The representation of facial temperature in the caudal trigeminal nucleus of the cat.

Abstract

SUMMARY1. In cats anaesthetized with urethane, extracellular micro-electrode recordings were made in the marginal layer of the trigeminal nucleus caudalis between the level of the obex and the Cl rootlets.2. Nearly 300 neurones were found whose discharge rate increased with a reduction of facial temperature and a few which were excited by an increase in temperature. Over half of the neurones in each group were specifically sensitive to temperature and the remainder had a weak input from mechanical stimulation of the face.3. Thermal receptive fields were all ipsilateral and found most frequently on the nose, lips, lower eyelid and pinna. There was a somatotopic organization of the receptive fields according to the three divisions of the trigeminal nerve.4. On quantitative thermal testing, the neurones showed responses which were similar to those of the skin temperature sensors.5. The thermal neurones could be antidromically fired by a stimulating electrode in the thalamus.

Physiological Properties of the Lamina I Spinoparabrachial Neurons in the Rat

“…In the present study, almost all spino-PB neurons (92%) responded to both noxious mechanical and noxious thermal stimuli and thus were bimodal. These findings are in agreement with some of the earliest studies of lamina I neurons (Christensen and Perl 1970;Dostrovsky and Hellon 1978) as well as with studies of lamina I spinothalamic neurons in the monkey (Ferrington et al 1987;Kenshalo et al 1979). However, in the cat, Craig and Kniffki (1985) reported a lower proportion (Ϸ65%) of neurons responding, at least, to both pinch and heat noxious stimuli, the other lamina I spinothalamic neurons responded to only one modality (pinch, noxious heat, or innocuous cold).…”

Thalamic Relay Site for Cold Perception in Humans

“…The responses to a maintained cold stimulus included both a dynamic response at the onset of cooling and a static, somewhat lower response during the maintained cold (see Fig. 2), similar to those of cold-sensitive neurons reported in lamina I of the spinal and medullary dorsal horn in animal studies (Christensen and Perl 1970;Craig and Hunsley 1991;Dickenson et al 1979;Dostrovsky and Craig 1996;Dostrovsky and Hellon 1978;Hutchison et al 1995;Poulos et al 1979). None of these cold-responsive neurons were activated by tactile (brush or touch) stimuli, although two neurons also responded to cutaneous heating.…”

Eugenol and carvacrol excite first- and second-order trigeminal neurons and enhance their heat-evoked responses

“…A tungsten microelectrode (FHC, Bowdoin, ME; 10 MΩ) was positioned using a hydraulic microdrive (David Kopf Instruments, Tujunga CA) to record single Vc units having heat-sensitive lingual receptive fields. We used a noxious heat stimulus (see below) to isolate Vc units and did not attempt to identify units responsive to innocuous warming that are quite rare (Dostrovsky & Hellon, 1978; Andrew & Craig, 2001). Unit activity was amplified and displayed using Powerlab and Spike 2 (Cambridge Electronic Design, Cambridge, UK) interfaces.…”