In the context of television consumption and its opportunity costs the
question arises how far experiencing mere representations of the outer world
would have the same neural and cognitive consequences than actively
interacting with that environment. Here we demonstrate that physical
interaction and direct exposition are essential for the beneficial effects of
environmental enrichment. In our experiment, the mice living in a simple
standard cage placed in the centre of a large enriched environment only
indirectly experiencing the stimulus-rich surroundings (IND) did not display
increased adult hippocampal neurogenesis. In contrast, the mice living in and
directly experiencing the surrounding enriched environment (DIR) and mice
living in a similar enriched cage containing an uninhabited inner cage (ENR)
showed enhanced neurogenesis compared to mice in control conditions (CTR).
Similarly, the beneficial effects of environmental enrichment on learning
performance in the Morris Water maze depended on the direct interaction of the
individual with the enrichment. In contrast, indirectly experiencing a
stimulus-rich environment failed to improve memory functions indicating that
direct interaction and activity within the stimulus-rich environment are
necessary to induce structural and functional changes in the hippocampus