Convergence patterns of afferent information from the temporomandibular joint and masseter muscle in the trigeminal subnucleus caudalis

Differential Effects of Estradiol on Encoding Properties of TMJ Units in Laminae I and V at the Spinomedullary Junction in Female Rats

“…No TMJ units were classified as LTM (i.e., displayed a convergent cutaneous RF that responded solely to innocuous brushing of facial skin). This differed from earlier studies (Kojima 1990) in which several TMJ units in Vc had an LTM-like cutaneous RF; however, in that study electrical search stimuli were used to identify TMJ units. The relative percentages of TMJ units classified as NS, WDR, or deep only in lamina V were not different between animal groups.…”

“…TMJ units in laminae I and V encoded the intensity of both mechanical and chemical stimulus modalities, properties consistent with a role in mediating spontaneous and movement-evoked jaw pain. Earlier recording studies of TMJ units used female (Kojima 1990) or male rats (Nishikawa et al 2004) or cats of either sex (Broton et al 1988) and combined the results from superficial and deep laminae. Similarly, most studies of joint-responsive units at spinal levels used only male animals and grouped the data from superficial and deep laminae (see Schaible 2004;Schaible and Grubb 1993), suggesting that selective effects of estrogen status on second-order neurons in superficial laminae of the dorsal horn would not have been detected.…”

Convergence of nociceptive information from temporomandibular joint and tooth pulp afferents on C1 spinal neurons in the rat

“…When considering collective data from Fos studies, particularly concerning the TMJ region after chemical stimulation and injury (Hathaway et al, 1995;Bereiter and Bereiter, 2000;Bereiter, 2001), it is possible to speculate that neurons in laminae I-II of the Vc/C2 region play an important role in processing the pain signal from the TMJ and surrounding masticatory muscles. Many neurons located at the caudalis and interpolaris in the trigeminal spinal nucleus receive nociceptive inputs from the TMJ and/or the masseter muscle (Mm) and have extensive convergence of afferent inputs, involving the TMJ, Mm, or the facial skin (Kojima, 1990;Ohya, 1992). In order to selectively stimulate the TMJ region only, we exposed the TMJ capsule by removing the Mm and directly stimulating the afferent terminal in the TMJ.…”

Acute and Chronic Craniofacial Pain: Brainstem Mechanisms of Nociceptive Transmission and Neuroplasticity, and Their Clinical Correlates

“…These studies have been numerous in recent years, since c-fos expression may provide a marker for neuronal populations responding to peripheral noxious stimuli (although the functional role played by the neurons expressing this proto-oncogene is still not entirely clear). Increased c-fos expression occurs, in caudalis neurons predominantly, following noxious stimulation of several different types of craniofacial tissues (Nozaki et al, 1992;Wakisaka et al, 1992;Coimbra and Coimbra, 1994; ELECTROPHYSIOLOGICAL EVIDENCE Numerous electrophysiological investigations have reported that the VBSNC, especially its subnucleus caudalis, contains neurons that can be activated by noxious stimulation Hu, 1990;Kojima, 1990;Dostrovsky et al, 1991;Nishida and Yokota, 1991;Hu et al, 1992a;Mokha, 1993;Peppel and Anton, 1993;Pozo and Cervero, 1993;Yu et al, 1993;Chiang et al, 1994Chiang et al, , 1997Chiang et al, , 1998McHaffie et al, 1994;Zhang et al, 1996;Meng et al, 1997; and see Dubner et al, 1978;Dubner and Bennett, 1983;Yokota, 1985;Sessle, 1987Sessle, , 1996. These studies have usually concentrated on the responses of these nociceptive neurons to cutaneous afferent inputs (although some of the more recent papers have reported on other types of afferent inputs; see Section IV).…”

“…This so-called afferent convergence involves, in addition to cutaneous afferents, V afferents supplying the dental pulp, jaw muscles, TMJ, cornea, cerebrovasculature, or dura Hu, 1990;Kojima, 1990;Dostrovsky et al, 1991;Pozo and Cervero, 1993;Yu et al, 1993;McHaffie et al, 1994;Chiang et al, 1994;Meng et al, 66 Grit Rev Oral Biol Med (2000) 1997; Burstein et al, 1998;and see Denny-Brown and Yanagisawa, 1973;Dostrovsky et al, 1991;Sessle and Hu, 1991;Sessle, 1996), and in some instances, the morphology of the neurons receiving convergent afferent inputs has been determined (Strassman et al, 1994b). Convergence of V cutaneous and cerebrovascular afferent inputs (as well as cervical afferent inputs) has also been reported for single neurons in the upper cervical spinal cord Angus-Leppan et al, 1994).…”