Involvement of frontal cortex in successive negative contrast

KLIGER, R., SOTELO, M. I., PAPINI, M. R. & MUZIO, R. N.

Montevideo

Congreso; XII Congress of the International Society for Neuroethology (ICN2016); 2016

International Society for Neuroethology

When animals trained to receive a large reward experience a surprising decrease in reward magnitude, their performance deteriorates below the level of a control group always exposed to the small reward magnitude. This phenomenon, called successive negative contrast (SNC) has been found in both consummatory (cSNC) and instrumental (iSNC) procedures. There is behavioral and neural evidence that their underlying mechanisms are different. However, whereas there is evidence those prefrontal cortex areas, are involved in cSNC, no such cortical involvement has been reported for iSNC. Lesions in ventrolateral orbital cortex and insular cortex make the cSNC effect disappear, whereas lesions in anterior cingulated cortex affect the recovery. The goal of this research is to study the role of those areas in an instrumental situation of contrast (iSNC) measuring neural activity. Two groups of rats received one trial per day in a runway situation: 32-4 (rewarded with 32 pellets for 12 daily trials and 4 pellets for others 12 daily trials) and 4-4 (rewarded always with 4 pellets). When animals showed the iSNC effect they were sacrificed. This protocol took place twice. First, brain slices were stained with silver nitrate and the NORs sizes were compared. The second time, c-Fos technique were used to register the immediate early genes neural activation. Activity between brain areas was compared. The difference between procedures and techniques are discussed.