MEMORY AND COGNITIVE ABILITIES IN UNIVERSITY PROFESSORS:

Professors from the University of California at Berkeley were administered a 90-min test battery of cognitive performance that included measures of reaction time, paired-associate learning, working memory, and prose recall. Age effects among the professors were observed on tests of reaction time, paired-associate memory, and some aspects of working memory. Age effects were not observed on measures of proactive interference and prose recall, though age-related declines are generally observed in standard groups of elderly individuals. The findings suggest that age-related decrements in certain cognitive functions may be mitigated in intelligent, cognitively active individualsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72229/1/j.1467-9280.1995.tb00510.x.pd

A new clinico-pathological classification system for mesial temporal sclerosis

We propose a histopathological classification system for hippocampal cell loss in patients suffering from mesial temporal lobe epilepsies (MTLE). One hundred and seventy-eight surgically resected specimens were microscopically examined with respect to neuronal cell loss in hippocampal subfields CA1–CA4 and dentate gyrus. Five distinct patterns were recognized within a consecutive cohort of anatomically well-preserved surgical specimens. The first group comprised hippocampi with neuronal cell densities not significantly different from age matched autopsy controls [no mesial temporal sclerosis (no MTS); n = 34, 19%]. A classical pattern with severe cell loss in CA1 and moderate neuronal loss in all other subfields excluding CA2 was observed in 33 cases (19%), whereas the vast majority of cases showed extensive neuronal cell loss in all hippocampal subfields (n = 94, 53%). Due to considerable similarities of neuronal cell loss patterns and clinical histories, we designated these two groups as MTS type 1a and 1b, respectively. We further distinguished two atypical variants characterized either by severe neuronal loss restricted to sector CA1 (MTS type 2; n = 10, 6%) or to the hilar region (MTS type 3, n = 7, 4%). Correlation with clinical data pointed to an early age of initial precipitating injury (IPI < 3 years) as important predictor of hippocampal pathology, i.e. MTS type 1a and 1b. In MTS type 2, IPIs were documented at a later age (mean 6 years), whereas in MTS type 3 and normal appearing hippocampus (no MTS) the first event appeared beyond the age of 13 and 16 years, respectively. In addition, postsurgical outcome was significantly worse in atypical MTS, especially MTS type 3 with only 28% of patients having seizure relief after 1-year follow-up period, compared to successful seizure control in MTS types 1a and 1b (72 and 73%). Our classification system appears suitable for stratifying the clinically heterogeneous group of MTLE patients also with respect to postsurgical outcome studies

The neuropathology of autism: defects of neurogenesis and neuronal migration, and dysplastic changes

Autism is characterized by a broad spectrum of clinical manifestations including qualitative impairments in social interactions and communication, and repetitive and stereotyped patterns of behavior. Abnormal acceleration of brain growth in early childhood, signs of slower growth of neurons, and minicolumn developmental abnormalities suggest multiregional alterations. The aim of this study was to detect the patterns of focal qualitative developmental defects and to identify brain regions that are prone to developmental alterations in autism. Formalin-fixed brain hemispheres of 13 autistic (4–60 years of age) and 14 age-matched control subjects were embedded in celloidin and cut into 200-μm-thick coronal sections, which were stained with cresyl violet and used for neuropathological evaluation. Thickening of the subependymal cell layer in two brains and subependymal nodular dysplasia in one brain is indicative of active neurogenesis in two autistic children. Subcortical, periventricular, hippocampal and cerebellar heterotopias detected in the brains of four autistic subjects (31%) reflect abnormal neuronal migration. Multifocal cerebral dysplasia resulted in local distortion of the cytoarchitecture of the neocortex in four brains (31%), of the entorhinal cortex in two brains (15%), of the cornu Ammonis in four brains and of the dentate gyrus in two brains. Cerebellar flocculonodular dysplasia detected in six subjects (46%), focal dysplasia in the vermis in one case, and hypoplasia in one subject indicate local failure of cerebellar development in 62% of autistic subjects. Detection of flocculonodular dysplasia in only one control subject and of a broad spectrum of focal qualitative neuropathological developmental changes in 12 of 13 examined brains of autistic subjects (92%) reflects multiregional dysregulation of neurogenesis, neuronal migration and maturation in autism, which may contribute to the heterogeneity of the clinical phenotype

Histopathological Findings in Brain Tissue Obtained during Epilepsy Surgery

BACKGROUND: Detailed neuropathological information on the structural brain lesions underlying seizures is valuable for understanding drug-resistant focal epilepsy. / METHODS: We report the diagnoses made on the basis of resected brain specimens from 9523 patients who underwent epilepsy surgery for drug-resistant seizures in 36 centers from 12 European countries over 25 years. Histopathological diagnoses were determined through examination of the specimens in local hospitals (41%) or at the German Neuropathology Reference Center for Epilepsy Surgery (59%). / RESULTS: The onset of seizures occurred before 18 years of age in 75.9% of patients overall, and 72.5% of the patients underwent surgery as adults. The mean duration of epilepsy before surgical resection was 20.1 years among adults and 5.3 years among children. The temporal lobe was involved in 71.9% of operations. There were 36 histopathological diagnoses in seven major disease categories. The most common categories were hippocampal sclerosis, found in 36.4% of the patients (88.7% of cases were in adults), tumors (mainly ganglioglioma) in 23.6%, and malformations of cortical development in 19.8% (focal cortical dysplasia was the most common type, 52.7% of cases of which were in children). No histopathological diagnosis could be established for 7.7% of the patients. / CONCLUSIONS: In patients with drug-resistant focal epilepsy requiring surgery, hippocampal sclerosis was the most common histopathological diagnosis among adults, and focal cortical dysplasia was the most common diagnosis among children. Tumors were the second most common lesion in both groups. (Funded by the European Union and others.

Regional changes in hippocampal T2 relaxation and volume: a quantitative magnetic resonance imaging study of hippocampal sclerosis

OBJECTIVE—The principal MRI features of hippocampal sclerosis are volume loss and increased T2 weighted signal intensity. Minor and localised abnormalities may be overlooked without careful quantitation. Hippocampal T2 relaxation time (HT2) can be quantified, but previously has only been measured on a few thick coronal slices with interslice gaps. In this study HT2 was measured along the entire length of the hippocampus on contiguous slices and used, with quantitative measures of hippocampal volume (HV) and distribution of atrophy, to better define the range of hippocampal sclerosis.
METHODS—Thirty patients with temporal lobe epilepsy, 10 patients with extratemporal localisation related epilepsy and extratemporal lesions, and 20 control subjects were studied using MRI T2 relaxometry and volumetry.
RESULTS—In controls and patients, HT2 was higher in the anterior than the posterior hippocampus. Using HV, morphometric, and HT2 data, patients with temporal lobe epilepsy were classified as unilateral diffuse hippocampal sclerosis (n=16), unilateral focal (n=6), bilaterally affected (n=6), and normal (n=2). In patients with unilateral hippocampal sclerosis, the anterior hippocampus was always affected. In three patients with normal HV, HT2 measurements disclosed unilateral focal abnormalities that corresponded to the EEG lateralisation of epileptic activity. Patients with bilateral hippocampal involvement had an earlier onset of epilepsy than patients with unilateral hippocampal sclerosis.
CONCLUSIONS—Measurement of regional abnormalities of HT2 along the length of the hippocampus provides further refinement to the MRI assessment of the hippocampi in patients with temporal lobe epilepsy and is complementary to volumetric and morphological data.