Herbert H. Zaretsky

A precision tooth-pulp stimulation technique for the assessment of pain threshold

Accurate and consistent pain threshold measurements for the tooth pulp can be achieved with careful preparation of a moisture-proof appliance and the use of a high-quality constant-current stimulator. Using an extant dental filling as the cathode, the usual problems associated with the control of the stimulation area and locus and, consequently, current density can be overcome. Repeated measurements showing less than ±5% variation over many months can be routinely achieved on the same individual. The technique has shown a high degree of sensitivity to common analgesic agents and is potentially useful for the investigation of variations in pain threshold over extended periods of time.

RECOGNITION OF MATCHING TASKS AND STIMULUS NOVELTY AS A FUNCTION OF UNILATERAL BRAIN DAMAGE

A 96-trial tachistoscope recognition task was given to 15 left-hemisphere-damaged, 12 right-hemisphere-damaged, and 30 non-brain-damaged subjects. Procedure called for a first stimulus presented for 250 msec. a 1-sec. pause, and a second stimulus for 250 msec. The stimuli were 12 animal drawings used in repeated series according to a random schedule. Six animals were familiar and six were novel. For half of the trials, the two pictures were of different animals. Size and position of the animal picture were controlled. Both reaction time and accuracy were independently scored. Judgments of same and different appear to function as if they are governed by different processes. For the control group, measures of same and different judgments do not correlate highly despite high internal consistency of subtests. Recognition of same becomes impaired with brain damage, but more so if the damage is rightsided. Recognition of different judgments shows considerably less sensitivity to the effects of unilateral brain damage.

Verbal Discrimination Learning as a Function of Brain Damage, Aging, and Institutionalization

The relationship between young non-brain-damaged nonpatients, elderly non-brain-damaged patients and elderly brain-damaged patients and the acquisition and extinction of verbal discrimination conditioned responses were investigated in this study. Four groups of 10 Ss each were used: one group of elderly brain-damaged patients with no speech impairment; one group of elderly non-brain-damaged patients; and one group of young nonpatient Ss used as a comparison group. The three elderly, brain-damaged and non-brain-damaged groups were unable to make a simple verbal discrimination, while the younger nonpatient group had a nearly perfect record of discrimination responses. No significant differences were obtained between the three elderly patient groups.