Functional imaging studies on mental rotation of hands have consistently pointed to the importance of the motor network implying the use of motor simulations for task solving. There is some evidence ...that the putamen may be a critical modulator of processing egocentric spatial orientation in mental rotation of hands and implicit motor imagery strategies have been described involving hand motor areas. This recruitment of resources processing representations of the own body is used in therapeutic mental rotation training. However, studies are lacking that investigate training-induced changes on the neuronal level. We used functional MRI to study the effects of long-term training on the neuro-functional correlates of mental rotation of hands in healthy volunteers and compared the training group to a passive control group. From pre- to post training, we found a transition of activation from the anterior putamen in unskilled performance to the posterior putamen in skilled performance. We also found an increase in activation in motor cortices and the supramarginal gyrus after learning. By contrast, members of the control group showed no improvements in performance and no pre/post-test differences in cortical activity. In conclusion, these findings suggest that increased neural efficiency after training in mental rotation of hands manifests as a decrease in visual imagery in conjunction with increased recruitment of motor-related regions. This is consistent with the obtained behavioral effects depicting motor imagery mediating expertise in mental rotation of hands.
Several biomarkers have been identified which enable a considerable prediction of hand-motor outcome after cerebral damage already in the subacute stage after stroke. We here review the value of MRI ...biomarkers in the evaluation of corticospinal integrity and functional recruitment of motor resources. Many of the functional imaging parameters are not feasible early after stroke or for patients with high impairment and low compliance. Whereas functional connectivity parameters have demonstrated varying results on their predictive value for hand-motor outcome, corticospinal integrity evaluation using structural imaging showed robust and high predictive power for patients with different levels of impairment. Although this is indicative of an overall higher value of structural imaging for prediction, we suggest that this variation be explained by structure and function relationships. To gain more insight into the recovering brain, not only one biomarker is needed. We rather argue for a combination of different measures in an algorithm to classify fine-graded subgroups of patients. Approaches to determining biomarkers have to take into account the established markers to provide further information on certain subgroups. Assessing the best therapy approaches for individual patients will become more feasible as these subgroups become specified in more detail. This procedure will help to considerably save resources and optimize neurorehabilitative therapy.
The basal forebrain cholinergic system (BFCS) is known to undergo moderate neurodegenerative alterations during normal aging and severe atrophy in Alzheimer's disease (AD). It has been suggested that ...functional and structural alterations of the BFCS mediate cognitive performance in normal aging and AD. But, it is still unclear to what extend age-associated cognitive decline can be related to BFCS in normal aging. We analyzed the relationship between BFCS volume and cognition using MRI and a comprehensive neuropsychological test battery in a cohort of 43 healthy elderly subjects spanning the age range from 60 to 85 years.
Most notably, we found significant associations between general intelligence and BFCS volumes, specifically within areas corresponding to posterior nuclei of the nucleus basalis of Meynert (Ch4p) and the nucleus subputaminalis (NSP). Associations between specific cognitive domains and BFCS volumes were less pronounced. Supplementary analyses demonstrated that especially the volume of NSP but also the volume of Ch4p was related to the volume of widespread temporal, frontal, and parietal gray and white matter regions. Volumes of these gray and white matter regions were also related to general intelligence. Higher volumes of Ch4p and NSP may enhance the effectiveness of acetylcholine supply in related gray and white matter regions underlying general intelligence and hence explain the observed association between the volume of Ch4p as well as NSP and general intelligence. Since general intelligence is known to attenuate the degree of age-associated cognitive decline and the risk of developing late-onset AD, the BFCS might, besides the specific contribution to the pathophysiology in AD, constitute a mechanism of brain resilience in normal aging.
•We examined the association between basal forebrain (BF) volumes and cognition in normal aging.•BF volumes were strongly related to general intelligence (g).•Association between BF volumes and specific cognitive domains were less pronounced.•g is known to attenuate age-associated cognitive decline and the risk to develop AD.•Thus, BF volume might constitute a mechanism of brain resilience in normal aging.
Several pathologic processes might contribute to the degeneration of the cholinergic system in aging. We aimed to determine the contribution of amyloid, tau, and cerebrovascular biomarkers toward the ...degeneration of cholinergic white matter (WM) projections in cognitively unimpaired individuals.
The contribution of amyloid and tau pathology was assessed through CSF levels of the Aβ
ratio and phosphorylated tau (p-tau). CSF Aβ
levels were also measured. Cerebrovascular pathology was assessed using automatic segmentations of WM lesions (WMLs) on MRI. Cholinergic WM projections (i.e., cingulum and external capsule pathways) were modeled using tractography based on diffusion tensor imaging data. Sex and APOE ε4 carriership were also included in the analysis as variables of interest.
We included 203 cognitively unimpaired individuals from the H70 Gothenburg Birth Cohort Studies (all individuals aged 70 years, 51% female). WM lesion burden was the most important contributor to the degeneration of both cholinergic pathways (increase in mean square error IncMSE = 98.8% in the external capsule pathway and IncMSE = 93.3% in the cingulum pathway). Levels of Aβ
and p-tau also contributed to cholinergic WM degeneration, especially in the external capsule pathway (IncMSE = 28.4% and IncMSE = 23.4%, respectively). The Aβ
ratio did not contribute notably to the models (IncMSE<3.0%). APOE ε4 carriers showed poorer integrity in the cingulum pathway (IncMSE = 21.33%). Women showed poorer integrity of the external capsule pathway (IncMSE = 21.55%), which was independent of amyloid status as reflected by the nonsignificant differences in integrity when comparing amyloid-positive vs amyloid-negative women participants (T
= -1.55;
= 0.123).
In cognitively unimpaired older individuals, WMLs play a central role in the degeneration of cholinergic pathways. Our findings highlight the importance of WM lesion burden in the elderly population, which should be considered in the development of prevention programs for neurodegeneration and cognitive impairment.
Introduction The effect of intracortical facilititation (ICF) is independent from hemispheric dominance and handedness (Bäumer et al., 2007). Short term training selectively increases excitability ...over the contralateral primary motor cortex (M1c) of the trained hand (e.g. Lotze et al., 2003). M1-excitability measurements after long-term training (several weeks) are rare but – to our knowledge – are even absent for ICF-parameters. Objectives To evaluate effects of ICF during a two week comprehensive period of training of the left hand in strongly right handed healthy participants. Materials and ethods Thirteen strongly right-handed healthy participants (23 ± 3.5 years; 6 women) underwent a two-week arm ability training (AAT) for their left, nondominant hand for one hour per day (Platz, 2004). Performance increase was expressed as percentual changes over time and averaged over all eight AAT-tasks. Focal TMS was delivered to the optimal scalp position for activation of the musculus abductor policis brevis (APB) of each hand using a figure-of-eight coil. Resting motor threshold (rMT) and intracortical facilitation (ICF; test stimulus intensity 120% rMT; conditioning stimulus 80% rMT; interstimulus interval 10 ms) were used as measures of corticomotor excitability. Results Training resulted in considerable improvement of the trained left (30 ± 3.5%) hand, but – to a lesser extent – also the non-trained right hand (18 ± 5.4%) performance. RMT was not altered over time. For ICF we found a strong time effect in ANOVA; but post hoc t-tests showed only a relevant decrease over time for the untrained side ( T (12) = 3.33; p = 0.006; Fig. 1). Conclusion Our study showed no significant changes in ICF for the trained hand side, but a decrease for the non trained hand’s motor cortex. It has been demonstrated that the interaction between an increase of unilateral movement and 10 h unilateral immobilization of the other hand is critical for excitability effects over M1c (Avanzino et al., 2011). We argue that interhemispheric changes induced by unilateral limb training of the non-dominant hand might be multifactorial; here we observed an increased interhemispheric balance in ICF after training the less experienced, and presumably in spontaneous behavior less intensively used hand.
Background The human cerebellum is involved in both motor and cognitive functions. In Multiple Sclerosis (MS), overall cerebellar gray matter (GM) volume loss has been previously described. We ...therefore hypothesized that regional cerebellar GM loss could be correlated with the subtests of the Multiple Sclerosis functional Composite Score (MSFC: timed 25-foot walk, 9-hole peg test, Paced Auditory Serial Addition Test). Patients and methods Voxel based morphometry (VBM) was used to investigate regional gray matter decline by calculating individual GM images from 45 MS patients using the VBM tool for the software statistic parametric mapping (SPM). Correlation analyses were performed on the MSFC subtests and the individual GM images. Results Each component of the MSFC was associated with a distinct regional cerebellar GM decrease. Impaired walking ability correlated with regional volume loss in lobule VI ( t = 5.16; punc. < .001), impaired arm ability with a cluster in lobule IX ( t = 3.95; punc. < .001) and cognitive impairment with volume loss in crus II ( t = 4.81; punc. < .001). Discussion We demonstrate correlation of distinct regional cerebellar volume changes with each of the tasks out of the MSFC. Our data emphasize the importance of cerebellar gray pathophysiology in MS.
Predicting motor recovery after stroke is a recognized aim in stroke rehabilitation. Here, we combine two different neuroimaging methods to test their prognostic power at the sub-acute stage after ...stroke. We measured resting state fMRI (rs-fMRI) and diffusion weighted imaging (DWI) in 19 stroke patients within the first days (5–9 days) after stroke and investigated short term (3 months) and long term (6 months) motor outcome. Resting-state functional connectivity (rs-FC) showed no relevant predictive value for motor outcome. We found trends for negative associations between the rs-FC of primary motor cortex (M1) of the lesioned hemisphere and dorsal premotor cortices (dPMC) of the contralesional side with grip force of the affected upper limb at 3 months. In addition, a poorer short-term outcome for pinch grip performance was associated with rs-FC of M1 and the supplementary motor area (SMA) in the lesioned hemisphere. In contrast DWI showed a predictive value for both short-term and long-term motor outcome. Integrity along the M1-pons tract showed good predictive value for a positive outcome at 6 months. Overall, structural connectivity measures derived from probabilistic DWI may offer better prognostic information than rs-fMRI at the early phase after stroke.
The innermost part of the tracking detector of the ATLAS experiment consists mainly of planar n+-in-n silicon pixel sensors. During the phase-0 upgrade, the Insertable B-Layer (IBL) was installed ...closest to the beam pipe. Its pixels are arranged with a pitch of 250 μm×50μm with a rectangular shaped n+ implantation. Based on this design modified pixel designs have been developed in Dortmund.
Six of these new pixel designs are arranged in structures of ten columns and were placed beside structures with the standard design on one sensor. Because of a special guard ring design, each structure can be powered and investigated separately. Several of these sensors were bump bonded to FE-I4 read-out chips. One of these modules was irradiated with reactor neutrons up to a fluence of 5×1015neqcm−2.
This contribution presents important sensor characteristics, charge collection determined with radioactive sources and hit efficiency measurements, performed in laboratory and test beam, of this irradiated device. It is shown that the new modified designs perform similar or better than the IBL standard design in terms of charge collection and tracking efficiency, at the cost of a slightly increased leakage current.
Neurophysiological pathology in CRPS type I is characterized by somatosensory and motor deficits. Transcranial magnetic stimulation (TMS) and functional MRI reveal decreased short intracortical ...inhibition (SICI) and smaller representation distance in the hand region of primary somatosensory cortex (S1) between the first and fifth digit in CRPS. Interestingly, an application of anesthetic cream to the forearm increases spatial tactile resolution (STR) and also SICI of hand muscles in healthy participants. As such, this intervention might be suited to reverse pathologic findings in CRPS patients and tested this in a double blinded placebo controlled study. In addition we used high spatial resolution fMRI of the thumb (D1) and pinky (D5) S1 BA 3b representation before and after intervention. Patients showed decreased STR over D1 (tip of thumb) on their affected side if compared to the unaffected side ( t = 2.31; p < 0.05). STR improved after anesthetic cream ( t = 3.0; p < 0.05) but not after placebo application. Pain intensity was not modulated after intervention. SICI was increased only after analgesic cream ( t = 2.22; p < 0.05) but not after placebo. We expect an association of D1–D5 distance and STR in our fMRI-data. In conclusion, temporary deafferentation of an area neighboring the CRPS-affected region can modulate neuropathological characteristics of CRPS and might be a promising strategy for therapeutic interventions.
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