DIFFERENTIATION OF A PRECISE TIMING RESPONSE.
(1/9)
Humans, monkeys, and rats were trained by a process of successive differentiations to press a bar for at least 1.00 sec but for no longer than 1.27 sec. Initially, animals were reinforced for all responses, then a minimum duration of response was gradually differentiated, below which no responses were reinforced. Finally, a maximum duration of response was differentiated above which no responses were reinforced. The duration of response in all three species approximated the minimum duration of response necessary for reinforcement. As the duration of response necessary for reinforcement increased, so did the mean duration of response in the three species. As the maximum allowable duration decreased, further compression of the mean occurred. The fact that the acquisition of the differentiation was approximately the same in all three species is a further indication of the control reinforcement exerts on operant responding. (+info)
Antidepressant-like effects of nicotine and transcranial magnetic stimulation in the olfactory bulbectomy rat model of depression.
(2/9)
Factors that distinguish college students with depressive symptoms with and without suicidal thoughts.
(8/9)
BACKGROUND: Suicide among college students is a significant public health concern. Although suicidality is linked to depression, not all depressed college students experience suicidal ideation (SI). The primary aim of this study was to determine potential factors that may distinguish college students with depressive symptoms with and without SI. METHODS: A total of 287 undergraduate college students with substantial depressive symptoms (Beck Depression Inventory [BDI] total score >13) with and without SI were compared across psychiatric and functional outcome variables. Independent sample t tests were conducted for each outcome variable using the suicide item of the BDI as a dichotomous (ie, zero vs nonzero score) grouping variable. RESULTS: Relative to students with substantial depressive symptoms without SI, those with SI were more symptomatic overall, having significantly higher levels of depressive symptoms, hopelessness, and anxiety. However, contrary to our expectations, nonsuicidal and suicidal students did not differ on measures of everyday functioning (ie, cognitive and physical functioning and grade point average). CONCLUSIONS: Our findings suggest that SI among college students is associated with increased subjective distress but may not adversely impact physical or cognitive functioning or academic performance. (+info)