37 research outputs found

    The Protective Action Encoding of Serotonin Transients in the Human Brain

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    The role of serotonin in human brain function remains elusive due, at least in part, to our inability to measure rapidly the local concentration of this neurotransmitter. We used fast-scan cyclic voltammetry to infer serotonergic signaling from the striatum of fourteen brains of human patients with Parkinson's disease. Here we report these novel measurements and show that they correlate with outcomes and decisions in a sequential investment game. We find that serotonergic concentrations transiently increase as a whole following negative reward prediction errors, while reversing when counterfactual losses predominate. This provides initial evidence that the serotonergic system acts as an opponent to dopamine signaling, as anticipated by theoretical models. Serotonin transients on one trial were also associated with actions on the next trial in a manner that correlated with decreased exposure to poor outcomes. Thus, the fluctuations observed for serotonin appear to correlate with the inhibition of over-reactions and promote persistence of ongoing strategies in the face of short-term environmental changes. Together these findings elucidate a role for serotonin in the striatum, suggesting it encodes a protective action strategy that mitigates risk and modulates choice selection particularly following negative environmental events

    Primary Neurocytoma in the Spinal Cord

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    Ganglioneurocytoma of the spinal cord: report of a case and review of literature

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    A case of ganglioneurocytoma of the spinal cord in a 51-year-old man is reported. Patient presented with a progressively worsening back pain and hyposthenia of lower limbs. Magnetic resonance imaging of the spinal cord revealed an intradural lesion in the T10–11 spinal segments, hyperintense on T1-weighted sequences. Complete resection was achieved. The patient did not show evidence of recurrence 12 months after surgery. On histology, the lesion was composed of round to oval cells with fine granular, slightly eosinophilic to clear cytoplasm suggesting a neurocytic differentiation. Some ganglion cells were observed. Neither significant cytologic atypia nor mitoses were present. The neoplastic cells were strongly positive with synaptophysin and negative with glial fibrillary acid protein. Neurocytomas are uncommon tumors typically arising within the lateral ventricles near the foramen of Monro. Extraventricular neurocytomas have been reported at various sites with rare examples in spinal cord. In the present paper, a case of ganglioneurocytoma of the spinal cord is reported with review of literature and discussion of differences compared to neurocytomas of other sites
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