Development of defensive behavior and conditioning to cat odor in the rat.

Laboratory rats show a range of defensive behaviors, including freezing, avoidance, and risk assessment upon exposure to cat odor, an unconditioned but highly effective threat stimulus. This study examined defensive behaviors, and the rapid conditioning to context plus cue, of these behaviors, in 18-, 26-, and 38-day-old male and female rats exposed to cat odor. Rats were placed individually in a runway with a cloth covered (control or saturated with cat fur/skin odor) block for a 10-min trial. On the following day, a similar trial involved an odorless block. On the odor exposure day, rats of all ages showed less contact with the odor block than with the control block. The 26- and 38-day-old rats, but not the 18-day-old rats, also showed locomotor suppression, more avoidance of the area where the odor block was located, and more risk assessment than no-odor controls. On a test of conditioned behavior 24 h following exposure, 26- and 38-day-old rats exhibited defensive behavior including avoidance and reduction of locomotion while 18-day-old pups did not.

Transplantation of fetal mesencephalic tissue in Parkinson's patients.

Patients with idiopathic Parkinson's disease who had become refractory to medical treatment underwent unilateral stereotactic transplantation of mesencephalic tissue obtained from 7- to 9-week-old postconception fetuses. Small pieces of tissue, less than 1 mm, were deposited in 9 sites in the putamen and 3 in the caudate. Patients were 4 men and 3 women and aged from 42 to 59 years (mean 50). Symptom durations were from 9 to 21 years (mean 14). The examinations were done at 3- to 4-month intervals pre- and postoperatively. Patients were examined for a minimum of 1 year postoperatively. The examinations consisted of neurological and general physical examinations, UCLA Parkinson's Disability Scale, Hoehn and Yahr rating and United Parkinson's Disease Rating Scale (PDRS), all in both 'on' and 'off' states. Video recordings and timed tests of a number of motor tests were performed. Patients also completed 7 consecutive days of hourly self-assessments prior to each visit. Fluorodopa PET scans were obtained pre- and 6 and 15 months postoperatively. The operations took place from mid-July 1992 to January 1993. Postoperative states have been free of complications. All have been on immunosuppressants. Levodopa was transiently decreased in the postoperative period, but raised to approximately the preoperative level thereafter. In late March 1993, 3 patients appeared to show modest improvement in the UCLA and UPDRS scales and in the patients' self-assessments.

Levodopa's awakening effect on patients with Parkinsonism.

The effects of levodopa on tests measuring auditory and visual perception, auditory, and visual short-term memory, verbal learning, and on attention and concentration were studied in 29 patients with Parkinsonism. Thirty-two control subjects matched with the Parkinsonism patients on age, educational level, and verbal IQ were administered the same tests to control for practice effects. Significant improvement occurred for the Parkinsonism patients in verbal learning (an intermediate memory test) and in auditory perception. These improvements were unrelated to changes in anticholinergic medications, increases in alertness or concentration, lessening of depression, or improved motor ability or control. There was no test evidence of levodopa improving visual perception, short-term auditory or visual memory, alertness or concentration. Thus, there is no objective test evidence for levodopa producing a generalized awakening or an alerting effect in Parkinsonism patients who are intellectually alert and well-orientated. Interpretation of the test findings suggests a specific awakening effect, that of improvement in intermediate memory but not in short-term memory. Overall, the Parkinsonism group scored below the control group on all tests, suggesting that cognitive impairment accompanies Parkinson's disease even in patients who are intellectually intact and well oriented.