Towards a clinico-pathological classification of granule cell dispersion in human mesial temporal lobe epilepsies

The dentate gyrus (DG) plays a pivotal role in the functional and anatomical organization of the hippocampus and is involved in learning and memory formation. However, the impact of structural DG abnormalities, i.e., granule cell dispersion (GCD), for hippocampal seizure susceptibility and its association with distinct lesion patterns in epileptic disorders, such as mesial temporal sclerosis (MTS) remains enigmatic and a large spectrum of pathological changes has been recognized. Here, we propose a clinico-pathological classification of DG pathology based on the examination of 96 surgically resected hippocampal specimens obtained from patients with chronic temporal lobe epilepsy (TLE). We observed three different histological patterns. (1) A normal granule cell layer was identified in 11 patients (no-GCP; 18.7%). (2) Substantial granule cell loss was evident in 36 patients (referred to as granule cell pathology (GCP) Type 1; 37.5%). (3) Architectural abnormalities were observed in 49 specimens, including one or more of the following features: granule cell dispersion, ectopic neurons or clusters of neurons in the molecular layer, or bi-lamination (GCP Type 2; 51%). Cell loss was always encountered in this latter cohort. Seventy-eight patients of our present series suffered from MTS (81.3%). Intriguingly, all MTS patients displayed a compromised DG, 31 (40%) with significant cell loss (Type 1) and 47 (60%) with GCD (Type 2). In 18 patients without MTS (18.7%), seven displayed focally restricted DG abnormalities, either cell loss (n = 5) or GCD (n = 2). Clinical histories revealed a significant association between DG pathology patterns and higher age at epilepsy surgery (p = 0.008), longer epilepsy duration (p = 0.004), but also with learning dysfunction (p < 0.05). There was no correlation with the extent of pyramidal cell loss in adjacent hippocampal segments nor with postsurgical seizure relief. The association with long-term seizure histories and cognitive dysfunction is remarkable and may point to a compromised regenerative capacity of the DG in this cohort of TLE patients.     

Self-perceived oral health and obesity among 65 years old in two Swedish counties

The aim of this study was to explore the association between oral health and obesity. The study was conducted in the spring of 2007 as a postal survey of all inhabitants born in 1942 and living in the two Swedish counties of Orebro and Osterg?tland.This questionnaire survey has been conducted everyfiveyears since 1992 but has been updated continually with additional questions and for the sweep used here, height and weight data were collected. A total of 8,313 individuals received the questionnaire and 6,078 of those responded (73.1%). The outcome variable oral health was measured using one global question and four detailed questions representing different aspects of oral health. The independent variable Body Mass Index (BMI) was calculated using self-reported height and weight. A difference in oral health between various BMI groups was found. The difference was both statistically significant and of clinical importance, particularly among the group with severe obesity who reported poorer self-perceived chewing capacity, lower satisfaction with dental appearance, increased mouth dryness and fewer teeth and lower overall satisfaction with oral health. In view of the increased risk of poor oral health demonstrated in this study for those with severe obesity, it may be of value to increase cooperation between dental care and primary health care for these patients.     

Impulsivity is associated with behavioral decision-making deficits

Impaired decision-making is a key-feature of many neuropsychiatric disorders. In the present study, we examined task performance in a healthy population consisting of those whose scores indicated high and low impulsivity on several behavioral decision-making tasks reflecting orbitofrontal functioning. The measures included tasks that assess decision-making with and without a learning component and choice flexibility. The results show that subjects high on impulsivity display an overall deficit in their decision-making performance as compared with subjects low on impulsivity. More specifically, subjects with high impulsivity show weaknesses in learning of reward and punishment associations in order to make appropriate decisions (reversal-learning task and Iowa Gambling Task), and impaired adaptation of choice behavior according to changes in stimulus-reward contingencies (reversal-learning task). Simple, non-learning, components of reward- and punishment-based decision-making (Rogers Decision-Making Task) seem to be relatively unaffected. Above all, the results indicate that impulsivity is associated with a decreased ability to alter choice behavior in response to fluctuations in reward contingency. The findings add further evidence to the notion that trait impulsivity is associated with decision-making, a function of the orbitofrontal cortex.     

Event-related potential responses to love-related facial stimuli

In event-related potential (ERPs) studies, emotional stimuli usually elicit an enhanced late positive potential (LPP), which is assumed to reflect motivated attention. However, whether a stimulus elicits emotional responses may depend on the individual's state, such as experiencing romantic love. It has been suggested that stimuli that are related to someone's beloved will elicit increased attention in that infatuated individual. In this study, participants who were in love viewed faces of their beloved, their friend, and of an unknown, beautiful person. The friend was included to control for familiarity, and the unknown person for perceived beauty. As expected, the LPP was larger in response to the face of the beloved than to the other two emotionally significant faces. Interpreting the LPP as reflecting motivated attention, this implies that romantic love is accompanied by increased attention for the face of one's beloved.