- Email: [email protected]
Effects of animal hypnosis on the performance and the extinction of an avoidance response
EBBS ABSTRACTS
365
The dependence of the behavlour of frontal pole-lesioned rats on the environmental temperature as a result of inertia of the thyroid-pituitary feed-back regulation ULF SODERBERG AND KNUT LARSSON - - Neurophysiological Laboratory, Ullerdker Hospital, S-75017 Uppsala and Department of Psychology, University of G6teborg, S-414 51 G6teborg (Sweden) Young adult Wistar rats with or without small bilateral frontal pole lesions were studied during exposure tbr 3 weeks to various ambient temperatures. Lesions in the rostral parts of the frontal lobes or even restricted to the posterior parts of the olfactory bulbs abolished the adjustment of the thyroid activity to changes in environmental temperature. The lesioned rats showed slight hyperthermia and reduced gain in weight. The water and food intake still varied with changes in temperature, but at slower rate and to lesser degree than in the controls, an effect that was more marked in animals with the lesion within the frontal lobes. The thyroid activity, measured as rate of release of 13q-labelled hormone, did not vary with temperature in the lesioned groups, whereas the controls exhibited a two-fold increase after exposure to cold (q- 10 °C) and 66-89 ~ reduction in the warm room (q- 30 °C). Thereby the brainlesioned rats resembled hypophysectomized animals bearing pituitary grafts in the anterior chamber of the eye. The results show that a lesion made far rostral to the hypothalamus can seriously interfere with an important activity of the hypothalarnus, leaving other parameters more or less intact. However, it has to be borne in mind that besides interruption of impulse conduction the lesions might have induced nerve degeneration extending into the frontal lobes or even as far as into the hypothalamus. The results indicate that a kind of asthenia can be induced by interruption of the frontal lobe input into the hypothalamus, in that the animals exhibited hyper- or hypothyroidism in response to hot or cold environment, although the same animals in normal room temperature (22 °C) had normal thyroid activity. The dependence of the behaviour on adequate adjustment of the thyroid activity was particularly apparent in the warm room, where the operated animals, being relatively hyperthyroid, showed marked restlessness compared to the behaviour of their controls. The findings emphasize the importance of a careful check of the environmental temperature in studies of effects of brain lesions on behaviour.
Effects of animal hypnosis on the performance and the ,extinction of an avoidance response Laboratorio di Neurofisiologia del CNR, Pisa, and Istituto di Fisiologia Umana della Universitgt, Siena (Italy)
G. CARLI, M. COLTELLIAND M. SABOURIN
-
-
Rabbit hypnosis is a transitory state characterized by absence of movement,
366
EBBS ABSTRACTS
hypotonia, abolition of righting mechanisms and depression of mono- and polysynaptic reflexes. In the present experiments avoidance conditioning paradigms were used to study both the levels of awareness and the amount of the motor blocking during hypnosis. Rabbits carrying EEG, EMG and EKG implanted electrodes were trained to avoid an electric shock (UCS) to the left foot by moving the left hind limb in response to a 4-sec sound (CS). Increase in the EMG activity of biceps femoris muscle interrupted CS and prevented UCS. Each daily session of training consisted of 30 stimulus presentations delivered at variable intervals of 1-2 min when the animal was not moving. The criterion of learning was established at 9 avoidance responses in 10 successive trials. After reaching criterion, 5 additional sessions of training led to a performance of 75-90 ~ of avoidance responses. Avoidance conditioning performance during hypnosis was tested in 3 rabbits. Thirty stimuli (CS) were alternatively presented under control and hypnosis conditions. No avoidance response occurred during hypnosis, although UCS always interrupted the episode. On the contrary, the performance during the 15 trials delivered under control conditions was neither affected by previous hypnoses nor by stimulus presentations during hypnosis. Also, extinction experiments were performed in 10 Ss. In the hypnotic group (N = 5), 30 stimuli (CS) not followed by UCS were presented during hypnosis, while the control Ss (N = 5) rested. As a result, in the test for extinction in the non-hypnotic state, a decreased resistance to extinction was observed in the hypnotic group.
Pituitary-adrenal hormones and the forced extinction of a passive avoidance response in, fhe rat B. Bonus - - Rudolf Magnus Institute for Pharmacology, Medical Faculty, University
of Utrecht, Vondellaan 6, Utrecht (The Netherlands) Pituitary-adrenal hormones play an important role in behavioural adaptation. Adrenocorticotropic hormone of pituitary origin (ACTH) or fragments of this peptide promote the retention of conditioned responses. Corticosteroids, on the other hand, enhance the elimination of these responses when reinforcement is not present 2. To further investigate the role of hormones in 'memory' processes, passive avoidance behaviour of the rat has been studied after a forced extinction procedure. Forced extinction consisted of a detention in the shock compartment at different intervals after a single learning trial in a simple step-through passive avoidance situation1. Forced extinction results in a suppression of passive avoidance behaviour. The shorter the interval between the learning trial and the forced extinction, the shorter is the latency to re-enter the shock compartment during the retention test. The longer the duration of the forced extinction, the more effective is the suppression of the response.
365
The dependence of the behavlour of frontal pole-lesioned rats on the environmental temperature as a result of inertia of the thyroid-pituitary feed-back regulation ULF SODERBERG AND KNUT LARSSON - - Neurophysiological Laboratory, Ullerdker Hospital, S-75017 Uppsala and Department of Psychology, University of G6teborg, S-414 51 G6teborg (Sweden) Young adult Wistar rats with or without small bilateral frontal pole lesions were studied during exposure tbr 3 weeks to various ambient temperatures. Lesions in the rostral parts of the frontal lobes or even restricted to the posterior parts of the olfactory bulbs abolished the adjustment of the thyroid activity to changes in environmental temperature. The lesioned rats showed slight hyperthermia and reduced gain in weight. The water and food intake still varied with changes in temperature, but at slower rate and to lesser degree than in the controls, an effect that was more marked in animals with the lesion within the frontal lobes. The thyroid activity, measured as rate of release of 13q-labelled hormone, did not vary with temperature in the lesioned groups, whereas the controls exhibited a two-fold increase after exposure to cold (q- 10 °C) and 66-89 ~ reduction in the warm room (q- 30 °C). Thereby the brainlesioned rats resembled hypophysectomized animals bearing pituitary grafts in the anterior chamber of the eye. The results show that a lesion made far rostral to the hypothalamus can seriously interfere with an important activity of the hypothalarnus, leaving other parameters more or less intact. However, it has to be borne in mind that besides interruption of impulse conduction the lesions might have induced nerve degeneration extending into the frontal lobes or even as far as into the hypothalamus. The results indicate that a kind of asthenia can be induced by interruption of the frontal lobe input into the hypothalamus, in that the animals exhibited hyper- or hypothyroidism in response to hot or cold environment, although the same animals in normal room temperature (22 °C) had normal thyroid activity. The dependence of the behaviour on adequate adjustment of the thyroid activity was particularly apparent in the warm room, where the operated animals, being relatively hyperthyroid, showed marked restlessness compared to the behaviour of their controls. The findings emphasize the importance of a careful check of the environmental temperature in studies of effects of brain lesions on behaviour.
Effects of animal hypnosis on the performance and the ,extinction of an avoidance response Laboratorio di Neurofisiologia del CNR, Pisa, and Istituto di Fisiologia Umana della Universitgt, Siena (Italy)
G. CARLI, M. COLTELLIAND M. SABOURIN
-
-
Rabbit hypnosis is a transitory state characterized by absence of movement,
366
EBBS ABSTRACTS
hypotonia, abolition of righting mechanisms and depression of mono- and polysynaptic reflexes. In the present experiments avoidance conditioning paradigms were used to study both the levels of awareness and the amount of the motor blocking during hypnosis. Rabbits carrying EEG, EMG and EKG implanted electrodes were trained to avoid an electric shock (UCS) to the left foot by moving the left hind limb in response to a 4-sec sound (CS). Increase in the EMG activity of biceps femoris muscle interrupted CS and prevented UCS. Each daily session of training consisted of 30 stimulus presentations delivered at variable intervals of 1-2 min when the animal was not moving. The criterion of learning was established at 9 avoidance responses in 10 successive trials. After reaching criterion, 5 additional sessions of training led to a performance of 75-90 ~ of avoidance responses. Avoidance conditioning performance during hypnosis was tested in 3 rabbits. Thirty stimuli (CS) were alternatively presented under control and hypnosis conditions. No avoidance response occurred during hypnosis, although UCS always interrupted the episode. On the contrary, the performance during the 15 trials delivered under control conditions was neither affected by previous hypnoses nor by stimulus presentations during hypnosis. Also, extinction experiments were performed in 10 Ss. In the hypnotic group (N = 5), 30 stimuli (CS) not followed by UCS were presented during hypnosis, while the control Ss (N = 5) rested. As a result, in the test for extinction in the non-hypnotic state, a decreased resistance to extinction was observed in the hypnotic group.
Pituitary-adrenal hormones and the forced extinction of a passive avoidance response in, fhe rat B. Bonus - - Rudolf Magnus Institute for Pharmacology, Medical Faculty, University
of Utrecht, Vondellaan 6, Utrecht (The Netherlands) Pituitary-adrenal hormones play an important role in behavioural adaptation. Adrenocorticotropic hormone of pituitary origin (ACTH) or fragments of this peptide promote the retention of conditioned responses. Corticosteroids, on the other hand, enhance the elimination of these responses when reinforcement is not present 2. To further investigate the role of hormones in 'memory' processes, passive avoidance behaviour of the rat has been studied after a forced extinction procedure. Forced extinction consisted of a detention in the shock compartment at different intervals after a single learning trial in a simple step-through passive avoidance situation1. Forced extinction results in a suppression of passive avoidance behaviour. The shorter the interval between the learning trial and the forced extinction, the shorter is the latency to re-enter the shock compartment during the retention test. The longer the duration of the forced extinction, the more effective is the suppression of the response.