Extended access nicotine self-administration with periodic deprivation increases immature neurons in the hippocampus.
CONCLUSIONS:
These findings demonstrate that extended versus limited access to nicotine self-administration differentially affects the generation of new oligodendroglia and new neurons during adulthood. The increases in the number of differentiating cells in extended access nicotine self-administering rats may consequently contribute to aberrant hippocampal neurogenesis and may contribute to maladaptive addiction-like behaviors dependent on the hippocampus.
http://www.ncbi.nlm.nih.gov/pubmed/25059540However it does not state that they mature.