Progress in brain research
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Case Reports
Multimodal neuroimaging in patients with disorders of consciousness showing "functional hemispherectomy".
Beside behavioral assessment of patients with disorders of consciousness, neuroimaging modalities may offer objective paraclinical markers important for diagnosis and prognosis. They provide information on the structural location and extent of brain lesions (e.g., morphometric MRI and diffusion tensor imaging (DTI-MRI) assessing structural connectivity) but also their functional impact (e.g., metabolic FDG-PET, hemodynamic fMRI, and EEG measurements obtained in "resting state" conditions). We here illustrate the role of multimodal imaging in severe brain injury, presenting a patient in unresponsive wakefulness syndrome (UWS; i.e., vegetative state, VS) and in a "fluctuating" minimally conscious state (MCS). In both cases, resting state FDG-PET, fMRI, and EEG showed a functionally preserved right hemisphere, while DTI showed underlying differences in structural connectivity highlighting the complementarities of these neuroimaging methods in the study of disorders of consciousness.
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It is well established that a spinal circuitry can generate locomotor movements of the hindlimbs in absence of descending supraspinal inputs. This is based, among others, on the observation that after a complete spinalization, cats can walk with the hindlimbs on a treadmill. ⋯ This review focuses mainly on the capacity of the spinal and supraspinal structures to reorganize spontaneously after incomplete SCI in animals (rats and cats). BMI approaches to foster recovery of functions after various types of SCI should take into account these changes at the various levels of the CNS.
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Resting state networks (RSNs), as imaged by functional MRI, are distributed maps of areas believed to be involved in the function of the "resting" brain, which appear in both resting and task data. The current dominant view is that such networks are associated with slow (∼0.015Hz), spontaneous fluctuations in the BOLD signal. ⋯ In addition, we show that RSNs exhibit different levels of phase synchrony at different frequencies. These findings challenge the notion that FMRI resting signals are simple "low frequency" spontaneous signal fluctuations.
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Somatostatin (SS) and SS receptors (ssts) are broadly expressed in the human body where they exert many physiological actions. Moreover, they can be expressed in many pathological tissues. Particularly, a high density of ssts has been described in human neuroendocrine tumors (NETs). ⋯ Indeed, SS-analogues coupled with (111)In are used to perform sst-scintigraphy, which is a very useful first-line imaging technique in the diagnosis and follow-up of GEP-NETs. Moreover, SS-analogues conjugated to (111)In or to other radioisotopes, such as (177)Lu or (90)Y, have promising effects in the treatment of advanced NETs. ssts are expressed in some non-neuroendocrine tumors as well and in some non-tumoral diseases, suggesting that SS-analogues might have a role in the diagnosis and treatment of these pathological conditions as well. The development of novel SS-analogues with new pharmacokinetic and pharmacodynamic characteristics may further improve the clinical applications of such compounds.
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Review
Sexual differentiation of the human brain in relation to gender identity and sexual orientation.
It is believed that during the intrauterine period the fetal brain develops in the male direction through a direct action of testosterone on the developing nerve cells, or in the female direction through the absence of this hormone surge. According to this concept, our gender identity (the conviction of belonging to the male or female gender) and sexual orientation should be programmed into our brain structures when we are still in the womb. However, since sexual differentiation of the genitals takes place in the first two months of pregnancy and sexual differentiation of the brain starts in the second half of pregnancy, these two processes can be influenced independently, which may result in transsexuality. ⋯ To what extent fetal programming may determine sexual orientation is also a matter of discussion. A number of studies show patterns of sex atypical cerebral dimorphism in homosexual subjects. Although the crucial question, namely how such complex functions as sexual orientation and identity are processed in the brain remains unanswered, emerging data point at a key role of specific neuronal circuits involving the hypothalamus.