Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085632 (apathy)
 4,089 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Paradoxical heat sensations during cooling of the skin were examined in two experiments. In Expt. I the number of occurrences of sensation was studied in 19 naive test subjects (Ss) when cooling from thermal indifference both without and with preceding heating. Without preceding heating 13 Ss reported sensations of paradoxical heat (9.8% of all stimulations). Preheating markedly facilitated the occurrence of the sensations (35% of all stimulations). In Expt. II the effects of cooling velocity (velocities 0.4, 0.7 and 2.0 degrees C/s) and the type of skin area stimulated (hairy or glabrous skin of the hand) on the thresholds of paradoxical sensations were studied in 4 Ss without and with preheating. Cooling velocity, type of skin area and preheating had significant effects on the sensation thresholds, the thresholds being the higher (i.e. the sensation appearing at lower stimulation temperatures) the higher the cooling velocity, if the stimuli were applied to the glabrous skin, or if no preheating was used. The results confirm the existence of paradoxical heat sensations during cooling of the skin and suggest that the sensation is mediated by polymodal units supplied by C-fibers.
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PMID:Paradoxical heat sensations during moderate cooling of the skin. 717 11

Hereditary sensory and autonomic neuropathy type III (HSAN III, Riley-Day syndrome, Familial Dysautomia) is characterised by elevated thermal thresholds and an indifference to pain. Using microelectrode recordings we recently showed that these patients possess no functional stretch-sensitive mechanoreceptors in their muscles (muscle spindles), a feature that may explain their lack of stretch reflexes and ataxic gait, yet patients have apparently normal low-threshold cutaneous mechanoreceptors. The density of C-fibres in the skin is markedly reduced in patients with HSAN III, but it is not known whether the C-tactile afferents, a distinct type of low-threshold C fibre present in hairy skin that is sensitive to gentle stroking and has been implicated in the coding of pleasant touch are specifically affected in HSAN III patients. We addressed the relationship between C-tactile afferent function and pleasant touch perception in 15 patients with HSAN III and 15 age-matched control subjects. A soft make-up brush was used to apply stroking stimuli to the forearm and lateral aspect of the leg at five velocities: 0.3, 1, 3, 10 and 30 cm/s. As demonstrated previously, the control subjects rated the slowest and highest velocities as less pleasant than those applied at 1-10 cm/s, which fits with the optimal velocities for exciting C-tactile afferents. Conversely, for the patients, ratings of pleasantness did not fit the profile for C-tactile afferents. Patients either rated the higher velocities as more pleasant than the slow velocities, with the slowest velocities being rated unpleasant, or rated all velocities equally pleasant. We interpret this to reflect absent or reduced C-tactile afferent density in the skin of patients with HSAN III, who are likely using tactile cues (i.e. myelinated afferents) to rate pleasantness of stroking or are attributing pleasantness to this type of stimulus irrespective of velocity.
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PMID:Disturbances in affective touch in hereditary sensory & autonomic neuropathy type III. 2472 98