Similarly, manipulations of rodent brain serotonin levels during early development, through either increases (produced in SERT or monoamine oxidase KO mice) or decreases (produced by parachlorophenylalanine or other treatments), alter the formation of the whisker (barrel) representation in the primary somatosensory cortex and promote aggressive and/or anxiety-related behaviors (Cases et al., 1995, 1996; Persico et al., 2000; Persico et al., 2001; Holmes et al., 2003; Jennings et al., 2006). The gene discussed is SLC6A4; the disease is Anxiety.