Differential effects of word length and visual contrast in the fusiform and lingual gyri during

Abstract

Previous studies have shown differential responses in the fusiform and lingual gyri during reading and suggested that the former is engaged in processing local features of visual stimuli and the latter is engaged in global shape processing. We used positron emission tomography in order to investigate how these regions are modulated by two common variables in reading: word length (three, six and nine letters) and perceptive similarity to the background (high and low contrast). Increasing both word length and visual contrast had a positive monotonic effect on activation in the bilateral fusiform. However, in the lingual gyrus, activation increased with increasing word length but decreased with increasing contrast. On the basis of previous studies, we suggest that (i) increasing word length increases the demands on both local feature and global shape processing, but (ii) increasing visual contrast increases the demands on local feature processing while decreasing the demands on global shape processing.

Cortical Effects of Shifting Letter Position in Letter Strings of Varying Length

“…Significance was not, however, reached for the subgroup of earliest cType I sources which were selected for the ROI analysis. A length effect around the occipital midline is in agreement with hemodynamic data of Mechelli et al (2000) and Indefrey et al (1997). It is noteworthy that not even the criterion search suggested length effects in activation patterns reminiscent of the Type II response.…”

Cognition and Brain Structure Following Early Childhood Surgery With Anesthesia

“…33 Moreover, cerebellar gray matter volume has previously been linked to nonverbal IQ, 34 and occipital cortex and lingual gyrus are associated with mathematical and advanced reading skills. 35,36 Interestingly, similar to results in patients after their exposure in the present study, children with 22q11.2 deletion syndrome also experience reductions in gray matter density in the anterior cerebellum that are associated with deficits in performance IQ and language delay. 37 However, it is important to note that because we used a conservative approach to detect group differences, the identified regions were relatively small and the exploratory analysis would not survive correction for the tens of thousands of voxels across the entire brain volume, thereby increasing the risk of a type I error.…”

Cortical Effects of Shifting Letter Position in Letter Strings of Varying Length

“…Two recent studies of reading, one using PET (Mechelli, Humphreys, Mayall, Olson, & Price, 2000) and one using fMRI (Indefrey et al, 1997), revealed monotonic increases in signal strength as a function of word length. These effects were visible in the midline posterior occipital cortex, bordering on the fusiform gyrus.…”