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PubMed1992

Chronic selective activation of excitatory opioid receptor functions in sensory neurons results in opioid 'dependence' without tolerance.

We previously showed that mouse sensory dorsal root ganglion (DRG) neurons chronically exposed to 1 microM D-ala2-D-leu5-enkephalin (DADLE) or morphine for > 2-3 days in culture become tolerant to the usual opioid inhibitory receptor-mediated effects, i.e. shortening of the duration of the calcium-dependent component of the action potential (APD), and supersensitive to opioid excitatory APD-prolonging effects elicited by low opioid concentrations. Whereas nanomolar concentrations of dynorphin(1-13) or morphine are generally required to prolong the APD of naive DRG neurons (by activating excitatory opioid receptors), femtomolar levels become effective after chronic opioid treatment. Whereas 1-30 nM naloxone or diprenorphine prevent both excitatory and inhibitory opioid effects but do not alter the APD of native DRG neurons, both opioid antagonists unexpectedly prolong the APD of most of the chronic opioid-treated cells. In the present study, chronic exposure of DRG neurons to 1 microM DADLE together with cholera toxin-B subunit (which selectively blocks GM1 ganglioside-regulated opioid excitatory, but not inhibitory, receptor functions) prevented the development of opioid excitatory supersensitivity and markedly attenuated tolerance to opioid inhibitory effects. Conversely, sustained exposure of DRG neurons to 1 nM DADLE, which selectively activates excitatory opioid receptor functions, resulted in characteristic opioid excitatory supersensitivity but no tolerance. These results suggest that 'dependence'-like properties can be induced in chronic opioid-treated sensory neurons in the absence of tolerance. On the other hand, development of some components of tolerance in these cells may require sustained activation of both excitatory, as well as inhibitory, opioid receptor functions.

Animals↗

PubMed1993

Vestibular function and sensory interaction in space flight.

The vestibular system and vestibulo-visual interaction were examined in 11 astronauts by the electrooculographic (EOG) method during short- and long-term flights on days 2, 3, 5, 9, 22, 50, 164, and 169 (experiments OPTOKINES and LABYRINTH). In space (flight days 2 and 3), they showed enhanced spontaneous vertical nystagmus, and disorders of tracking of vertical and diagonal movements of the stimulus which improved after active head movements. Early increasing of the reactivity of the cupulo-endolymphatic system (flight days 2-3) was replaced after 5 days of flight with a reduction of the vestibular function and an increase of the significance of the visual input in the formation of oculomotor responses to combined vestibulo-optokinetic stimulation. The type of spontaneous ocular reaction and vestibular stimulation of oculomotor activity under the conditions of weightlessness represented, on one hand, the general responses of sensory systems to weightlessness and, on the other hand, specificity of integrating and adaptive processes.

Electrooculography↗

PubMed1988

Laryngeal reflex mechanism during deglutition--observation of subglottal pressure and afferent discharge.

In this investigation, particular attention was paid to elucidate the laryngeal reflex mechanism of protective closure and the sensory function of the larynx during deglutition. For this purpose, three different experimental procedures were adopted: (1) subglottal pressure of felines was measured during deglutition using a pressure transducer; (2) subglottal pressure of human beings was measured during deglutition using a pressure transducer; and (3) afferent discharges from superior and recurrent laryngeal nerves of felines were recorded. The following conclusions appear justified. (1) Feline and human subglottal pressure during deglutition showed the following pattern. The pressure rises with onset of deglutition, temporarily drops during laryngeal elevation, rises again during the downward movement of the larynx, and drops again at the end of the glutition. This pattern was not affected by the resection of the unilateral recurrent laryngeal nerve. (2) The superior laryngeal nerve is involved in the sensory function of the pharynx, larynx, and trachea. At least two types of afferent discharges from superficial and internal sensory nerves are suspected. Afferent discharges from the recurrent laryngeal nerves in the larynx and trachea are not as distinct as those of the superior laryngeal nerve, and this seems to correspond with various changes in the thorax. During deglutition, afferent discharges were recorded from superior to recurrent laryngeal nerves.

Animals↗

PubMed2001

Gender-dependent behavioral and sensory effects of a commercial mixture of polychlorinated biphenyls (Aroclor 1254) in rats.

Developmental exposure to polychlorinated biphenyls (PCBs) has been associated with behavioral and cognitive deficits in humans and animal models. Perinatal exposure to PCBs has also been associated with sensory deficits in animal models. These effects were hypothesized to be mediated in part by ortho-substituted PCBs, which do not or weakly bind to the aryl hydrocarbon (Ah) receptor. The present studies were designed to determine whether perinatal exposure to Aroclor 1254, a commercial mixture of > 99% ortho-substituted PCBs, would affect cognitive and sensory function in Long-Evans rats. Adult male and female offspring of female rats fed Aroclor 1254 (Lot #124-191; doses of 0, 1, or 6 mg/kg/day; gestational day 6 through postnatal day 21; n = eight/group) were trained to perform a signal detection task capable of assessing sensory thresholds. Training included autoshaping and operant conditioning. Thresholds for detecting a 1-s light stimulus were determined under background illuminations ranging from 2 lux to complete darkness. Female rats exposed to Aroclor 1254 autoshaped more rapidly than control females, at a rate akin to control males. Control females had lower thresholds than control males at all levels of background illumination. These differences were abolished by Aroclor 1254, which reduced thresholds in males and increased thresholds in females. These data extend previous findings of gender-specific effects of PCBs on neurobehavioral development to measures of acquisition and sensory function.

Animals↗

PubMed1993

A C-terminal truncation results in high-level expression of the functional photoreceptor sensory rhodopsin I in the archaeon Halobacterium salinarium.

Expression of the gene encoding the halobacterial photoreceptor sensory rhodopsin I (SRI), sopI, was studied by means of homologous gene targeting. A sopI- Halobacterium salinarium mutant strain was constructed by homologous replacement of sopI with a novobiocin-resistant gyrB from Haloferax Aa 2.2. Cells bearing gyrB were resistant to novobiocin, indicating that the Haloferax gene is functional in H. salinarium. Complementation of this deletion strain with sopI fused to the bacterio-opsin promoter resulted in the recovery of all phenotypical attributes of SRI. This establishes the first direct correlation between sopI and the function of its gene product. In the complemented deletion strain, functional expression of sopI occurred from the bop locus, where sopI had integrated by homologous recombination. This shows that cotranscription of sopI and the gene encoding the SRI signal transducer, htrI, which is found in the wild type, is not a prerequisite for photosensory activity. Deletion of the last 43 bp at the 3' end of sopI resulted in a 10-fold increase in the amount of SRI, without affecting the activity of the pigment. The mRNA level of the truncated gene was not affected as compared to that of the wild type. We propose that regulation occurs at the protein level, probably through a negative determinant of protein stability located in the C-terminus of SRI. Replacement of the last 28 amino acids of bacteriorhodopsin by the last 29 amino acids of SRI results in a decrease of the bacteriorhodopsin, supporting our observations. The C-terminus of SRI is the first domain with a downregulating influence on protein levels thus far identified in H. salinarium. The system for SRI overexpression we present here greatly facilitates biochemical and biophysical studies on the photoreceptor and allows investigation of the molecular interactions underlying the signal transduction chain of halobacterial phototaxis.

Amino Acid Sequence↗

PubMed1996

Effect of low-level laser treatment on neurosensory deficits subsequent to sagittal split ramus osteotomy.

OBJECTIVES: Low-level laser treatment has been advocated as a possible treatment for patients with paresthesia. An objectively verified improvement in sensory function is relevant if, at the same time, it is perceived as a subjective improvement by the patient. The aim of this double blind clinical study was to see if low-level laser treatment with a GaAlAs laser (820 nm, Rønvig, Denmark) resulted in objectively verified improvement in sensory function and whether this correlated with the patient's subjective evaluation subsequent to treatment. STUDY DESIGN: The 13 patients in this study had all undergone saggittal split ramus osteotomy resulting in either compression or traction of the inferior alveolar nerve as reported by the surgery notes. The material was collected from a consecutive series of patients at the Karolinska Hospital, all of whom had shown reduced sensibility at their final 2-year postoperative checkup. The patients were randomly divided into two groups; one (eight subjects) group received real low-level laser treatment (4 x 6 J per treatment along the distribution of the inferior alveolar nerve, at the following points extraoral: lateral third of lower lip, intraoral; buccally to the apex of the second premolar tooth and the apex of the second molar tooth; lingually in the region of the mandibular foramen; for a total of 20 treatments). The other group received an equivalent placebo treatment. The study was conducted in a double blind fashion for both patient and doctor as the low-level laser equipment had two settings, A and B, one of which was an unknown void setting. The degree of mechanoceptor neurosensory deficit was assessed by Semmes Weinstein monofilaments (North Coast Medical, USA) and the degree of thermoceptor neurosensory deficit was assessed by a Thermotester (Somedic, Sweden). The degree of subjective neurosensory deficit was assessed by means of a visual analogue scale. Both variables and the degree of subjective injury were comparable between the two groups before starting treatment. RESULTS: The patients in the real low-level laser treatment group experienced a subjective improvement in both lip (p = 0.01) and chin (p = 0.02) after completion of the course of treatment. In addition, this group showed a significant decrease in the area of mechanoperception neurosensory deficit (p = 0.01) compared with no difference in the placebo group. The real low-level laser treatment group exhibited a strong tendency toward improvement in mechanoreceptor neurosensory deficit in the areas of most damage for both lip and chin. This improvement was especially pronounced in the lip region (p = 0.06). No similar tendency was demonstrated in the placebo group. Neither group showed any significant change or tendency to improvement in thermoception on completion of the course of treatment. CONCLUSION: In conclusion GaAlAs low-level laser treatment results in both a subjective and objective improvement in mechanical sensory perception in long-standing neurosensory deficit in the inferior alveolar nerve.

Adult↗

PubMedDate not supplied

The assessment and treatment of patients who have sensory loss following cortical lesions.

The assessment of tactile and proprioceptive sensory function in patients with severe sensory deficits resulting from cortical lesions is reviewed. The importance of using age-appropriate normative data to interpret the scores on these tests is discussed in the context of the frequency of ipsilateral disturbances in somesthetic sensation following unilateral cerebral lesions. Tactile and proprioceptive sensory deficits not only affect the processing of sensory information but also result in impairments in manual control. Fine-motor skills, such as those required for grasping and manipulating small objects, must therefore be evaluated in these patients. The treatment of patients with severe sensory deficits focuses on improving the perception of sensory information arising from receptors in the hand and on retraining motor function. The procedures used for sensory re-education and retraining are described.

Aged↗

PubMed2000

Interobserver test-retest reliability of the Randot preschool stereoacuity test.

PURPOSE: Random dot stereoacuity can be quantified to between 40 and 800 seconds of arc in preschool children by using the Randot Preschool Stereoacuity test (Stereo Optical Co, Inc, Chicago, Ill). To incorporate this test into clinic and research settings, the reliability of its stereoacuity scores obtained by separate examiners needs to be evaluated. The purpose of this study was to evaluate its interobserver test-retest reliability. METHODS: Participants included 102 consecutive children with binocular sensory function ranging from fine to no measurable stereopsis. Clinical research participants included children with anomalous binocular vision caused by strabismus, cataracts, anisometropia, and ptosis. In a prospective study, random dot stereoacuity was measured twice under masked testing conditions by 2 examiners within a 1-hour period. RESULTS: Interobserver test-retest reliability of the Randot Preschool Stereoacuity test is high among a population of children with diverse binocular sensory function. The correlation coefficient between individual test scores was highly significant (r = 0.97, P<.001). Mean differences between the 2 scores (0.021 log seconds of arc) were not significantly different from zero (t(99) = 1.33, P>.1). The upper and lower limits of agreement were narrow, reflecting both the large sample size and the small variation between the 2 test scores. Interobserver test-retest reliability of the Randot Preschool Stereoacuity test was nearly constant across levels of functional stereoacuity, patient categorization, and age at the time of the test. CONCLUSIONS: The high agreement between the Randot Preschool Stereoacuity test scores by 2 independent observers supports its use in clinical management and research settings for the quantitative assessment of binocular sensory vision, as well as in multicentered research studies.

Child↗

PubMed1992

A technique for the treatment of neuroma in-continuity.

A surgical technique for the management of a neuroma in-continuity, in which motor function is preserved and sensory function is reconstructed with nerve grafting, is presented. Tedious and potentially damaging dissection within the neuroma in-continuity is avoided. The functioning motor fascicles are identified proximal and distal to the injury site with electrical nerve stimulation eliciting muscle contraction. These motor fascicles are preserved. The electrically silent and nonfunctioning sensory fascicles are divided proximal and distal to the neuroma and reconstructed with autogenous nerve grafts. These nerve grafts bypass the functioning motor portion of the neuroma in-continuity.

Adult↗

PubMed2001

The leukocyte common antigen-related protein tyrosine phosphatase receptor regulates regenerative neurite outgrowth in vivo.

Drosophila and leech models of nervous system development demonstrate that protein tyrosine phosphatase (PTP) receptors regulate developmental neurite outgrowth. Whether PTP receptors regulate neurite outgrowth in adult systems or in regenerative states remains unknown. The leukocyte common antigen-related (LAR) receptor is known to be present in rodent dorsal root ganglion (DRG) neurons; therefore, the well established model of postcrush sciatic nerve regeneration was used to test the hypothesis that LAR is required for neurite outgrowth in the adult mammalian nervous system. In uninjured sciatic nerves, no differences in nerve morphology and sensory function were detected between wild-type and LAR-deficient littermate transgenic mice. Sciatic nerve crush resulted in increased LAR protein expression in DRG neurons. In addition, nerve injury led to an increase in the proportion of LAR protein isoforms known to have increased binding affinity to neurite-promoting laminin-nidogen complexes. Two weeks after nerve crush, morphological analysis of distal nerve segments in LAR-deficient transgenic mice demonstrated significantly decreased densities of myelinated fibers, decreased axonal areas, and increased myelin/axon area ratios compared with littermate controls. Electron microscopy analysis revealed a significant twofold reduction in the density of regenerating unmyelinated fibers in LAR-/- nerves distal to the crush site. Sensory testing at the 2 week time point revealed a corresponding 3 mm lag in the proximal-to-distal progression of functioning sensory fibers along the distal nerve segment. These studies introduce PTP receptors as a major new gene family regulating regenerative neurite outgrowth in vivo in the adult mammalian system.

Animals↗

PubMed1996

Sensori-motor function, gait patterns and falls in community-dwelling women.

Tests of vision, vestibular function, peripheral sensation, strength, reaction time, balance and gait were administered to 183 community-dwelling women aged 22-99 years. Walking speed, stride length and cadence declined with age with corresponding increases in stance duration and percentage of the stride in the stance phase. Visual acuity and contrast sensitivity, tactile and vibration sense in the lower limb, vestibular function (as assessed by the vestibular X Writing Test), quadriceps and ankle dorsiflexion strength and reaction time were significantly associated with all five gait parameters. Postural sway measures were associated with walking speed, stride length and percentage of the stride in the stance phase. Multiple regression analyses revealed seven sensori-motor measures as significant predictors for one or more of the gait parameters: low contrast visual acuity, tactile sensitivity, vibration sense, vestibular X-test writing performance, quadriceps strength, reaction time and sway. Quadriceps strength was included as a predictor variable for every gait parameter and in each case had the strongest beta weight. Women who fell on two or more occasions in a one-year prospective period had significantly reduced and more variable cadence and significantly increased stance duration (measured in absolute terms and as a percentage of stride) than those who did not fall or fell on one occasion only. The study findings elucidate the relative importance of specific physiological systems in the maintenance of normal gait and identify temporal gait measures that are associated with falling in older people.

Accidental Falls↗

PubMed1996

Intrathecal catheterization in the rat. Improved technique for morphologic analysis of drug-induced injury.

BACKGROUND: The authors previously described an in vivo model suitable for investigation of functional impairment induced by intrathecally injected local anesthetic. However, meaningful histologic analysis could not be performed because catheterization, per se, induced morphologic changes in control animals. In the current experiments, the authors sought to identify an alternative, less reactive, catheterization technique for intrathecal drug administration. METHODS: Twenty-five rats received an intrathecal infusion of normal saline through a catheter composed of either 28-gauge polyurethane, 32-gauge polyimide, 32-gauge polyurethane, PE-10 polyethylene, or PE-10 polyethylene that had been stretched to twice its original length. Seven days after infusion, sensory function was assessed using the tail-flick test, and the spinal cord and nerve roots were prepared for neuropathologic evaluation. RESULTS: There was no significant difference in sensory function among groups. Animals in which 28-gauge polyurethane, 32-gauge polyimide, PE-10, and double-stretched PE-10 had been implanted had moderate to severe nerve injury in 11%, 14%, 23%, and 8% of fascicles, respectively, whereas none of the animals in which 32-gauge polyurethane was implanted had any evidence of moderate or severe damage. CONCLUSIONS: Morphologic changes induced by intrathecal catheterization in the rat can be minimized by the use of 32-gauge polyurethane tubing.

Animals↗

PubMed2006

Category-specific effects on the identification of non-manipulable objects.

Theories of category-specific effects on visual object identification predict easier identification of non-living than living objects. The Sensory-Functional theory credits greater representational weighting of the visual properties of living objects independent of greater weighting of the functional properties of non-living objects. It predicts a lost or reversed non-living advantage for non-manipulable objects. Normal participants matched pictures of non-manipulable objects with words describing three levels of identity while visual object similarity, and concept familiarity were controlled. Consistent with the Sensory-Functional theory, living objects were matched faster than non-living objects. Concept familiarity facilitated subordinate matches. Visual similarity hampered subordinate matches and facilitated basic matches.

Adolescent↗

PubMed1976

Sacral agenesis. Neurologic and neuropathologic features.

The neurologic deficits in sacral agenesis involve motor function much more than sensory function, in a lumbosacral distribution; autonomic involvement, with neurogenic bladder, is variable. Relative sensory sparing may be due to the derivation of sensory nerves from neural cre, t tissue, which is uninvolved. An occult sacral meningomyelocele with ectopic neural tissue was found at necropsy in one of our patients. Primary amyoplasia may account for small but histologically normal muscles derived from the same somites as the aplastic vertebrae.

Abnormalities, Multiple↗

PubMed2004

Brief report: assessment of sensory abnormalities in people with autistic spectrum disorders.

Sensory functioning has long been considered crucial in the life of people with autistic spectrum disorders (ASD) (Gillberg, C., & Coleman, M. (1992). The Biology of Autistic Syndromes (2nd ed.). London: Mac Keith press.) However, much of the research is methodologically flawed and based on child populations and adults' retrospective accounts (O'Neill, M.C 1995). Sensory-perceptual abnormalities in autism. Psychological Perspectives in Autism-Conference Proceedings 1995 (pp. 55-61). Autism Research Unit, University of Sundarland). Such sensory dysfunction may contribute to poor person/environment fit and subsequent challenging behaviour. This paper presents an assessment tool developed to explore the sensory functioning of adults with ASD.

Adult↗

PubMed2006

Gestational 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure effects on sensory cortex function.

Gestational exposure to environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) poses a significant threat to normal growth and differentiation of the developing brain. To characterize the impact of gestational TCDD exposure on subsequent cortical function, pregnant Long Evans rats were exposed to a single acute dose (100 or 700ng/kg b.w. via gavage) on gestational day 15. This dosing regimen had no significant effect on birth index. After the TCDD-exposed animals were born and reached maturity, neural activity was recorded under urethane anesthesia from neurons in primary somatic sensory cortex. Spontaneous activity was reduced by approximately 50% in barrel cortex compared to corn oil vehicle controls. The magnitude of neuronal response to sensory (whisker) stimuli also was significantly reduced, and responses did not achieve control levels at any stimulus intensity. The greatest deficit was in the short latency component of the cortical responses. These decrements in cortical responsiveness were present in young F1 generation TCDD-exposed animals and persisted for up to 180 days. Because glutamate receptors are crucial to the evoked responses and show developmental regulation, selected iontotropic glutamate receptor subunits (NMDA NR2A+NR2B and GluR1) were profiled for RNA levels in the cortex of F1 generation rats. The expression of NR2B (NMDA receptor) and GluR1 (AMPA receptor) subunits was significantly reduced in the TCDD-exposed F1 generation animals compared to vehicle controls. The results indicate that gestational TCDD exposure results in cortical deficits that are paralled by diminished expression of certain NMDA and AMPA receptor subunits at a time when synapses are being formed for the first time in cortex.

Action Potentials↗

PubMed1997

Somatosensory- and motor-evoked potentials in a rabbit model of spinal cord ischemia and reperfusion injury.

STUDY DESIGN: Occlusion of the infrarenal abdominal aorta was applied to adult rabbits, which induced spinal cord ischemia, followed by disocclusion and reperfusion. Cortical somatosensory- and motor-evoked potentials were monitored continuously up to 24 hours and correlated to hind limb motor and sensory status. OBJECTIVES: To investigate cortical somatosensory-, and motor-evoked potentials in the rabbit model of spinal cord ischemia and reperfusion injury, especially their changes during reperfusion and their relationship to hind limb motor and sensory function. SUMMARY OF BACKGROUND DATA: Various evoked potentials have been widely studied in neurologic prognosis of spinal cord ischemia. Little information is available from previous studies to correlate cortical somatosensory- and motor-evoked potentials with secondary paraplegia occurring during the reperfusion phase. METHODS: Acute spinal cord ischemia was induced in eight anesthetized rabbits by occlusion of the infrarenal abdominal aorta just beneath left renal artery for 40 minutes. Cortical somatosensory-evoked potentials, elicited by stimulating the posterior tibial nerve and recorded at the skull surface corresponding to sensory projection area, and motor-evoked potentials, elicited by stimulating the skull surface corresponding to the motor projection area and recorded at L4 lamina of the vertebral arch, were monitored immediately before and at different time points during ischemia and reperfusion up to 24 hours after disocclusion. Hind limb motor and sensory functions were evaluated and correlated with cortical somatosensory- and evoked-potentials. RESULTS: Cortical somatosensory-evoked potentials disappeared gradually after the start of occlusion and reappeared during reperfusion. Motor-evoked potentials did not change significantly during occlusion, but deteriorated after disocclusion; they correlated well with hind limb motor and sensory status. CONCLUSIONS: Reperfusion injuries to the spinal cord might occur in the rabbit model after disocclusion. Cortical somatosensory-evoked potentials seemed to be a very sensitive index for spinal cord ischemia, whereas motor-evoked potentials correlated well with the course of reperfusion injuries after disocclusion and reflected long-term follow-up hind limb motor function better than cortical somatosensory-evoked potentials.

Animals↗

PubMed1995

The addition of 7.5% glucose does not alter the neurotoxicity of 5% lidocaine administered intrathecally in the rat.

BACKGROUND: Recent reports of major and minor neurologic sequelae after spinal anesthesia have generated concern regarding the safety of some currently used intrathecal agents. The role of glucose, if any, in neurotoxic injury associated with spinal anesthesia is not known. The current experiments sought to determine whether the presence of 7.5% glucose alters the neurotoxicity of intrathecally administered 5% lidocaine. METHODS: Two experiments were performed. First, 48 rats were implanted with an intrathecal catheter and randomly divided into eight equal groups. Each animal received a single intrathecal infusion of 5% lidocaine (groups P1-P4) or 5% lidocaine with 7.5% glucose (G1-G4) for 0.5, 1, 2, or 4 h at a rate of 1 microliter/min. Sensory function was assessed using the tail-flick test; a deficit was defined as a complete lack of response to the heat stimulus at the proximal, mid or distal portion of the tail persisting 4 days after the infusion. In the second experiment, 60 rats were randomly divided into two groups to receive a 1-h intrathecal infusion of 5% lidocaine or 5% lidocaine with 7.5% glucose. Animals were evaluated for increase in the latency of the tail-flick reflex 4 days after infusion. RESULTS: In the first experiment, the two lidocaine solutions produced similar dose-dependent loss of sensory function. In the second experiment, the two solutions induced similar alterations in tail-flick latency. CONCLUSIONS: The presence of 7.5% glucose does not affect the potential of intrathecally administered 5% lidocaine to induce sensory impairment. These findings provide further support for the hypothesis that recent injuries after spinal anesthesia resulted from a direct neurotoxic effect of the local anesthetic.

Anesthesia, Spinal↗