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The Cause of Pressure Sores
Published in J G Webster, Prevention of Pressure Sores, 2019
The first and most important change is the loss of pain sensation. When tissue, particularly the skin, is becoming ischemic, a strong sensation of pain is normally sent by C fibers along the spinothalamic tracts through the spinal cord to the thalamus of the brain. From there the impulse is sent by neurons to a somatic sensory area in the postcentral gyrus of the cerebral cortex creating the feeling of pain (Ganong 1989). This uncomfortable feeling causes an individual to move, thus relieving the pressure and restoring blood flow to the tissue. Since the SCI person does not feel pain in portions of his body that are connected to the detached portion of the spinal cord, he is unaware when tissue damage is occurring in these regions. This problem is further enhanced since SCI persons tend to move less than mobile individuals thus increasing the opportunities for ischemia due to pressure to occur.
EEG signal classification of tinnitus based on SVM and sample entropy
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Mai Jianbiao, Wang Xinzui, Li Zhaobo, Liu Juan, Zhang Zhongwei, Fu Hui
The FC5 channel reflects the left frontal lobe, which is responsible for thinking, planning and central executive functions as well as motor execution, suggesting that tinnitus patients may be particularly disrupted in functions such as thinking due to the effects of tinnitus. The P4 channel reflects the parietal lobe, which is responsible for somatosensory perception, and the C1 and CP1 channels reflect the postcentral gyrus, which mainly receives somatosensory information. All regions of interest (ROIs) comparing sample entropy results for the healthy and tinnitus groups had greater mean entropy for the tinnitus group than for the healthy group in δ rhythm. In θ rhythm, the mean entropy of the tinnitus group was less than that of healthy individuals. Statistical differences were found in multiple ROIs (p < 0.05). Compared to normal subjects, the mean sample entropy of the α1 rhythm was lower in the tinnitus group than in the healthy group, the mean sample entropy of the α2, β1 rhythms was higher in the tinnitus patients than in the healthy group, and the mean entropy of the tinnitus patients was lower in the higher frequency bands (β2、β3 and γ rhythms) than in the healthy group in all ROI. The brain can be thought of as a chaotic system. Neuronal activity in the cerebral cortex produces asynchronous and synchronous firing through spontaneous EEG activity. Entropy measures the amount of statistical information carried by a random sequence, and an increase in entropy can be seen as an increase in chaotic behaviour within the brain.
Noninvasive vagus nerve stimulation in Parkinson’s disease: current status and future prospects
Published in Expert Review of Medical Devices, 2021
Hilmar P. Sigurdsson, Rachael Raw, Heather Hunter, Mark R. Baker, John-Paul Taylor, Lynn Rochester, Alison J. Yarnall
To our knowledge, only one study has investigated the dynamic, online changes in brain function during tcVNS. Frangos and Komisaruk [65] placed two electrodes over the right cervical vagus nerve in 13 healthy participants undergoing fMRI imaging. In comparison to pre-nVNS rest and reference stimulation (placed on the right sternocleidomastoid muscle), 2 min of continuous tcVNS elicited increased BOLD response in several regions of the forebrain that contain cholinergic neurons or receive dense cholinergic projections from the nbM including bilateral dorsolateral prefrontal cortex (DLPFC), caudate nucleus, and thalamus, left (contralateral) visceral area of the postcentral gyrus, and cerebellum (see Figure 1). During an analysis focused on the lower brainstem, greater BOLD response was noted in the ipsilateral nucleus of solitary tract (NTS, ipsilateral to the stimulation), bilateral parabrachial complex (PB), as well as in SN and ventral tegmental area (VTA) during stimulation relative to control. This study additionally showed that activity in the SN (the source of the nigrostriatal pathway transmitting DA from SN to caudate and putamen; an area severely affected in PD) and VTA (from which DA is transmitted to ventral striatum [mesolimbic pathway] and to PFC [mesocortical pathway]; an area less affected in PD) outlasted the period of tcVNS stimulation. As such, tcVNS may be better suited for targeting key regions of neurodegeneration in PD that underpin gait and cognitive impairments. Further studies are, however, warranted.
Tactile perception of skin: research on late positive component of event-related potentials evoked by friction
Published in The Journal of The Textile Institute, 2020
Wei Tang, Xiangyong Lu, Si Chen, Shirong Ge, Xianghong Jing, Xiaoyu Wang, Rui Liu, Hua Zhu
When a finger scan across the fabric surface, the tactile perception is mainly processed in somatic cortex located at postcentral gyrus. The electrodes of postcentral gyrus are measured and the test results are shown in Figure 7.