FOS and pneumocystosis: In the posterior part of the DMS, post hoc analysis revealed that the number of working memory effort-elicited c-Fos+ cells was significantly higher in the chronic PCP group than in the chronic saline group (p < 0.01), and the number of c-Fos+ cells was significantly higher at 90 min after the working memory effort relative to basal condition in the chronic PCP group (p < 0.01) (Fig 3A).