TÍTULO
O PAPEL DAS VIBRISSAS MISTACIAIS NO COMPORTAMENTO EXPLORATÓRIO DO RATO NO LABIRINTO EM CRUZ ELEVADO

TIPO: Disertação de mestrado

AUTOR: Luis Fernando Cárdenas cardenas@usp.br

IDIOMA: Portugués

ORIENTADOR: Prof. Dr. Silvio Morato de Carvalho silmorat@ffclrp.usp.br

FECHA DE LA DEFENSA: 10 de Agosto de 1999

ENTIDADES QUE FINANCIARON LA INVESTIGACIÓN: FAPESP Processo, 93/03331-3

INSTITUCIÓN QUE OTORGÓ EL TÍTULO
Laboratorio de Comportamento Exploratorio, Unidade de Psicobiologia,
Faculdade de Filosofia, Ciencias y Letras de Ribeirão Preto, Universidade de São Paulo,
Av. Bandeirantes, 3900, 14040-901. Riberião Preto, SP, Brasil

PALABRAS CLAVE: Vibrisas, comportamiento exploratorio, rata, laberinto en cruz elevado

Exploratory behavior in the rat is characterized by a preference for dark environments and by a trend to remain close to vertical surfaces (thigmotaxis). When allowed to freely explore an elevated plus-maze a rat will exhibit a smaller number of entries into the open arms and a smaller time spent in them. This characteristic pattern of behavior can be reverted by the

administration of anxiolytic drugs. Although broadly used in the study of fear and anxiety,

it still remains unclear what or which are the aversive stimuli that induce the avoidance from the open arms. The present study investigated the role of environmental illumination and thigmotaxis (mediated by mistacial vibrissae) in the exploratory behavior of rats submitted to the elevated plus-maze test. To this end, the vibrissae were removed acutely (5 min before testing) or chronically: days (8, 14 or 25; daily cutting) or in the day of birth and

the rats were tested in the plus-maze under two environmental conditions, brightness (150 Lux) or darkness (2 Lux). Results showed that in the darkness rats with vibrissae removed entered more and stayed longer in the open arms than rats with intact vibrissae or rats with removed vibrissae tested under brightness. These results suggest a possible anxiolytic-like effect cause by vibrissa removal added to the absence of light. The increase in exploration of

the open arms could be due to the effect of the joint absence of information from both sensorial systems (visual and tactile from the vibrissae) an effect that did not happen when information was lacking from just any one system. Further studies should be performed in order to unravel the neuronal mechanisms involved in the phenomenon.