Learning experiences are potent modulators of adult hippocampal
neurogenesis (AHN). However, the vast majority of findings on the
learning-induced regulation of AHN derive from aversively-motivated
tasks, mainly the water maze paradigm, in which stress is a confounding
factor that affects the AHN outcome. Currently, little is known regarding
the effect of appetitively-motivated training on AHN. Hence we studied
how spatial learning to find food rewards in a hole-board maze modulates
AHN (cell proliferation and immature neurons) and AHN-related hippocampal
neuroplasticity markers (BDNF, IGF-II and CREB phosphorylation) in mice.
The 'Trained' mice were tested for both spatial reference and working
memory and compared to 'Pseudotrained' mice (exposed to different baited
holes in each session, thus avoiding the reference memory component of
the task) and 'Control' mice (exposed to the maze without rewards). In
contrast to Pseudotrained and Control mice, Trained mice reduced the
number of proliferating hippocampal cells but they notably increased
their population of immature neurons assessed by immunohistochemistry.
This evidence shows that hole-board spatial reference learning diminishes
cell proliferation in favor of enhancing young neurons' survival.
Interestingly, the enhanced AHN in the Trained mice (specifically in the
suprapyramidal blade) positively correlated with their reference memory
performance, but not with their working memory. Furthermore, the Trained
animals increased the hippocampal protein expression of all the
neuroplasticity markers analyzed by western blot. Results show that the
appetitively-motivated hole-board task is an useful paradigm to
potentiate and/or investigate AHN and hippocampal plasticity minimizing
aversive variables such as fear or stress.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.
This study was funded by grants from the Spanish Ministry of Economy and
Competitiveness (Agencia Estatal de Investigación) co-funded by the European
Research Development Fund -AEI/FEDER, UE- (PSI2015-73156-JIN ‘Jóvenes
Investigadores grant’ to E.C.O. and PSI2013-44901-P to L.J.S. and C.P.), from ‘Junta
de Andalucía’ SEJ1863 to C.P. and from University of Málaga (Plan Propio 2017 –
‘Ayudas para proyectos puente’) to M.G.F.
Author P.S.P. holds a ‘Juan de la Cierva-formación‘grant from the Spanish Ministry of
Economy, Industry and Competitiveness (code: FJCI-2015-23925) and a ‘D.3. Estancia
de investigadores de reconocido prestigio en la UMA‘ grant from the University of
Málaga. Authors R.D.M.F. and D.L.G.M. hold ‘FPU’ grants from the Spanish Ministry of
Education, Culture and Sports (code: FPU14-01610 and FPU13/04819, respectively).
Author F.J.P. holds a ‘Miguel Servet’ grant (code: CP14/00212) from the National
System of Health-Instituto de Salud Carlos-III co-funded by FEDER, UE