Innovations In Clinical Neuroscience

MAY-JUN 2017

A peer-reviewed, evidence-based journal for clinicians in the field of neuroscience

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Innovations in CLINICAL NEUROSCIENCE [ V O L U M E 1 4 , N U M B E R 5 – 6 , M A Y – J U N E 2 0 1 7 ] 18 TABLE 4. Heightened somatic awareness: clinical correlation 41 –49 CATEGORY REPRESENTATIVE DISEASE DESCRIPTION BRAIN AREAS INVOLVED Pain Fibromyalgia • Widespread, chronic pain at various points throughout the body in response to seemingly subthreshold stimuli • Associated with various other symptoms, as well including fatigue, memory deficits, and psychiatric illness • Decreased connectivity to rostral anterior cingulate cortex (rACC) results in lower pain thresholds. • Decreased functional connectivity between the rACC and periaqueductal grey results in decreased pain inhibitory processes. • Increased activation of the somatosensory cortices might lead to pain amplification symptoms; lower intensity stimuli can cause pain in fibromyalgia patients but not controls. • The posterior insula and secondary somatosensory cortices are largely responsible for stimulus intensity; increased stimulation is observed in patients with diffuse hyperalgesia or allodynia. • High levels of insula connectivity, as seen in fibromyalgia, correlate with pain activation triggered by lower intensity stimuli in patients. • Increased orbitofrontal cortex (OFC) activity is involved in evaluation of noxious events, motivation to respond, and anticipation of pain relief. Pruritus Lichen simplex chronicus Skin disorder characterized by skin lichenification following excessive scratching and rubbing • Itch induction results in a more diffuse pattern of activation when compared to healthy subjects. • Positive correlation exists between disease severity and activations of the ACC and dorsolateral prefrontal cortex. • Overreaction to itch stimuli in the medial parietal cortex is associated with "itch" memory. • Significantly higher activity in the basal ganglia, including the striatum, is associated with motivation and craving; overactivity might explain the excessive, pathological scratching that is commonly seen. • The intensity of activity in motor-related regions during scratching significantly and positively correlate with the intensity of pleasurable sensations. Nausea Idiopathic gastroparesis/ functional dyspepsia (FD) • Characterized by delayed gastric emptying and symptoms thereof in the absence of gastric outlet obstruction • Predominant presenting symptoms are nausea, vomiting, and abdominal pain; severe anxiety and depression are common; 33–86% meet criteria for FD with gastric emptying delay • FD defined by presence of one or more of four chronic symptoms (epigastric pain, epigastric burning, early satiation, postprandial fullness) after considering and dismissing differential diagnoses of other organic, systemic, or metabolic diseases • Increased orbitofrontal cortex activity is involved in the monitoring of visceral sensations and is closely related to psychological disorders, such as anxiety and depression. • Increased activity in insula cortex, considered to be key region of the salience- brain network that identifies the item among several stimuli, results in visceral stimuli-guiding by behavior. • Increased activity in ACC, which is particularly important for attention to pain, endogenous opioid system-related placebo analgesia, and regulating affective component of pain experience, results in recognition and subsequent increase in intensity of visceral sensations. • Visceral sensations are involved in ascending visceral pain pathway and are processed in somatosensory cortex. • Since FD is a chronic disease, somatosensory cortex receives afferent ascending visceral signals from internal organs repeatedly, and consequent sensitization of the brain could result in abnormal central modulation of sensory information and peripheral abnormalities, such as visceral hypersensitivity (i.e., increased recognition of nausea, pain). • Activity of amygdala and hippocampus is interpreted as the anticipation or response to the visceral stimuli and the recall of previous negative memories (e.g., unpleasant visceral sensations, anxiety).

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