Julia D. Irwin

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Following exposure to inescapable shock, mice exhibit deficits of escape performance, which are progressively more pronounced as training continues. Comparable effects were produced by DA and NE depletion by alpha-MpT and reserpine, NE depletion by FLA-63, and DA receptor blockade through haloperidol. Treatment with PCPA or 5-HTP did not influence(More)
Exposure to acute uncontrollable footshock increased utilization of central norepinephrine (NE), and in some brain regions, most notably the hypothalamus, a decline in amine concentrations was induced. Utilization of NE was likewise increased in mice exposed to footshock on 14 consecutive days, but the NE reduction was not evident, suggesting that the(More)
Self-control means choosing a large delayed reward over a small immediate reward; impulsiveness is its opposite. The metabolic hypothesis states that the amount of self-control across species correlates negatively with metabolic rate (Tobin & Logue, 1994). Foraging honeybees have high metabolic rates; the metabolic hypothesis would predict little(More)
Exposure to acute inescapable shock resulted in a decline of hypothalamic norepinephrine (NE), and an increase of plasma corticosterone concentrations. With repeated application of the stressor over 15 successive days the reduction of NE was eliminated and concentrations of the amine actually exceeded those of control animals. In contrast to the NE(More)
Acute inescapable shock provokes an increase of norepinephrine (NE) utilization, leading to transient reductions of amine concentrations. In contrast, increased amine levels are evident after chronic shock, apparently because of a compensatory increase in synthesis. In acutely shocked animals subsequent re-exposure to even a limited amount of shock(More)
Exposure to inescapable shock disrupted performance in both shock- and water-escape tasks. These deficits were prevented in mice that were previously trained in the same task. However, an asymmetrical immunization effect was seen in a cross-stressor paradigm. Whereas deficits of water-escape performance engendered by inescapable shock were prevented by(More)
The effects of inescapable shock on subsequent escape performance and shock-elicited activity were examined in six lines of mice selectively bred for differences in general locomotor activity. The line differences in locomotor activity were found to be unrelated to the differences observed on shock-elicited activity. However, escape performance following(More)
A series of experiments assessed the effects of pimozide on spontaneous alternation in a Y- and 8-arm radial maze, and on approach to food or cues that had previously been associated with food. Mice treated with pimozide (0.2, 0.4 and 0.8 mg/kg) displayed a dose dependent reduction of alternation performance, without engendering a perseverative tendency and(More)
The effects of inescapable shock on subsequent T-maze water escape and position discrimination performance were evaluated in seven experiments. Escapable shock did not disrupt water escape performance; however, escape performance was retarded 24 hr after inescapable shock. These deficits were not apparent if escape was possible upon stress inception;(More)