All had normal or corrected-to-normal vision. None had a history of neurological or psychiatric disease. All participants gave informed consent after the experimental procedure was explained and were paid for participation. This study was approved by the research ethical committee of the University Medical Center Hamburg-Eppendorf. Eighteen of the 36 subjects (8 females and 10 males, mean age = 26.3 ± 4.6 years, age range: 21–41 years) were assigned pseudo-randomly to ABT-737 clinical trial Experiment 1 (semantic Inhibitors,research,lifescience,medical categorization) and the remaining 18 subjects (9 females and 9 males, mean age = 26.6 ±

5.2 years, age range: 21–38 years) were assigned to Experiment 2 (silently thinking about a word’s meaning). None of the subjects participating in Experiment 2 took part in Experiment Inhibitors,research,lifescience,medical 1. Stimuli Critical items were 60 morphologically simplex concrete German nouns of the open class category. These items

were adapted from a previous fMRI study of the neural representation of the bilingual mental lexicon (Isel et al. 2010). Half of the words (n = 30) referred to natural entities (e.g., Fruchtfruit), whereas the other half (n = 30) referred to manmade entities (e.g., Koffersuitcase). The mean age Inhibitors,research,lifescience,medical of acquisition (AoA) of the critical words was 2.7 years (±0.1) for the 30 natural concrete nouns and 3.3 years (±0.1) for the 30 manmade concrete nouns. Target words were matched for word frequency (mean word frequency: natural nouns = 34 [SEM = 7.9], manmade nouns = Inhibitors,research,lifescience,medical 22 [SEM = 5.9]; CELEX database, Baayen et al. 1995), word length (mean word length: natural nouns = 5.4 letters [SEM = 0.2], manmade nouns = 5.8 letters [SEM = 0.2]) as well as for concreteness and imageability (MRC Psycholinguistics database, Coltheart 1981). Prime words in the related and

unrelated conditions were matched for frequency (mean word frequency: related condition = 28 [SEM = 6.8], unrelated = 31 [SEM = 7.3]; CELEX database, Baayen et al. 1995). In the related condition, prime–target word pairs were associatively related and therefore were matched for associative strength2 (mean association strength: natural nouns = 39.7% [SEM = 2.9%], manmade nouns: Inhibitors,research,lifescience,medical 42.1% [SEM = 2.3%]). In the unrelated condition, prime and target Digestive enzyme words did not present either a phonological/orthographic, morphological, or semantic/associative link. Finally, in both the related and unrelated conditions, natural noun targets were primed by natural nouns whereas manmade noun targets were primed by manmade nouns. Table ​Table11 displays examples of word pairs in the related and unrelated conditions. Table 1 Examples of word pairs in the related and unrelated conditions In addition, we selected 420 filler pairs (300 word–word pairs, 60 “blank screen”–word pairs [12.5%; neutral condition], and 60 symbol pairs [12.5%]). Among the 300 word–word pairs, half of them were constituted of two natural nouns, whereas the other half was constituted of two manmade nouns.