Neuroanatomy of Creativity
Abstract
Creativity has long been a construct of interest to philosophers, psychologists and, more recently, neuroscientists. Recent efforts have focused on cognitive processes likely to be important to the manifestation of novelty and usefulness within a given social context. One such cognitive process – divergent thinking – is the process by which one extrapolates many possible answers to an initial stimulus or target data set. We sought to link well established measures of divergent thinking and creative achievement (Creative Achievement Questionnaire – CAQ) to cortical thickness in a cohort of young (23.7 ± 4.2 years), healthy subjects. Three independent judges ranked the creative products of each subject using the consensual assessment technique (Amabile, 1982) from which a “composite creativity index” (CCI) was derived. Structural magnetic resonance imaging was obtained at 1.5 Tesla Siemens scanner. Cortical reconstruction and volumetric segmentation were performed with the FreeSurfer image analysis suite. A region within the lingual gyrus was negatively correlated with CCI; the right posterior cingulate correlated positively with the CCI. For the CAQ, lower left lateral orbitofrontal volume correlated with higher creative achievement; higher cortical thickness was related to higher scores on the CAQ in the right angular gyrus. This is the first study to link cortical thickness measures to psychometric measures of creativity. The distribution of brain regions, associated with both divergent thinking and creative achievement, suggests that cognitive control of information flow among brain areas may be critical to understanding creative cognition.
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One research group has contributed much to the newest phase of EEG studies of creativity, with initial studies showing lower levels of cortical arousal during creative problem solving, and stronger alpha synchronization in centroparietal cortices associated with more original responses (Fink and Neubauer, 2006). This same group found the creativity–alpha power relationship to be mediated by the personality characteristic of Introversion–Extraversion (Fink and Neubauer, 2008). Finally, in a combined EEG/fMRI study, they were able to interpret EEG alpha band synchronization, particularly within the frontal lobe, with active cognitive processes rather than cortical idling (Fink et al., 2009a). Thus, there is considerable heterogeneity of findings across EEG studies of creative cognition, making it difficulty to draw robust conclusions regarding the impact or direction of alpha activity, synchronization and localization of these factors within frontal, posterior, or even lateralized hemispheric cortices. Moreover, when such relationships are found, they appear to be mediated by giftedness (Jausovec, 2000; Jin et al., 2006), personality variables (Fink and Neubauer, 2008), and sex (Razumnikova, 2004).
The neurobiology of creativity also has been investigated with brain imaging techniques including regional cerebral blood flow, single photon emission computerized tomography (SPECT), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI). One early study (Carlsson et al., 2000) was undertaken in 12 healthy male subjects stratified by either high or low scores on the creative functioning test (Smith and Carlsson, 1990). Blood flow measures were compared during performance of verbal fluency and DT. The highly creative group was characterized by bilateral frontal activation during DT compared to predominantly left hemisphere activation in the low creative group. Interestingly, better performance on the DT task was negatively correlated with higher activity within superior frontal regions. Such inverse correlations are suggestive of neural or network efficiency and have also been reported in neuroimaging studies of intelligence (Haier et al., 1988, 1992; Neubauer et al., 2004), although these efficiencies are now hypothesized to exist mainly for the frontal lobes (Neubauer and Fink, 2009). In another study, SPECT was used with 12 highly creative subjects while performing figural and verbal creativity tasks. These authors found a positive relationship between the creativity index and cerebral blood flow in the right postcentral gyrus, bilateral rectus gyrus, right inferior parietal lobule, and right parahippocampal gyrus (Chavez et al., 2004). PET was used to study nine healthy subjects as they performed verbal insight tasks (Starchenko et al., 2003). These authors found that the creative process activated left Brodmann area (BA) 40 and the cingulate gyrus (BA 32). This same group used PET to study normal subjects as they performed verbal creativity tasks and observed brain activations in the left parietotemporal brain regions (BAs 39 and 40) (Bechtereva et al., 2004). One fMRI study attempted to localize creative story generation within the brains of a cohort of eight normal subjects (Howard-Jones et al., 2005). When creative story generation was contrasted with uncreative story generation, significant activations were observed within bilateral medial frontal gyri (BAs 9 and 10) and the left anterior cingulate (BA 32). A novel study had subjects generate responses to the Rorschach inkblots (Asari et al., 2008). These researchers found that when unique responses were compared to more frequently generated responses, greater activations were observed within the right temporal pole (BA 38). When a less stringent threshold was used, additional regions associated with unique blot generation were identified within the left orbitofrontal region (BA 11), left cingulate (BA 32), and the left parietal cortices (BA 39). Thus, across functional studies, there appears to be some convergence, as noted previously, suggesting importance of the parietal cortex (BAs 39 and 40) to the creative process, the cingulate (BA 32) involved with internal selection, and frontal regions being engaged relevant to task complexity (BAs 8, 9, and 47) (Starchenko et al., 2003).
