Abnormalities of cortical thickness in postictal psychosis

Postictal psychosis (PIP), the occurrence of psychotic episodes following a seizure, is a common and serious comorbidity in patients with epilepsy. Yet, the anatomical correlates remain poorly defined. Here, we used quantitative MRI morphometry to identify structural abnormalities in the cortex of patients with PIP relative to patients with epilepsy without PIP and age- and gender-matched normal healthy controls. Comparison of patients with epilepsy and PIP with patients with epilepsy without PIP revealed increased cortical thickness in the right lateral prefrontal cortex, right anterior cingulate cortex, and right middle temporal gyrus. The PIP group was distinguished from the EC and NC groups by thicker cortex in the right rostral anterior cingulate cortex and thinner cortex in the right angular gyrus and the left middle temporal region. Findings indicate that PIP is associated with thickening of the right anterior cingulate cortex, which may serve as a marker for patients at risk for developing PIP.

Hyperfamiliarity for faces

OBJECTIVE

To report 4 cases of hyperfamiliarity for faces (HFF) and review 5 previously reported cases.

METHODS

We identified cases of HFF from PubMed search and references in prior reports.

RESULTS

Three of our 4 cases had pathologic findings that were most extensive in the left temporal lobe. HFF occurred after a tonic-clonic seizure (cases 1 and 3), during simple partial seizures (case 2), and in the setting of an increase in simple partial seizure frequency but not during seizures (case 4). All 9 cases were adults with 1 or more seizures; symptoms first occurred after seizures in 5 cases and during seizures in 1 case. Ictal symptoms lasted from seconds to minutes and from 2 days to more than 7 years in the other 6 cases. The duration of HFF was not associated with the presence or extent of a structural lesion. While in several cases HFF appears to result from a postictal Todd paralysis, the mechanism underlying persistent cases is uncertain.

CONCLUSIONS

This modality (visual)-specific and stimulus (face)-specific syndrome is associated with diverse structural, functional imaging, and neurophysiologic findings. Lesions are more often left-sided and involve the temporal lobe. Epilepsy and seizures were present in all 9 cases, suggesting a pathophysiologic relationship, which likely varies among cases. Although only reported in 9 patients, HFF is probably much more common than it is diagnosed.

Detection of cortical thickness correlates of cognitive performance: Reliability across MRI scan sessions, scanners, and field strengths

In normal humans, relationships between cognitive test performance and cortical structure have received little study, in part, because of the paucity of tools for measuring cortical structure. Computational morphometric methods have recently been developed that enable the measurement of cortical thickness from MRI data, but little data exist on their reliability. We undertook this study to evaluate the reliability of an automated cortical thickness measurement method to detect correlates of interest between thickness and cognitive task performance. Fifteen healthy older participants were scanned four times at 2-week intervals on three different scanner platforms. The four MRI data sets were initially treated independently to investigate the reliability of the spatial localization of findings from exploratory whole-cortex analyses of cortical thickness-cognitive performance correlates. Next, the first data set was used to define cortical ROIs based on the exploratory results that were then applied to the remaining three data sets to determine whether the relationships between cognitive performance and regional cortical thickness were comparable across different scanner platforms and field strengths. Verbal memory performance was associated with medial temporal cortical thickness, while visuomotor speed/set shifting was associated with lateral parietal cortical thickness. These effects were highly reliable - in terms of both spatial localization and magnitude of absolute cortical thickness measurements - across the four scan sessions. Brain-behavior relationships between regional cortical thickness and cognitive task performance can be reliably identified using an automated data analysis system, suggesting that these measures may be useful as imaging biomarkers of disease or performance ability in multicenter studies in which MRI data are pooled.

Volumetric cerebral characteristics of children exposed to opiates and other substances in utero

Morphometric cerebral characteristics were studied in children with prenatal poly-substance exposure (n=14) compared to controls (n=14) without such exposure. Ten of the substance-exposed children were born to mothers who used opiates (heroin) throughout the pregnancy. Groups were compared across 16 brain measures: cortical gray matter, cerebral white matter, hippocampus, amygdala, thalamus, accumbens area, caudate, putamen, pallidum, brainstem, cerebellar cortex, cerebellar white matter, lateral ventricles, inferior lateral ventricles, and the 3rd and 4th ventricles. In addition, continuous measurement of thickness across the entire cortical mantle was performed. Volumetric characteristics were correlated with ability and questionnaire assessments 2 years prior to scan. Compared to controls, the substance-exposed children had smaller intracranial and brain volumes, including smaller cerebral cortex, amygdala, accumbens area, putamen, pallidum, brainstem, cerebellar cortex, cerebellar white matter, and inferior lateral ventricles, and thinner cortex of the right anterior cingulate and lateral orbitofrontal cortex. Pallidum and putamen appeared especially reduced in the subgroup exposed to opiates. Only volumes of the right anterior cingulate, the right lateral orbitofrontal cortex and the accumbens area, showed some association with ability and questionnaire measures. The sample studied is rare and hence small, so conclusions cannot be drawn with certainty. Morphometric group differences were observed, but associations with previous behavioral assessment were generally weak. Some of the volumetric differences, particularly thinner cortex in part of the right lateral orbitofrontal cortex, may be moderately involved in cognitive and behavioral difficulties more frequently experienced by opiate and poly-substance-exposed children.

Neuroimaging H.M.: a 10-year follow-up examination

In 1997, Corkin et al. described the anatomical boundaries of the amnesic patient H.M.'s surgical resection, based on a comprehensive analysis of magnetic resonance imaging (MRI) scans collected in 1992 and 1993 (Corkin et al. (1997) J Neurosci 17:3964-3979). We subsequently scanned H.M. on several occasions, employing more advanced data acquisition and analysis methods, and now describe additional details about his brain anatomy and pathology. This account combines results from high-resolution T1-weighted scans, which provide measures of cortical and subcortical morphometry, diffusion tensor images, which provide quantitative information about white matter microstructure and the anatomy of major fasciculi, and T2-weighted images, which highlight damage to deep white matter. We applied new MRI analysis techniques to these scans to assess the integrity of areas throughout H.M.'s brain. We documented a number of new changes, including cortical thinning, atrophy of deep gray matter structures, and a large volume of abnormal white matter and deep gray matter signal. Most of these alterations were not apparent in his prior scans, suggesting that they are of recent origin. Advanced age and hypertension likely contributed to these new findings.

Size does matter in the long run: hippocampal and cortical volume predict recall across weeks

OBJECTIVE

To study the morphometric determinants of recall of verbal material for an extended period in an adult lifespan sample.

METHODS

Healthy adults of varying ages were studied using automated segmentation of MRI scans with volumes of hippocampus, cortex, and white matter, and verbal memory tests assessing recall after 5 minutes, 30 minutes, and a mean period of 11 weeks. Stepwise regression analyses were performed with 5 minutes, 30 minutes, and 11-week recall as the dependent variables. Hippocampal, cortical, and white matter volumes were included in the initial set of predictor variables in each case, and the analyses were repeated with age as an additional predictor variable.

RESULTS

When age was not included, cortical volume was the only variable predicting recall after 5 and 30 minutes, whereas hippocampal and cortical volumes predicted recall after 11 weeks. When age was included in the model, this was the only variable predicting recall after 5 and 30 minutes, whereas age and hippocampus gave contributions in prediction of recall after several weeks.

CONCLUSION

This study supports a critical role of cortical and hippocampal size in recall. Hippocampal size seems more important in recall after 11 weeks than after a shorter time interval.