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Biomedical subjects

D J Gelb

Publications and source records attributed to D J Gelb.

10 recordsLinked to original sources
PubMed1994

Teaching neurology residents in the outpatient setting.

OBJECTIVE: To determine how residency programs are responding to the shift of neurological practice into the outpatient setting. DESIGN: A nine-item questionnaire was sent to the directors of all US neurology residency programs. Each item had two parts, the first describing the current program, and the second describing an "ideal" program designed to optimize resident education. The same questionnaire was also sent to all house officers and faculty associated with a single residency program to assess variability in perceptions. SETTING: United States neurology residency programs (mail survey). PARTICIPANTS: Directors of neurology residency programs and all house officers and faculty members at a single residency program. RESULTS: Eighty-one (70%) of the 116 questionnaires distributed were returned. There were four areas of general consensus among the program directors: (1) more time should be devoted to outpatient care during residency training; (2) more continuity at the resident level should be provided for patients seen in subspecialty clinics; (3) faculty should provide more supervision of residents when they see follow-up patients; and (4) conferences specifically directed at outpatient management issues should be developed. CONCLUSIONS: Neurology residency directors agree that current approaches to teaching in the outpatient setting fall short of an educationally ideal system. Four areas of perceived deficiency have been identified. Creative solutions will be necessary to correct these perceived deficiencies.

Ambulatory Care↗
PubMed1993

Alternative calculation of the global clinical dementia rating.

The Clinical Dementia Rating (CDR) is a widely used instrument for rating the global severity of dementia, with scores in six independently rated categories used as a basis for computing a global score. We have found that the algorithms currently used to calculate the global score from the six component scores produce results that are sometimes inconsistent with the goals of the rating scale. We systematically analyzed these incongruities and developed an alternative algorithm that eliminates them while retaining the fundamental features of the original method.

Aged↗
PubMed1991

Change in pattern of muscle activity following botulinum toxin injections for torticollis.

Twenty patients with torticollis had electromyographic studies of their neck muscles performed before and after a series of local injections of botulinum toxin. The pattern of muscle activity changed after the injections, and this effect persisted even after head position had returned to baseline. Patients who did not experience any clinical benefit from the injections also demonstrated a change in the pattern of muscle activity. These results suggest that the underlying abnormality in torticollis usually involves a general motor program for head position, rather than the activity of individual neck muscles.

Adult↗
PubMed1989

Controlled trial of botulinum toxin injections in the treatment of spasmodic torticollis.

We administered local injections of botulinum toxin to 20 patients with torticollis in a blinded, placebo-controlled study. Each patient received four sets of injections: three different doses of botulinum toxin and one placebo. The order of the sessions was random and unknown to the patients. Sixteen of the patients (80%) reported subjective improvement to at least one dose of botulinum toxin; 11 (55%) reported substantial improvement. No objective benefit was documented. Side effects were minor and transient, although dysphagia occurred in four. Some patients reported that the effect waned despite persistent relaxation or even flaccidity of previously overactive muscles, suggesting a change in the pattern of muscle activity after botulinum toxin injections.

Adult↗
PubMed1988

Neuromuscular effects distant from the site of botulinum neurotoxin injection.

We assessed the severity and temporal profile of distant neuromuscular effects from a single dose (280 units) of botulinum neurotoxin injected into neck muscles for torticollis. We performed single-fiber EMG studies on the biceps brachii of six patients to measure jitter (20 pairs) and fiber density on the initial treatment day and then again, at least once more, after 2 to 12 weeks. No patient developed weakness beyond the neck muscles or decrement of the biceps response to repetitive 3-Hz nerve stimulation. Between the baseline and the last follow-up study, the average of mean MCD increased from 29 microseconds to 38 microseconds (31%). Mean fiber density increased concurrently or earlier from 1.35 to 1.79 (33%). There were no electrophysiologic signs of presynaptic blockade, even at 2 and 4 weeks. The effects we observed are compatible with stimulation of terminal sprouting by the neurotoxin, without significant presynaptic inhibition of acetylcholine release. We therefore believe that higher dosages of the neurotoxin may be used if clinically indicated.

Adult↗
PubMed1984

Modified line-element theory for spatial-frequency and width discrimination.

Recent data from several laboratories have shown that spatial-frequency discrimination is not a smooth function of frequency but rather exhibits alternate peaks and troughs. A model for spatial-frequency discrimination analogous to line-element models for color discrimination is presented here and shown to provide a reasonable fit to the available data. This model is based on the predicted responses of six spatial-frequency-tuned mechanisms, whose sensitivity curves have been estimated in previously published masking experiments. In order to fit the data it is necessary to pool responses from units centered under the stimulus as well as from spatially neighboring units. Thus it appears that the visual system utilizes both spatial and spatial-frequency information in discrimination tasks.

Color Perception↗
PubMed1983

Shifts in perceived size as a function of contrast and temporal modulation.

It has been suggested that perceived size depends upon the distribution of responses among a localized population of different size-tuned mechanisms. If so, then manipulations which alter this distribution should also affect perceived size. We therefore studied the effects of luminance contrast and mode of temporal presentation on size perception. Both manipulations produce significant shifts in perceived size. The results suggest that at least two factors contribute to the size percept. For small and intermediate size patterns, perceived size depends primarily on the local distribution of size-tuned mechanism responses, whereas for wide patterns, the spatial distribution of mechanism responses plays a major role.

Humans↗
PubMed1983

Shifts in perceived size due to masking.

It has been suggested that perceived size depends upon the distribution of responses among a localized population of different size-tuned mechanisms. If so, then spatial frequency masking, which alters the distribution of responses, should produce shifts in a test pattern's perceived size. We have found this to be the case. The magnitude and direction of the shifts depend only on the frequency difference in octaves (delta omega) between mask and standard. The results are not antisymmetric about the point delta omega = 0, however, as they would be if perceived size were based purely on local size-tuning properties. Our results suggest that size perception depends both on these local properties and on the spatial distribution of mechanism responses.

Adaptation, Ocular↗