Two immunohistochemically identified populations of calcitonin gene-related peptide (CGRP)-immunoreactive axons in human skin

Double labelling immunofluorescence has shown two populations of unmyelinated sensory axons in human skin that contain immunoreactivity (IR) to calcitonin gene-related peptide (CGRP). One population also contains IR to substance P (SP), whilst the other also contains IR to somatostatin (SOM). Axons containing both CGRP-IR and SOM-IR comprised more than 75% of CGRP-IR axons associated with the epidermis; the rest of the CGRP-IR axons contained SP-IR. No axons contained both SP-IR and SOM-IR. Some dermal blood vessels were surrounded by axons containing both CGRP-IR and SP-IR, but most CGRP-IR perivascular axons contained SOM-IR without SP-IR. Sweat glands were well supplied with sensory axons containing CGRP-IR and weak SOM-IR but not SP-IR. Therefore, CGRP is a histochemical marker for a larger number of unmyelinated cutaneous afferents in human skin than is SP. CGRP itself may have a role in the mediation of responses to stimulation of at least two populations of sensory axons.     

Cortical evoked potentials and somatosensory perception in chronic spinal cord injury patients

The correlation between somatosensory evoked potentials (SEPs) and sensory perception was studied in 110 patients with traumatic chronic spinal cord lesions. Perception thresholds over the legs for light touch, vibratory sensibility, temperature and thermal pain were tested together with recordings of tibial and peroneal SEPs. Tibial nerve SEPs correlated better with sensory perception than peroneal nerve SEPs. Normal tibial nerve SEPs were not present with absent or trace vibratory sensibility and vice versa. However, we found many exceptions to the correlation between temperature and pain perception and SEPs. Light touch, vibratory sensibility, and SEPs were highly correlated between each other, while temperature and pain perception correlated poorly to these other modalities. This represents an evident segregation of touch perception, vibratory sensibility and SEPs, which are thought to share dorsal columns as a common ascending pathway, and temperature and pain perception known to be related to the spinothalamic system.     

基于Sihler’s技术的踝和足背皮神经的整体分布模式研究

目的 揭示踝及足背皮神经的整体分布模式,为皮瓣移植感觉重建提供形态学指导。 方法 成年尸体24具,紧贴肌表面摘取含皮下脂肪的踝及足背皮肤,用改良的Sihler’s染色法显示并观察皮神经整体分布模式。 结果 在Sihler’s染色的标本中,肉眼可见隐神经支配踝前区（40.01±7.6）%、踝后区（30±6.7）%、以及部分足背内侧缘。腓浅神经支配踝前区（60.03±6.8）%,其足背内侧皮神经支配足背内侧区、第1、2趾背及第3趾背内侧半;95.83%的足背中间皮神经分布到第3趾背外侧半、第4、5趾背。腓肠神经支配踝后区（70±5.3）%,其足背外侧皮神经支配足背外侧缘皮肤。腓深神经分布到第1、2趾背相对面。初级神经支密度以踝前区最高,次级及以下神经支密度和总的神经支密度均以足背内侧区最高。 结论 在踝或足背的皮瓣移植中,建议把踝前区或足背内侧区设计为利于感觉重建的首选供区或感觉需求较高的受区。     

受虐待小学生感觉统合能力的发展特点及其与虐待经历的关系

目的 探讨受虐待小学生感觉统合能力的发展特点及其与各种儿童虐待形式的关系.方法 对179例小学生进行了儿童期虐待史自评量表(PRCA)和儿童感觉统合能力发展评定量表(SIFS)测试.结果 受虐待组小学生SIFS各因子分均低于无虐待组,9～10岁组在学习能力发展维度的得分高于11～12岁组[(34.20±6.02)分vs(31.85±7.92)分,t=2.26,P＜0.05];男女生之间SIFS各因子分没有明显差异.PRCA各因子分和总分与SIFS各因子分呈负相关(r=-0.154～-0.513,P＜0.05或P＜0.01).忽视对大肌肉及平衡、触觉防御及情绪、本体感不佳和学习能力发展不良均具有负向预测作用(Beta值=-0.161～-0.309,t=-2.126～-4.722,P＜0.05或P＜0.01);性虐待对大肌肉及平衡、本体感不佳和学习能力发展不良具有负向预测作用(Beta值=-0.213～-0.293,t=-2.778～-3.967,P＜0.01);情感虐待对触觉防御及情绪和学习能力发展不良具有负向预测作用(Beta值=-0.168～-0.201,t=-2.375～-2.771,P＜0.05或P＜0.01);本研究中未发现躯体虐待有任何预测作用.结论 儿童虐待可对小学生感觉统合能力的发展造成不良影响,情感虐待、忽视和性虐待可显著预测个体的感觉统合能力发展水平.     

腰骶脊髓损伤患者肛管直肠功能障碍的研究

目的研究腰骶脊髓损伤患者肛管直肠功能状况。方法以115例腰骶脊髓损伤患者为脊髓损伤组,以22例尿道下裂和血尿患者为对照组,检测两组的肛管直肠功能。结果脊髓损伤组最大肛管收缩压为(56.7±31.1)mmHg(1mmHg=0.133kPa),对照组为(87.2±29.2)mmHg,两组比较,差异有统计学意义(P<0.01);在行咳嗽动作时,脊髓损伤组31例(27.0%)肛管压力瞬时升高,但之后出现大幅度、持续性下降;在行模拟排便动作时,97例(84.3%)表现为盆底功能紊乱型肛管直肠压力曲线。直肠肛管抑制反射在所有受检者均存在,脊髓损伤组诱发持续性直肠肛管抑制反射所需直肠气囊容量和直肠感觉阈值分别为(134.8±48.5)ml和(95.9±54.3)ml,对照组分别为(55.9±17.9)ml和(42.3±13.1)ml,两组比较,差异均有统计学意义(P<0.01)。结论多数腰骶脊髓损伤患者不能自主收缩肛门外括约肌,直肠感觉功能受到严重损害;部分腰骶脊髓损伤患者咳嗽肛管反射通路可能受到损害;直肠肛管抑制反射可能受到中枢神经系统的调控。     

Differentiation of pain ratings in combat-related posttraumatic stress disorder

Although posttraumatic stress disorder (PTSD) is associated with chronic pain, preliminary evidence suggests reduced experimental pain sensitivity in this disorder. The questions addressed in the present study were whether pain perception would also be reduced in PTSD patients who are not suffering from chronic pain symptoms, and whether a reduction in pain sensitivity would also be present in combat veterans who did not develop PTSD. For this, we determined thermal detection and pain thresholds in 10 male combat-related PTSD patients, 10 combat control subjects (no PTSD) and 10 healthy controls without combat experience. All subjects were pain free. First, we measured thermal sensory thresholds with ramped heat and cold stimuli using the method of limits. Ramped thermal sensory stimulation revealed no deficits for the detection of (non-noxious) f2.1thermal stimuli between groups. In contrast, heat and cold pain thresholds in both combat groups (PTSD and combat controls) were significantly increased compared to healthy controls. However, these stimuli could not distinguish between the two groups due to ceiling effects. When using longer-lasting heat stimulation at different temperatures (30 s duration; method of fixed stimuli), we found significantly lower frequency of pain reports in PTSD patients compared with both combat and healthy controls, as well as significantly lower pain ratings. Our results suggest an association of PTSD with reduced pain sensitivity, which could be related to PTSD-related (neuro-)psychological alterations or to a pre-existing risk factor for the disorder.     

Effect of reduced cutaneous cues on motion perception and postural control

To investigate whether the sensory perception could be a more direct assessment of sensory deficit as oppose to the postural performance, we examined the effect of reduced cutaneous cues on motion perception and motion control. The subject was translated in a mediolateral direction with a single sinusoidal acceleration at a stimulus frequency of 0.25 Hz with a peak acceleration magnitude ranging from 0.25 to 8 mG in the dark. Two different plantar cutaneous conditions were provided: the control condition (barefoot) and the reduced cutaneous condition (foot on a spongy surface). For each foot-sole sensory condition, the subject completed six sets of 33 randomly ordered translation stimuli. After each translational stimulus, the subject reported their perceived direction of motion by pressing a hand-held button. The center of pressure (COP) and joint kinematics of the quiet stance were also measured. The results showed a significant increase in perception threshold as well as COP variation in the anteroposterior direction in the reduced cutaneous cue trials. However, a non-significant increase in COP in the mediolateral direction was shown. Multivariate covariance analysis of joint kinematics showed changes in postural coordination, such as increased reliance on hip strategy under reduced cutaneous cues condition, that have not been differentiated by univariate measures. The observed discrepancy in the significance of the contribution of plantar cutaneous cues to the detection threshold and the COP variation implies that the ‘perception’ could provide more direct and sensitive assessment of the sensory degradation than the ‘action’.     

Tactile-auditory saltation: Spatiotemporal integration across sensory modalities

The perceptual phenomena of sensory saltation involve the systematic displacement of a target stimulus (the attractee) towards a subsequent stimulus (the attractant), which occurs closely in time and space. Here, we demonstrate the existence of cross-modal tactile-auditory saltation. Tactile stimuli were delivered to the forehead and spatially congruent stereoscopic auditory stimuli were presented via headphones to a total of 20 participants. After a reference stimulus at one of five spatial positions, the attractee was presented at a fixed position, followed by the attractant at a different fixed position with a delay of 81, 121, or 181 ms. Participants rated whether the attractee was perceived left or right of the reference in 2 uni-modal and 2 cross-modal (different reference/attractee vs. attractant mode) configurations. Saltation was present in all uni- and cross-modal configurations at an attractee-attractant delay of 81 ms. At delays of 81 ms the overall displacements were stronger than at delays of 121 ms, and tactile attractants generally induced stronger displacements than auditory attractants. The results indicated the existence of cross-modal tactile-auditory saltation, suggesting the application of the saltation phenomenon as a powerful approach for examining multi-modal sensory representations in future studies.     

Down regulation of TRPC1 by shRNA reduces mechanosensitivity in mouse dorsal root ganglion neurons in vitro

Mechanosensitivity is a crucial but poorly understood property of the sensory nervous system. Transient receptor potential (TRP) channels, which have been found to be responsible for the detection of other sensory stimuli such as temperature and pungent chemicals, have been suggested to also recognize stretch or pressure to cell membranes. TRPC1 is one candidate from studies in oocytes but evidence in native sensory neurons has been lacking. Therefore, we have measured an increase in intracellular Ca²⁺ levels upon mechanical activation of native mouse dorsal root ganglion (DRG) neurons in culture using hypoosmolar buffer. Our results show that down regulation of TRPC1 with short hairpin RNA results in a 65% reduction of neurons with stretch activated responses. These results implicate a direct or indirect involvement of TRPC1 in the mechanosensitivity of DRG neurons.     

Immunohistochemical colocalization of TREK-1, TREK-2 and TRAAK with TRP channels in the trigeminal ganglion cells

TREK belongs to a subfamily of tandem pore domain K⁺ channels, and consists of three subunits, TREK-1, TREK-2 and TRAAK. We examined the distribution of TREK-1, TREK-2 and TRAAK immunoreactive neurons in rat trigeminal sensory neurons. In the trigeminal ganglia, 31%, 43% and 60% of neurons were immunoreactive for TREK-1, TREK-2 and TRAAK, respectively. Mean sizes of TREK-1, TREK-2 and TRAAK immunoreactive trigeminal ganglion neurons were 447 ± 185, 445 ± 23 and 492 ± 12 mm², respectively. Furthermore, TREK channels were colocalized with cationic TRP channels, TRPV1, TRPV2 and TRPM8. TREK-1 immunoreactive neurons were colocalized with TRPV1 (57%), TRPV2 (11%) and TRPM8 (33%). TREK-2-immunoreactive neurons were colocalized with TRPV1 (33%), TRPV2 (9%) and TRPM8 (19%). TRAAK immunoreactive neurons were colocalized with TRPV1 (47%), TRPV2 (10%) and TRPM8 (22%). The present results revealed that TREK-1, TREK-2 and TRAAK channels colocalized with thermosensitive TRP channels in some small trigeminal ganglion neurons.