Passive Reading

Lubdha M. Shah, MD

Key Facts

Anatomy-based Imaging Issues

Primarily for localization of language comprehension areas in dominant hemisphere region of posterior superior temporal gyrus/parietal angular gyrus (Wernicke area)
Usually yields an additional language response in region of dominant hemisphere lateral inferior/middle frontal gyri (Broca area)
Language processing
- Meaning of words and sentences (semantics)
- Sound structure of words (phonology)
- Rules for combinations of words (syntax)
Reading (and passive viewing) involves automatic semantic processing

Design

Block design: 4 minutes
Presentation of text reading blocks alternating with blank screen fixation
- Visual presentation of short (2-4 sentences) narrative paragraphs for 10 seconds each
- 2 consecutive narrative text presentations per 20-second block
- Comparison can be made to activation produced by nonsense reading
Video feed can evaluate whether patient’s eyes are open
- Ask subject after the scan if he/she was able to keep eyes focused on center of screen

Applications

Presurgical planning for language lateralization
- Particularly in patients with temporal lesions
Combined task analysis of several language tasks is more robust and reliable compared to individual task analysis

(Left) Axial MPRAGE with overlay of BOLD signal during reading task illustrates expected activation in bilateral visual cortices in the occipital lobes

. (Right) 3D surface rendering displays activation in the receptive speech area

. Activation in the premotor

and visual

areas is also noted. Anterior temporal cortex is involved in semantic and syntax processes whereas the posterior temporal lobe is activated during language comprehension.