Research

 

1. The Functional Organization of the Prefrontal Cortex

The PFC comprises multiple distinct sub-regions including the ventrolateral (VLPFC), dorsolateral (DLPFC), and rostrolateral (RLPFC) sectors. While considerable empirical work suggests that these sub-regions support distinct processes, a coherent theory of the functional organization of the PFC has remained elusive. This line of research is aimed at discerning this functional organization. We have found evidence for a rostro-to-caudal gradient of abstraction in the representations supported by the PFC, with concrete, moderately abstract, and highly abstract information being supported by the VLPFC, DLPFC, and RLPFC respectively (Christoff, Keramatian, Gordon, Smith, Maedler, 2009; Brain Research). This study complimented a review of episodic memory, working memory, reasoning, and multitasking studies suggesting a hierarchical organization of lateral PFC regions (Christoff & Gabrieli, 2000).

2. Neural Basis of Mind-Wandering.

An ubiquitous aspect of daily life is periodically becoming engrossed in our thoughts and losing track of a task at hand (i.e., mind-wandering). Yet, the neural underpinnings of mind-wandering remain unknown. While prior work suggested that frontal and posterior regions along the medial wall of the cortex (so called “default network” regions) may be the principle substrate underlying mind-wandering, our recent work (Christoff, Gordon, Smallwood, Smith, & Schooler, 2009; PNAS) suggests that default network regions and executive network regions (e.g., lateral prefrontal cortex, dorsal anterior cingulate cortex) are concurrently engaged during mind-wandering—a finding predicted by behavioural theories of off-task thought. This research utilizes a combination of objective measure of mind-wandering (errors in task performance), subjective self-reports, and brain imaging.

3. Creativity (Melissa)

4. Examining RLPFC Function using Real-Time fMRI Training.

The rostrolateral prefrontal cortex (RLPFC) plays a pivotal role in higher order cognition, enabling some of the most complex forms of human thought. We examined whether individuals can learn to regulate the level of activation in high level regions such as the RLPFC using real-time fMRI feedback training. We found that individuals can learn to successfully up-regulate activation in this region by turning attention inwardly towards their own thoughts (i.e., engaging in meta-cognitive awareness) and successfully down-regulate this region by turning attention to viscero-somatic sensations arising from the external world (McCaig, Keramatian, Liu, Dixon, & Christoff, submitted).

5. Default and Executive Network Probing (Heather)

6. Goal Directed Problem Solving and Executive Control.

While it is clear that the RLPFC participates in a variety of complex cognitive processes, its precise contribution to human thought has been difficult to discern. Our neuroimaging findings (Christoff et al., 2001; Christoff, Ream, Geddes, & Gabrieli, 2003) suggest that introspective evaluation/meta-cognitive awareness may be a unifying principle to explain the role of the RLPFC in memory, reward learning, multitasking, and moral reasoning.

7. Spontaneous Thought.

When there is no external task to perform, thoughts often flow in a spontaneous and unconstrained manner, and is a prevalent aspect of waking mental activity. We have begun to examine the neural basis of such spontaneous thought. An initial fMRI study (Christoff, Ream, & Gabrieli, 2004; Cortex) found evidence of a considerable contribution from regions in the medial temporal lobe, visual cortex, and the rostrolateral PFC, suggesting that long-term memory, visual imagery, and introspection may form the basis of spontaneous thought. Elucidating the cognitive and neural basis of spontaneous thought has important implications given that its association with creativity, memory consolidation, decision making, etc., (Christoff, Gordon, & Smith, in press).