FAILURE TO INDUCE LONG-TERM DEPRESSION BY AN ANTI-CORRELATION PROCEDURE IN AREA CA1 OF THE RAT HIPPOCAMPAL SLICE

We have independently in our two laboratories re-examined the report b y Stanton and Sejnowski (Nature, 339, 215 - 218, 1989) that single sti muli to a test pathway in area CA1 of the hippocampal slice, when deli vered between short bursts of stimuli to a second, convergent pathway, produce an associative long-term depression (LTD) in the test pathway . While robust associative LTP was observed when stimuli to the two in puts were correlated in time, the anti-correlation procedure failed to induce LTD; rather, a trend towards potentiation was observed. This r esult was obtained using both submerged and interface chambers, and in two different strains of rat. A transient depression lasting for a fe w minutes could usually be elicited by strong tetanic stimulation; thi s depression was not restricted to activated pathways.