Brain white matter fiber bundles in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) have abnormalities not usually seen in unaffected subjects. Ideal algorithm of the localization-specific properties in white matter integrity might reveal the changes of tissue properties varying along each tract, while previous studies only detected the mean DTI parameters of each fiber. The aim of this study was to investigate whether these abnormalities of nerve fiber tracts are localized to specific regions of the tracts or spread throughout and to analyze which of the examined fiber tracts are involved in the early stages of Alzheimer's disease. In this study, we utilized VBA, TBSS as well as AFQ together to comprehensively investigate the white matter fiber impairment on 25 CE patients, 29 MCI patients and 34 normal control (NC) subjects. Two tract profiles, fractional anisotropy (FA) and mean diffusivity (MD), were extracted to evaluate the white matter integrity at 100 locations along each of 20 fiber tracts and then we validated the results with 27 CE patients, 21 MCI patients and 22 NC from the ADNI cohort. Also, we compare the AFQ with VBA and TBSS in our cohort. In comparison with NC, AD patients showed widespread FA reduction in 25% (5 /20) and MD increase in 65%(13/20) of the examined fiber tracts. The MCI patients showed a regional FA reduction in 5% (1/20) of the examined fiber tracts (right cingulum cingulate) and MD increase in 5%(1/20) of the examined fiber tracts (left arcuate fasciculus). Among these changed tracts, only the right cingulum cingulate showed widespread disruption of myelin or/and fiber axons in MCI and aggravated deterioration in AD, findings supported by FA/MD changes both by the mean and FA changes by point wise methods and TBSS. And the AFQ findings from ADNI cohort showed some similarity with our cohort, especially in the pointwise comparison of MD profiles between AD vs NC. Furthermore, the pattern of white matter abnormalities was different across neuronal fiber tracts; for example, the MCI and AD patients showed similar FA reduction in the middle part of the right cingulum cingulate, and the anterior part were not damaged. However, the left arcuate fasciculus showed MD elevation located at the temporal part of the fibers in the MCI patients and expanding to the temporal and middle part of the fibers in AD patients. So, the AFQ may be an alternative complementary method of VBA and TBSS, and may provide new insights into white matter degeneration in MCI and its association with AD.

• MeSH
• Alzheimerova nemoc diagnostické zobrazování   patologie   MeSH
• bílá hmota diagnostické zobrazování   patologie   MeSH
• interpretace obrazu počítačem metody   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nervová vlákna patologie   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• zobrazování difuzních tenzorů metody   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Recent findings suggest that neural complexity reflecting a number of independent processes in the brain may characterize typical changes during epileptic seizures and may enable to describe preictal dynamics. With respect to previously reported findings suggesting specific changes in neural complexity during preictal period, we have used measure of pointwise correlation dimension (PD2) as a sensitive indicator of nonstationary changes in complexity of the electroencephalogram (EEG) signal. Although this measure of complexity in epileptic patients was previously reported by Feucht et al (Applications of correlation dimension and pointwise dimension for non-linear topographical analysis of focal onset seizures. Med Biol Comput. 1999;37:208-217), it was not used to study changes in preictal dynamics. With this aim to study preictal changes of EEG complexity, we have examined signals from 11 multicontact depth (intracerebral) EEG electrodes located in 108 cortical and subcortical brain sites, and from 3 scalp EEG electrodes in a patient with intractable epilepsy, who underwent preoperative evaluation before epilepsy surgery. From those 108 EEG contacts, records related to 44 electrode contacts implanted into lesional structures and white matter were not included into the experimental analysis.The results show that in comparison to interictal period (at about 8-6 minutes before seizure onset), there was a statistically significant decrease in PD2 complexity in the preictal period at about 2 minutes before seizure onset in all 64 intracranial channels localized in various brain sites that were included into the analysis and in 3 scalp EEG channels as well. Presented results suggest that using PD2 in EEG analysis may have significant implications for research of preictal dynamics and prediction of epileptic seizures.

• MeSH
• elektroencefalografie * metody   MeSH
• epilepsie patofyziologie   MeSH
• lidé MeSH
• mladý dospělý MeSH
• Check Tag
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH

Several recent studies suggest that quantitative description of signal complexity using algorithms of nonlinear analysis could uncover new information about the autonomic system that is not reflected using common methods applied to measures of autonomic activity. With this aim we have performed complexity analysis of electrodermal activity (EDA) assessed in 106 healthy university students during rest conditions and non-conflicting and conflicting Stroop task. Complexity analysis applied to EDA was performed using Skinner's algorithm for pointwise correlation dimension (PD2). Results have shown that EDA responses during the Stroop Colour Word test are related to significantly increased or decreased complexity. Particularly significant result is that PD2 has a unique ability to predict to an extent the change in EDA response to stress i.e. that subjects with low initial PD2 tended to respond to experimental stress by its increase and subjects with high initial PD2 values tended to respond by its decrease. This response was not found in EDA measures where increase of the EDA presented predominant response to experimental stress in majority of the subjects. These findings suggest that PD2 is more sensitive to subtle aspects of functionally and spatially distributed modulatory influences of various parts of the brain that are involved in the EDA modulation and provides novel information in comparison to traditional methods.

• MeSH
• algoritmy MeSH
• autonomní nervový systém fyziologie   patofyziologie   MeSH
• dospělí MeSH
• galvanická kožní odpověď fyziologie   MeSH
• konflikt (psychologie) MeSH
• lidé MeSH
• mladý dospělý MeSH
• psychický stres patofyziologie   MeSH
• statistika jako téma MeSH
• Stroopův test MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Recently, a specific role of nonlinear dynamics and complexity in neural and cognitive processes has been proposed, and there are several reported studies suggesting that smokers might display characteristic changes in the EEG dimensional complexity in comparison to non-smokers. With the aim to extend these findings to autonomic activity, we have examined dimensional complexity in bilateral electrodermal activity (EDA) that reflects limbic modulation influences and may provide information on specific emotional processes related to sympathetic activity. In the present study EDA was assessed in 35 smokers (mean age 23.4, SD=1.4) and 41 non-smokers (mean age 23.2, SD=1.8) during resting conditions. Calculation of dimensional complexity in both groups similarly as in previous reported studies was performed using an algorithm for pointwise correlation dimension (PD2). The results of nonlinear and statistical analysis of EDA records indicate increased complexity during rest conditions (indexed by PD2) in smokers compared to non-smokers (Mann-Whitney test; p<0.01), even though EDA measurement does not discriminate the groups (Mann-Whitney test; p>0.05). These results present a first supportive evidence that EDA complexity may exhibit an electrophysiological marker that could potentially explain the role of complex dynamics in the autonomic nervous system related to smoking habits and addiction.

• MeSH
• algoritmy MeSH
• dospělí MeSH
• elektrická stimulace metody   přístrojové vybavení   MeSH
• elektroencefalografie MeSH
• financování organizované MeSH
• galvanická kožní odpověď fyziologie   MeSH
• interpretace statistických dat MeSH
• kognice fyziologie   účinky léků   MeSH
• kouření patofyziologie   MeSH
• limbický systém fyziologie   účinky léků   MeSH
• mozek fyziologie   účinky léků   MeSH
• nelineární dynamika MeSH
• pozornost fyziologie   účinky léků   MeSH
• reakční čas fyziologie   MeSH
• senzitivita a specificita MeSH
• studie případů a kontrol MeSH
• Check Tag
• dospělí MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH