Relationship between change of spine expression pattern and integration pattern into an information acquired circuit of adult born neurons

In the adult hippocampus, newly born neurons are functionally integrated into existing circuits and play important roles in hippocampus-dependent memory. However, it remains unclear how neural plasticity regulates the integration pattern of new neurons into preexisting circuits. We had observed that LTP induction at 12-day after birth of new neurons increased later spinogenesis of their neurons. We then investigated the rate of circuit activity-dependent Zif268 expression, as indicator of the functional integration, in BrdU-labeled new born cells. When we induced LTP at 12-day after birth of new neurons, induction ratio of activity-dependent Zif268 expression in their neurons was significantly increased at 16-day after the LTP induction. This data strongly suggests that LTP induction at approximately 1-2-week after birth of new neurons enhances later functional integration of their neuron into activated circuits.