Abstract
Various cognitive theories aim to explain human deductive reasoning: (1) mental logic theories claim syntactic language-based proofs
of derivation, (2) the mental model theory proposes cognitive processes of constructing and manipulating spatially organized mental
models, and (3) imagery theories postulate that such abilities are based on visual mental images. To explore the neural substrates of
human deductive reasoning, we examined BOLD (blood oxygen level dependent) contrasts of twelve healthy participants during relational
and conditional reasoning with whole-brain functional magnetic resonance imaging (fMRI). The results indicate that, in the absence of
any correlated visual input, reasoning activated an occipitoparietalfrontal network, including parts of the prefrontal cortex (Brodmanns
area, BA, 6, 9) and the cingulate gyrus (BA 32), the superior and inferior parietal cortex (BA 7, 40), the precuneus (BA 7), and the visual
association cortex (BA 19). In the discussion, we first focus on the activated occipito-parietal pathway that is well known to be involved
in spatial perception and spatial working memory. Second, we briefly relate the activation in the prefrontal cortical areas and in the
anterior cingulate gyrus to other imaging studies on higher cognitive functions. Finally, we draw some general conclusions and argue that
reasoners envisage and inspect spatially organized mental models to solve deductive inference problems.
