Criterion #9 in Table 1 notes that an endophenotype can inform an animal model, which can help us to understand the neurobehavioral mechanisms captured by an endophenotype as well as associated gene function. For instance, a number of animal models of PPI deficits have been developed, with the hope of understanding the etiology and pathophysiology of schizophrenia. Reduced PPI in rats is associated with increased perseverative responding during task switching (Freudenberg, Dieckmann, Winter, Koch, & Schwabe, 2007), which is often characteristic of schizophrenic patients during tasks such as the Wisconsin Card Sorting Test, which also requires behavioral flexibility and switching. Reduced levels of methylation of NRG1 have been reported in rats bred for reduced levels of PPI, and methylation levels are reduced in brain regions associated with both PPI and schizophrenia, such as medial PFC, hippocampus, nucleus accumbens (Rhein et al., 2013). This type of finding may lead to understanding epigenetic changes associated with schizophrenia as well as potential therapeutic targets. Oscillatory activity in the EEG of mice selectively bred to respond positively to alcohol administration resembles event-related time-frequency findings
