Paced Auditory Serial Addition Test (PASAT)

Jeffrey S. Anderson, MD, PhD

Key Facts

Design

Block design
4- to 6-minute task (6 blocks of 20-30 seconds)

Stimuli

Auditory PASAT: Present a continual sequence of numbers at a fixed pace
- Patient must add the last 2 numbers in their mind each time a new number is presented
Visual PASAT: Numbers are displayed one at a time on the screen at a fixed pace

Instructions

“You will be presented with a sequence of numbers; each time you hear a new number, add it to the previous number in your mind”

Preprocessing

Distortion, motion, slice timing correction, coregistration to MPRAGE, optional smoothing

Statistical Model

General linear model: Block design

Applications

Activates dorsolateral prefrontal (Brodmann 9, 46), intraparietal sulcus (7, 40), lateral premotor (6), SMA (32), frontal eye fields (8), and medial cerebellum

Alternatives

Visual attention (cursor, visual search, random pattern comparison) or working memory tasks (Sternberg, n-back, Tower of London)

Uses

Used in group designs to assess performance of working memory in patient populations
Used in individual subjects for presurgical mapping

Pitfalls

Difficult to assess task performance

Activation map for an auditory PASAT task is shown for 1 patient. Image is the average of 2 sequences, 6-minutes each. Hot colors show greater activation during the PASAT blocks, and cool colors show greater activation during the rest blocks. Significance is set at q < 0.05, false discovery rate corrected. For the task, the patient listened to a list of single-digit numbers. Each time a new number was heard, she added in her mind the previous 2 numbers. Rest blocks contained no stimuli. Task activation is seen in auditory cortex, dorsolateral prefrontal cortex, intraparietal sulcus, medial cerebellum, frontal eye fields, and supplementary motor area.

TERMINOLOGY

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