Functional magnetic resonance imaging of a child with Alice in Wonderland syndrome during an episode of micropsia

Abstract

Background: Alice in Wonderland syndrome is a perceptual disorder involving brief, transient episodes of visual distortions (metamorphopsia) and can occur in conjunction with certain viral infections. We used functional magnetic resonance imaging to examine visual processing in a 12-year-old boy with viral-onset Alice in Wonderland syndrome during an episode of micropsia (reduction in the perceived size of a form).

Methods: Functional magnetic resonance imaging was conducted in response to a passive viewing task (reversing checkerboard) and an active viewing task (line-length decisions in the context of the Ponzo illusion).

Results: In both tasks, the child with Alice in Wonderland syndrome showed reduced activation in primary and extrastriate visual cortical regions but increased activation in parietal lobe cortical regions as compared with a matched control participant.

Conclusions: The active experience of micropsia in viral-onset Alice in Wonderland syndrome reflects aberrant activity in primary and extrastriate visual cortical regions as well as parietal cortices. The disparate patterns of activity in these regions are discussed in detail.

FIG 1

Passive and active viewing tasks. A, The black-and-white radial checkerboard reversed at 8 Hz in 30 second blocks. B, The Ponzo illusion. Each image (n = 64) remained on screen for 2 seconds, with a variable inter-stimulus interval (ISI). Participants were instructed to indicate, by pressing a button, which vertical line appeared longer.

FIG 2

A, Mean percentage of BOLD signal change for each ROI: supra-threshold positive voxels per ROI for the child with Alice in Wonderland syndrome (AWS) and the control participant (CON). Percentage of positive voxels is shown rather than the raw numbers since each region has a different total number of voxels. Statistically significant differences between participants for each ROI are indicated by an asterisk. B, Representative images of functional activation (vs fixation) for each participant overlaid on their own anatomical MRI, showing occipital lobe (1,2; calcarine gyri shown) and parietal lobe (3,4; superior parietal lobule shown) activation patterns. See e-Supplement 1 for methods and definitions of anatomical boundaries. ROI, region of interest; L Calc, left calcarine gyrus; R Calc, right calcarine gyrus; L Ling, left lingual gyrus; R Ling, right lingual gyrus; SPL, superior parietal lobule; LIPL, left inferior parietal lobule; RIPL, right inferior parietal lobule; LSPL, left superior parietal lobule; RSPL, right superior parietal lobule.

FIG 3

A, Mean percentage of BOLD signal change for each ROI: suprathreshold positive voxels per ROI for the child with Alice in Wonderland syndrome (AWS) and the control participant (CON). Percentage of positive voxels is shown rather than the raw numbers since each region has a different total number of voxels. Statistically significant differences between participants for each ROI are indicated by an asterisk. B, Representative images of functional activation (vs fixation) for each participant overlaid on their own anatomical MRI, showing occipital lobe (1,2; calcarine gyri shown) and parietal lobe (3,4; superior parietal lobule shown) activation patterns. See e-Supplement 1 for methods and definitions of anatomical boundaries. ROI, region of interest; L Calc, left calcarine gyrus; R Calc, right calcarine gyrus; L Ling, left lingual gyrus; R Ling, right lingual gyrus; SPL, superior parietal lobule; LIPL, left inferior parietal lobule; RIPL, right inferior parietal lobule; LSPL, left superior parietal lobule; RSPL, right superior parietal lobule.