Figure 4.

The cellular and experimental effects of x-ray on adult brain. Adult neurogenesis occurs in the caudate nucleus, hippocampus and olfactory bulb (left upper panel, A); environmental factors can positively (environmental enrichment) or negatively modulate adult brain plasticity (right upper panel, B); of many physical, chemical and genetic factors modulating plasticity, x-rays are a recognized potent inhibitor of neurogenesis (left lower panel, C). The inhibition of neurogenesis in a mouse model is more striking in males than in females, and with repetitive, chronic rather than with acute exposures (right lower panel, D, modified from ref 70, Silasi et al.).