Background: White matter hyperintensities (WMH) on MRI scans indicate lesions of the subcortical fiber system. The regional distribution of WMH may be related to their pathophysiology and clinical effect in vascular dementia (VaD), Alzheimer’s disease (AD) and healthy aging. Methods: Regional WMH volumes were measured in MRI scans of 20 VaD patients, 25 AD patients and 22 healthy elderly subjects using FLAIR sequences and surface reconstructions from a three-dimensional MRI sequence. Results: The intraclass correlation coefficient for interrater reliability of WMH volume measurements ranged between 0.99 in the frontal and 0.72 in the occipital lobe. For each cerebral lobe, the WMH index, i.e. WMH volume divided by lobar volume, was highest in VaD and lowest in healthy controls. Within each group, the WMH index was higher in frontal and parietal lobes than in occipital and temporal lobes. Total WMH index and WMH indices in the frontal lobe correlated significantly with the MMSE score in VaD. Category fluency correlated with the frontal lobe WMH index in AD, while drawing performance correlated with parietal and temporal lobe WMH indices in VaD. Conclusions: A similar regional distribution of WMH between the three groups suggests a common (vascular) pathogenic factor leading to WMH in patients and controls. Our findings underscore the potential of regional WMH volumetry to determine correlations between subcortical pathology and cognitive impairment.

Objective: Correlations between corpus callosum size and interhemispheric EEG coherence were investigated as measures of interhemispheric connectivity in patients with Alzheimer's disease. Methods: 11 patients underwent both magnetic resonance imaging and quantitative electroencephalography to assess corpus callosum size and interhemispheric coherence. For comparison, corpus callosum size was measured in 24 healthy elderly control subjects. Results: Corpus callosum cross sectional area was significantly reduced in Alzheimer patients relative to controls. Posterior interhemispheric coherence (a and b frequencies) correlated significantly with the size of posterior corpus callosum area, and anterior coherence (d, h, and a frequencies) with the size of anterior corpus callosum area in the Alzheimer patients. Conclusion: Region specific correlations between corpus callosum size and EEG coherence suggest that the decline in interhemispheric connectivity in Alzheimer's disease results from a specific loss of cortical association neurones projecting through the corpus callosum.

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Alzheimer's disease (AD) involves not only gray matter but also white matter pathology, as reflected by atrophy of the corpus callosum (CC). Since decreased CC size may indicate reduced functional interhemispheric connectivity, differences in callosal size may have cognitive consequences that may become specifically apparent in neuropsychological tasks that tap hemispheric laterality. In the present study, we examined callosal functioning with a dichotic listening task in 25 Alzheimer patients, 20 healthy elderly and 20 healthy elderly with subjective memory complaints. We found decreased performance, increased ear asymmetry, and decreased callosal size in the AD group compared to healthy elderly. As expected, in the healthy elderly, we found significant negative correlations between ear asymmetry and callosal size, specifically in the anterior and posterior callosal subareas. While the association with the posterior subareas (isthmus and splenium) points at involvement of temporal areas mediating language processing, the association with the anterior subarea (the rostrum and genu) points at involvement of frontal areas mediating attention and executive functions. Remarkably however, in contrast to the healthy elderly, callosal size was not related to ear asymmetry in the AD group. The absence of an association between callosal atrophy and ear asymmetry implies that other pathological processes, next to reduced callosal functioning, attribute to ear asymmetry in AD. Difficulties to attend specifically to the left ear during dichotic listening in some of the AD patients, points at decreased attention and executive functions and suggests that pathology of specifically the frontal areas is involved.

There is evidence that early event-related potential components, such as the early posterior negativity (EPN; 200-300 ms), are modulated by emotional words. This study addressed the automaticity of this early response in an emotional Stroop task. The results show that the EPN was modulated by emotional connotation. In addition, an enhanced frontal P3 and an enhanced, more broadly distributed, late positive potential emerged as response to emotional words. The present results suggest that this early event-related potential activity represents the fast and automatic processing of emotional words. Furthermore, as the EPN originates from the posterior visual association cortex, the present results suggest a role of these areas in the automatic processing of emotional connotation.

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Recently, there is a growing interest in meditation as an attentional and emotional regulatory strategy. To examine whether meditative practice is associated with successful emotion regulation, we examined the neurophysiological correlates of cognitive reappraisal in practitioners of a yogic meditative technique and controls. Participants were presented aversive pictures and were asked to cognitively change their appraisal of the affective meaning of the pictures by coming up with an alternative more positive interpretation of each picture. We found reduced magnitude of Event-Related Potentials (P300 and early time intervals of the late positive potential, LPP) following cognitive reappraisal of aversive pictures in both groups. However, in the yogic group, reduced magnitude was sustained during the later intervals of the LPP, while it subsided in the control group. Moreover, reduced amplitude of the late LPP correlated positively with experience of the technique. Results suggest a relation between yogic meditative practice and sustained attenuation of emotional response following emotion regulation. Increased positive affect and familiarity with cognitive emotion regulation in the yogic group may explain this effect. Whether this is a direct causal effect of the practice or can be attributed to characteristics of the participants that preexisted the training needs further examination in a randomized longitudinal study.

Sex differences in event-related potentials were examined in 23 women and 24 men during a mental rotation task. We found an early (130-400 ms) and a late (400-700 ms) ERP mental rotation effect. The late rotation effect, which is thought to indicate the onset of the cognitive process of mental rotation, emerged about 100 ms earlier in men than in women. Moreover, men showed about 100 ms shorter response latencies to the task than women. These findings suggest that the faster response in men can be explained as a result of actual mental rotation taking place earlier. Furthermore, we found increased involvement of the right hemisphere specifically in men, probably pointing at a holistic strategy in men during mental rotation.