سرکوب محرک‌ خارجی تمپورال در اختلال اضطراب فراگیر و افسردگی اساسی

The duration abnormality of the exteroceptive suppressions, or silent periods, of peripheral or jaw-closing muscle activities induced by transcranial magnetic or trigeminal electrical stimuli in patients suffering from anxiety or depression is ill-defined. We therefore studied the exteroceptive suppression periods of the temporalis muscle electromyography elicited by trigeminal territory electrical stimuli, Zuckerman–Kuhlman’s Personality Questionnaire, and Plutchik–van Praag’s Depression Inventory (PVP) in 12 patients suffering from generalized anxiety disorder (GAD) and 16 from major depression (MD) as well as in 17 healthy volunteers. Durations of the second suppression period (ES2) sociability scores were decreased in GAD patients, while PVP and neuroticism–anxiety scores were elevated in both GAD and MD patients. There was a positive correlation between ES2 duration and sociability score in the GAD group. This study indicates that anxiety can modify the temporalis ES2 duration through cortical descending inhibitory controls.

A slight painful stimulus over the mental nerves induces early (ES1) and late (ES2) exteroceptive suppressions, or silent periods, of jaw-closing muscle activity (for recent studies, see Ellrich et al., 1997 and Cruccu and Romaniello, 1998). ES1 is assumed to be a pontine di- or oligosynaptic reflex and ES2 is considered to be a pontomedullary polysynaptic circuit reflecting the excitability of inhibitory brain stem interneurons, which are located in the medullary reticular formation near the spinal trigeminal nucleus (pars caudalis) (reviewed in Schoenen, 1993a). Because of the different methods employed, ES2 duration abnormalities in patients suffering from chronic tension-type headache, temporomandibular disorder and chronic low back pain are controversial (reviewed in De Laat et al., 1998). For instance, the reduced or abolished temporalis ES2 after labial commissure stimulation in chronic tension-type headache sufferers is reported in some earlier studies but not in later ones (e.g. Schoenen et al., 1987 and Bendtsen et al., 1996; reviewed in Schoenen and Bendtsen, 2000). Physiologically, the inhibitory brain stem interneurons mediating ES2 receive strong input from limbic brain structures like the periaqueductal gray matter or raphe magnus nucleus, while the periaqueductal gray matter receives input from the medial prefrontal and insular cortex (reviewed in Bandler and Shipley, 1994). The shortened or abolished ES2 suggests that these interneurons are less activated or excessively inhibited.