SHORT-LATENCY STRESSOR EFFECTS ON TONIC IMMOBILITY FEAR REACTIONS OF JAPANESE-QUAIL DIVERGENTLY SELECTED FOR ADRENOCORTICAL RESPONSIVENESS TO IMMOBILIZATION

Despite evidence for a positive association between adrenocortical act ivation and fearfulness, the effects of chronic (12 to 20 h) exposure to stressful stimulation on the fear reactions of Japanese quail genet ically selected for high (HS) or low (LS) plasma corticosterone respon se to immobilization stress are not straightforward. The present study examined tonic immobility fear responses in quail of both lines that, immediately prior to testing, either had been allowed to remain undis turbed or had been exposed to an acute stressor similar to that used i n the selection program (i.e., a short-latency stressor; 5 min of immo bilization). Tonic immobility responses were generally more pronounced in quail of the HS line than the LS line, and they were exaggerated i n both lines after exposure to stress treatment. The findings provide further support for the suggestion that selection for exaggerated or r educed adrenocortical responsiveness may have been accompanied by a co ncomitant and unconscious effect on under in fearfulness.