Abstract
The Letter Cancellation Task (LCT) is a widely used pen-and-paper probe of attention in clinical and research settings. Despite its popularity, the neural correlates of the task are not well understood. The present study uses functional magnetic resonance imaging (fMRI) and specialized tablet technology to identify the neural correlates of the LCT in 32 healthy older adults between 50–85 years of age, and further investigates the effect of healthy aging on performance. Subjects performed the LCT in its standard pen-and-paper administration and with the tablet during fMRI. Performance on the tablet was significantly slower than on pen-and-paper, with both response modes showing slower performance as a function of age. Across all ages, bilateral brain activation was observed in the cerebellum, superior temporal lobe, precentral gyrus, frontal gyrus, and occipital and parietal areas. Increasing age correlated with reduced brain activity in the supplementary motor area, middle occipital gyrus, medial and inferior frontal gyrus, cerebellum and putamen. Better LCT performance was correlated with increased activity in the middle frontal gyrus, and reduced activity in the cerebellum. The brain regions activated are associated with visuospatial attention and motor control, and are consistent with the neural correlates of LCT performance previously identified in lesion studies.
Highlights
Cancellation tasks have long been used in psychology research, as complex probes of attention that combine both visual selectivity and motor response
The tablet version was performed with a median of 3.2 omissions and 1.1 commissions, over all subjects and the five task blocks included in the functional magnetic resonance imaging (fMRI) experiment
Tablet Letter Cancellation Task (LCT) performance may have been affected by the visual acuity of subjects in the magnet bore, even though fMRI-compatible lenses were provided to subjects to correct their vision
Summary
Cancellation tasks have long been used in psychology research, as complex probes of attention that combine both visual selectivity and motor response. Administered in paper-and-pencil format, these tasks consist of patterns of letters, numbers or symbols interspersed with a target letter, number or symbol, with the instruction to cross out (cancel) all of the targets. Task performance can be scored straightforwardly by using measures such as the completion time and the number of errors. Thereafter, Diller et al (1974) constructed nine different cancellation tasks (using letters, numbers, words, shapes and pictures), including the single letter LCT fMRI of Letter Cancellation in Older Adults that is presently in wide use. The basic task consists of six 52-letter rows, with the target letter randomly interspersed 18 times in each row. Other cancellation tasks present items in random spatial distributions rather than in linear rows, such as the symbol cancellation test developed by Mesulam (1985)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
