Left Fingertip Research Articles

Contribution of visual and proprioceptive information to the precision of reaching movements

Ren et al. (J Neurophysiol 96:1464-1477, 2006) found that saccades to visual targets became less accurate when somatosensory information about hand location was added, suggesting that saccades rely mainly on vision. We conducted two kinematic experiments to examine whether or not reaching movements would also show such strong reliance on vision. In Experiment 1, subjects used their dominant right hand to perform reaches, with or without a delay, to an external visual target or to their own left fingertip positioned either by the experimenter or by the participant. Unlike saccades, reaches became more accurate and precise when proprioceptive information was available. In Experiment 2, subjects reached toward external or bodily targets with differing amounts of visual information. Proprioception improved performance only when vision was limited. These results indicate that the reaching system has a better internal model for limb positions than does the saccade system.

Measurement of Plethysmogram and Statistical Method for Analysis

The plethysmogram is measured at different points of human body by using the photo interrupter, which sensitively depends on the physical and mental situation of human body. In this paper the statistical method of the data-analysis is investigated to discuss the dependence of plethysmogram on stress and aging. The first one is the representation method based on the return map, which provides usuful information for the waveform, the flucuation in phase and the fluctuation in amplitude. The return map method makes it possible to understand the fluctuation of plethymogram in amplitude and in phase more clearly and globally than in the conventional power spectrum method. The second is the Lisajous plot and the correlation function to analyze the phase difference between the plethysmograms of the right finger tip and of the left finger tip. The third is the R-index, from which we can estimate “the age of the blood flow”. The R-index is defined by the global character of plethysmogram, which is different from the usual APG-index. The stress- and age-dependence of plethysmogram is discussed by using these methods.

Methods for measuring agreement: glucose levels in gingival crevice blood

The aim of the present study was to compare conclusions drawn by two different methods for comparison of blood glucose determination in capillary fingerstick blood (CFB) and gingival crevice blood (GCB). Glucose levels in CFB and GCB oozing from the gingiva after periodontal probing were measured in 31 patients with gingivitis or periodontitis using a novel, very sensitive self-monitoring device (Freestyle, TheraSense Inc.) developed for off-finger tip glucose testing. Correlation analysis revealed that measurements of glucose levels in CFB from left and right finger tips were highly correlated pointing to excellent performance of the device, whereas CFB and GCB measurements were moderately, but highly significantly, correlated. A thorough analysis of agreement revealed, on the other hand, questionable performance of the device for screening hypoglycaemic patients. The mean difference of measurements in CFB samples was +3.2+/-12.7 mg/dl. The 95% limits of agreement were -21.7 and +28.2. The mean difference of glucose determination in CFB and GCB samples was -22.0+/-26.6 mg/dl, and limits of agreement were -74.4 and +30.1. By plotting differences on means of measurements and doing linear regression analysis no systematic trend of change in differences with increasing mean of measurements was ascertained. Analysis of agreement revealed that performance of the Freestyle measuring device yielded considerably large limits of agreement, and gingival crevice blood cannot be recommended for measuring blood glucose levels.

Stance stability with unilateral and bilateral light touch of an external stationary object

Unilateral light fingertip touch of a stationary object has a significant stabilizing effect on postural sway during stance. The purpose of this study was to find out if this effect is enhanced by bilateral light touch of parallel stationary objects. The postural sway of 54 healthy subjects was tested in four stance conditions: no touch; unilateral left light touch of the left handle of a walker; unilateral right light touch of the right handle of the same walker; and bilateral light touch of the two handles. During testing, subjects stood blindfolded on two foam pads placed on the left and right force plates of the Tetrax balance system. Testing in each condition lasted 45 s and was executed twice in a random order. As expected, postural sway was significantly reduced by unilateral left or right light fingertip touch. It was significantly further decreased by bilateral light touch. In addition, light touch conditions were associated with a reduction in pressure fluctuations between the heel and forefoot of the same foot as well as those of the contralateral foot, with a concomitant increase in weight shift fluctuations between the two feet. The decrease in postural sway with bilateral light touch suggests cortical modulation of the bilateral touch inputs, with enhancement of the stabilizing response.

A Case of Solitary Glomus Tumor

We report a case of subungual solitary glomus tumor in a 28-year-old female, who has suffered from pain and tenderness of the left 4th finger tip for about 5 years. Simple surgical excision was performed for removal of the tumor mass and for the relief of the subjective symptoms. No recurrence has been observed for 5 months following excision of the tumor.

Partial masking in electrocutaneous sensation: a model for sensation matching, with applications to loudness recruitment.

A model for partial masking and other threshold-elevation effects is presented in the context of a sensation-matching paradigm. The model is applied to an electrocutaneous experiment in which the subjects adjusted stimulus intensity on the right-hand fingertip to match sensation levels of standard stimuli presented to the left fingertip. Concurrent mechanical stimulation on the right fingertip masked sensation magnitude in a way consistent with the model. Similarities between this tactile masking effect and analogous auditory phenomena are explored. When applied to loudness matching, the model describes the general shape of loudness contours and it shows that the steep slopes observed in auditory masking and "recruitment" can be a consequence of a threshold shift alone, without a supranormal growth in loudness. The model also shows that a small response bias can distort plots of sensation matching, leading to the suggestion that some varieties of loudness recruitment may not have a sensory basis.

Essential hyperhidrosis: Correlation of digital blood flow and capillary ultrastructure after unilateral sympathectomy

A patient with essential hyperhidrosis was studied in whom complete relief was effected on the left side by unilateral sympathectomy, whereas the nonsympathectomized right side remained hyperhidrotic. Rheoplethysmographic recordings of digital blood flow were obtained, and capillaries in digital biopsy specimens from right and left fingertips were examined electron microscopically. The volumes and rates of inflow were greater in the nonsympathectomized right fingertip than in the sympathectomized left fingertip in a comfortable environment; and the volumes and rates of blood flow in the right fingertip changed appreciably with ambient temperature changes, whereas the blood flow to the left fingertip changed little. The lumens of the capillaries in the nonsympathectomized right fingertip appeared dilated as compared with those of the left fingertip which were constricted. These data indicate that (1) the cells of the capillary endothelium may change significantly in size and shape to alter capillary luminal diameter, and (2) capillaries may participate in the generalized disorder of the sympathetic nervous system associated with essential hyperhidrosis.

Effects of Cold and Hot Stimuli on Peripheral Vascular System of Workers in Hot Environments

The static conditions of peripheral vascular systems were observed on the workers in hot environments and dynamic changes to cold and hot stimuli were also examined.Six men 22 to 27 years old engaged in hot environments for about three years were originally selected for this study, and simultaneously six clerks of the same ages were examined as a control group. They were measured before and after working in summer and winter respectively on the changes of capillary figures and pulse waves in the left fingertip skin at the room temperature, than on the changes to cold and hot stimuli (7±2°C, 49±2°C) for every ten seconds applied on the back of the same hand. The results obtained were as follows: 1) The effects of working in hot environments were not found in the width of skin capillary figures, but a tendency toward lowering after working was seen in the visible height of capillaries, especially in summer. 2) Ordinary redustions in the amplitude of pulse waves were observed after working in both seasons, but these changes were not shown as characterisitic of the hot environmental group. It is considered that the tension of peripheral blood vessels may be changed by working. 3) The chnges to cold stimuli before working were observed to be more insensitive (prolongation of the reaction time) in summer, more sensitive in winter in the hot environmental group, than that of the control group, and no significant changes were found between the both groups after working. The changes to hot stimuli before working were also observed to be more sensitive in the hot envitonmental group than that of the control group, especially in summer, but no significant difference after working was shown between the both groups. In winter, a tendency of sensitive reaction was seen in the hot environmental group after working compared with the control group, in spite of no significant difference was recognized in both groups before working. The workers engaged in hot environments are relatively stable for cold stimuli and labile for hot stimuli after working and it suggests that the acclimatized workers have been prepared to escape the heat stress in the body. 4) As a rule, the crest time shortens in winter compared with summer. The ratio of the time necessary for constriction of blood vessels to the duration of pulse waves (t/d) was lower in the hot environmental group than the control group before working, especially in summmer, but this difference was not significant between the both groups after working.