fMRI Activation of the Fusiform Gyrus and Amygdala to Cartoon Characters but not to Faces in a boy with Autism

Looking specifically at the fusiform gyrus during a fMRI differenciation task

By Nidhi Joseph

IntroductionAutism is a neurodevelopmental disorder marked by social impairments, communication difficulties and stereotyped patterns of behaviour.

Studies have shown that the right lateral fusiform gyrus (FG), an occipito-temporal visual cortical area, know as the fusiform facial area (FFA) is activated in humans when we look at faces; Gauthier et al., 1999

Objects of expertise are also found to recruit the FFA (Gauthier et al., 1999)

So, specialization for faces in the FFA is an example of a more general phenomenon related to experience, individuation, and configural processing (Tarr & Gauthier, 2000)

Objects activate the medial Fusiform Gyrus

Subjects

• DD:- 12 year old boy with Autism- Special interested in Digimon, a Japenese cartoon series. Watched it daily

• TDC:- A ‘typical’ 10 year old male- Aware of Digimon, but only watched it occasionally

Experimental task

Subjects were shown unfamiliar faces and objects and Digimon characters.

Two images at a time shown, from one category

Asked to identify if they were the same or different using a button box

• Tasks were performed while inside an fMRI scanner

• 18 oblique coronal sections were viewed

• The Green strip here, indicates the slides that the Fusiform Gyrus was located on

Results• DD: -no FFA activation to unfamiliar faces, activation to Digimon in the area

where we would expect the FFA

(t(30) = 6.38, P < 0.001)

• TDC: -showed a greater response to unfamiliar faces than Digimon in the

Fusiform Gyrus

(t(31) = 3.44, P = 0.002) • INTERESTING!

-Digimon with Masked faces- less activation in DD when compared up unmasked but more activation in TDC than to objects

-TDC also showed least activation with familiar faces

DD’s results

SUBJECT

DD TDCMEA

N P

ERCE

NT

SIGN

AL C

HAN

GE

Discussion DD’s FG activation pattern- differences in the amount of time he has spent

looking at or thinking about people and Digimon

Expert at Digimon (Gauthier et al., 1999)

Activation is possible even in the absence of prior “specialization” for faces

damage can be extremely selective (nearby areas can support non-face recognition like digimon)

• Cannot say conclusively that the digimon faces aren’t involved in activating the FFA area

• FFA decreases with repeated exposure to the same face (Buckner et al., 1998)

My opinion on the paper

PROs• Visuals were great! • Congruent with other research • could be useful developing therapy for autism

CONs• Slightly unclear • Brain images for TDC as well• Bigger sample size needed• Autistic people with expertise in different things, preferable

non-face objects

Questions?

References

• Buckner, R. L., Goodman, J., Burock, M., Rotte, M., Koustaal, W., Schac-ter, D., et al. (1998). Functional-anatomic correlates of object priming in humans revealed by rapid presentation event-related fMRI. Neuron, 20, 285–296

• Gauthier, I., Tarr, M. J., Moylan, J., Skudlarski, P., Gore, J. C., & An- derson, A. W. (2000b). The fusiform “face area” is part of a network that processes faces at the individual level. Journal of Cognitive Neu- roscience, 12, 495–504, 912

• Grelottiet al., 2005. fMRI activation of the fusiform gyrus and amygdala to cartoon characters but not to faces in a boy with autism. Neuropsychologia 43(3):373-8

• Tarr, M. T., & Gauthier, I. (2000). FFA: A flexible fusiform area for subordinate-level visual processing automatized by expertise. Nature Neuroscience, 3, 764–769