Cross‐modal plasticity in blind individuals has been reported over the past decades showing that nonvisual information is carried and processed by “visual” brain structures. However, despite multiple ...efforts, the structural underpinnings of cross‐modal plasticity in congenitally blind individuals remain unclear. We mapped thalamocortical connectivity and assessed the integrity of white matter of 10 congenitally blind individuals and 10 sighted controls. We hypothesized an aberrant thalamocortical pattern of connectivity taking place in the absence of visual stimuli from birth as a potential mechanism of cross‐modal plasticity. In addition to the impaired microstructure of visual white matter bundles, we observed structural connectivity changes between the thalamus and occipital and temporal cortices. Specifically, the thalamic territory dedicated to connections with the occipital cortex was smaller and displayed weaker connectivity in congenitally blind individuals, whereas those connecting with the temporal cortex showed greater volume and increased connectivity. The abnormal pattern of thalamocortical connectivity included the lateral and medial geniculate nuclei and the pulvinar nucleus. For the first time in humans, a remapping of structural thalamocortical connections involving both unimodal and multimodal thalamic nuclei has been demonstrated, shedding light on the possible mechanisms of cross‐modal plasticity in humans. The present findings may help understand the functional adaptations commonly observed in congenitally blind individuals.
The absence of visual stimuli from birth changes the pattern of thalamocortical connectivity, specifically between visual, auditory and multimodal structures. Our findings bring new evidence for the possible neural underpinnings of cross‐modal plasticity in blind individuals.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
COVID-19 has become a dramatic health problem during this century. In addition to high mortality rate, COVID-19 survivors are at increased risk for cardiovascular diseases 1-year after infection. ...Explanations for these manifestations are still unclear but can involve a constellation of biological alterations. We hypothesized that COVID-19 survivors compared with controls exhibit sympathetic overdrive, vascular dysfunction, cardiac morpho-functional changes, impaired exercise capacity, and increased oxidative stress.
Nineteen severe COVID-19 survivors and 19 well-matched controls completed the study. Muscle sympathetic nerve activity (microneurography), brachial artery flow-mediated dilation and blood flow (Doppler-Ultrasound), carotid-femoral pulse wave velocity (Complior), cardiac morpho-functional parameters (echocardiography), peak oxygen uptake (cardiopulmonary exercise testing), and oxidative stress were measured ~3 months after hospital discharge. Complementary experiments were conducted on human umbilical vein endothelial cells cultured with plasma samples from subjects.
Muscle sympathetic nerve activity and carotid-femoral pulse wave velocity were greater and brachial artery flow-mediated dilation, brachial artery blood flow, E/e' ratio, and peak oxygen uptake were lower in COVID-19 survivors than in controls. COVID-19 survivors had lower circulating antioxidant markers compared with controls, but there were no differences in plasma-treated human umbilical vein endothelial cells nitric oxide production and reactive oxygen species bioactivity. Diminished peak oxygen uptake was associated with sympathetic overdrive, vascular dysfunction, and reduced diastolic function in COVID-19 survivors.
Our study revealed that COVID-19 survivors have sympathetic overactivation, vascular dysfunction, cardiac morpho-functional changes, and reduced exercise capacity. These findings indicate the need for further investigation to determine whether these manifestations are persistent longer-term and their impact on the cardiovascular health of COVID-19 survivors.
Amputation in adults is associated with an extensive remapping of cortical topography in primary and secondary sensorimotor areas. Here, we used tactile residual limb stimulation and 3T functional ...magnetic resonance imaging in humans to investigate functional connectivity changes in the sensorimotor network of patients with long-term lower limb traumatic amputations with phantom sensation, but without pain. We found a pronounced reduction of inter-hemispheric functional connectivity between homologous sensorimotor cortical regions in amputees, including the primary (S1) and secondary (S2) somatosensory areas, and primary (M1) and secondary (M2) motor areas. We additionally observed an intra-hemispheric increased functional connectivity between primary and secondary somatosensory regions, and between the primary and premotor areas, contralateral to amputation. These functional connectivity changes in specialized small-scale sensory-motor networks improve our understanding of the functional impact of lower limb amputation in the brain. Our findings in a selective group of patients with phantom limb sensations, but without pain suggest that disinhibition of neural inputs following traumatic limb amputation disrupts sensorimotor topology, unbalancing functional brain network organization. These findings step up the description of brain plasticity related with phantom sensations by showing that pain is not critical for sensorimotor network changes after peripheral injury.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
maladaptive changes in the autonomic nervous system (ANS) have been observed in short and long-term phases of COVID-19 infection. Identifying effective treatments to modulate autonomic imbalance ...could be a strategy for preventing and reducing disease severity and induced complications.
to investigate the efficacy, safety, and feasibility of a single session of bihemispheric prefrontal tDCS on indicators of cardiac autonomic regulation and mood of COVID-19 inpatients.
patients were randomized to receive a single 30-min session of bihemispheric active tDCS over the dorsolateral prefrontal cortex (2 mA; n = 20) or sham (n = 20). Changes in time post-pre intervention in heart rate variability (HRV), mood, heart rate, respiratory rate, and oxygen saturation were compared between groups. Additionally, clinical worsening indicators and the occurrence of falls and skin injuries were evaluated. The Brunoni Adverse Effects Questionary was employed after the intervention.
there was a large effect size (Hedges’ g = 0.7) of intervention on HRV frequency parameters, suggesting alterations in cardiac autonomic regulation. An increment in oxygen saturation was observed in the active group but not in the sham after the intervention (P = 0.045). There were no group differences regarding mood, incidence and intensity of adverse effects, no occurrence of skin lesions, falls, or clinical worsening.
a single prefrontal tDCS session is safe and feasible to modulate indicators of cardiac autonomic regulation in acute COVID-19 inpatients. Further research comprising a thorough assessment of autonomic function and inflammatory biomarkers is required to verify its potential to manage autonomic dysfunctions, mitigate inflammatory responses and enhance clinical outcomes.
•Bihemispheric prefrontal tDCS is safe and feasible in hospitalized patients with COVID-19.•Bihemispheric prefrontal tDCS showed a large effect size on heart rate variability in COVID-19 inpatients.•Oxygen saturation may be improved through prefrontal tDCS.•Bihemispheric prefrontal tDCS seems promising to enhance clinical outcomes after severe infections.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Previous studies show that COVID-19 survivors have elevated muscle sympathetic nerve activity (MSNA), endothelial dysfunction, and aortic stiffening. However, the neurovascular responses to mental ...stress and exercise are still unexplored. We hypothesized that COVID-19 survivors, compared with age- and body mass index (BMI)-matched control subjects, exhibit abnormal neurovascular responses to mental stress and physical exercise. Fifteen severe COVID-19 survivors (aged: 49 ± 2 yr, BMI: 30 ± 1 kg/m
) and 15 well-matched control subjects (aged: 46 ± 3 yr, BMI: 29 ± 1 kg/m
) were studied. MSNA (microneurography), forearm blood flow (FBF), and forearm vascular conductance (FVC, venous occlusion plethysmography), mean arterial pressure (MAP, Finometer), and heart rate (HR, ECG) were measured during a 3-min mental stress (Stroop Color-Word Test) and during a 3-min isometric handgrip exercise (30% of maximal voluntary contraction). During mental stress, MSNA (frequency and incidence) responses were higher in COVID-19 survivors than in controls (
< 0.001), and FBF and FVC responses were attenuated (
< 0.05). MAP was similar between the groups (
> 0.05). In contrast, the MSNA (frequency and incidence) and FBF and FVC responses to handgrip exercise were similar between the groups (
> 0.05). MAP was lower in COVID-19 survivors (
< 0.05). COVID-19 survivors exhibit an exaggerated MSNA and blunted vasodilatory response to mental challenge compared with healthy adults. However, the neurovascular response to handgrip exercise is preserved in COVID-19 survivors. Overall, the abnormal neurovascular control in response to mental stress suggests that COVID-19 survivors may have an increased risk to cardiovascular events during mental challenge.
Fipronil is a pyrazole insecticide used to control undesirable insect populations. Due to its large-scale application, there is the potential for surface waters’ contamination, with toxic action for ...non-target organisms, and consequent impacts on aquatic ecosystems. Planarians are potential non-target aquatic invertebrates to these insecticides. They are widespread in tropical freshwaters and have been proposed as good candidates to assess the toxic effects of freshwater systems contaminated by insecticides. Thus, the present study aims to evaluate the sublethal concentrations of a fipronil-based insecticide that may affect the planarian physiology. After chronic exposure to Regent 800 WG®, a significant decrease in locomotor velocity (LOEC—6.25 mg·L−1), regeneration of the auricles and photoreceptors (LOEC—3.13 mg·L−1), and reproduction (fecundity—LOEC 12.5 mg·L−1) were observed. The results of our study demonstrate that long-term exposure to a pyrazole insecticide can compromise non-target aquatic invertebrates while reinforcing the need for a better investigation of complementary parameters (such as behavior, regeneration, and reproduction) for a more accurate risk assessment of commercial pesticide toxicity in freshwater systems.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Neurofeedback by functional magnetic resonance imaging (fMRI) is a technique of potential therapeutic relevance that allows individuals to be aware of their own neurophysiological responses and to ...voluntarily modulate the activity of specific brain regions, such as the premotor cortex (PMC), important for motor recovery after brain injury. We investigated (i) whether healthy human volunteers are able to up-regulate the activity of the left PMC during a right hand finger tapping motor imagery (MI) task while receiving continuous fMRI-neurofeedback, and (ii) whether successful modulation of brain activity influenced non-targeted motor control regions. During the MI task, participants of the neurofeedback group (NFB) received ongoing visual feedback representing the level of fMRI responses within their left PMC. Control (CTL) group participants were shown similar visual stimuli, but these were non-contingent on brain activity. Both groups showed equivalent levels of behavioral ratings on arousal and MI, before and during the fMRI protocol. In the NFB, but not in CLT group, brain activation during the last run compared to the first run revealed increased activation in the left PMC. In addition, the NFB group showed increased activation in motor control regions extending beyond the left PMC target area, including the supplementary motor area, basal ganglia and cerebellum. Moreover, in the last run, the NFB group showed stronger activation in the left PMC/inferior frontal gyrus when compared to the CTL group. Our results indicate that modulation of PMC and associated motor control areas can be achieved during a single neurofeedback-fMRI session. These results contribute to a better understanding of the underlying mechanisms of MI-based neurofeedback training, with direct implications for rehabilitation strategies in severe brain disorders, such as stroke.
Preparing to grasp emotionally laden stimuli de Oliveira, Laura Alice Santos; Imbiriba, Luís Aureliano; Russo, Maitê Mello ...
PloS one,
09/2012, Volume:
7, Issue:
9
Journal Article
Peer reviewed
Open access
Contemporary theories of motor control propose that motor planning involves the prediction of the consequences of actions. These predictions include the associated costs as well as the rewarding ...nature of movements' outcomes. Within the estimation of these costs and rewards would lie the valence, that is, the pleasantness or unpleasantness of a given stimulus with which one is about to interact. The aim of this study was to test if motor preparation encompasses valence.
The readiness potential, an electrophysiological marker of motor preparation, was recorded before the grasping of pleasant, neutral and unpleasant stimuli. Items used were balanced in weight and placed inside transparent cylinders to prompt a similar grip among trials. Compared with neutral stimuli, the grasping of pleasant stimuli was preceded by a readiness potential of lower amplitude, whereas that of unpleasant stimuli was associated with a readiness potential of higher amplitude.
We show for the first time that the sensorimotor cortex activity preceding the grasping of a stimulus is affected by its valence. Smaller readiness potential amplitudes found for pleasant stimuli could imply in the recruitment of pre-set motor repertoires, whereas higher amplitudes found for unpleasant stimuli would emerge from a discrepancy between the required action and their aversiveness. Our results indicate that the prediction of action outcomes encompasses an estimate of the valence of a stimulus with which one is about to interact.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Muscular activity influences the craniofacial skeletal morphology.•Muscle function depends, in part, on genetic variations.•Variants in ACTN3 influence the sagittal and vertical craniofacial ...patterns.•Variants in MYO1H influence the sagittal craniofacial pattern.•Patient’s ethnicity could modify these associations.
This study aimed to evaluate the association of genetic variants inACTN3 and MYO1H with craniofacial skeletal patterns in Brazilians.
This cross-sectional study enrolled orthodontic and orthognathic patients selected from 4 regions of Brazil. Lateral cephalograms were used and digital cephalometric tracings and analyzes were performed for craniofacial phenotype determination. Participants were classified according to the skeletal malocclusion in Class I, II or III; and according to the facial type in Mesofacial, Dolichofacial or Brachyfacial. Genomic DNA was extracted from saliva samples containing exfoliated buccal epithelial cells and analyzed for genetic variants inACTN3 (rs678397 and rs1815739) and MYO1H (rs10850110) by real-time PCR. Chi-square or Fisher’s exact tests were used for statistical analysis (α = 5%).
A total of 646 patients were included in the present study. There was statistically significant association of the genotypes and/or alleles distributions with the skeletal malocclusion (sagittal skeletal pattern) and facial type (vertical pattern) for the variants assessed inACTN3 (P < 0.05). For the genetic variant evaluated in MYO1H, there was statistically significant difference between the genotypes frequencies for skeletal Class I and Class II (P < 0.05). The reported associations were different depending on the region evaluated.
ACTN3 and MYO1H are associated with sagittal and vertical craniofacial skeletal patterns in Brazilian populations.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The vertebrate head–trunk interface (occipital region) has been heavily remodelled during evolution, and its development is still poorly understood. In extant jawed vertebrates, this region provides ...muscle precursors for the throat and tongue (hypopharyngeal/hypobranchial/hypoglossal muscle precursors, HMP) that take a stereotype path rostrally along the pharynx and are thought to reach their target sites via active migration. Yet, this projection pattern emerged in jawless vertebrates before the evolution of migratory muscle precursors. This suggests that a so far elusive, more basic transport mechanism must have existed and may still be traceable today.
Here we show for the first time that all occipital tissues participate in well-conserved cell movements. These cell movements are spearheaded by the occipital lateral mesoderm and ectoderm that split into two streams. The rostrally directed stream projects along the floor of the pharynx and reaches as far rostrally as the floor of the mandibular arch and outflow tract of the heart. Notably, this stream leads and engulfs the later emerging HMP, neural crest cells and hypoglossal nerve. When we (i) attempted to redirect hypobranchial/hypoglossal muscle precursors towards various attractants, (ii) placed non-migratory muscle precursors into the occipital environment or (iii) molecularly or (iv) genetically rendered muscle precursors non-migratory, they still followed the trajectory set by the occipital lateral mesoderm and ectoderm. Thus, we have discovered evolutionarily conserved morphogenetic movements, driven by the occipital lateral mesoderm and ectoderm, that ensure cell transport and organ assembly at the head–trunk interface.
•At the vertebrate head–trunk interface, all tissues engage in stereotype cell movements.•A ventrally–rostrally directed stream of cells leads along the floor of the pharynx to the developing jaw and outflow tract of the heart.•The cell movements are spearheaded by the lateral mesoderm and surface ectoderm; muscle precursors for throat and tongue muscles (hypopharyngeal muscles); neural crest cells and outgrowing axons of the hypoglossal nerve follow.•Hypopharyngeal muscle precursors follow the trajectory set by the lateral mesoderm and ectoderm, even when challenged with ectopic attractants or when rendered non-migratory.•The newly discovered cell movements are the likely ground state for cell transport and organ assembly at the head–trunk interface before actively migrating muscle precursors evolved in “bony” (osteichthyan) vertebrates.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
