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At least 235 records · Page 13Linked to original sources
PubMed1984

The function of intradental nerves in relation to the sensations induced by dental stimulation.

Stimulation of intradental nerves has been widely used in pain research as a method for selective activation of pain pathways. It is believed that the only sensation experienced by human subjects in response to activation of pulp nerves is that of pain. However, this concept is not strictly correct. With electrical stimulation at threshold level or near to it a sensation which is not necessarily painful ("prepain") is experienced. When the stimulus intensity is increased suprathreshold, the sensation tends to change to a painful and unpleasant one. The changes in sensations are probably caused by activation of intradental nerve units with different thresholds and conduction velocities. In cats the fastest conducting pulp nerve fibres have the lowest thresholds and slowly conducting units are activated at much higher current levels. In most experiments on human teeth using natural stimuli like hot and cold the only sensation experienced has been pain. It seems also difficult for the subjects to find any difference between different stimuli. Correspondingly, in animal experiments it has been shown that different stimuli applied to dentine are capable of activating the same intradental nerve units probably with a common mechanism (hydrodynamic). However, some recent studies indicate that sensation of cold could be induced by stimulating human teeth.

Animals↗
PubMed2002

Internally simulated movement sensations during motor imagery activate cortical motor areas and the cerebellum.

It has been proposed that motor imagery contains an element of sensory experiences (kinesthetic sensations), which is a substitute for the sensory feedback that would normally arise from the overt action. No evidence has been provided about whether kinesthetic sensation is centrally simulated during motor imagery. We psychophysically tested whether motor imagery of palmar flexion or dorsiflexion of the right wrist would influence the sensation of illusory palmar flexion elicited by tendon vibration. We also tested whether motor imagery of wrist movement shared the same neural substrates involving the illusory sensation elicited by the peripheral stimuli. Regional cerebral blood flow was measured with H215O and positron emission tomography in 10 right-handed subjects. The right tendon of the wrist extensor was vibrated at 83 Hz ("illusion") or at 12.5 Hz with no illusion ("vibration"). Subjects imagined doing wrist movements of alternating palmar and dorsiflexion at the same speed with the experienced illusory movements ("imagery"). A "rest" condition with eyes closed was included. We identified common active fields between the contrasts of imagery versus rest and illusion versus vibration. Motor imagery of palmar flexion psychophysically enhanced the experienced illusory angles of plamar flexion, whereas dorsiflexion imagery reduced it in the absence of overt movement. Motor imagery and the illusory sensation commonly activated the contralateral cingulate motor areas, supplementary motor area, dorsal premotor cortex, and ipsilateral cerebellum. We conclude that kinesthetic sensation associated with imagined movement is internally simulated during motor imagery by recruiting multiple motor areas.

Adolescent↗
PubMed2001

P3 event-related potential, dopamine D2 receptor A1 allele, and sensation-seeking in adult children of alcoholics.

BACKGROUND: Research has indicated a close relationship between the P3 event-related potential and the dopamine D2 receptor A1 allele in individuals at high risk for alcoholism. Other research has suggested an association between the dopamine D2 receptor A1 allele and sensation-seeking. In this study, we further examined the relationships between the P3, the A1 allele, and sensation-seeking in a sample of nonalcoholic adult children of alcoholics. METHODS: Participants (n = 57; range, 19-30 years; 41 women), who performed a visual novelty oddball task to elicit the P3, were asked to fill in personality questionnaires, including Zuckerman's Sensation-Seeking Scale, and were classified according to the presence of the dopamine D2 receptor A1 allele. The effects of sex, age, and socioeconomic status were assessed to determine whether these variables affected the relations between the P3, the A1 allele, and sensation-seeking. RESULTS: A small P3 amplitude was associated with high sensation-seeking, particularly with high disinhibition. The presence of the A1 allele was also associated with high disinhibition, but only in men. By contrast, P3 amplitudes and latencies were not associated with the presence of the A1 allele. CONCLUSIONS: Although a small P3 amplitude, high sensation-seeking, and the presence of the A1 allele were all associated with alcoholism risk, these findings indicate that these three characteristics together do not reflect a common risk factor in alcoholism.

Adult↗
PubMed1991

[Blood flow capacity of the vertebra and cervical artery affected by propagated sensation with acupuncture excitation].

The researchers made some improvement of the measure method of head total blood flow capacity. Excitations of propagated sensation were induced in 55 cases of cervical vertebra disease [acupoints: Shousanli (LI 10), Dazhu(UB 11), Shenzhu (Du 12), Houxi (SI 3)], and 66 cases of cerebral ischemia disease caused by insufficiency of vertebra artery blood supply [acupoints: Hegu (LI 14), Quchi (LI 11), Jugu (LI 16), Tianliao (SJ 15)] by acupuncture. The result showed that obvious effect (P less than 0.05-0.01) was found in the group in which propagated sensation reached the affected area, some effect in the propagated sensation group, and little effect in the local sensation group. The result indicated that the method of acupuncture excitation of propagated sensation could relieve vascular and muscle convulsion and ease the degree of vascular tension and obstruction. It could increase the blood flow capacity of cervical and vertebra artery significantly, so that it could play the role of promoting blood circulation to remove blood stasis and improving tissue nutrition and autonomic nerve function. This study showed further that to let acupuncture excited propagated sensation reach the affected area was an important method of promoting clinical effect.

Acupuncture Therapy↗
PubMed1985

Phantom breast sensations following mastectomy.

Eighty-nine patients were studied for the incidence and nature of phantom breast sensations (PBS) after a modified mastectomy. Twenty-nine (33%) reported experiencing pain or itching in the breast or the more vague sensation that the breast was still present. Phantom breast sensations appeared generally within the first 3 postoperative months. The duration varies from a few seconds to a few minutes. There were great individual differences in the frequency at which PBS appeared. Forty-one percent had the experience monthly or more often. All of the patients with a high frequency of PBS (12) belonged to the group of 13 women who suffered under these sensations. The occurrence of PBS was not related to left or right mastectomy, radiotherapy, adjuvant chemotherapy, having a sexual partner, or a history of lactation. At the time of operation, women who later developed PBS generally were younger, premenopausal, more often had children, and had a preoperative history of breast sensations. Before the modified mastectomy, these four factors could be used to indicate the probability at which the woman would develop PBS.

Adult↗
PubMed1991

Changes in anal canal sensation after childbirth.

Obstetic trauma predisposes to faecal incontinence. Anal canal sensation is impaired in incontinent patients. To assess the effect of childbirth on anal canal sensation anal mucosal electrosensitivity was measured in 122 primiparous patients in the immediate postnatal period and in 74 at 6 months postpartum. There were 35 normal vaginal deliveries, 36 forceps deliveries, 20 ventouse extractions, ten vaginal breech deliveries and 21 caesarean sections. Sensation was impaired in the lower, mid and upper anal canal immediately after delivery in those patients who had a normal vaginal delivery or a forceps delivery when compared with controls or with those delivered by caesarean section. Women who had ventouse deliveries had impaired sensation immediately after delivery in the mid anal canal compared with controls and those undergoing caesarean section. By 6 months there were no differences between any group. Patients who sustained a division of the external anal sphincter at delivery had impaired sensation which persisted in the upper anal canal at 6 months.

Anal Canal↗
PubMed2001

Ernst Mach and the episode of the monocular depth sensations.

Although Ernst Mach is widely recognized in psychology for his discovery of the effects of lateral inhibition in the retina ("Mach Bands"), his contributions to the theory of depth perception are not as well known. Mach proposed that steady luminance gradients triggered sensations of depth. He also expanded on Ewald Hering's hypothesis of "monocular depth sensations," arguing that they were subject to the same principle of lateral inhibition as light sensations were. Even after Hermann von Helmholtz's attack on Hering in 1866, Mach continued to develop theories involving the monocular depth sensations, proposing an explanation of perspective drawings in which the mutually inhibiting depth sensations scaled to a mean depth. Mach also contemplated a theory of stereopsis in which monocular depth perception played the primary role.

Austria↗
PubMed1995

Paradoxical heat sensation in uremic polyneuropathy.

Sensory aspects of uremic neuropathy were studied in 36 patients using clinical assessment and quantitative sensory tests (QST). The outstanding abnormality in sensory quality was perception of heat in response to low temperature stimuli. This paradoxical heat sensation was found in the foot in 42% (15) of patients, far beyond the normal prevalence of 10%. Paradoxical sensation was positively related to cold hypoesthesia (P = 0.0004) suggesting disinhibition as a possible mechanism. Paradoxical heat sensation also positively related to creatinine level (P = 0.0012). Pruritus was present in 20 patients (56%), intensity not related to any biochemical or clinical parameter. Signs of sensory polyneuropathy (PNP), based on at least two abnormal parameters in the clinical assessment or QST, were found in 39% of patients (14), of whom 11 had paradoxical heat sensation. Thus, in 4 patients (11%), this sensory aberration preceded other signs for PNP. Paradoxical heat sensation seems to be a common and often early expression of the sensory neuropathy in uremia.

Adolescent↗
PubMed1984

Influence of skin temperature distribution on thermal sensation in a cool environment.

Thermal sensation and distribution of skin temperatures in persons exercising at 36.5 W on a bicycle ergometer and resting in a cool environment (10 degrees C) in two different clothings, one with the insulation mainly over the trunk (1.22 clo), and one with well insulated limbs (1.67 clo), were studied. Their general thermal sensations varied from slightly warm to slightly cool. The placing of the insulation had a decisive influence on skin temperature distribution, so that skin temperature was always high in well-insulated areas. When the insulation was placed over the limbs, a greater amount of heat was lost than if a similar insulation was placed on the trunk. Neither Tsk nor skin temperature distribution correlated with general thermal sensation. Instead, mean body temperature seemed to be the determinant of general thermal sensation in these conditions. The best prediction of general thermal sensation was obtained by adding Tre with a weighting factor of 0.8-0.9 and Tsk with a weighting factor of 0.1-0.2.

Adolescent↗
PubMed1995

Psychosensory modulation of colonic sensation in the human transverse and sigmoid colon.

BACKGROUND & AIMS: Psychosensory stimulation increases the perception of stimuli in different regions of the human colon. The aim of this study was to determine the perception of pain and gas during distention of two colonic regions in healthy volunteers during stress and relaxation. METHODS: In 22 healthy subjects, phasic distentions of transverse and sigmoid colon were performed using infinitely compliant balloons, and symptoms were measured before and during one of three randomized treatments: sham or active relaxation or mental stress. Anxiety ratings and somatic cold-pain sensitivity were included in a multivariate regression model. RESULTS: Mental stress increased levels of anxiety (P < 0.05) and the sensation of gas (P < 0.01), but not pain (P = NS), during transverse colon distentions and the sensations of gas and pain during sigmoid distentions (P < 0.05). Active relaxation reduced only sensation of gas in the sigmoid colon. Somatic pain sensitivity and pretreatment colonic sensory scores were significantly associated with the sensory scores during treatments. CONCLUSIONS: Psychosensory stimulation increases colonic sensation during short-term distention in two regions of the human colon; relaxation alone exerts a smaller influence on sensations arising in the sigmoid colon.

Adult↗
PubMed1992

Altered sensation following mandibular implant surgery: a retrospective study.

To determine the prevalence of complications involving altered sensation after implant surgery in the mandible, a retrospective questionnaire study was conducted of 266 patients treated with osseointegrated implants. Of the responding patients (80%), 37% reported altered sensation following implant surgery, with long-term changes occurring in 13% of patients. In more than 60% of symptomatic patients the onset was within 1 week of the first stage of surgery and most frequently involved the lip and chin. Resolution of transient changes usually occurred within 6 months and the majority of patients who reported alterations in sensation believed that the benefits of the implant surgery outweighed the disadvantages experienced. The prevalence of altered sensation was significantly higher in women compared with men and in those with a history of diabetes. These data indicate the need for prospective studies to further evaluate altered sensation after mandibular implant surgery so that specific risk factors can be identified and more accurate information made available to prospective patients.

Activities of Daily Living↗
PubMed1989

The contribution of the nasopalatine nerve to sensation of the hard palate.

This study investigates which areas of the hard palate are innervated by the nasopalatine nerve and determines whether division of this nerve results in a detectable alteration in sensation. In the first part of this study the area of the hard palate from which sharp and blunt sensation could be evoked was investigated in 20 subjects after anaesthetising both anterior (formerly greater) palatine nerves. Sensation remained in the region of the incisive papilla and gingival margin of the central incisors in all patients and, in some, extended as far back as the first premolars. In the second part of the study, sharp and blunt sensation of the hard palate were tested before and after incisive bundle division. No significant alteration in sensation was found in any of the 20 patients tested.

Adolescent↗
PubMed1996

Detection, discrimination and sensation of visceral stimuli.

Afferent visceral signals serve mostly regulatory functions and produce vague, diffuse body sensations, which are not well reflected in experimental paradigms requiring distinct and localized 'visceral perceptions'. A series of studies is summarized which compared behavioral discrimination of gastrointestinal distension stimuli with subjective sensation ratings in relation to basic perceptual operations such as detection, localization, graduation, and identification. Results showed that detection of gastrointestinal stimuli is possible without the subject's awareness (discrimination without reportable sensation). This process does not depend on stimulus intensity at volumes below those sufficient for subjective sensation. The latter is necessary, however, for intensity discrimination (graduation). Contrary to exteroception (e.g. vision), conscious subjective sensation is also required for stimulus localization. These differences in processing could not be explained by simple differences in response criteria. An intensity-dependent two-process model of gastrointestinal interoception is derived which differs from standard models of somatosensory information processing.

Adult↗
PubMed2005

Corneal barrier function, tear film stability, and corneal sensation after photorefractive keratectomy and laser in situ keratomileusis.

PURPOSE: To compare corneal sensation, corneal barrier function, tear secretion, and tear film stability after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). DESIGN: Prospective, nonrandomized clinical trial. METHODS: In a prospective study, 28 eyes of 15 patients underwent PRK and 115 eyes of 59 patients underwent LASIK to correct myopia. Corneal sensation, corneal epithelial barrier function, tear secretion, and tear film stability were examined preoperatively and 1 week and 1, 3, 6, and 12 months postsurgery. RESULTS: Both PRK and LASIK significantly compromised corneal sensation, increased epithelial barrier function, reduced tear secretion, and deteriorated tear film stability (P < .05, Wilcoxon signed-rank test). Deterioration of corneal sensation was significantly greater after LASIK than after PRK by 3 months postoperatively (P < .05, Wilcoxon rank sum test). Increases in corneal epithelial permeability were more prolonged after LASIK than after PRK. A significant intergroup difference in permeability was observed 1 month after surgery (P < .01). Tear breakup time was significantly shorter in the LASIK group than in the PRK group up to 3 months after surgery (P < .045). CONCLUSIONS: LASIK induces greater and more prolonged damage to corneal sensation, corneal barrier function, and tear film stability than PRK.

Adolescent↗
PubMed2005

Is catheter cause of subjectivity in sensations perceived during filling cystometry?

OBJECTIVES: To investigate the impact of the catheter on perceptions of filling. In our previous study, we demonstrated that some patients perceived sensations despite a lack of filling during cystometry. METHODS: The study included 45 patients with lower urinary tract symptoms attributed to benign prostatic hyperplasia. The average patient age was 57.9 years (range 48 to 79). Patients were draped to keep them from seeing their penis and the filling bag, pump, and screen process. In the first phase, the catheter was fixed to the penile skin without introducing it through the urethra, and the patient was told the test had begun. At the end of the first phase, the bladder was emptied. Before the second phase, an 8F urodynamic catheter was introduced, but during the test, nothing was infused. During the third phase, filling cystometry was performed with a 50-mL/min pump speed. The bladder was emptied after all three phases. The times that elapsed until each sensation was perceived, in seconds, were used to compare the sensations. RESULTS: In the first phase, 21 patients reported a first sensation, 10 reported first desire, and 4 reported normal desire, despite a lack of catheterization. No statistically significant difference was found between the mean first sensation/first desire, first sensation/normal desire, first desire/normal desire ratios of the patients who perceived sensations in the three phases and the strong desire/normal desire ratios of the patients in the second and third phases (P >0.05 for all). CONCLUSIONS: Although the perceptions were reported in the first and second phases, the catheter could not be the sole cause of the subjectivity.

Aged↗
PubMed1995

Decreased corneal sensation as an initial feature of Acanthamoeba keratitis.

BACKGROUND: Herpes simplex keratitis is the most common misdiagnosis in patients with Acanthamoeba keratitis, which is increasing in frequency and is associated with daily wear soft contact lenses. Both entities usually present as unilateral keratitis. The manifestations of superficial Acanthamoeba keratitis (i.e., unilaterality, dendriform appearance, positive response to antivirals, and decreased corneal sensation) increase the opportunity for misdiagnosis as herpes simplex keratitis. The authors have encountered six patients with Acanthamoeba keratitis in whom the correct diagnosis was delayed from 2 weeks to 3 months. METHODS: All six patients underwent testing with the Cochet-Bonnet esthesiometer and extensive pharmacologic treatment for herpes simplex keratitis. Corneal scrapings were taken between 2 and 6 weeks after the initial examination. RESULTS: In all six patients, corneal sensation was decreased significantly. Drug therapy was ineffective. Cultures were positive for Acanthamoeba. Five of six patients underwent penetrating keratoplasty. CONCLUSIONS: Decreased corneal sensation has contributed to the misdiagnosis of Acanthamoeba as herpes simplex keratitis. Misdiagnosis results in delayed treatment and worse outcome. The authors found that significantly decreased corneal sensation is a frequent finding in early Acanthamoeba keratitis. Therefore, physicians should consider Acanthamoeba keratitis as an alternative diagnosis in patients with presumed herpes simplex keratitis with decreased corneal sensation.

Acanthamoeba↗
PubMed2003

Sensation seeking and startle modulation by physically threatening images.

The potential moderating effect of sensation seeking on anxious reactivity to threatening experiences was assessed using the affective modulation of startle-blink paradigm. Startle blinks, as measured by electromyographic (EMG) activity in response to loud (100 dB) white-noise stimuli, were elicited during the presentation of positive, neutral, and threatening visual images. Unlike participants low in sensation seeking who showed blink potentiation during threatening versus neutral images, participants high in sensation seeking showed equal magnitudes of startle to neutral and threatening images. The results suggest that individuals high compared with low on sensation seeking are less anxiously reactive to physically threatening visual stimuli. No attenuation in startle magnitude was elicited by positive images among low or high sensation seekers suggesting that the positive images employed in the current study were not arousing enough to activate the appetitive arousal system.

Adolescent↗
PubMed2004

Visual sensation during phacoemulsification and intraocular lens implantation using topical and regional anesthesia.

PURPOSE: To evaluate patients' visual sensations at different stages of phacoemulsification and posterior chamber intraocular lens (PC IOL) implantation under topical and regional anesthesia. SETTING: Department of Ophthalmology, United Christian Hospital and Tseung Kwan O Hospital, Kowloon, Hong Kong, China. METHODS: Seventy-six consecutive patients having phacoemulsification were randomized to a topical anesthesia group (n = 35) or regional anesthesia group (n = 41). The topical anesthesia group received lidocaine hydrochloride 2% gel (Xylocaine) and the regional anesthesia group, a peribulbar or retrobulbar injection of lignocaine 2%. The patients' visual sensations, including light and color sensations, shape of objects, and visual patterns, were evaluated at different stages of surgery. RESULTS: Two patients (4.9%) in the regional anesthesia group and none in the topical anesthesia group experienced total loss of light sensation throughout surgery (P =.50). There was a significant association between color perception and the type of anesthesia at stages 1 and 2 (P<.05) but not at stages 3, 4, and 5 (P>.05). The perception of objects and visual patterns had no association with the type of anesthesia at any stage (P>.05). Of all patients in the study, 56 (73.7%) reported color changes as surgery proceeded. Both groups saw waves, defined as curves with periodic fluctuations in amplitude, at all stages. The perception of some colors and a rectangular moving object was significantly associated with the type of anesthesia at some or all stages (P<.05). CONCLUSIONS: Patients having phacoemulsification and PC IOL implantation under topical or regional anesthesia had a wide spectrum of visual sensations that were similar at most stages of surgery. Patients in the topical anesthesia group perceived more colors at the early stages and more blue throughout surgery than patients in the regional anesthesia group.

Aged↗