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B J Sessle

Publications and source records attributed to B J Sessle.

At least 19 recordsLinked to original sources
PubMed1992

Trigeminal and dorsal column nuclei projections to the anterior pretectal nucleus in the rat.

The projections of the trigeminal (V) sensory nuclei (VSN) and the dorsal column nuclei (DCN) to the anterior pretectal nucleus (APT) of the rat were investigated by the use of anterograde and retrograde transport of wheat-germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). Injections of WGA-HRP into the APT retrogradely labeled neurons in the contralateral VSN and DCN. The labeled neurons in the VSN were most concentrated in the rostral V subnucleus interpolaris (Vi), but were also found in caudal V subnucleus oralis (Vo). No labeled neurons were seen in V subnucleus caudalis. In the DCN, retrogradely labeled neurons were observed in rostral portions of both the cuneate (Cu) and gracile (Gr) nuclei. Injections of WGA-HRP into the rostral Vi or caudal Vo resulted in dense anterograde terminal labeling in the ventral two-thirds of the APT; the labeling was maximal in the ventromedial part of the caudal half of the APT and did not extend into its most rostral portion. Labeling resulting from injections of tracer into Cu or Gr was located primarily in the ventral half of the APT, was maximal in the mid-levels of the nucleus and extended into its rostral portions. These results indicate the existence of prominent somatosensory projections to the APT and are consistent with recent findings suggesting a role for the APT in sensorimotor integration.

Animals↗
PubMed1979

Effects of upper respiratory tract stimuli on neonatal respiration: reflex and single neuron analyses in the kitten.

Respiratory effects of electrical and chemical stimuli applied to nerves or sites associated with the respiratory tract were tested in kittens aged 6-70 days. Cessation of respiration occurred especially with superior laryngeal nerve stimulation and infusion of water and sodium bicarbonate into the larynx. The apneic reflex was more powerful and prolonged than that previously noted in adult cats and was sometimes irreversible. Brain stem respiratory neurons of the neonate also showed marked susceptibility to these stimuli: the respiratory-related rhythm of 80% could be powerfully suppressed, and only 25% received excitatory inputs. The susceptibility of the neonatal respiratory system to these stimuli may have physiopathological significance in conditions such as the sudden infant (crib) death syndrome.

Age Factors↗
PubMed1978

Oral--facial pain: old puzzles, new postulates.

Dental examples are given (e.g. referred pain, V neuralgia) which exemplify the multifactorial and puzzling nature of pain. Pain results from a noxious stimulus activating some of the small-diameter myelinated and unmyelinated afferent nerve fibres that innervate skin, mucosa, teeth etc. It is complex experience including the sensation experienced as well as the emotional, cognitive and motivational reactions evoked by the stimulus. Pain is not a simple function of the magnitude of damage caused by the stimulus, but also depends on factors such as the person's emotions, past experience of pain, and other concomitant sensory experiences (e.g. with acupuncture). Early postulates of pain failed to take all these factors into account. In the V system (Fig. 1), the specificity theory would maintain that there exists a 'private pain path' from oral-facial tissues to the cerebral cortex, with nerve fibres and brain cells in this path responsive only to stimulu of a noxious character (Fig. 2). But anatomical, physiological and psychological observations have failed to give full support to this theory and other postulates of pain. Although some details of the more recently proposed gate control theory have not been sustantiated, this theory has provided a good general framework for viewing pain and has stimulated much recent research. It emphasizes sensory interaction between large and small-diameter afferent nerve fibres in the gate control system, and regulation over central pain transmission through the gate by descending central controls (Fig. 3). In the V system, brain cells involved in central pain transmission have now been found (Fig. 4), and sensory interactions and descending controls on these brain cells noted (Fig. 5). Neural mechanisms such as these have been implicated in pain, and in its control by procedures such as acupuncture, suggestion, distraction and narcotic analgesia.

Brain↗
PubMed1976

Inputs to trigeminal brain stem neurones from facial, oral, tooth pulp and pharyngolaryngeal tissues: I. Responses to innocuous and noxious stimuli.

Responses evoked in anaesthetized or decerebrate cats by stimulation of afferents supplying the face, mouth, pharynx, larynx, tooth pulp and jaw muscles were recorded from single neurones located in the trigeminal (V) main sensory nucleus, V nucleus oralis, and adjacent regions. Many cells (both V-thalamic relay and non-relay with localized V mechanoreceptive cutaneous fields could be activated by stimulation of a number of these afferents. A particularly prominent short-latency (often monosynaptic) input was noted from the canine tooth pulp, stimulation of which is generally considered to elicit only responses of pain in man. Control experiments showed that pulp-evoked responses were not the result of stimulus spread to tissues outside the pulp. The interaction of these various inputs to neurones at this level of the V brain stem complex typically resulted in a prolonged period of inhibition that was sometimes preceded by a short-lasting facilitatory phase. This inhibitory effect was also apparent in neurones located outside the complex, although a late facilitatory phase was frequently also noted. Our findings indicate a significant nociceptive input to V main sensory-oralis neurones, a proportion of which relay directly to the ventrobasal thalamus. The interactions described may be involved in perceptual and reflex aspects of responses to noxious and innocuous V stimuli.

Adaptation, Physiological↗
PubMed1976

Inputs to trigeminal brain stem neurones from facial, oral, tooth pulp and pharyngolaryngeal tissues: II. Role of trigeminal nucleus caudalis in modulating responses to innocuous and noxious stimuli.

Trigeminal (V) tractotomy and cold block of synaptic transmission in V nucleus caudalis were used to show that caudalis modulates the responses to innocuous and noxious stimuli of single V main sensory-oralis neurones recorded in anaesthetized or decerebrate cats. Cold block caused a reversible depression of mechanosensitivity of 91 of 105 V-thalamic relay and non-relay cells tested; V tractotomy also decreased sensitivity. The possibliity that the effects observed with cold block of caudalis were caused by direct spread of cooling to the main sensory-oralis region, and not by depression of a tonic, net facilitatory influence of caudalis on main sensory-oralis cells, was ruled out by several controls. With cold block of caudalis there also occurred a reversible shrinkage in mechanoreceptive field size and reversible reduction in sensitivity of rapidly adapting and slowly adapting mechanoreceptive neurones. Occasionally no change or an increase in sensitivity occurred, the latter suggesting the liklihood of an inhibitory influence from caudalis as well as the facilitatory influence. The effects of interactions of innocuous and noxious V stimuli were likewise subject to ascending influences from caudalis. Cold block also reversibly depressed responses to tooth pulp and V cutaneous noxious stimuli, although pulp-evoked responses were depressed less than mechanical or infraorbital nerve-elicited responses. Our results indicate that caudalis, as well as acting as a relay site to thalamus, also exerts a predominantly facilitatory influence on the relay to the thalamus and local reflex centres of mechanoreceptive and nociceptive information through the V main sensory-oralis region. The findings also might in part explain the analgesia, partial loss of tactile sensibility, and relief from V neuralgia reported after V tractotomy.

Adaptation, Physiological↗
PubMed1976

Descending influences of periaqueductal gray matter and somatosensory cerebral cortex on neurones in trigeminal brain stem nuclei.

Single relay (to thalamus) and nonrelay neurones that responded to innocuous and/or noxious oral-facial stimuli were located in trigeminal brain stem nuclei oralis and caudalis. The responses of the cells and the digastric muscle to these stimuli were tested with conditioning stimulation of the periaqueductal gray matter (PGM) and somatosensory cerebral cortex in cats. A greater suppression of nociceptive responses with PGM stimulation was noted, and this effect may contribute to the profound analgesic action that has been reported to occur with PGM stimulation.

Analgesia↗