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This series of studies was designed to investigate the residual erectile capacity of paraplegic rats. Results from human studies suggest that erectile capacity in paraplegic men may be maintained following psychogenic, but not reflexogenic, stimulation. Using an animal model to overcome methodological difficulties associated with human studies, reflexogenic stimulation was defined as local stimulation of the genitals, and psychogenic stimulation as stimulation of a key central structure. Results from higher CNS stimulation showed that electrical stimulation of the medial preoptic area of the hypothalamus reliably triggers penile responses in rats and elicits penile responses as a post-stimulation effect. Optimal stimulation parameters were identified and used to maximize the effect on spinal animals. The effect of central stimulation was then compared to that of local stimulation to examine whether truly sexual responses were elicited. Results demonstrated that central stimulation elicits primarily erectile responses with a few urine-marking responses. The two stimulation sources were then used to test the residual erectile capacity of paraplegic rats whose lesions interrupted the L6-S1 fibers. Results showed that a high proportion of animals (85%) indeed maintain erectile responses to central stimulation but lose reflex activity from the genital area. These results support the hypothesis under study and are discussed in terms of the neural substrates of erection and their implication at the human level.