH differential diagnosis.

Cortical morphology of visual creativity.

BACKGROUND AND OBJECTIVE: The volume of cortical tissue devoted to a function often influences the quality of a person's ability to perform that function. Up to now only white matter correlates of creativity have been reported, and we wanted to learn if the creative visuospatial performance on the figural Torrance Test of Creative Thinking (TTCT) is associated with measurements of cerebral gray matter volume in the regions of the brain that are thought to be important in divergent reasoning and visuospatial processing. METHODS: Eighteen healthy college educated men (mean age=40.78; 15 right-handers) were recruited (via advertisement) as participants. High-resolution MRI scans were acquired on a 1.5T MRI scanner. Voxel-based morphometry regression analyses of TTCT to cortical volume were restrained within the anatomic regions identified. RESULTS: One significant positive focus of association with TTCT emerged within the right parietal lobe gray matter (MNI coordinates: 44, -24, 63; 276 voxels). CONCLUSIONS: Based on theories of parietal lobe function and the requirements of the TTCT, the area observed may be related due to its dominant role in global aspects of attention and visuospatial processing including the capacity for manipulating spatial representations.

Does gender influence cognitive outcome after traumatic brain injury?

The aim of this study was to determine whether males and females differ in post-acute cognitive outcome following traumatic brain injury (TBI). Performances of 83 men and 75 women with mild to severe TBI were compared on measures of cognitive functions typically impacted by TBI (i.e., processing speed, executive functioning, and memory). Participants completed selected subtests of the Cambridge Neuropsychological Test Automated Battery (CANTAB). Among the participants with mild TBI, women scored significantly higher than men on a test of visual memory. There were no other significant gender differences in cognitive outcomes. These findings overall suggest that cognitive outcome after TBI does not differ according to gender, with the possible exception of memory functioning. Further research is needed to replicate this finding and determine which moderating variables may impact on the relationship between gender and cognitive outcome after TBI.

Hemispheric connectivity and the visual-spatial divergent-thinking component of creativity.

BACKGROUND/HYPOTHESIS: Divergent thinking is an important measurable component of creativity. This study tested the postulate that divergent thinking depends on large distributed inter- and intra-hemispheric networks. Although preliminary evidence supports increased brain connectivity during divergent thinking, the neural correlates of this characteristic have not been entirely specified. It was predicted that visuospatial divergent thinking would correlate with right hemisphere white matter volume (WMV) and with the size of the corpus callosum (CC). METHODS: Volumetric magnetic resonance imaging (MRI) analyses and the Torrance Tests of Creative Thinking (TTCT) were completed among 21 normal right-handed adult males. RESULTS: TTCT scores correlated negatively with the size of the CC and were not correlated with right or, incidentally, left WMV. CONCLUSIONS: Although these results were not predicted, perhaps, as suggested by Bogen and Bogen (1988), decreased callosal connectivity enhances hemispheric specialization, which benefits the incubation of ideas that are critical for the divergent-thinking component of creativity, and it is the momentary inhibition of this hemispheric independence that accounts for the illumination that is part of the innovative stage of creativity. Alternatively, decreased CC size may reflect more selective developmental pruning, thereby facilitating efficient functional connectivity.

A multivariate approach to aggression and the orbital frontal cortex in psychiatric patients.

The association between orbital frontal cortex (OFC) volume and aggression was investigated in an at-risk psychiatric population. Forty-one psychiatric patients were referred for magnetic resonance imaging and a standardized psychometric assessment of aggression (Lifetime History of Aggression-Revised). Nineteen matched controls had lower levels of aggression and greater OFC volume, establishing the appropriateness of the psychiatric group for studying aggression pathophysiology. Consistent with study hypotheses, left OFC gray matter volume predicted 34% of the variance in self-reported aggression ratings. When impulsivity was not controlled for, left OFC gray matter only accounted for 26% of aggression variance, suggesting a complex relationship between impulsivity and OFC-aggression pathophysiology. Contrary to study hypotheses, right OFC gray matter volume did not predict degree of aggressive behavior. Current models do not account for lateralization, yet this may be quite important. Greater consideration should be given to laterality in OFC regulation of social/emotional behavior. Regulatory focus theory, positing two motivational systems, promotion and prevention, lateralized to the left and right hemispheres, respectively, may provide an explanatory framework for these results. Dysregulation of the left hemisphere 'promotion' motivational system may help to explain the aggressive behavior present in psychiatric populations.