NeuroImage
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Endoscopic procedures performed in the United States routinely involve the use of conscious sedation as standard of care. The use of sedation reduces patient discomfort and anxiety while improving the technical quality of the procedure, and as a result, over 98% of clinicians have adopted the practice. The tremendous benefits of sedation are offset by heightened costs, increased patient discharge time, and cardiopulmonary complication risks. ⋯ Anesthetic drugs, such as propofol, operate by suppressing cerebral metabolism. fNIRS imaging methods have the ability to detect these drug related effects as well as neuronal activity through the measurement of local cerebral hemodynamic changes. In the present study, 41 patients were continuously monitored using fNIRS while undergoing outpatient elective colonoscopy with propofol sedation. The preliminary results indicated that oxygenated hemoglobin changes in the dorsolateral prefrontal cortex, as assessed by fNIRS were correlated with changes in response to bolus infusions of propofol, whereas other standard physiological measures were not significantly associated.
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Diffuse optical tomography (DOT) has been used by several groups to assess cerebral hemodynamics of cerebral ischemia in humans and animals. In this study, we combined DOT with an indocyanine green (ICG)-tracking method to achieve interleaved images of cerebral hemodynamics and blood flow index (BFI) using two middle cerebral artery occlusion (MCAO) rat models. To achieve volumetric images with high-spatial resolution, we first integrated a depth compensation algorithm (DCA) with a volumetric mesh-based rat head model to generate three-dimensional (3D) DOT on a rat brain atlas. ⋯ The acquired animal data were further analyzed using the integrated rat-atlas-guided DOT method to form time-evolving 3D images of both cerebral hemodynamics and BFI. In particular, we were able to show and identify therapeutic outcomes of a thrombolytic treatment applied to the embolism-induced ischemic model. This paper demonstrates that volumetric DOT is capable of providing high-quality, interleaved images of cerebral hemodynamics and blood perfusion in small animals during and after ischemic stroke, with excellent 3D visualization and quantifications.
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Previous functional near-infrared spectroscopy (fNIRS) studies indicated that the prefrontal cortex (PFC) is involved in the maintenance of the postural balance after external perturbations. So far, no studies have been conducted to investigate the PFC hemodynamic response to virtual reality (VR) tasks that could be adopted in the field of functional neurorehabilitation. The aim of this fNIRS study was to assess PFC oxygenation response during an incremental and a control swing balance task (ISBT and CSBT, respectively) in a semi-immersive VR environment driven by a depth-sensing camera. ⋯ This study has demonstrated that the oxygenation increased over the PFC while performing an ISBT in a semi-immersive VR environment. These data reinforce the involvement of the PFC in attention-demanding balance tasks. Considering the adaptability of this virtual balance task to specific neurological disorders, the absence of motion sensing devices, and the motivating/safe semi-immersive VR environment, the ISBT adopted in this study could be considered valuable for diagnostic testing and for assessing the effectiveness of functional neurorehabilitation.
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Randomized Controlled Trial
Gray matter and intrinsic network changes in the posterior cingulate cortex after selective serotonin reuptake inhibitor intake.
Preclinical studies have demonstrated that serotonin (5-HT) challenge changes neuronal circuitries and microarchitecture. However, evidence in human subjects is missing. Pharmacologic magnetic resonance imaging (phMRI) applying selective 5-HT reuptake inhibitors (SSRIs) and high-resolution structural and functional brain assessment is able to demonstrate the impact of 5-HT challenge on neuronal network morphology and functional activity. ⋯ Short-term administration of SSRIs changes gray matter structures, consistent with previous work reporting enhancement of neuroplasticity by serotonergic neurotransmission. Furthermore, increased gray matter in the PCC is associated with increased functional connectivity in one of the brain's metabolically most active regions. Our novel findings provide convergent evidence for dynamic alterations of brain structure and function associated with SSRI pharmacotherapy.
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Randomized Controlled Trial
The primary somatosensory cortex contributes to the latest part of the cortical response elicited by nociceptive somatosensory stimuli in humans.
Nociceptive laser pulses elicit temporally-distinct cortical responses (the N1, N2 and P2 waves of laser-evoked potentials, LEPs) mainly reflecting the activity of the primary somatosensory cortex (S1) contralateral to the stimulated side, and of the bilateral operculoinsular and cingulate cortices. Here, by performing two different EEG experiments and applying a range of analysis approaches (microstate analysis, scalp topography, single-trial estimation), we describe a distinct component in the last part of the human LEP response (P4 wave). We obtained three main results. ⋯ Second, the scalp and source configurations of the P4 wave follow a clear somatotopical organization, indicating that this response is likely to be partly generated in contralateral S1. Third, single-trial latencies and amplitudes of the P4 are tightly coupled with those of the N1, and are similarly sensitive to experimental manipulations (e.g., to crossing the hands over the body midline), suggesting that the P4 and N1 may have common neural sources. These results indicate that the P4 wave is a clear and distinct LEP component, which should be considered in LEP studies to achieve a comprehensive understanding of the brain response to nociceptive stimulation.