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M F Jacquin

Publications and source records attributed to M F Jacquin.

90 records · Page 5Linked to original sources
PubMed1984

Trigeminal sensorimotor mechanisms and eating in the rat.

Photographic, electrophysiological and neurobehavioral analyses were used to examine the contribution of trigeminal inputs to the behavioral organization of eating in the rat. During eating, jaw opening was always preceded by a period of perioral contact with the food source. Mechanical or electrical stimulation of oral and perioral areas in anesthetized animals elicited compound action potentials in the mylohyoid nerve (jaw-opener innervation) at short latencies and low stimulus intensities. Trigeminal orosensory deafferentation (sparing jaw muscle afferents and efferents) abolished or significantly reduced mouth opening during eating. We conclude that trigeminal orosensory inputs provide an essential link in the stimulus-response chain mediating eating in the rat.

Animals↗
PubMed1984

Axon arbors of functionally distinct whisker afferents are similar in medullary dorsal horn.

Using the intra-axonal horseradish peroxidase (HRP) technique, we have found that the central axon arbors of functionally distinct mystacial whisker primary afferents in rat medullary dorsal horn were all similar with respect to their shape and density of terminal boutons. Arbors from slowly adapting, rapidly adapting, velocity or nociceptive biased whisker afferents all appeared to form a series of highly localized terminal aggregates within a specific rostrocaudal segment of the superficial or deep half of the lamina III-IV magnocellular region. Other trigeminal afferents adhered to previously described somatosensory structure-function relationships in the cat lumbosacral spinal cord. These findings suggest that topographic constraints, as well as functional considerations, are important in determining primary afferent terminal arbor patterns in the medullary dorsal horn.

Afferent Pathways↗
PubMed1984

Organization of the infraorbital nerve in rat: a quantitative electron microscopic study.

The normal organization of the rat's infraorbital (IO) nerve was studied using conventional electron microscopic (EM) methods. Just caudal to the infraorbital foramen, at the level of the anterior superior alveolar foramen, the nerve was composed of 18-25 fascicles which ranged from 575 to 87,923 micron2 in cross-sectional area. Complete axon counts from thin sections taken at this level demonstrated that the IO nerve contained an average of 19,740 (S.D. = 2054) myelinated and 13,319 (S.D. = 1159) unmyelinated axons. The average diameter (including the myelin sheath) for medullated fibers was 4.42 micron (S.D. = 1.76) and that for unmyelinated axons was 0.60 micron (S.D. = 0.16). The fiber diameter distributions for both myelinated and unmyelinated axons were essentially unimodal.

Animals↗
PubMed1984

Trigeminal sensorimotor mechanisms and ingestive behavior.

Selective section of trigeminal orosensory nerves was carried out to assess the contributions of trigeminal orosensation to the control of food and water intake in the rat. Trigeminal orosensory deafferentation reduces a responsiveness to food and water, disrupts jaw-opening and tongue protrusion reflexes mediating eating and drinking, impairs dietary self-selection and reduces the level of long-term body weight regulation. The magnitude of the feeding behavior deficits is a joint function of the extent of the denervation and the sensory properties of the diet, and recovery takes place along a palatability gradient. Analysis of feeding and drinking patterns and of learned instrumental behaviors indicates that deafferentation reduces the probability of initiating a feeding or drinking bout and profoundly disrupts performance of operant responses reinforced with food or water. We conclude that the trigeminal system contributes to both the sensorimotor and motivational control of ingestive behavior. Its motivational contributions differ in both kind and magnitude from those of the gustatory system.

Afferent Pathways↗
PubMed1984

Trigeminal denervation and operant behavior in the rat.

Selective section of trigeminal sensory and motor nerves was carried out in two experiments designed to examine the contribution of this sensorimotor system to the control of instrumental responses reinforced with food or water. Unilateral section of either V sensory or V motor nerves had no significant effect on lever pressing. Bilateral section significantly reduced lever pressing, and the deficit was greatest in subjects with trigeminal motor nerve section. Thus trigeminal orosensory or oromotor denervation disrupts performance on a food- or water-reinforced task whose execution does not require a trigeminally mediated response. The results are discussed in terms of motivational and reinforcement accounts of instrumental learning.

Animals↗
PubMed1984

Altered somatosensory receptive fields in hamster colliculus after infraorbital nerve section and xylocaine injection.

The effects of acute infraorbital (i.o.) nerve section upon the responses of somatosensory cells in the rostral part of the deep layers of the hamster's superior colliculus were studied using standard extracellular single-unit recording and receptive field mapping techniques. In nine animals a given cell's receptive field was determined both before and after i.o. nerve section and, in all cases, new areas of sensitivity were unmasked within 15 min after the nerve was cut. In a given electrode penetration where the i.o. nerve was sectioned (n = 13), somatosensory cells recorded after the nerve was cut, as the electrode was being withdrawn from the colliculus, exhibited receptive fields considerably different from those of somatosensory cells isolated during the descent of the recording electrode. Seventeen deep-layer somatosensory cells (in eight hamsters) were tested before and after subcutaneous injections of xylocaine into their receptive fields. This manipulation unmasked new areas of cutaneous sensitivity for sixteen units. Of these, the new receptive fields of nine cells disappeared as sensitivity in the original receptive field returned; five ultimately retained both the new and old receptive fields; in two instances, sensitivity in the original receptive field never returned over the 3 h of testing. Control experiments (n = 7) demonstrated that the changes observed did not result from spontaneous alterations in receptive field borders, changes induced by variations in the level of general anaesthesia, or non-specific trauma associated with the xylocaine injections or the surgery required to expose the i.o. nerve.

Animals↗
PubMed1984

Trigeminal reflexes and ingestive behavior in the rat.

Photographic, electrophysiological, and neurobehavioral analyses were used to examine the contribution of trigeminally mediated jaw-opening reflexes to the control of ingestive behavior in the rat. During eating and drinking, jaw opening was always preceded by a period of perioral contact with the food or water source. Stimulation (electrical, mechanical) of perioral areas in anesthetized animals elicited jaw-opening reflexes (recorded from the mylohyoid nerve trunk) at short latencies and low stimulus intensities. Trigeminal orosensory deafferentation (sparing jaw muscle afferents and efferents, taste, vision, and olfaction) abolished or significantly reduced mouth opening during eating or drinking. It is concluded that motivational processes operate through trigeminal reflexes to generate eating in the rat.

Animals↗
PubMed1983

Central projections of the normal and 'regenerate' infraorbital nerve in adult rats subjected to neonatal unilateral infraorbital lesions: a transganglionic horseradish peroxidase study.

Application of horseradish peroxidase (HRP) to the proximal stump of the transected infraorbital (IO) nerve in the orbit was employed in normal adult rats to demonstrate the ganglionic representation of and brainstem innervation by the trigeminal (V) branch which supplies primarily the mystacial vibrissae. In the V ganglion, somal clusters resembling the barrels or barreloids which comprise the central representations of the whiskers were not visible. In the trigeminal brainstem nuclear complex (TBNC), however, barrel-like aggregates of HRP-labeled terminals could be clearly seen throughout subnucleus interpolaris and, to a lesser extent, in the principal sensory nucleus, subnucleus caudalis and the first cervical segment. In adult rats subjected to neonatal IO nerve section and vibrissae follicle cauterization, transganglionic HRP transport from the 'regenerate' IO nerve indicated an almost exclusive projection to the marginal layer of the medullary and rostral cervical dorsal horn.

Animals↗
PubMed1983

Reorganization of trigeminal primary afferents following neonatal infraorbital nerve section in hamster.

The infraorbital nerve was sectioned and the ipsilateral whisker follicles were cauterized in hamsters within 12 h of birth. Sixty to ninety days later application of HRP to the proximal stumps of the ipsilateral lingual, inferior alveolar, mylohyoid and auriculotemporal nerves resulted in increased numbers of labeled somata in trigeminal ganglion regions which contain primarily infraorbital cell bodies in normal animals. The labeled central processes of mandibular nerves also occupied portions of the brainstem trigeminal complex normally innervated by infraorbital axons. These findings represent the first anatomical demonstration of trigeminal primary afferent plasticity.

Afferent Pathways↗
PubMed1983

Trigeminal orosensation and ingestive behavior in the rat.

A deafferentation procedure was used to examine the contributions of trigeminal orosensation to the control of ingestive behavior in the rat. The procedure removed somatosensory input from the mouth, sparing olfaction, lingual taste, and vibrissae inputs as well as proprioceptive afferents from and efferents to the jaw muscles. Rats with sections of tongue or jaw muscle efferents served as oromotor controls. Bilateral trigeminal orosensory deafferentation was followed by an array of effects on ingestive behavior whose magnitudes were proportional to the extent of the deafferentation. The "trigeminal syndrome" includes a disruption of food and water intake (aphagia, adipsia), impairments in the sensorimotor control of eating and drinking, decreased responsiveness to food and water, and a reduction in the level of body weight regulation. Trigeminal deafferentation spared elementary ingestive movement patterns (biting, licking, chewing) but disrupted their control by the perioral stimuli, which normally elicit them, so that eating and drinking sequences were either aborted or inefficient. Deficits in food intake varied with the sensory properties of the diet. Recovery of intake took place along a palatability gradient, and recovery of water intake paralleled that of dry food. The chronically reduced body weight was caused by a persistent hypophagia and reflects reduced responsiveness to food. These findings suggest a considerable degree of overlap in the neural mechanisms mediating the sensorimotor and motivational control of intake in the rat.

Alveolar Process↗
PubMed1983

Gustation and ingestive behavior in the rat.

Gustatory deafferentation was produced by combined bilateral section of the chorda tympani and glossopharyngeal nerves and the pharyngeal branch of the vagus nerve. The procedure did not affect the condition of the mouth, impair orientation to sensory stimuli, or severely disrupt the consummatory sequence. Nevertheless, deafferented subjects showed reduced responsiveness to food and water, elevated QHCl aversion thresholds, and impaired feeding efficiency. Food and water intake and body weight remained below control levels for at least 40-50 days postoperatively. Food intake deficits were not observed when the rats were offered ad lib pablum, a result suggesting that increased palatability could compensate for decreased gustatory input. The order of recovery of food intake through different diet types suggests a heightened responsiveness to taste stimuli. The effects of gustatory deafferentation are compared with those seen after section of trigeminal orosensory nerves (Jacquin & Zeigler, 1983), and the differential contributions of oral "taste" and oral "touch" are discussed.

Animals↗
PubMed1983

Complex somatosensory receptive fields of cells in the deep laminae of the hamster's superior colliculus.

Responses to separate and simultaneous application of noxious and innocuous tactile stimuli were examined for neurons recorded from the deep layers of the hamster's superior colliculus. Forty-four percent of the units isolated were responsive only to innocuous, primarily cutaneous, stimuli; 10% were activated only by noxious stimulation; and 15% were characterized as having a wide dynamic range. The remaining 31% of the somatosensory cells recorded had complex receptive field properties which have not heretofore been described for tectal neurons in any species. Ten percent of all somatosensory cells had no excitatory receptive fields, but their spontaneous discharges could be suppressed by low threshold and/or noxious stimulation of discrete portions of the body. In 18% of the units which we recorded, innocuous and noxious stimuli had opposing effects upon cellular activity. Most of these neurons had small receptive fields in which innocuous tactile stimuli yielded excitation and larger fields, often including most of the body surface, where noxious stimulation suppressed both spontaneous activity and the responses normally elicited by appropriate tactile stimulation. Finally, a very small number of units (3% of all somatosensory cells recorded) had multiple receptive fields in which low threshold stimulation produced opposing effects on spontaneous activity. Somatosensory units were recorded in all of the deep laminae, but cells with complex response characteristics were isolated primarily in stratum griseum profundum.

Animals↗
PubMed1982

Dissociation of hunger and self-stimulation by trigeminal deafferentation in the rat.

Section of trigeminal orosensory or oromotor nerves reduces food intake and disrupts performance of a food-reinforced lever pressing response but increases the rate of an identical level pressing response reinforced by electrical stimulation of the lateral hypothalamus. Our findings suggest that trigeminal orosensation plays a critical role in the neural control of hunger in the rat. The results also fail to support a response-oriented theory of intracranial self-stimulation where the latter is thought to involve selective facilitation of sensorimotor circuits underlying species-typical consummatory behavior.

Afferent Pathways↗
PubMedDate not supplied

Intra-axonal Neurobiotin injection rapidly stains the long-range projections of identified trigeminal primary afferents in vivo: comparisons with HRP and PHA-L.

Currently available methods for studying the morphology of physiologically characterized primary afferents are limited by difficulties inherent in impaling thin fibers and by the limited distances over which conventional tracers move during the course of a recording session. We have encountered an alternative method that overcomes these limitations. Neurobiotin (NB; Vector) injections into rat trigeminal (V) primary afferents in the brain stem or V ganglion provided rapid, long-range staining with recording and electrophoretic parameters that are commonly used to eject horseradish peroxidase (HRP) or Phaseolus vulgaris leucoagglutinin (PHA-L). When NB was injected into brain stem fibers responsive to vibrissal deflection with A-beta conduction velocities, collaterals were darkly stained in each of the 4 V subnuclei, as well as the cervical dorsal horn. Labeled fibers were also seen in the V root and peripherally in the infra-orbital nerve for a distance up to 15 mm from the injection site (30 mm total). Cell bodies in the ganglion were never labeled. When NB was injected into V ganglion cells with low- or high-threshold receptive fields and A-beta or A-delta conduction velocities, parent axons were stained in the V spinal tract to the level of the obex, and collaterals were visible in each of the 4 V subnuclei. Such long-range staining occurred within 4 h of tracer injection. HRP never stained brain stem fibers following ganglion cell injections and, when injected centrally with the same survival intervals used with NB, dark staining was limited to within 4 mm of the injection site. Unlike NB or HRP, PHA-L injections rarely produced useful data, either because of the high mortality accompanying attempts to achieve a 1-2 week survival period or because injected neurons were not recovered. Due to its rapid and robust transport, NB is a more convenient and reliable tracer than PHA-L for producing long-range staining of the projections of identified ganglion cells. Intracellular injection of NB also produces rapid Golgi-like staining of fibers over much greater distances than HRP under equivalent staining parameters.

Afferent Pathways↗