William Semple

Higher brain blood flow at amygdala and lower frontal cortex blood flow in PTSD patients with comorbid cocaine and alcohol abuse compared with normals.

Posttraumatic stress disorder (PTSD) patients with histories of cocaine and alcohol abuse (CA-PTSD) were compared with normal volunteers. Positron emission tomography (PET) scans with 15O-butanol were used to compare regional cerebral blood flow (rCBF) between the groups during rest and during an auditory continuous performance task (ACPT). CA-PTSD patients had significantly higher rCBF in right amygdala and left parahippocampal gyrus than normals during the ACPT. Normals had higher rCBF at frontal cortex during the resting scan and during the ACPT. The role of the amygdala in attention and fear conditioning suggests that increased amygdala rCBF may be related to clinical features of PTSD. Cocaine use may be associated with increased amygdala rCBF in PTSD patients. Amygdala and frontal cortex attention system components may be reciprocally related and their relative contributions to processing of neutral stimuli perturbed in CA-PTSD.

Regional cerebral metabolic asymmetries replicated in an independent group of patients with panic disorder

BACKGROUND Abnormal left/right (L/R) hemispheric ratios of regional cerebral glucose metabolic rates (rCMRglc) (hippocampus and inferior prefrontal cortex) have been noted in unmedicated panic disorder patients. METHODS An independent group of panic disorder patients placed on imipramine was studied with positron-emission tomography, testing for evidence of normalization versus persistence of the abnormal rCMRglc ratios. Differences in orbital frontal rCMRglc values between the imipramine-treated and the previously reported unmedicated panic disorder patients were tested examining for evidence that the differences would resemble those noted in obsessive-compulsive disorder (OCD) patients treated with clomipramine. RESULTS We found the same abnormally low L/R hippocampal and posterior inferior prefrontal rCMRglc ratios in the imipramine-treated panic disorder patients. In addition, we found posterior orbital frontal rCMRglc decreases in the imipramine-treated panic disorder patients compared with the unmedicated panic disorder patients. CONCLUSIONS These abnormal asymmetries found in unmedicated panic disorder patients and now in imipramine-treated panic disorder patients may reflect a trait abnormality. The orbital frontal rCMRglc differences between the imipramine-treated and unmedicated patients are similar to changes noted in OCD patients treated with clomipramine and may reflect direct or indirect effects of imipramine treatment in panic disorder patients.

Computer-aided techniques for aligning interleaved sets of nonidentical medical images

We have developed an X-window based, interactive manual technique for aligning medical images of the brain. Our methods were designed to allow easy correction of artifacts that resulted from motion during the acquisition of interleaved sets of MR images. Real-time feedback about the alignment of the data volume proved helpful to the user in obtaining a satisfactory correction. This feedback was possible by focussing on a limited number of slices at one time. Contrary to intuition, the observed motion artifact was primarily found to occur in one direction. Elimination of said artifact, however, required sub-pixel translation of images. We also did some preliminary work on automated extensions of our manual alignment technique. These automated algorithms utilized mathematical morphology for segmenting the brain and a 2-dimensional implementation of the Principal Axes technique for re-alignment of the segmented images.

Pet study correlates of psychometric psychoticism in normals

Recent positron emission tomography (PET) studies of patients with psychosis have found decreased glucose metabolism in prefrontal cortex. We examined whether psychometric psychoticism in normals was associated with reduced glucose metabolism in prefrontal cortex in 44 males (mean age 33.27 SD 10.95) and 41 females (mean age 33.04 years SD 10.87). All subjects completed the Eysenck Personality Questionnaire (EPQ), and underwent the PET scan procedure on a Scanditronix scanner during performance of an auditory continuous performance task. ume of a control region (superior frontal gyms). An analysis of the temporal sulco-gyral pattern showed a non-parallel, discontinuous pattern in schizophrenic patients (Chi Square=l0.8, df=l, p I 0.001, phi=0.60). These findings suggest that a subset of schizophrenics show localized reductions in gray matter of the temporal lobe that are intercorrelated thus suggesting a disturbance of a neural network in schizophrenia. Moreover, degree of thought disorder was related to reduced volume of left posterior STG, an area important as a substrate of language. That the gyral pattern was also disrupted strongly implicates a neurodevelopmental disturbance may be important in the aetiology of schizophrenia.