 | Enmanuelle Pardilla University of Puerto Rico, Río Piedras PsychologyMentor(s)Tracey J. Shors, Ph.D. Megan Anderson Department of Psychology Rutgers University |
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| The formation of trace memories increases the survival while decreasing the proliferation of newly generated cells in the hippocampus of the adult brain | ||
| Thousands of new neurons are generated in the dentate gyrus of the hippocampus each day. Many of the new cells die within weeks of being born. However most of the cells can be rescued from death if learning occurs (Gould et al., 1999; Shors, 2009). Therefore learning increases the survival of new neurons. It is unclear whether learning increases the proliferation of these new cells in the hippocampus. To address this question groups of rats were trained on a learning task, known as trace eyeblink conditioning, right after being labeled with BrdU or one week later when the cells are about to die. Rats were first implanted with electrodes to deliver the unconditioned stimulus eyelid stimulation and record eyeblinks. Rats were then habituated to the conditioning chamber. As controls, some rats were kept naïve for each time point. Training consisted of 600 trials over four days. Rats were either sacrificed four days after the BrdU injection to observe the effects of learning on proliferation or 28 days later to illustrate the effects of learning on survival. An ANOVA indicated a significant effect of learning on survival between groups (F3,38 =8.4, p < .001). A post hoc analysis indicated that the number of BrdU-labeled cells that were generated 30 minutes before training decreased after training. In contrast, the number of cells that were generated one week before training increased, as shown previously. These results indicate that the experience of training decreases the number of cells that are being generated while at the same time increases the survival of cells that are already present and are about to die. Stress of training may be the cause of decreased proliferation. Alternatively, the decrease in proliferation may compensate for the increase in survival after learning. (Funded by NSF Research Experience for Undergraduate IOS - 0444364) |