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Biomedical subjects

A Poplawsky

Publications and source records attributed to A Poplawsky.

13 recordsLinked to original sources
PubMed1991

Septal lesions lower responding under fixed-ratio schedules of reinforcement.

Albino Sprague-Dawley rats with complete septal lesions and rats with control operations were studied under fixed-ratio (FR) schedules of reinforcement. Both groups were trained for 10 sessions each under FR 10, 20, 40, 60, 80, and 100. In contrast to findings from progressive FR studies and some simple FR studies, septal lesions resulted in lower overall and local response rates along with longer postreinforcement pauses. These effects were especially evident during the FR 100 schedule of reinforcement. A comparison of reinforcement rate as a function of FR size within the context of behavioral economics (i.e., a demand function) indicated that septal lesions did not alter the reward value of food. These findings suggest that responding on FR schedules of reinforcement can be altered by the various procedures used to train rats to reach the terminal value of a reinforcement schedule.

Analysis of Variance↗
PubMed1990

Nimodipine accelerates recovery from the hyperemotionality produced by septal lesions.

Rats with large electrolytic lesions of the septal area were given the calcium channel antagonist nimodipine (70 micrograms/kg, ip) or its vehicle on the day of surgery and for 3 subsequent days. They were tested for emotionality and compared to control rats for 10 days beginning on the third day after surgery. Forty days after surgery all animals were trained in a two-way active avoidance task for 120 trials. Nimodipine reduced the hyperemotionality found after septal lesions as early as the first test day, and increased the rate of recovery toward control levels on subsequent days. Both septal-lesion groups exhibited more avoidance responses than controls, even though the intertrial crossings were enhanced only in rats with septal lesions that did not receive nimodipine.

Animals↗
PubMed1989

Brief ganglioside treatment produces delayed enhancement of functional recovery after medial septal lesions.

The effects of a 5-day ganglioside (GM1) treatment (30 mg/kg) on body weight and water intake subsequent to medial septal lesions were evaluated for 44 consecutive days. In addition, activity, rearing, and repetitive motor acts were measured on postsurgery days 5, 10, 40, and 60. The rate of increase in the body weights of rats with medial septal lesions treated with GM1 was equivalent to that of controls, while untreated rats with such lesions had reduced body weights. Rats with medial septal lesions treated with GM1 also exhibited movement times and frequency of repetitious motor acts similar to those of control rats by postsurgery day 60. No differences were found in water intake between any of the groups. Rats with medial septal lesions, whether treated with GM1 or not, had equivalent frequencies of rearings that were lower than control rats. This study emphasizes that even brief regimes of GM1 administration can exert behavioral changes in brain-damaged rats well after the treatment was administered, i.e. 40-60 days after surgery.

Animals↗
PubMed1989

The effects of lateral, medial, or complete septal lesions on positive conditioned suppression in rats.

This study investigated the effects of lateral, medial, or complete septal lesions in rats on lever pressing and US-approach behaviors during the presentation of a light followed by two free food pellets. Ten days after surgery, groups of rats received 20 sessions of a random interval (RI) 60-s schedule of food reinforcement. The positive conditioned suppression paradigm consisted of 20 sessions of a 10-s light paired with free food while the rats were responding on the RI 60-s schedule. All groups of rats significantly suppressed lever pressing during the 10-s light presentation. During the last four sessions of the 10-s light condition, rats with lateral septal lesions had a significant increase in food-tray entries during the light presentation, while the other groups decreased lever pressing without a change in food-tray entries during the 10-s light presentation. Although rats with septal damage generally have difficulty inhibiting responses in a variety of operant situations, rats with lateral, medial, or complete septal lesions showed no impairment in positive conditioned suppression. This study also suggests that when the spatial arrangement of the CS and the type of US were manipulated to minimize sign-tracking and goal-tracking behaviors, emotional reactions during the presentation of the CS must be considered a factor influencing positive conditioned suppression.

Animals↗
PubMed1987

The GM1 ganglioside hastens the reduction of hyperemotionality after septal lesions.

The purpose of the present study was to assess the effects of ganglioside treatment on changes in emotional, activity, and avoidance behaviors following septal brain damage. Rats were treated with GM1-gangliosides either before and after septal lesions, or only after septal lesions and tested for emotionality on 10 consecutive days beginning on the second day after surgery. The ganglioside treatment decreased the emotionality of rats with septal damage on the first test day, and enhanced their rate of recovery to control levels of emotionality. Septal rats treated with gangliosides had activity, rearing, and avoidance behaviors equivalent to nontreated septal rats; however, lesioned rats treated with GM1 showed reduced intertrial crossings during avoidance conditioning. These results suggest that the changes in emotional behavior of septal rats treated with GM1 occur shortly after the lesion.

Animals↗
PubMed1986

Autoshaping a leverpress in rats with lateral, medial, or complete septal lesions.

Rats with either control operations or lateral, medial, or complete septal lesions received 600 trials of leverpress training using an autoshaping procedure, i.e., food delivery followed a 10 s illuminated lever presentation, or occurred immediately after a leverpress. Rats with complete septal lesions acquired the leverpress faster than controls and had more food-tray entries per minute during the first 100 trials than the other groups. Rats with lateral or medial septal lesions had leverpress and food-tray entries equivalent to controls. The facilitation of autoshaping a leverpress may partially be explained by the general increase in motor reactivity to stimuli found following septal lesions.

Animals↗
PubMed1985

The effect of training procedures on fixed-interval responding following septal lesions in rats.

Two experiments were conducted to assess the effects of training procedures on fixed-interval (FI) performance of rats with septal lesions. In Experiment 1, rats with septal lesions that had extensive preoperative FI experience responded at higher rates than did control rats in early periods of the FI and at lower rates during the later period of the FI for the first 10 sessions after surgery. Their subsequent FI behavior became equivalent to that of control rats. In Experiment 2, septal rats that were trained on an FI schedule of reinforcement entirely after surgery by gradually increasing the FI requirements had FI performance equivalent to that of rats with control operations. The results suggest that septal lesions result in a transient disruption in the FI performance of rats with previous FI experience without affecting the acquisition of appropriate FI behavior.

Animals↗
PubMed1985

ACTH4-10 produces a transient decrease in septal hyperemotionality.

The administration of doses of ACTH4-10 that have been shown to be effective in producing enhanced peripheral nerve regeneration did not produce the enhanced rate of decline in hyperemotionality produced by administration of the ACTH4-9 variant Org 2766. Long-term changes in septal reactions in training situations were likewise not affected by ACTH4-10. These results indicate that, despite similar peripheral nerve growth effects, these two ACTH-related agents (ACTH4-10 and Org 2766) produce quite different long- and short-term effects on rats with septal area damage.

Adrenocorticotropic Hormone↗
PubMed1979

Effects of septal lesions and adrenalectomies on the acquisition and extinction of shuttle avoidance in the rat.

Rats with septal lesions and rats with both septal lesions and adrenalectomies (SEP-ADX) acquired avoidance behaviors faster and extinguished these behaviors slower than rats with adrenalectomies or control lesions. Rats with septal lesions also showed increased intertrial crossings during habituation, acquisition, and extinction while rats in group SEP-ADX only had increased intertrial crossings during acquisition. These findings are consistent with the hypothesis that the avoidance performance of rats with septal lesions is a result of neural rather than hormonal factors.

Adrenalectomy↗
PubMed1975

Effects of septal-fiber knife cuts on rat open-field social behavior.

Rats that received various septal fiber knife cuts were observed in an open-field to assess preoperative and postoperative social behaviors. Ventral septal fiber knife cuts isolated septum knife cuts and anterior-lateral knife cuts result in increases in contact time; in decreasesin aggressive behaviors/100 sec contact time; and in no change in the number of contacts. Anterior, posterior, or dorsal fiber knife cuts failed to produce significant changes in contact time, aggressive or submissive behavior, number of contacts, and activity. A postoperative decrease in initiating aggressive behaviors may explain increases in contact time following ventral septal fiber, isolated septum, and anterior-lateral knife cuts. The ventral-septal fiber tracts were critical in mediating social behavior, imply that - in relation to social behavior - there is a functional connection through the ventral fibers between structures beneath the septum (hypothalamus) and the septal nuclei.

Aggression↗