Comparative induction of long-term depression between dorsal and ventral hippocampal CA1 in the anesthetized rat.

We studied whether a protocol reported as in vivo prefrontal long-term depression (LTD) induction protocol, also induced LTD in the anesthetized rat hippocampal CA1, and whether differences in LTD induction existed between dorsal and ventral CA1, by low-frequency stimulation (LFS) (1 Hz, 900) or low-frequency burst stimulation (LFBS) (5-pulse burst at 4 ms interpulse intervals at 1 Hz, 900), hippocampo-prefrontal LTD induction protocol. Though LFS failed to induce stable LTD in dorsal or ventral CA1, LFBS reliably induced LTD in the ventral not dorsal CA1. This similarity between ventral hippocampal and hippocampo-prefrontal LTD induction thus implies their serial integration process, ventral CA3-CA1-prefrontal cortex pathway and observed dorsal and ventral differences involved in behavioral functions such as learning.