Spatiotemporal dependency of age-related changes in brain signal variability.

Recent theoretical and empirical work has focused on the variability of network dynamics in maturation. Such variability seems to reflect the spontaneous formation and dissolution of different functional networks. We sought to extend these observations into healthy aging. Two different data sets, one EEG (total n = 48, ages 18-72) and one magnetoencephalography (n = 31, ages 20-75) were analyzed for such spatiotemporal dependency using multiscale entropy (MSE) from regional brain sources. In both data sets, the changes in MSE were timescale dependent, with higher entropy at fine scales and lower at more coarse scales with greater age. The signals were parsed further into local entropy, related to information processed within a regional source, and distributed entropy (information shared between two sources, i.e., functional connectivity). Local entropy increased for most regions, whereas the dominant change in distributed entropy was age-related reductions across hemispheres. These data further the understanding of changes in brain signal variability across the lifespan, suggesting an inverted U-shaped curve, but with an important qualifier. Unlike earlier in maturation, where the changes are more widespread, changes in adulthood show strong spatiotemporal dependence.

Hippocampal signal complexity in mesial temporal lobe epilepsy: a noisy brain is a healthy brain.

Patients with mesial temporal lobe epilepsy (mTLE) show structural and functional abnormalities in hippocampus and surrounding mesial temporal structures. Brain signal complexity appears to be a marker of functional integrity or capacity. We examined complexity in 8 patients with intracranial hippocampal electrodes during performance of memory tasks (scene encoding and recognition) known to be sensitive to mesial temporal integrity. Our patients were shown to have right mesial temporal seizure onsets, permitting us to evaluate both epileptogenic (right) and healthy (left) hippocampi. Using multiscale entropy (MSE) as a measure of complexity, we found that iEEG from the epileptogenic hippocampus showed less complexity than iEEG from the healthy hippocampus. This difference was reliable for encoding but not for recognition. Our results indicate that both functional integrity and cognitive demands influence hippocampal signal complexity.

ACE and ACTN3 genes polymorphisms among female Hungarian athletes in the aspect of sport disciplines.

The aim of the study was to determine the importance of two sport-associated gene polymorphisms, alpha-actinin-3 R577X (ACTN3) and angiotensin-converting enzyme I/D (ACE), among Hungarian athletes in different sports. The examination was carried out only on women (n = 100). Sport-specific groups were formed in order to guarantee the most homogeneous clusters. Human genomic DNA was isolated from blood, and genotyping was performed by polymerase chain reaction. To measure the differences between the participating groups, Chi-squared test was performed using Statistica 9.0 for Windows® (significance level: p < 0.05). In comparing the ACE I/D allele frequencies, significant difference was detected between water polo (I = 61.11%; D = 38.89%) and combat sports (I = 35.71%, D = 64.29%) athletes (p < 0.03). There was no statistical difference when ACE I/D alleles in combat sports and kayaking/rowing (p > 0.05) were compared. A similarity was detectable in the I allele frequencies of the water polo (61.11%) and kayaking/rowing (56.67%) groups. The ACTN3 R/X polymorphism showed no differences in comparison with the sport groups. R allele frequencies were higher in every group compared to the X allele. The potential significance of the ACE I allele in sports of an aerobic nature was not clearly confirmed among Hungarian athletes.

Retrospective Study of the Hungarian National Transplant Team's Cardiorespiratory Capacity.

The low availability of donor organs requires long-term successful transplantation as an accepted therapy for patients with end-stage renal and liver diseases. The health benefits of regular physical activity are well known among healthy individuals as well as patients under rehabilitation programs. Our aim was to describe the cardiorespiratory capacity of the Hungarian National Transplant Team. Twenty-five kidney (n = 21) or liver (n = 4) transplant athletes participated in this study. Maximal cardiorespiratory capacity (VO2max) was measured on a treadmill with the use of gas analysis. After a resting pulmonary function test, subjects completed a vita maxima test until exhaustion. Aerobic capacity of transplant athletes was higher than the age- and sex-predicted cardiorespiratory fitness (VO2max, 109.9 ± 21.7% of the predicted values; P = .0101). Resting respiratory function indicators exceeded 80% of predicted age- and sex-matched normal values. There were positive correlations between VO2max and workload (r(2) = 0.40; P = .0463), metabolic equivalent (r(2) = 0.72; P < .0001), and oxygen pulse (r(2) = 0.30; P = .0039). However, age showed negative correlation with VO2max (r(2) = 0.32; P = .0031), and there was no significant correlation between graft age and maximal oxygen consumption (r(2) = 0.15; P = .4561). Although the small amount of participants can not represent the general kidney and liver transplant population, the excellent cardiorespiratory performance suggests that a normal level of physical capacity is available after transplantation and can be even higher with regular physical activity. This favorable physiologic background leads to a state that provides proper graft oxygenization, which is an important factor in long-term graft survival.

Hippocampal-neocortical networks differ during encoding and retrieval of relational memory: functional and effective connectivity analyses.

Encoding and retrieval of relational information requires interaction between the hippocampus and various neocortical regions, but it is unknown whether the connectivity of hippocampal-neocortical networks is different at input and output stages. To examine this, we conducted a network analysis of event-related fMRI data collected during a face-recognition, remember/know paradigm. Directed analyses in the medial temporal lobe identified a small region in the left hippocampus that showed differential activation for encoding and retrieval of recollected versus familiar items. Multivariate seed partial least squares (PLS) analysis was used to identify brain regions that were functionally connected to this hippocampal region at encoding and retrieval of 'remembered' items. Anatomically based structural equation modeling (SEM) was then used to test for differences in effective connectivity of network nodes between these two memory stages. The SEM analysis revealed a reversal of directionality between the left hippocampus (LHC) and left inferior parietal cortex (LIPC) at encoding and retrieval. During encoding, activation of the LHC had a positive influence on the LIPC, whereas during retrieval the reverse pattern was found, i.e., the LIPC activation positively influenced LHC activation. These findings emphasize the importance of hippocampal-parietal connections and underscore the complexity of their interactions in initial binding and retrieval/reintegration of relational memory. We also found that, during encoding, the right hippocampus had a positive influence on the right retrospenial cortex, whereas during retrieval this influence was significantly weaker. We submit that examining patterns of connectivity can be important both to elaborate and constrain models of memory involving hippocampal-neocortical interactions.

Confabulation and multiple sclerosis: a rare association.

BACKGROUND: Fantastic confabulation in the context of Multiple Sclerosis (MS) has not previously been reported in the literature. The association is of interest because clearly demonstrable brain pathology in MS together with other cognitive and behavioural correlates may further our understanding of the neural basis underlying confabulation. METHODS: A single case report with magnetic resonance imaging of the brain and detailed neuropsychological evaluation. RESULTS: Confabulation occurred together with disinhibited and stimulus bound behaviour. While the patient's physical and emotional state limited the range of psychometric tests administered, the results revealed an inability to maintain focused, regulated information processing. Although memory difficulties were present, they were not in the nature of a severe amnesic disorder. The patient appeared to have a broad fund of knowledge, but the associations binding the information together and putting it into context were loose. All three features of a triad of responses previously described in confabulating patients were present, namely an inability to withhold answers, to monitor one's own responses and provide verbal self corrections. MRI of the brain showed bilateral periventricular lesions and discrete frontal lesions with 53% of the total lesion volume distributed in frontal areas. Cortical atrophy, most marked in frontal regions also was conspicuous. CONCLUSIONS: Confabulation linked to frontal lobe involvement may occur as part of the changes in mentation found in MS. It is, however, rare and although associated with impaired memory, may be found in the absence of a severe amnesic disorder. This conclusion is discussed in the light of observations from the literature suggesting that frontal involvement is a prerequisite before fantastic confabulation occurs.

Spatiotemporal analysis of event-related fMRI data using partial least squares.

Partial least squares (PLS) has proven to be a important multivariate analytic tool for positron emission tomographic and, more recently, event-related potential (ERP) data. The application to ERP incorporates the ability to analyze space and time together, a feature that has obvious appeal for event-related functional magnetic resonance imaging (fMRI) data. This paper presents the extension of spatiotemporal PLS (ST-PLS) to fMRI, explaining the theoretical foundation and application to an fMRI study of auditory and visual perceptual memory. Analysis of activation effects with ST-PLS was compared with conventional univariate random effects analysis, showing general consensus for both methods, but several unique observations by ST-PLS, including enhanced statistical power. The application of ST-PLS for assessment of task-dependent brain-behavior relationships is also presented. Singular features of ST-PLS include (1) no assumptions about the shape of the hemodynamic response functions (HRFs); (2) robust statistical assessment at the image level through permutation tests; (3) protection against outlier influences at the voxel level through bootstrap resampling; (4) flexible analytic configurations that allow assessment of activation difference, brain-behavior relations, and functional connectivity. These features enable ST-PLS to act as an important complement to other multivariate and univariate approaches used in neuroimaging research.

Prediction of neuropsychiatric outcome following mild trauma brain injury: an examination of the Glasgow Coma Scale.

The relationship between the Glasgow Coma Scale (GCS) and neuropsychiatric outcome was examined in 57 consecutive subjects with mild traumatic brain injury (TBI) attending a follow-up clinic. Subjects were grouped according to initial GCS score (15 versus 13-14) and contrasted at an average of 5-6 months post-injury. As expected, those with GCS 13-14 had longer PTA (p = 0.001) and a higher rate of abnormal brain CT scans (p = 0.005). However, no significant differences emerged for indices of neuropsychiatric status, including measures of neurobehavioural symptoms/signs, overall psychological distress, psychiatric 'caseness', functional and psychosocial outcome, frequency of common somatic complaints, and rate of return to work. Subsidiary analyses based upon the presence/absence of CT abnormalities and the duration of PTA (<1 hour versus 1-24 hours) also failed to predict outcome, although a trend associating longer PTA with lower functional outcome was observed. Thus, despite early neurosurgical differences, the results suggest that initial GCS scores do not clearly translate into neuropsychiatric sequelae at follow-up within the rubric of GCS 13-15.