Somatosensory Pathways

Wall, Patrick D.; Dubner, R

doi:10.1146/annurev.ph.34.030172.001531

Cited by 56 publications

(17 citation statements)

References 31 publications

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“…One possibility is suggested by the anti-nociceptive connections present in the spinal cord. There, collaterals of dorsal column afferent fibers enter the spinal gray and access circuits that inhibit pain transmission (Wall and Dubner, 1972). Descending intratrigeminal projections include both GABAergic and glycinergic components (Han et al, 2008), so intratrigeminal descending projections may also function as a gate, restricting the access of nociceptive trigeminal signals to higher order tract cells.…”

Section: Discussionmentioning

confidence: 99%

Morphology and connections of intratrigeminal cells and axons in the macaque monkey

Warren¹,

May²

2013

Front. Neuroanat.

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Trigeminal primary afferent fibers have small receptive fields and discrete submodalities, but second order trigeminal neurons often display larger receptive fields with complex, multimodal responses. Moreover, while most large caliber afferents terminate exclusively in the principal trigeminal nucleus, and pars caudalis (sVc) of the spinal trigeminal nucleus receives almost exclusively small caliber afferents, the characteristics of second order neurons do not always reflect this dichotomy. These surprising characteristics may be due to a network of intratrigeminal connections modifying primary afferent contributions. This study characterizes the distribution and morphology of intratrigeminal cells and axons in a macaque monkeys. Tracer injections centered in the principal nucleus (pV) and adjacent pars oralis retrogradely labeled neurons bilaterally in pars interpolaris (sVi), but only ipsilaterally, in sVc. Labeled axons terminated contralaterally within sVi and caudalis. Features of the intratrigeminal cells in ipsilateral sVc suggest that both nociceptive and non-nociceptive neurons project to principalis. A commissural projection to contralateral principalis was also revealed. Injections into sVc labeled cells and terminals in pV and pars oralis on both sides, indicating the presence of bilateral reciprocal connections. Labeled terminals and cells were also present bilaterally in sVi and in contralateral sVc. Interpolaris injections produced labeling patterns similar to those of sVc. Thus, the rostral and caudal poles of the macaque trigeminal complex are richly interconnected by ipsilateral ascending and descending connections providing an anatomical substrate for complex analysis of oro-facial stimuli. Sparser reciprocal crossed intratrigeminal connections may be important for conjugate reflex movements, such as the corneal blink reflex.

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Section: Discussionmentioning

confidence: 99%

Morphology and connections of intratrigeminal cells and axons in the macaque monkey

Warren¹,

May²

2013

Front. Neuroanat.

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“…The functional properties of the neurons that compose this system have been intensively studied and appear to be well suited to subserve fine tactile discrimination and localization, vibra-tory sensibility and kinesthesial,13,; 34,38,61. A number of studies have, however, raised serious questions concerning the role of the DC-ML system in sensory detection and discrimination of somatic stimuli because complete transections of the dorsal columns do not produce the marked sensory deficits that would have been expected from neurophysiological analyses 6,47,48,6°,61.…”

Section: Introductionmentioning

confidence: 99%

Detection thresholds to stimulation of ventrobasal complex in cats

Swett

Bourassa

1980

Brain Research

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“…Although the involvement of NG in sensorimotor integration is not a new concept (Wall and Dubner, 1972), its involvement in pain has recently come under discussion, as a component of either an ensemble of systems that mutually and dynamically contribute to various somatovisceral experiences, including pain (Berkley and Hubscher, 1995;Berkley, 1997Berkley, , 1998, or a pelvic "visceral pain pathway" (Willis et al, 1999).…”

Section: Functional Significancementioning

confidence: 99%

Estrous Changes in Responses of Rat Gracile Nucleus Neurons to Stimulation of Skin and Pelvic Viscera

Bradshaw

Berkley

2000

J. Neurosci.

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Multi-and single-unit recording was performed in the gracile nucleus in urethane-anesthetized rats to examine estrous variations in responses of its neurons to brushing the hindquarters and mechanical stimulation of the uterus, vaginal canal, cervix, and colon. Six rats each were studied in each of the four estrous stages: proestrus (P), estrus (E), metestrus (M), and diestrus (D). The magnitude of multi-unit responses to gentle brushing of the perineum, hip, and tail, but not the foot and leg, was significantly greater during proestrus than during other stages. Of 70 single units responsive to brush, 56 (80%) responded to stimulation of at least one viscus. Although this percentage did not change with estrous stage, the direction and latency of some responses did. Pressure on the cervix evoked significantly more inhibitory (vs excitatory) responses in P than in E and M, and the response latency was significantly longer in D and P than in E and M. The direction of response to vaginal distention did not change with estrous stage, but response latency was significantly longer in D than in P and E. Uterine distention evoked significantly more inhibitory responses in D than in P, with no estrous changes in latency. Responses to colon distention did not change. These variations in both magnitude of response to tactile stimulation and characteristics of response to stimulation of reproductive organs, but not the colon, correlate with changes in mating behaviors of the female rat, suggesting that the gracile nucleus is a component of neural systems that control reproductive behaviors.Key words: female; dorsal column; reproduction; plasticity; somatosensory; pain It is well known that neurons in the gracile nucleus (NG) receive input from low-threshold cutaneous primary afferent fibers, respond vigorously to gentle tactile stimulation of small areas of the hindquarters, and convey that information to the thalamus and somatosensory regions of the cerebral cortex. It has been found recently, however, that NG neurons in the rat also respond to innocuous and noxious stimulation of female pelvic organs, such as the cervix, uterus, vagina, and colon (Hubscher, 1994;Berkley and Hubscher, 1995).Such convergent responsiveness suggests that NG may be a component of neural systems that coordinate reproductive behaviors. These behaviors in the female rat include a group of complex pacing and darting movements collectively called "proceptive behaviors," which are important for successful mating (Erskine, 1989), as well as "lordosis," which is a mating posture important for copulation and successful fertilization (Schwartz-Giblin et al., 1989;Pfaff, 1997). Both behaviors vary with the rat's estrous cycle in a similar way. Proceptive behaviors occur during the female rat's fertile period when she is sexually receptive, that is, during the afternoon and evening of proestrus and during the early morning of estrus (Erskine, 1989). This period is when estrogen and progesterone rise and fall in conjunction with ovulation (Freeman, 1994). L...

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Somatosensory Pathways

Cited by 56 publications

References 31 publications

Morphology and connections of intratrigeminal cells and axons in the macaque monkey

Morphology and connections of intratrigeminal cells and axons in the macaque monkey

Detection thresholds to stimulation of ventrobasal complex in cats

Estrous Changes in Responses of Rat Gracile Nucleus Neurons to Stimulation of Skin and Pelvic Viscera

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