Postural sway and heart rate were recorded in young men viewing emotionally engaging pictures. It was hypothesized that they would show a human analog of "freezing" behavior (i.e., immobility and heart rate deceleration) when confronted with a sustained block of unpleasant (mutilation) images, relative to their response to pleasant/arousing (sport action) or neutral (objects) pictures. Volunteers stood on a stabilometric platform during picture viewing. Significantly reduced body sway was recorded during the unpleasant pictures, along with increased mean power frequency (indexing muscle stiffness). Heart rate during unpleasant pictures also showed the expected greater deceleration. This pattern resembles the "freezing" and "fear bradycardia" seen in many species when confronted with threatening stimuli, mediated by neural circuits that promote defensive survival.

Previous studies have indicated that amputation or deafferentation of a limb induces functional changes in sensory (S1) and motor (M1) cortices, related to phantom limb pain. However, the extent of cortical reorganization after lower limb amputation in patients with nonpainful phantom phenomena remains uncertain. In this study, we combined functional magnetic resonance (fMRI) and diffusion tensor imaging (DTI) to investigate the existence and extent of cortical and callosal plasticity in these subjects. Nine "painless" patients with lower limb amputation and nine control subjects (sex-and age-matched) underwent a 3-T MRI protocol, including fMRI with somatosensory stimulation. In amputees, we observed an expansion of activation maps of the stump in S1 and M1 of the deafferented hemisphere, spreading to neighboring regions that represent the trunk and upper limbs. We also observed that tactile stimulation of the intact foot in amputees induced a greater activation of ipsilateral S1, when compared with controls. These results demonstrate a functional remapping of S1 in lower limb amputees. However, in contrast to previous studies, these neuroplastic changes do not appear to be dependent on phantom pain but do also occur in those who reported only the presence of phantom sensation without pain. In addition, our findings indicate that amputation of a limb also induces changes in the cortical representation of the intact limb. Finally, DTI analysis showed structural changes in the corpus callosum of amputees, compatible with the hypothesis that phantom sensations may depend on inhibitory release in the sensorimotor cortex.

Why do humans born without the corpus callosum, the major interhemispheric commissure, lack the disconnection syndrome classically described in callosotomized patients? This paradox was discovered by Nobel laureate Roger Sperry in 1968, and has remained unsolved since then. To tackle the hypothesis that alternative neural pathways could explain this puzzle, we investigated patients with callosal dysgenesis using structural and functional neuroimaging, as well as neuropsychological assessments. We identified two anomalous white-matter tracts by deterministic and probabilistic tractography, and provide supporting resting-state functional neuroimaging and neuropsychological evidence for their functional role in preserved interhemispheric transfer of complex tactile information, such as object recognition. These compensatory pathways connect the homotopic posterior parietal cortical areas (Brodmann areas 39 and surroundings) via the posterior and anterior commissures. We propose that anomalous brain circuitry of callosal dysgenesis is determined by long-distance plasticity, a set of hardware changes occurring in the developing brain after pathological interference. So far unknown, these pathological changes somehow divert growing axons away from the dorsal midline, creating alternative tracts through the ventral forebrain and the dorsal midbrain midline, with partial compensatory effects to the interhemispheric transfer of cortical function.callosal agenesis | callosal plasticity | human connectome

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The human primary motor cortex (M1) undergoes considerable reorganization in response to traumatic upper limb amputation. The representations of the preserved arm muscles expand, invading portions of M1 previously dedicated to the hand, suggesting that former hand neurons are reassigned to the control of remaining proximal upper limb muscles. Hand allograft offers a unique opportunity to study the reversibility of such long-term cortical changes. We used transcranial magnetic stimulation in patient LB, who underwent bilateral hand transplantation 3 years after a traumatic amputation, to longitudinally track both the emergence of intrinsic (from the donor) hand muscles in M1 as well as changes in the representation of stump (upper arm and forearm) muscles. The same muscles were also mapped in patient CD, the first bilateral hand allograft recipient. Newly transplanted intrinsic muscles acquired a cortical representation in LB's M1 at 10 months postgraft for the left hand and at 26 months for the right hand. The appearance of a cortical representation of transplanted hand muscles in M1 coincided with the shrinkage of stump muscle representations for the left but not for the right side. In patient CD, transcranial magnetic stimulation performed at 51 months postgraft revealed a complete set of intrinsic hand-muscle representations for the left but not the right hand. Our findings show that newly transplanted muscles can be recognized and integrated into the patient's motor cortex.amputation ͉ longitudinal ͉ plasticity ͉ reorganization ͉ TMS I t is now well established that the adult brain is highly influenced by changes occurring at the body's periphery. Evidence from human and animal models show that, when deprived of its afferent sensory input and/or its motor effectors, the primary sensory (S1) and motor (M1) cortical regions undergo plastic modifications (1-10).Traumatic upper limb amputation in humans produces lifelong consequences. Patients often report a global feeling that the missing body part is still present. This feeling is frequently associated with specific sensory and kinesthetic sensations and pain in the missing limb. Many patients further describe that the phantom limb can be moved voluntarily (review in refs. 11 and 12).Functional investigation of human M1 reorganization after amputation has demonstrated that instead of becoming inactive, the hand area is now activated during proximal limb movements (5,13,14), and that cortical stimulation of this region evokes contraction of proximal upper limb muscles (4, 9, 15, 16). Face and forearm motor representations that surround the representation of the missing hand have also been shown to expand into the de-efferented cortex (16,17), with the expansion of lip movements into the former hand area correlating positively with the amount of phantom limb pain (18). Studies employing TMS paired-pulse protocols have shown less intracortical inhibition in the region corresponding to the amputated limb when compared with the intact limb's region (19,20), suggest...

ResumoAs terapias intensivas pediátricas (TIP) têm reduzido significativamente a morbimortalidade infantil e gerado um grupo de crianças com cuidados especiais. Entretanto, no domicílio recebem cuidados de familiares, cujo senso comum não foi formado para atendê-los, interferindo em sua qualidade de vida e nas freqüentes re-internações hospitalares. Conhecer o egresso da terapia intensiva é ir além da sobrevida, é oferecer também melhor qualidade de vida. Neste sentido, desenvolvemos o método epidemiológico investigando, em duas instituições públicas do Rio de Janeiro, o tempo e número de internação, tipo e quantidade de diagnóstico, entre 1994 e 1999, cujas crianças estavam na faixa de 29 dias a 12 anos. Os resultados apontam que 6,3% (85) das 1355 crianças internadas foram consideradas com necessidades especiais, tiveram até 09 reinternações que consumiram até 60 dias de suas vidas. A cada internação somava-se um a dois diagnósticos àquele de base, evidenciando uma cronificação do estado da criança. Descritores: enfermagem; saúde da criança; terapia intensiva 1 A problemática da criança egressa da terapia intensiva A tecnologia de ponta das Unidades de Terapia Intensiva Pediátrica (UTIP) tem possibilitado maiores chances de vida para as crianças. Aquelas que sobrevivem às doenças complexas ou a lesões traumáticas, muitas vezes, se tornam portadoras de disfunções que exigem severas mudanças de vida, além de cuidados especiais, sendo denominadas de crianças com necessidades especiais de cuidados de saúde (1)(2)(3) . Gruski(1) descreve essas crianças, como aquelas que apresentam limitações no seu estilo de vida e nas suas funções normais de acordo com a idade e requerem cuidados médicos contínuos para manter o seu estado de saúde. Por terem um estado de saúde crônico, por vezes, necessitam de terapêutica medicamentosa e suporte tecnológico a longo prazo. As crianças com necessidades especiais são aquelas que têm ou estão com maior comprometimento físico, de desenvolvimento, de comportamento, ou condições emocionais, e que requerem serviços de saúde relacionados a um tipo, ou quantidade muito além do que as crianças normalmente exigem (2:127) .Quando criticamente doentes, no ambiente das TIP's, estas crianças contam com a atuação de profissionais tecnicamente capacitados para realizar o tratamento e os cuidados, respaldados em um saber científico. Entretanto, a qualidade de vida das sobreviventes será tanto melhor e maior em função do tipo de cuidado prestado pelas famílias no domicílio, tendo em vista a demanda de atenção e complexidade do quadro da criança no pós-alta (4) . O modelo de orientação para a pós-alta está centrado na transmissão vertical de conhecimentos. Sendo que a forma autoritária, vertical e prescritiva deste modelo, só acentua o abismo entre o saber científico e o senso comum. O senso comum de acordo com Cabral (5) , é a visão de mundo mais aceita entre as classes sociais não eruditas, que é complexa e encerra uma concepção de mundo ocasional e desagregada. Para ela, as famílias destas criança...

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.