Functional neuroimaging evidence for high cognitive effort on the Word Memory Test in the absence of external incentives

Abstract

Primary objective: This study presents data from a functional neuroimaging experiment which brings into question whether poor performance on the Word Memory Test (WMT) can be construed as straightforward evidence for ‘poor effort’ in the context of cognitive assessment, as asserted in a recent report in this journal.

Methods and procedures: Functional magnetic resonance image (fMRI) data were acquired from four participants without brain injury who engaged in the delayed recognition (DR) portion of Green's WMT protocol.

Outcomes and results: Compared to a simple perceptual identification control task, this study found a highly reliable activation pattern across all participants which was restricted almost exclusively to cortical areas most commonly associated with task difficulty, memory load, concentration and other forms of cognitive effort These areas include dorsolateral prefrontal cortex, anterior insula, superior parietal cortex and the dorsal anterior cingulate.

Conclusions: These findings demonstrate that the WMT activates numerous cortical regions that are critical for cognitive effort. Given the extensive neural network necessary to perform the WMT, this study raises important questions about what WMT ‘failure’ truly means in patients with traumatic brain injury, who have increased likelihood of disruption within this neural network of vision, language, attention, effort and working memory.

• fMRI
• word memory test
• neuropsychological assessment
• symptom validity testing
• malingering