The increase of the functional entropy of the human brain with age

We use entropy to characterize intrinsic ageing properties of the human brain. Analysis of fMRI data from a large dataset of individuals, using resting state BOLD signals, demonstrated that a functional entropy associated with brain activity increases with age. During an average lifespan, the entropy, which was calculated from a population of individuals, increased by approximately 0.1 bits, due to correlations in BOLD activity becoming more widely distributed. We attribute this to the number of excitatory neurons and the excitatory conductance decreasing with age. Incorporating these properties into a computational model leads to quantitatively similar results to the fMRI data. Our dataset involved males and females and we found significant differences between them. The entropy of males at birth was lower than that of females. However, the entropies of the two sexes increase at different rates, and intersect at approximately 50 years; after this age, males have a larger entropy

Excitability of the Motor Cortex Ipsilateral to the Moving Body Side Depends on Spatio-Temporal Task Complexity and Hemispheric Specialization

Unilateral movements are mainly controlled by the contralateral hemisphere, even though the primary motor cortex ipsilateral (M1ipsi) to the moving body side can undergo task-related changes of activity as well. Here we used transcranial magnetic stimulation (TMS) to investigate whether representations of the wrist flexor (FCR) and extensor (ECR) in M1ipsi would be modulated when unilateral rhythmical wrist movements were executed in isolation or in the context of a simple or difficult hand-foot coordination pattern, and whether this modulation would differ for the left versus right hemisphere. We found that M1ipsi facilitation of the resting ECR and FCR mirrored the activation of the moving wrist such that facilitation was higher when the homologous muscle was activated during the cyclical movement. We showed that this ipsilateral facilitation increased significantly when the wrist movements were performed in the context of demanding hand-foot coordination tasks whereas foot movements alone influenced the hand representation of M1ipsi only slightly. Our data revealed a clear hemispheric asymmetry such that MEP responses were significantly larger when elicited in the left M1ipsi than in the right. In experiment 2, we tested whether the modulations of M1ipsi facilitation, caused by performing different coordination tasks with the left versus right body sides, could be explained by changes in short intracortical inhibition (SICI). We found that SICI was increasingly reduced for a complex coordination pattern as compared to rest, but only in the right M1ipsi. We argue that our results might reflect the stronger involvement of the left versus right hemisphere in performing demanding motor tasks

Diagnosis of human granulocytic anaplasmosis in Belgium by combining molecular and serological methods

We report here one new, hospitalized case of Anaplasma phagocytophilum in Belgium. The clinical presentation of anaplasmosis, its treatment and the molecular and serological relevant laboratory methods are briefly developed

Pre-exposure intradermal rabies vaccination: a non-inferiority trial in healthy adults on shortening the vaccination schedule from 28 to 7 days.

&lt;p&gt;&lt;b&gt;Background: &lt;/b&gt;The existing four-week pre-exposure rabies vaccination schedule is costly and often not practicable. Shorter effective schedules would result in wider acceptance.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methods: &lt;/b&gt;We conducted a non-inferiority trial in 500 healthy adults comparing the safety and immunogenicity of a two-visit (day 0 and day 7) intradermal (ID) primary vaccination (two doses of 0.1 ml ID of the human diploid cell culture rabies vaccine (HDCV) at day 0 and 7) versus a standard three-visit schedule (single dose of 0.1 mL ID at day 0, 7, and 28). One to three years after primary vaccination, a single booster dose of 0.1 mL ID of HDCV was given to evaluate the anamnestic rabies antibody response. The primary endpoint for immunogenicity was the percentage of subjects with an adequate antibody level &amp;gt;0.5 IU/mL seven days after the booster injection. The safety endpoint was the proportion of participants developing adverse reactions following the primary vaccination and/or booster dose.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Results: &lt;/b&gt;All subjects in both study groups possessed a rabies antibody titer &amp;gt;0.5 IU/mL on day 7 following the booster dose. Following the booster dose, subjects exposed to the double-dose two-visit ID schedule had a geometric mean titer of 37 IU/ml versus 25 IU/ml for the single-dose three-visit schedule (p&amp;lt;0.001). Local reactions at the injection site following primary vaccination were mild and transient.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusion: &lt;/b&gt;In healthy adults, ID administration of a double dose of 0.1 ml of HDCV over two-visits (day 0 and day 7) was safe and not inferior to the single-dose three-visit schedule.&lt;/p&gt;</p

Action prediction in younger versus older adults: Neural correlates of motor familiarity

Contains fulltext : 116607.pdf (publisher's version ) (Open Access)Generating predictions during action observation is essential for efficient navigation through our social environment. With age, the sensitivity in action prediction declines. In younger adults, the action observation network (AON), consisting of premotor, parietal and occipitotemporal cortices, has been implicated in transforming executed and observed actions into a common code. Much less is known about age-related changes in the neural representation of observed actions. Using fMRI, the present study measured brain activity in younger and older adults during the prediction of temporarily occluded actions (figure skating elements and simple movement exercises). All participants were highly familiar with the movement exercises whereas only some participants were experienced figure skaters. With respect to the AON, the results confirm that this network was preferentially engaged for the more familiar movement exercises. Compared to younger adults, older adults recruited visual regions to perform the task and, additionally, the hippocampus and caudate when the observed actions were familiar to them. Thus, instead of effectively exploiting the sensorimotor matching properties of the AON, older adults seemed to rely predominantly on the visual dynamics of the observed actions to perform the task. Our data further suggest that the caudate played an important role during the prediction of the less familiar figure skating elements in better-performing groups. Together, these findings show that action prediction engages a distributed network in the brain, which is modulated by the content of the observed actions and the age and experience of the observer.15 p