Abstract Details

Title Space, Time, and Causal Inference: A tDCS Study

Topic Neural Repair/Rehabilitation

Presentation(s) IN11 - (-)

Poster/Presentation
Number 002

Objective

Background The ability to infer causality is a central feature of human cognition. Causal inferences are partly built upon elemental spatial and temporal information in the environment. We previously reported that the right parietal cortex (rPC) contributes to spatial aspects of causal inference (Straube & Chatterjee, 2010; Woods et al., 2012), while others report that the frontal cortices contribute to decision-making aspects of causal inference (Fonlupt, 2003; Fugelsang et al., 2005).

Design/Methods Participants (n=16) underwent three transcranial direct current stimulation (tDCS) sessions, receiving 1.5 mA's right anode-left cathode stimulation for 20 minutes to the frontal (F3/F4) or parietal cortices (CP3/CP4), or a 30 second sham stimulation. tDCS electrode montages were selected based on computational current density models. Behaviorally, participants inferred causality before and during stimulation in billiard-ball style launching events; a blue ball approaches and contacts a red ball. Spatial and temporal inferences of causality were assessed separately by parametrically varying the spatial trajectories and the temporal delays of the movement of the second ball in separate blocks.

Results Frontal and parietal stimulation significantly decreased the probability of spatial causality judgments (Generalized Linear Model - Session x Location: [Chi]2=6.4, p=.04; Frontal mean difference (MD)=6%, p=.003; Parietal MD=4%, p=.02). Only frontal stimulation significantly decreased the probability of temporal causality judgments (MD=4%, p=.04). Parietal stimulation also significantly improved reaction time for spatial judgments of causality (Session x Location: [Chi]2=15.7, p<.001; MD=72 ms, p<.001).

Conclusions Our results are consistent with the hypothesis that the parietal cortex contributes to causal inference because of its specific role in processing spatial relations. In contrast, our results suggest that the contribution of the frontal cortices relates to their role in decision-making.

Authors/Disclosures
PRESENTER	No disclosure on file
Anjan Chatterjee, MD, FAAN (Univ of Pennsylvania Med Ctr/Dept of Neuro)	The institution of Dr. Chatterjee has received research support from Templeton Religion Trust. The institution of Dr. Chatterjee has received research support from Henry Jackson Foundation.
	No disclosure on file
	No disclosure on file
Roy H. Hamilton, MD, MS, FANA, FAAN	Dr. Hamilton has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Highland Instruments. Dr. Hamilton has received personal compensation in the range of $10,000-$49,999 for serving as an officer or member of the Board of Directors for McKnight Brain Research Foundation. Dr. Hamilton has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Neurology (Journal). The institution of Dr. Hamilton has received research support from NIH. The institution of Dr. Hamilton has received research support from Department of Defense. The institution of Dr. Hamilton has received research support from Chan Zuckerberg Initiative.
Pedro M. Abreu, MD	No disclosure on file

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