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Circadian modulation of learning and memory in pigeons: analysis of sensitization and classical fear conditioning of acoustic response

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Author(s):
Luis Otavio Siqueira
Total Authors: 1
Document type: Doctoral Thesis
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
Defense date:
Examining board members:
Elenice Aparecida de Moraes Ferrari; Luiz Silveira Menna Barreto; Jose Lino de Oliveira Bueno; Maria Filomena Ceolim; Francesco Langone
Advisor: Elenice Aparecida de Moraes Ferrari
Abstract

Exploratory behavior allows the inspection, localization, identification and the correct evaluation of the environmental events. The exploration also is related with curiosity related to new stimuli. The reflex behaviors that preceed the exploratory reactions are characterized as pre- exploratory and also have an important adaptative function. There are few studies that analyse the influence of time of the day on this response. Thus, the present study investigated the circadian variation of response to aversive sounds in pigeons. Experiment I, used a new equipment especially designed for automatic recording of response of acoustic response amplitude. The system is composed by an experimental chamber, with a load cell under the floor and a computer interface for contrai, storage and data analysis. Experiment 11 analyzed the sensitization of sound response in different times of the day. The experimental protocol used: (a) baseline with 5 acoustic stimulus presentation with inter-stimulus-interval between sounds of the 30s; (b) training, starting 5 min afier the last sound, with apresentation of two electric shocks with interval between electric shocks of the 5 min and (c) test, starting 10 min afier the last shock, with 40 acoustic stimuli. The Control Group animais received no stimulation. Experiment 11I, used 1 min time intervals between (a) the end of the baseline and the trainning, (b) the two electric shocks and (c) the last electric shock and test. Experiment IV investigated the trace fear conditioning, using 2 groups: Experimental, with 3 sound shock associations; Random, with 3 shocks and 3 sounds in the random arder and Contrai, only exposed to experimental chamber. Ali the experiments used a skeleton photoperiod with 2 light pulses (15 min) to 6h (ZTOO) and 18h (ZT12) and sub-groups for each time of test: ZT02, ZT06, ZT10, ZT14, ZT18 and ZT22. In a general, the data showed that both sensitization and classical fear conditioning resulted in increases of the amplitude of sound responses with variations depending on the time of the test. Taken together, the data indicated a modulation of aversive leaming by the circadian pacemaker (AU)