Mapping the neural systems that mediate the Paced Auditory Serial Addition Task (PASAT)

Abstract

The paced auditory serial addition task (PASAT), in which subjects hear a number-string and add the two most-recently heard numbers, is a neuropsychological test sensitive to cerebral dysfunction. We mapped the brain regions activated by the PASAT using positron emission tomography (PET) and 15O-water to measure cerebral blood flow. We parsed the PASAT by mapping sites activated by immediate repetition of numbers and by repetition of the prior number after the presentation of the next number in the series. The PASAT activated dispersed non-contiguous foci in the superior temporal gyri, bifrontal and biparietal sites, the anterior cingulate and bilateral cerebellar sites. These sites are consistent with the elements of the task that include auditory perception and processing, speech production, working memory, and attention. Sites mediating addition were not identified. The extent of the sites activated during the performance of the PASAT accounts for the sensitivity of this test and justifies its use in a variety of seemingly disparate conditions.

Differential SPECT Activation Patterns Associated with PASAT Performance May Indicate Frontocerebellar Functional Dissociation in Chronic Mild Traumatic Brain Injury

“…Our results, showing activation in the dorsolateral prefrontal cortex, right and left superior temporal gyrus, right and left medial frontal cortex, and cerebellum in healthy control subjects, are consistent with the above hypothesis. This distribution is in agreement with previous studies that reported a similar regional activation pattern with PASAT in healthy control subjects (8,21). We observed a pattern of activation in mild-TBI patients different from that in healthy control subjects.…”

Active inhibition of task-irrelevant sounds and its neural basis in patients with attention deficits after traumatic brain injury

“…These areas of activation are consistent with a previous study using the PASAT [28], and it therefore appears that activity in these brain regions is required for the task we used. These results suggest that working memory is necessary for the PASAT, and that the active inhibition required to filter out the distracting stimuli was impaired in the patients with TBI.…”

“…It has been reported that the left superior temporal gyrus, anterior cingulate cortex, and extensive brain regions from prefrontal to parietal cortices are active during the PASAT [28]. In this study, we found significant activity in every ROI except the R-LPFC in healthy subjects, but only in the L-APFC and L-LPFC in patients with TBI.…”

Normal-Appearing White Matter Permeability Distinguishes Poor Cognitive Performance in Processing Speed and Working Memory

“…33 Both the Symbol Digit Modalities Test and Paced Auditory Serial Addition Test correlate with several brain imaging findings such as lesion volume and central cerebral atrophy. [34][35][36] The correlation expectedly increases with disease duration and SPMS subtype reflecting greater disease burden and axonal degeneration. 18 Previous studies also show that NAWM abnormalities, even independent of lesion location, may correlate with cognition response.…”