One-year reliability of vibration sensitivity thresholds in human beings.

Vibration sensitivity of the 3rd and 5th digits was evaluated in 36 female volunteers (between 22 and 36 years of age at the beginning of the study) previously screened for the absence of neurological disorders. Both fingers were tested in the same subjects on weeks 1, 2 and 52 in a balanced crossover design. Twenty-nine volunteers completed all 3 sessions. All participants gave their informed consent prior to participation. The test session was divided into trials. Each trial consisted of 2 sequential intervals, identified by a signal, and vibration was applied to the fingertip during either the first or the second interval. The subject was instructed to press the push button corresponding to the interval that contained vibration (two-interval forced-choice procedure). Vibration amplitudes were varied according to the up-down transformed rule for the estimation of the amplitude corresponding to 75% correct detection. Vibration sensitivity thresholds were stable as reflected by the lack of a trend over time, and by the compound symmetry of the variance-covariance matrix, which reflects stability of threshold variances as well as of intersession correlations over time. Reliability of vibration sensitivity makes this test potentially suitable for longitudinal evaluation of somatosensory functions.

Behavioral effects of 0 and 0.05% blood alcohol in male volunteers.

Five behavioral tests were evaluated to determine their sensitivity to the subtle central nervous system (CNS) depressant effects produced by ingestion of ethanol. Twenty-one adult male volunteers received 0 and 1.4 ml 100 proof vodka/kg body weight according to a "double-blind" crossover design. Behavioral tests were conducted between 15 and 65 minutes after ethanol ingestion, when blood alcohol concentrations (BAC's) were between 0.05 and 0.06%. Tests evaluated were Archimedes spiral, digit span memory, critical flicker fusion, stabilometry and tachistoscope. Multivariate analysis of variance (MANOVA) using composite scores representing the individual tests indicated that the battery as a whole was sensitive to ethanol effects. Repeated measures analysis of variance (ANOVA) on each test indicated that critical flicker fusion, stabilometry and tachistoscope contributed more to the overall sensitivity of the battery than did digit span memory and Archimedes spiral.

Validation of human behavioral tests using ethanol as a CNS depressant model.

This study evaluated the sensitivity of a battery of tests proposed for use in determining the depressant effects of chemicals on human central nervous system (CNS) function. The first step in the development of such tests was to determine if the tests could detect the effects produced by a known CNS depressant, ethanol. Five behavioral tests, digit span memory, simple reaction time, tachistoscopic perception, flicker fusion and anticipation timing (velocity estimation) were evaluated to determine their sensitivity to the effects of ethanol at blood levels between 0.05-0.06%. Thirty-one adult male volunteers received 0 and 1.4 ml 100 proof vodka/kg body weight according to a double-blind crossover design. Tests were conducted before treatment and between 30 and 70 minutes after an ethanol or control drink was ingested. Multivariate analysis of variance (MANOVA), using composite scores representing the individual tests, indicated that the battery as a whole detected statistically significant ethanol effects. Repeated measures analysis of variance (ANOVA) comparing performance after drinking ethanol to control performance on each of the individual tests indicated a significant decrement in reaction time, tachistoscopic perception and anticipation timing.