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P Wade

Publications and source records attributed to P Wade.

26 records · Page 2Linked to original sources
PubMed1982

A normative study of postural tremor of the hand.

In a normative study of amplitude, frequency, and variability of postural tremor of the hand in 97 normal subjects, 15 to 80 years old, tremor was transduced using accelerometers and characterized by power spectral analysis. Tremor amplitude ranged from a 0.0015- to 0.035-g peak at the dominant frequency. The modal tremor amplitude was 0.01-g peak, and the threshold for "visible tremor" was 0.007-g peak. The modal tremor frequency was constant at about 7 Hz in those subjects up to 70 years old and thereafter decreased to about 6 Hz. The mean range of variability of the dominant frequency was 2.5 Hz. The tremor pattern, characterized by the shape of spectra, varied greatly from a single finely tuned peak to multiple broad peaks. More than two thirds of normal subjects showed complex spectral patterns with more than one peak of significance. Passive resonance of the hand tissues was an important factor in determining dominant tremor frequencies in most subjects. Many subjects showed a strong, albeit variable , cardioballistic component. The results provide baseline data for studies of the effects of drugs on tremor, particularly in cases of "essential" tremor, and provide warnings that such studies require objective recording methods for adequate evaluation and need recourse to measurement of several factors of the tremor to elucidate the component of tremor affected by a drug. A scaling of tremor can be used in terms of reference to the strength of gravitational acceleration (1.0 g), which provides simple numerical relationships.

Adolescent↗
PubMed1982

Loudness adaptation: real or illusory.

There is general agreement that, except at low sensation levels, the loudness of a continuous pure tone does not appear to change with time. By contrast, using a simultaneous dichotic loudness balancing procedure (SDLB) a substantial fall in loudness can be revealed. As a result it has been held that the latter does not represent a loudness loss in real terms but is a manifestation of some form of central binaural interaction possibly involving localization mechanisms. In two studies reported here, one involving a loudness scaling procedure using as a standard a reference tone of 65 dB (HL) and the other a loudness doubling procedure, a loudness loss has been clearly demonstrated following sustained stimulation with a continuous 60-dB (HL), 1000-Hz tone applied monaurally. The progression of the loudness loss with time follows a similar course to that found with the SDLB procedure. In consequence it is concluded that both represent a loudness loss in real terms and that inability to detect a change in loudness over time of a continuous tone results from the absence of any reference standard by which it can be judged.

Acoustic Stimulation↗
PubMed1981

The relationship between peak velocity of saccadic eye movements and serum benzodiazepine concentration.

1 Six healthy male volunteers received single oral doses of 10 mg diazepam, 20 mg temazepam, 15 mg flurazepam, 5 mg nitrazepam, 10 mg desmethyl-diazepam and placebo in a double-blind randomized fashion. 2 Peak velocity of saccadic eye movements, serum benzodiazepine concentration, and subjective ratings of wakefulness and co-ordination were measured at intervals up to 12 h after drug administration. 3 All active treatments produced a statistically significant decrease in peak saccadic velocity. The effect of temazepam and diazepam was generally more pronounced than that of flurazepam, nitrazepam and desmethyl-diazepam. 4 There were log-linear correlations between peak saccadic velocity and serum benzodiazepine concentration after ingestion of temazepam, diazepam and nitrazepam. 5 These results demonstrate a clear relationship between serum benzodiazepine concentration and its effect on a convenient measure of brainstem reticular formation function.

Adult↗
PubMed1980

Mechanism of rotatory eye movements in opsoclonus.

'Rotatory nystagmus', in which the visual axis of the eye moves involuntarily in the horizontal and vertical planes describing a closed loop trajectory, was analysed by means of combined video and electro-oculography in a patient with multiple sclerosis having numerous ocular signs of cerebellar disease. The rotations were sporadic, isolated single cycles having stereotyped, crescentiform loop shapes. Each consisted of a combination of a single cycle of vertical ocular flutter, the onset of which was followed 40 to 50 milliseconds later by a single cycle of horizontal ocular flutter. The timing relationship between flutters suggest that the vertical and horizontal systems had become somehow entrained. Rotatory nystagmus is saccadic in nature and arises from a unique timing relationship between vertical and horizontal flutter.

Adult↗