Variability and interhemispheric asymmetry of the responses to paired-coil TMS of the primary motor cortex.
Trial-to-trial variability of the motor evoked potentials (MEP) to transcranial magnetic stimulation (TMS) is a well-known phenomenon. However, the relationship between the fluctuations of the different types of the motor output and other motor system parameters such as corticospinal excitability, interhemispheric inhibition (IHI) and their interhemispheric asymmetry have not yet been fully investigated. We studied 20 young healthy right-handed volunteers. Four TMS sessions were performed (two single-pulse TMS and two paired-coil TMS with IHI paradigm sessions for each hemisphere), 70 stimuli were delivered during every session. Coefficient of quartile variation (CQV) was used to quantify trail-to-trail variability of MEPs amplitude. Resting motor threshold values were correlated between hemispheres (r = .842, p < .001). IHI phenomenon from the left hemisphere was obtained in 18 out of 20 volunteers, while IHI phenomena from the right hemisphere was shown in 16 out of 20. A strong correlation between the variability of MEP‘s amplitudes during IHI paradigm and the degree of IHI was found for the left hand (r = −.718, p < .001). We also observed a strong correlation between CQV of MEPs from both hands to single-pulse TMS (r = .632, p = .004). A side-specific correlation between the variability of the responses to single-pulse and paired-coil TMS was found for the dominant hemisphere (r = .524, p = .021). Our preliminary results demonstrate the importance of the trial-to-trial variability of the MEPs and its interhemispheric specificity as a defining characteristics of the motor system. This study was partially supported by ofi-m RFBR grant 17-29-02518, by HSE Basic Research Program and Russian Academic Excellence Project ‘5-100’.
Despite extensive research on face recognition, only a few studies have examined the integration of perceptual features with semantic, biographical, and episodic information. In order to address this issue, we used repetitive transcranial magnetic stimulation (rTMS) to target the left inferior frontal gyrus (IFG) and the left occipital face area (OFA) during a face recognition task. rTMS was delivered during the encoding of "context" faces (i.e., linked to an occupation, e.g., "lawyer") and "no-context" faces (i.e., linked to a nonword pattern, e.g., "xxxx"). Subjects were then asked to perform a recognition memory task. Accuracy at retrieval showed a mild decrease after left OFA stimulation, whereas rTMS over the left IFG drastically compromised memory performance selectively for no-context faces. On the other hand, absence of rTMS interference on context faces might be due either to the fact that pairing an occupation to a face makes the memory trace stronger, therefore less susceptible to rTMS interference, or to a different functional specificity of the left IFG subregions.
The right temporoparietal junction (rTPJ) is a polysensory cortical area that plays a key role in perception and awareness. Neuroimaging evidence shows activation of rTPJ in intersensory and sensorimotor conflict situations, but it remains unclear whether this activity reflects detection or resolution of such conflicts. To address this question, we manipulated the relationship between touch and vision using the so-called mirror-box illusion. Participants' hands lay on either side of a mirror, which occluded their left hand and reflected their right hand, but created the illusion that they were looking directly at their left hand. The experimenter simultaneously touched either the middle (D3) or the ring finger (D4) of each hand. Participants judged, which finger was touched on their occluded left hand. The visual stimulus corresponding to the touch on the right hand was therefore either congruent (same finger as touch) or incongruent (different finger from touch) with the task-relevant touch on the left hand. Single-pulse transcranial magnetic stimulation (TMS) was delivered to the rTPJ immediately after touch. Accuracy in localizing the left touch was worse for D4 than for D3, particularly when visual stimulation was incongruent. However, following TMS, accuracy improved selectively for D4 in incongruent trials, suggesting that the effects of the conflicting visual information were reduced. These findings suggest a role of rTPJ in detecting, rather than resolving, intersensory conflict.
The neural mechanisms underlying perceptual learning are still under investigation. Eureka effect is a form of rapid, long-lasting perceptual learning by which a degraded image, which appears meaningless when first seen, becomes recognizable after a single exposure to its undegraded version. We used online interference by focal 10-Hz repetitive transcranial magnetic stimulation (rTMS) to evaluate whether the parietal cortex (PC) is involved in Eureka effect, as suggested by neuroimaging data. RTMS of the PC did not affect recognition of degraded pictures when displayed 2s after the presentation of their undegraded version (learning phase). However, rTMS delivered over either right or left intraparietal sulcus simultaneously to the undegraded image presentation, disrupted identification of the degraded version of the same pictures when displayed 30 min after the learning phase. In contrast, recognition of degraded images was unaffected by rTMS over the vertex or by sham rTMS, or when rTMS of either PC was delivered 2s after the presentation of the undegraded image. Findings strongly support the hypothesis that both PC at the level of the intraparietal sulcus play a pivotal role in the Eureka effect particularly in consolidation processes, and contribute to elucidate the neural network underlying rapid perceptual learning
Materials of the all-Russian scientific-practical conference with international participation
Objective: Glioblastoma is a highly aggressive and invasive brain and Central Nervous System (CNS) tumor. Current treatment options do not prolong overall survival significantly because the disease is highly prone to relapse. Therefore, research to find new therapies is of paramount importance. It has been discovered that glioblastomas contain a population of cells with stem-like properties and that these cells are may be responsible for tumor recurrence.
Methods: A review of relevant papers and clinical trials in the field was conducted. A PubMed search with related keywords was used to gather the data. For example, “glioblastoma stem cells AND WNT signaling” is an example used to find information on clinical trials using the database ClinicalTrials.gov.
Results: Cancer stem cell research has several fundamental issues and uncertainties that should be taken into consideration. Theoretically, a number of treatment options that target glioblastoma stem cells are available for patients. However, only a few of them have obtained promising results in clinical trials. Several strategies are still under investigation.
Conclusion: The majority of treatments to target cancer stem cells have failed during clinical trials. Taking into account a number of biases in the field and the number of unsuccessful investigations, the application of the cancer stem cells concept is questionable in clinical settings, at least with respect to glioblastoma.
Data management and analysis is one of the fastest growing and most challenging areas of research and development in both academia and industry. Numerous types of applications and services have been studied and re-examined in this field resulting in this edited volume which includes chapters on effective approaches for dealing with the inherent complexity within data management and analysis. This edited volume contains practical case studies, and will appeal to students, researchers and professionals working in data management and analysis in the business, education, healthcare, and bioinformatics areas.
Aim. To study the relationship between cerebral perfusion and severity of cerebral small vessel disease (SVD) in the context of the rehabilitation potential in acute ischemic stroke (IS).
Material and methods. 50 patients with IS and 10 persons of the control group were examined. All patients underwent standard examinations, including brain MRI with an assessment of lacunes, enlarged perivascular spaces (PVS), leukoareosis and cerebral microbleeds (CMB). Cerebral blood flow (CBF) was quantified in the middle cerebral artery territory according to ASPECTS scale by non-contrast magnetic resonance ASL-perfusion.
Results. In patients with IS, unlike the control group, a lower CBF in M3 white matter within both hemispheres and in the cortical part of M6 of the ipsilateral hemisphere is revealed. The number of lacunes in the contralateral hemisphere is related to perfusion in 8 ASPECTS areas. The number of PVS is associated with CBF in insula, lenticular nucleus, M3 of the opposite hemisphere, M6 and internal capsule of the affected hemisphere. The severity of leukoareosis correlates with CBF in 4 zones of the opposite hemisphere. The greatest number of correlations with CBF in basal ganglia was observed for CMBs of the affected hemisphere. Total severity of SVD is also associated with CBF in several areas. The severity of neurological deficiency and dynamics of patient`s mobility, functional and cognitive status correlates with CBF. Conclusion. Global perfusion status is associated with severity of SVD and rehabilitation potential in acute period of IS.
Given many developing economies depend on primary commodities, the fluctuations of commodity prices may imply significant effects for the wellbeing of children. To investigate, this paper examines the relationship between child mortality and commodity price movements as reflected by country-specific commodity terms-of-trade. Employing a panel of 69 low and lower-middle income countries over the period 1970-2010, we show that commodity terms-of-trade volatility increases child mortality in highly commodity-dependent importers suggesting a type of ‘scarce’ resource curse. Strikingly however, good institutions appear able to mitigate the negative impact of volatility. The paper concludes by highlighting this tripartite relationship between child mortality, volatility and good institutions and posits that an effective approach to improving child wellbeing in low to lower-middle income countries will combine hedging, import diversification and improvement of institutional quality.