Frontal Activity during the Digit Symbol Substitution Test Determined by Multichannel Near-Infrared Spectroscopy

Abstract

Backgrounds: The digit symbol substitution test (DSST) is a clinically useful and widely accepted tool for the detection of various psychiatric disorders. Investigating neural activity during the DSST is useful when considering the relationship between the poor performance on the DSST and neurocognitive deficits. However, obtaining reliable functional imaging of the neural mechanisms associated with this test is challenging due to motion artifacts. Aims: To circumvent this problem, we examined frontal lobe activity during the DSST using multichannel near-infrared spectroscopy, a noninvasive functional imaging technique that does not interfere with the DSST procedure. Methods: Twenty-five healthy volunteers were enrolled in this study. Changes in the concentration of oxygenated hemoglobin (oxyHb) during the DSST were determined bilaterally in 52 measurement points (channels) on the frontal area. Results: We found significant increases in oxyHb in more than 70% of the channels, with the intensity of the increase being more pronounced in the left hemisphere. Several channels showed significant positive correlations between changes in oxyHb and DSST performance. Some of the channels with a significant increase in oxyHb during the DSST did not show a correlation with the DSST performance. Conclusions: Our findings indicate that the DSST could prove useful as a frontal lobe stimulating task. Further examinations of DSST/near-infrared spectroscopy analyses of neural mechanisms in patients with psychiatric and neurological diseases are necessary to assess its effectiveness in clinical practice for the evaluation of neuropsychopathology.

The Wechsler Digit Symbol Substitution Test as the Best Indicator of the Risk of Impaired Driving in Alzheimer Disease and Normal Aging

“…Visuospatial perception, selective attention, response speed, visuomotor coordination and incidental memory of the association of digit symbol pairs may play a role in digit symbol substitution test performances. It is also considered to reflect executive processing, which is consistent with the frontal activity recently demonstrated during its execution [75] . The multicomposite qualities of the DSST are confirmed in our study by its significant correlations with all cognitive measures, and, more specifically, by the significant correlations ranging from 0.50 to 0.62 with the cognitive measures associated with the 3 unsafe indicators taken in isolation.…”

Physical Activity and Cognitive Function among Older Adults with an Elevated Gamma Gap

“…The DSST, a component of the Wechsler Adult Intelligence Test and a test of visuospatial and motor speed-of-processing, has a considerable executive function component and is frequently used as a sensitive measure of frontal lobe executive functions [17]. The DSST was used to assess participant cognitive function tasks of pairing (each digit, 1–9, has a symbol it is associated with) and information processing.…”

Executive Function and Survival in the Context of Chronic Illness

“…The Digit Symbol subtest is part of the processing speed factor of the WAIS-R and has been interpreted as a measure of executive function in the research literature [34][35][36][37][38][39][40] in part because of its requirements for shifting of attention (i.e., alternating from digit string to symbol key), holding and manipulation of information in working memory (i.e., the key of digits and corresponding symbols), and inhibition of inappropriate responses (i.e., copying the digit rather than it's corresponding symbol). A recent study by Nakahachi and colleagues using near infra-red spectroscopy [41] demonstrated that performance of the Digit Symbol test activated areas of the cortex known to be associated with executive functions [42].…”