Noninvasive brain stimulation to lateral prefrontal cortex alters the novelty of creative idea generation.

Theories of the processes involved in creative cognition posit that cognitive control has a negative effect on creative idea generation but a positive effect on creative idea evaluation. Brain stimulation research has started to examine empirically the effects of cognitive control, with several reports of decreased cognitive control facilitating creative ideation. Such studies have shown how decreased cognitive control mechanisms facilitate creative idea generation, potentially by allowing participants access to less inhibited weaker-related associations, thereby increasing novelty. In the current study, we advance this line of work by investigating how cognitive control affects creative thinking, potentially inhibiting or facilitating novel idea generation based on task demands. Participants read sentences with the final word missing and were instructed to complete the sentence with an uncommon (but appropriate) ending. Participants performed this task while undergoing either anodal (excitatory), cathodal (inhibitory), or sham (control) transcranial direct current stimulation over their left prefrontal cortex. These responses were then rated for their novelty and appropriateness by an independent sample of raters. We found that anodal stimulation increased the appropriateness and decreased the novelty of participants' responses. Contrary to previous studies, we did not find that cathodal stimulation increased the novelty of participants' responses, which may be due to the nature of our task. Overall, we demonstrate how cognitive control mechanisms may inhibit novel idea generation.

Decoding levels of representation in reading: A representational similarity approach.

Multiple levels of representation are involved in reading single words: visual representations of letter shape, orthographic representations of letter identity and order, phonological representations of the word's pronunciation, and semantic representations of its meaning. Previous lesion and neuroimaging studies have identified a network of regions recruited during word reading, including ventral occipital-temporal regions and the angular gyrus (AG). However, there is still debate about what information is being represented and processed in these regions. This study has two aims. The first is to help adjudicate between competing hypotheses concerning the role of ventral occipital cortex in reading. The second is to adjudicate between competing hypotheses concerning the role of the AG in reading. Participants read words in the scanner while performing a proper name detection task and we use a multivariate pattern analysis technique for analyzing fMRI data - representational similarity analysis (RSA) - to decode the type of information being represented in these regions based on computationally explicit theories. Distributed patterns of activation in the left ventral occipitotemporal cortex (vOT) and the AG show evidence of some type of orthographic processing, while the right hemisphere homologues of the vOT supports visual, but not orthographic, information processing of letter strings. In addition, there is evidence of left-lateralized semantic processing in the lvOT and evidence of top-down feedback in the lvOT. Taken together, these results suggest an interactive activation theory of visual word processing in which both the lvOT and lAG are neural loci of an orthographic level of representations.