Emotional and cognitive reinforcement of rat hippocampal long-term potentiation by different learning paradigms

In earlier studies we have shown that a protein-synthesis-independent, early, long-term potentiaton (early-LTP) that lasts up to 4–5 hours can be transformed (reinforced) into a protein-synthesis-dependent late-LTP that lasts >8 hours by either an emotional challenge (e.g. swim stress) or mastering a cognitive task (e.g. spatial learning). In the present study we show that LTP-reinforcement by spatial training depends on the specific constraints of the learning paradigm. In a holeboerd paradigm, LTP-reinforcement is related to the formation of a lasting reference memory whereas water-maze training gives more heterog-enous results. Thus, cognitive aspects interfere with emotionally challenging components of the latter paradigm. These data indicate that different spatial-learning tasks are weighted distinctly by the animal. Thus, we show that aspects of specific spatial-learning paradigms such as shifts of attention and emotional content directly influence functional plasticity and memory formation.