Effects of depression on sensory/motor vs. central processing in visual mental imagery

Abstract

Visual mental imagery is often affected by those experiencing a major depressive disorder (MDD), and is commonly used in cognitive behavioural therapy to treat these patients. However, the nature of imagery in this population has not been studied in depth. Moreover, it remains unclear what aspects of cognitive processing are responsible for psychomotor retardation observed in some patients with MDD. Control participants and participants who were experiencing MDD performed a mental image generation task, a mental image rotation task, and a task that required them to identify objects seen from canonical vs. noncanonical viewpoints. In all three tasks, participants with MDD performed “central processing” (which leads to the decisions required by the task) as well as control participants, but were slower in sensory/motor processing. These results suggest that the psychomotor retardation observed in patients with depression may result from an encoding or motor output deficit rather than a cognitive deficit.

Acknowledgments

This study was conducted in preparation for an undergraduate honors thesis, which was supported by a Harvard College Research Grant and a Mind/Brain/Behavior Research Grant of Harvard University. The research was also supported by NIH Grant 5 R01 MH60734-03.

The authors would like to thank Mandy Stern for her help in collecting data for this study, and they would like to acknowledge the following people for assistance in preparing this manuscript: Jennifer Best, Pearl Chiu, Christen Deveney, Jennifer Shephard, and William Thompson.