No abstract

Methamphetamine induces monoamine depletions thought to contribute to cognitive and behavioral dysfunctions. Previously, we reported that methamphetamine-induced neurotoxicity is associated with impaired formation of stimulus-response associations. Additionally, subjective observations suggested that behavioral flexibility might be affected. Thus, the present study examined whether methamphetamine neurotoxicity induces perseverative behavior. Rats were pretreated with (±)-methamphetamine (4×10 mg/kg, 2-hr intervals) or saline. Three weeks later, rats were trained to press a lever on one side of an operant chamber and then retrieve the reinforcer from a magazine on the opposite side until they reached criterion (>50 reinforcers/30-min). After four consecutive sessions performing the task at criterion, rats were sacrificed and brains removed for monoamine determinations. Methamphetamine-pretreated rats had ~50% loss of striatal dopamine and prefrontal serotonin. Methamphetamine- and saline-pretreated rats were not different in the number of sessions required to reach criterion or in the total numbers of lever presses and or head entries made across the four consecutive sessions at criterion-level performance. However, methamphetamine-pretreated rats earned fewer reinforcers, because they made extra lever-presses and head entries when they should have been retrieving the reinforcer or returning to the lever. Latencies for methamphetamine-pretreated rats to switch between the two behaviors also were significantly slower than latencies for controls. Interestingly, the degree of additional lever-presses negatively correlated with serotonin-transporter binding in the prefrontal cortex, even in saline-pretreated controls. These data suggest that methamphetamine-induced partial monoamine toxicity is associated with perseveration and that the degree of perseveration may depend on serotonin innervation of the frontal cortex.

No abstract

The association between self-monitoring (regulation and control of nonverbal and expressive behavior) and blood pressure was examined in a field study of 594 municipal employees. For persons not taking antihypertensive medication, the Acting/Extraversion scale was mildly positively associated with resting blood pressure among whites in general, blue collar, clerical, and professional groups. Stronger positive correlations were obtained for attorneys and customer service representatives. These results are contrasted with slightly negative associations for blacks in general, first-level supervisors, and a group of previously studied union stewards. An interactive effect was also obtained between Acting/Extraversion and relative participation in work versus nonwork groups and activities; Acting/Extraversion and systolic pressure were inversely related for employees more active in extrawork groups but not related among other workers. Differential consequences of greater or lesser interpersonal involvement and emotional regulation in different jobs are considered.

Repeated measurements of resting blood pressure and heart rate were obtained at the worksite for a sample of 441 male municipal employees ranging widely in age (M = 41 yr.), job level, and education. As a result of unusually high diastolic values (M = 91), over-all uncontrolled hypertension rates were very high (33% of the men exceeding 160 systolic or 95 diastolic including those on medication). Higher rates were obtained for blue collar as opposed to white collar employees and for those plant workers in the Division of Water as opposed to Sewerage and Drainage. Net of age, weight, smoking, education, and anti-hypertensive medication use, higher systolic and diastolic mean values were obtained for supervisors who were primarily employed as foremen and clerical personnel. Inter-plant differences in blood pressure were also found for primarily blue collar Sewers and Drains employees, though whites' and blacks' values were nearly identical. Comparisons with national blood pressure data indicate significant effects for level of job and education which again disfavored supervisors and clerical employees and in addition men who had more education. Whites' and blacks' blood pressures deviated significantly from expected values, the differences favoring blacks. Social psychological mechanisms which may mediate these effects are discussed.