Figure 4. Individual atrophy patterns of the language network and cortical area.

Reconstruction of the direct (long segment, red) and indirect (anterior segment, green; posterior segment, yellow) pathways of the arcuate fasciculus in some representative patients with primary progressive aphasia (PPA) with different degrees of repetition impairment (repetition = 100 normal repetition). Individual significant atrophy patterns of the temporo-parietal cortex are also shown (warmer colors represent a significant reduction and corresponding p values are displayed by the color bar). The blue arrows indicate the cortical projections of the indirect pathway to the TPJ. (A) Three patients with agrammatic PPA variant. (A.a) A patient with severe repetition deficits (repetition = 36) and marked volume loss of the anterior segment of the indirect pathway but preserved posterior segment. The cortical atrophy involves only the most inferior part of the TPJ. (A.b) The patient presented with significant repetition deficits (repetition = 42) but in this case volume loss was more evident for temporo-parietal cortex and the posterior segment. (A.c) The patient presented with mild repetition deficits without detectable evidence of cortical atrophy and white matter volume loss. (B) Three patients with logopenic PPA. (B.a) The patient had severe repetition deficits (repetition = 40) and marked volume loss of both anterior and posterior segments of the indirect pathway. Severe cortical atrophy was also evident in the TPJ for this patient. (B.b) The patient showed moderate repetition deficits associated with reduced volume of both segments of the indirect pathway but no cortical atrophy. (B.c) The patient, who presented with intact repetition, showed no cortical atrophy in the TPJ and normal tract volume of the anterior and posterior segments. Note that the left patients in A and B with normal long segment volume indicate that the atrophy of the indirect pathway is not associated with the severity of repetition impairment.