Plasma corticosterone levels during extinction of a lever-press response in hippocampectomized rats

The Hippocampus as a Cognitive Map

“…Second, the absence of a reaction to non-reward in the runway could indicate the absence of the specific expectation of reward in the goal box; that is, no mismatch occurs. This seems quite plausible to us, and it is consistent with the fact that hippocampal animals do not show the characteristic elevation of plasma corticosterone upon the withdrawal of reward (Coover, Goldman, and Levine 1971b), a function apparently associated with the occurrence of environmental mismatch (see pp. 360-1).…”

“…The absence of such a mismatch, however, does not mean that extinction becomes impossible. In fact, in both the Cohen (1970) and the Coover et al (1971b) studies the hippocampal animals showed extinction, albeit somewhat more slowly than did controls. The absence of the mismatch function does imply, however, that extinction might proceed in different ways in intact and hippocampal animals.…”

“…The one situation in which hippocampal rats fail to demonstrate normal plasma corticosterone elevations concerns the extinction of an appetitive response (Coover et al 1971b). Thus, mismatch mobilizes the pituitary-adrenal system in normal, but not hippocampal, animals.…”

“…Resting levels Mason 1958Mason 1959 Endroczi and Lissak 1960 Van Wimersma Griedanus and de Wied 1969Knigge 1961 Endroczi and Nyakas 1971Slusher and Hyde 1961Moberg et al 1971 Endroczi and Lissak 1962Coover et al 1971bMandell et al 1963 Endroczi 1972 Nakadate and de Groot 1963 Kawakami et al 1973Galicich et al 1965 Lengvari and Halasz Slusher 1966 Wilson and Critchlow 1973Rubin et al 1966Kearley et al 1974Fendler et al 1961Jackson and Regenstein 1974Bohus et al 1968 III. Behavioural studies Porter 1954 Bohus 1971 Endroczi et al 1959Dupont et al 1972Knigge 1961 Endroczi 1972 Kim and Kim 1961 Wilson and Critchlow 1973 Endroczi and Lissak 1962Kearley et al 1974Knigge and Hays 1963Lovely 1975Davidson and Feldman 1967Iuvone and Van Hartesveldt 1976 Coover et al 19716 Andy et al 1962 Bland and Vanderwolf 1972b Votaw and Lauer 1963bLevitt and O'Hearn 1972Ursin et al 1966 Brown and Feldman et al 1967 Oliver et al 1974Coury 1967Jackson and Gardner 1974Musty et al 1967Nagy and Decsi 1974Grant and Jarrard 1968Lico et al 1974Siegel and Flynn 1968Rogozea et al 1969Siegfried et al 1975Mountford 1969…”

“…Endroczi (1972) has shown that the pituituary-adrenal system responds strongly to unmet expectancies, such as the withdrawal of expected rewards or closing down an alley normally used to get to water in a maze. Similarly, Bohus (1973), Coover et al (1971a) and Coover, Ursin, and Levine (1973) have all provided evidence that 'one of the conditions which will activate the neuroendocrine mechanisms leading to subsequent release of ACTH is a change in expectancies' (Coover el al. 1973, p. 174).…”