['Pharmacological manipulation of serotonergic neurotransmission in healthy volunteers impacts on cognitive test performance. Specifically, markers of serotonin function are associated with attention and executive functioning, long-term memory, and general cognitive ability. The serotonin transporter (SERT) protein is a key regulator in the serotonin system. We hypothesized that higher performance on tests sensitive to serotonin would be associated with higher SERT levels in specific fronto-striatal brain regions.', "Thirty-two healthy subjects (25 males, mean age 26.0 years, range 19-37) underwent positron emission tomography using the SERT ligand [(11)C]DASB. Subjects underwent the following tests: Stroop Color Word Test, Trail Making Test B, Rey's Auditory Verbal Learning Test and Complex Figure Test, logical reasoning subtest from Intelligenz-Struktur-Test 2000 R, and a Danish version of National Adult Reading Test.", 'We found positive associations between performance on the Stroop Color Word Test and right-sided dorsolateral prefrontal SERT binding (R(2)\u2009=\u20090.12, p\u2009=\u20090.048). Furthermore, scores of logical reasoning (correlating with IQ) and educational level associated positively with SERT binding in the caudate, most prominent on the left side (logical reasoning: R(2)\u2009=\u20090.34, p\u2009=\u20090.0026 (left), R(2)\u2009=\u20090.2, p\u2009=\u20090.022 (right), educational level: R(2)\u2009=\u20090.19, p\u2009=\u20090.012 (left), R(2)\u2009=\u20090.15, p\u2009=\u20090.027 (right)). Scores of logical reasoning also associated with left-sided ventrolateral prefrontal cortex (R(2)\u2009=\u20090.24, p\u2009=\u20090.014). There were no significant associations between SERT binding and tests of long-term episodic memory.'] Is cognitive function related to fronto-striatal serotonin transporter levels -- a brain PET study in young healthy subjects?