Central Modulation of Pain
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
The somatosensory cortex is important for the localization and sensation of pain. Functional magnetic resonance imaging studies have showed that a large brain network is activated during acute pain. These include the primary somatosensory cortex and secondary somatosensory cortex with the adjacent insula region, anterior cingulate cortex, ventromedial prefrontal cortex and thalamus. These regions of the brain form the ‘pain matrix’. The functions of these cortical areas are summarized in Table 70.2. The anterior cingulate cortex and the prefrontal cortex directly feedback to the PAG, which activates the descending anti-nociceptive pathways. Damage to the prefrontal cortex reduces the ability to evaluate the severity of pain. Cingulotomy decreases the emotional aspects of pain.
Chronic Pain Management and Arthritis
Deborah Fish Ragin in Health Psychology, 2017
The second category is neuropathic pain, best described as a malfunction of our nervous system. It is believed to result from lesions of or damage to the somatosensory system, a network of receptors and pathways that transmit sensory information about us and our environment—such as pain, temperature, and position and movement of our body—to our central nervous system. Common examples of neuropathic pain caused by lesions include spontaneous shooting or burning sensations, greater discomfort than normal in response to normally painful stimulus, and sensations of aching, throbbing, or soreness when encountering nonpainful stimuli (University of Bristol, 2012). Illnesses such as diabetes, certain types of cancer, or chronic alcohol use can trigger neuropathic pain because of the damage they can cause to the nervous system.
Benjamin Libet (1916–2007)
Andrew P. Wickens in Key Thinkers in Neuroscience, 2018
It had been known since the work of Penfield in the 1930s that an electrical stimulus applied to the somatosensory cortex could induce a touch sensation that appeared to arise from the corresponding part of the skin or body. In fact, Penfield had shown that the somatosensory cortex has a topographical or map-like relationship with the body – so the brain areas representing the legs and feet are found in the gyrus near the top of the head and the face and head at its lowest end. Hence, Libet would have known the likely effects of stimulation, or what parts of the body were likely to be “felt” after stimulation. However, Libet began his investigations by trying to establish the barest threshold parameters needed to produce a conscious reaction in his subjects – and to this end he stimulated their somatosensory cortex with electrodes placed on its surface and varied the frequency, duration and intensity of the electrical pulses. This led Libet to discover that the most important determinant of producing a conscious touch sensation was the duration of stimulation. That is, when Libet stimulated the cortex with brief pulses of small amplitude current for periods up to about 500 msecs, the subjects reported nothing. But when he went beyond a stimulation period of 500 msecs (or half a second), the subjects typically reported a sensation such as a touch on the skin. These results were intriguing: they implied that at least half a second of brain processing was necessary for a simple conscious percept to emerge from the stimulation.
Exploring the effectiveness of immersive Virtual Reality interventions in the management of musculoskeletal pain: a state-of-the-art review
Published in Physical Therapy Reviews, 2021
Niamh Brady, Joseph G. McVeigh, Karen McCreesh, Ebonie Rio, Thomas Dekkers, Jeremy S. Lewis
Currently there is uncertainty around the mechanisms underlying the effect that VR has on pain and range of movement. Persistent pain is associated with sensory changes and functional reorganization of the somatosensory cortex. Melzack [38] proposed that the neurosignature for pain experience is determined by the synaptic architecture of the neuromatrix, which is produced by genetic and sensory influences. The neurosignature projects to various areas of the brain to create a sense of awareness of self, feelings, emotions, and activation of behavior. Riva et al. [5] describe a brain mechanism called ‘embodied simulations’, which contribute to the body neuromatrix. VR technology shares this basic mechanism [5]. Like the brain, VR technology maintains a simulation of the body and the space around it so that it can accurately predict the consequences of an individual’s actions within the virtual world. By doing this, VR may be able to trick the predictive coding mechanisms used by the brain [5], generating the feeling of presence in the virtual body and altering the experience of the body, including the pain experience. Riva et al. [5] suggest that VR as an embodied medicine may offer a new platform for augmenting the experience of the body for clinical goals and may explain the mechanisms behind clinical improvements demonstrated in VR literature to date. In addition, using VR to demonstrate the change in experience of neck pain reported by Harvie et al. [23] or other types of pain may offer a valuable education tool for explaining pain.
Thalamocortical neural responses during hyperthermia: a resting-state functional MRI study
Published in International Journal of Hyperthermia, 2018
Jing Zhang, Shaowen Qian, Qingjun Jiang, Guanzhong Gong, Kai Liu, Bo Li, Yong Yin, Gang Sun
With unique cytoarchitecture and firing patterns in human brain, the thalamus acts as a core structure that contains wide-spread connections with distinct zones of the cerebral cortex, named thalamocortical network previously [13,14], providing a valuable approach for imaging cortical–subcortical neural activity [15]. The thalamus acts as a key hub of spinothalamic tract and thalamocortical radiations, involving with both sensory information transmission from bottom neural activity and cognition processing from top neural activity [16]. The former one supports the information transmission of pain, temperature, touch and pressure, whereas the latter one contains a large number of fibres that extend from different nuclei of the thalamus and projects to visual cortex, somatosensory cortex, auditory cortex and prefrontal cortex, supporting high-level functions, such as consciousness regulation, alertness, executive control and so on. During recent years, emerging studies using functional connectivity and structural diffusion tracts have demonstrated that thalamocortical connectivity acts as a remarkable indicator for altered cortical–subcortical brain activity in schizophrenia, epilepsy and attention-deficit/hyperactivity disorder [14,17–19].
Association between pain drawing and psychological factors in musculoskeletal chronic pain: A systematic review
Published in Physiotherapy Theory and Practice, 2019
Felipe Reis, Fernanda Guimarães, Leandro Calazans Nogueira, Ney Meziat-Filho, Tiago A. Sanchez, Timothy Wideman
This systematic review shows that there are few (heterogeneous) studies that have investigated the relationship of psychological factors to PD, which indicates the need for further research. Although not highly consistent, the results from the included studies point to a very weak positive correlation between symptoms of depression and the PD. We recommend further studies using other instruments developed specifically to identify depression (e.g. Beck Depression Inventory, Center for Epidemiologic Studies Depression Scale, and Inventory for Depression) and more accurate (computer-based) methods of PD assessment to verify this relation. It is also important to recognize that several studies have demonstrated that chronic pain changes the somatosensory cortex leading to altered perceptions of their painful body regions. Two-point discrimination test is a clinical marker for evaluating alterations of S1 cortical reorganization. To the best of our knowledge, there is no study that investigates the relation between pain extent and two-point discrimination test. Thus, we strongly recommend new studies considering the relation between pain extent to other somatosensory, psychological, emotional, cognitive and behavioral factors.
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