Adam E. Green

Individual Differences in Delay Discounting Relation to Intelligence, Working Memory, and Anterior Prefrontal Cortex

Lower delay discounting (better self-control) is linked to higher intelligence, but the basis of this relation is uncertain. To investigate the potential role of working memory (WM) processes, we assessed delay discounting, intelligence (g), WM (span tasks, 3-back task), and WM-related neural activity (using functional magnetic resonance imaging) in 103 healthy adults. Delay discounting was negatively correlated with g and WM. WM explained no variance in delay discounting beyond that explained by g, which suggests that processes through which WM relates to delay discounting are shared by g. WM-related neural activity in left anterior prefrontal cortex (Brodmanns area 10) covaried with g, r = .26, and delay discounting, r = -.40, and partially mediated the relation between g and delay discounting. Overall, the results suggest that delay discounting is associated with intelligence in part because of processes instantiated in anterior prefrontal cortex, a region known to support the integration of diverse information.

Musical imagery: Sound of silence activates auditory cortex

Auditory imagery occurs when one mentally rehearses telephone numbers or has a song ‘on the brain’ — it is the subjective experience of hearing in the absence of auditory stimulation, and is useful for investigating aspects of human cognition. Here we use functional magnetic resonance imaging to identify and characterize the neural substrates that support unprompted auditory imagery and find that auditory and visual imagery seem to obey similar basic neural principles.

Frontopolar cortex mediates abstract integration in analogy

Integration of abstractly similar relations during analogical reasoning was investigated using functional magnetic resonance imaging. Activation elicited by an analogical reasoning task that required both complex working memory and integration of abstractly similar relations was compared to activation elicited by a non-analogical task that required complex working memory in the absence of abstract relational integration. A left-sided region of the frontal pole of the brain (BA 9/10) was selectively active for the abstract relational integration component of analogical reasoning. Analogical reasoning also engaged a left-sided network of parieto-frontal regions. Activity in this network during analogical reasoning is hypothesized to reflect categorical alignment of individual component terms that make up analogies. This parieto-frontal network was also engaged by the complex control task, which involved explicit categorization, but not by a simpler control task, which did not involve categorization. We hypothesize that frontopolar cortex mediates abstract relational integration in complex reasoning while parieto-frontal regions mediate working memory processes, including manipulation of terms for the purpose of categorical alignment, that facilitate this integration.

Intellect as distinct from Openness: Differences revealed by fMRI of working memory

Relatively little is known about the neural bases of the Big Five personality trait Openness/Intellect. This trait is composed of 2 related but separable aspects, Openness to Experience and Intellect. On the basis of previous behavioral research (C. G. DeYoung, J. B. Peterson, & D. M. Higgins, 2005), the authors hypothesized that brain activity supporting working memory (WM) would be related to Intellect but not to Openness. To test this hypothesis, the authors used functional magnetic resonance imaging (fMRI) to scan a sample of 104 healthy adults as they performed a difficult WM task. Intellect (and not Openness) was found to correlate with WM accuracy and with accuracy-related brain activity, in left lateral anterior prefrontal cortex and posterior medial frontal cortex. Neural activity in these regions mediated the association between Intellect and WM performance, implicating these regions in the neural substrate of Intellect. Intellect was also correlated significantly with scores on tests of intelligence and WM capacity, but the association of Intellect with brain activity could not be entirely explained by cognitive ability.

Connecting Long Distance: Semantic Distance in Analogical Reasoning Modulates Frontopolar Cortex Activity

Solving problems often requires seeing new connections between concepts or events that seemed unrelated at first. Innovative solutions of this kind depend on analogical reasoning, a relational reasoning process that involves mapping similarities between concepts. Brain-based evidence has implicated the frontal pole of the brain as important for analogical mapping. Separately, cognitive research has identified semantic distance as a key characteristic of the kind of analogical mapping that can support innovation (i.e., identifying similarities across greater semantic distance reveals connections that support more innovative solutions and models). However, the neural substrates of semantically distant analogical mapping are not well understood. Here, we used functional magnetic resonance imaging (fMRI) to measure brain activity during an analogical reasoning task, in which we parametrically varied the semantic distance between the items in the analogies. Semantic distance was derived quantitatively from latent semantic analysis. Across 23 participants, activity in an a priori region of interest (ROI) in left frontopolar cortex covaried parametrically with increasing semantic distance, even after removing effects of task difficulty. This ROI was centered on a functional peak that we previously associated with analogical mapping. To our knowledge, these data represent a first empirical characterization of how the brain mediates semantically distant analogical mapping.

Neural Correlates of Creativity in Analogical Reasoning

Brain-based evidence has implicated the frontal pole of the brain as important for analogical mapping. Separately, cognitive research has identified semantic distance as a key determinant of the creativity of analogical mapping (i.e., more distant analogies are generally more creative). Here, we used functional magnetic resonance imaging to assess brain activity during an analogy generation task in which we varied the semantic distance of analogical mapping (as derived quantitatively from a latent semantic analysis). Data indicated that activity within an a priori region of interest in left frontopolar cortex covaried parametrically with increasing semantic distance, even after removing effects of task difficulty. Results implicate increased recruitment of frontopolar cortex as a mechanism for integrating semantically distant information to generate solutions in creative analogical reasoning.

Evaluation of a structural polymorphism in the ankyrin repeat and kinase domain containing 1 (ANKK1) gene and the activation of executive attention networks

The specificity of genetic effects on brain activation is a central issue in understanding how molecular actions at the synapse relate to anatomic patterns of brain activity. In an effort to understand the basis for the specificity of gene-associated brain activity, we explore a well-studied genetic polymorphism, TaqIA, which lies downstream of the DRD2 gene in the protein-encoding region of a neighboring gene, ANKK1, which is not expressed in the brain. We utilize the attention network test and find that carriers of the A1 allele show gene-associated functional activation in an anatomically specific, dopamine-rich region of the brain comprising the anterior cingulate gyrus, a finding partially consistent with prior data from functional imaging genetics. A review of the patterns of expression for ANKK1 and DRD2 and the extent of linkage disequilibrium between the two genes sheds light on additional criteria for the selection of candidate genes in imaging-genetic studies.

A Gene–Brain–Cognition Pathway: Prefrontal Activity Mediates the Effect of COMT on Cognitive Control and IQ

A core thesis of cognitive neurogenetic research is that genetic effects on cognitive ability are mediated by specific neural functions, however, demonstrating neural mediation has proved elusive. Pairwise relationships between genetic variation and brain function have yielded heterogeneous findings to date. This heterogeneity indicates that a multiple mediator modeling approach may be useful to account for complex relationships involving function at multiple brain regions. This is relevant not only for characterizing healthy cognition but for modeling the complex neural pathways by which disease-related genetic effects are transmitted to disordered cognitive phenotypes in psychiatric illness. Here, in 160 genotyped functional magnetic resonance imaging participants, we used a multiple mediator model to test a gene-brain-cognition pathway by which activity in 4 prefrontal brain regions mediates the effects of catechol-O-methyltransferase (COMT) gene on cognitive control and IQ. Results provide evidence for gene-brain-cognition mediation and help delineate a pathway by which gene expression contributes to intelligence.

Automatic activation of categorical and abstract analogical relations in analogical reasoning

We examined activation of concepts during analogical reasoning. Subjects made either analogical judgments or categorical judgments about four-word sets. After each four-word set, they named the ink color of a single word in a modified Stroop task. Words that referred to category relations were primed (as indicated by longer response times on Stroop color naming) subsequent to analogical judgments and categorical judgments. This finding suggests that activation of category concepts plays a fundamental role in analogical thinking. When colored words referred to analogical relations, priming occurred subsequent to analogical judgments, but not to categorical judgments, even though identical four-word stimuli were used for both types of judgments. This finding lends empirical support to the hypothesis that, when people comprehend the analogy between two items, they activate an abstract analogical relation that is distinct from the specific content items that compose the analogy.

Frontopolar activity and connectivity support dynamic conscious augmentation of creative state

No ability is more valued in the modern innovation‐fueled economy than thinking creatively on demand, and the “thinking cap” capacity to augment state creativity (i.e., to try and succeed at thinking more creatively) is of broad importance for education and a rich mental life. Although brain‐based creativity research has focused on static individual differences in trait creativity, less is known about changes in creative state within an individual. How does the brain augment state creativity when creative thinking is required? Can augmented creative state be consciously engaged and disengaged dynamically across time? Using a novel “thin slice” creativity paradigm in 55 fMRI participants performing verb‐generation, we successfully cued large, conscious, short‐duration increases in state creativity, indexed quantitatively by a measure of semantic distance derived via latent semantic analysis. A region of left frontopolar cortex, previously associated with creative integration of semantic information, exhibited increased activity and functional connectivity to anterior cingulate gyrus and right frontopolar cortex during cued augmentation of state creativity. Individual differences in the extent of increased activity in this region predicted individual differences in the extent to which participants were able to successfully augment state creative performance after accounting for trait creativity and intelligence. Hum Brain Mapp 36:923–934, 2015.