61, F[1, 25] = 14.81, p = 0.0007, Figure 2A) and production (r = 0.73, F[1, 25] = 28.00, p < 0.0001, Figure 2B). In contrast, buy Fulvestrant FA in the left ECFS did not correlate with either comprehension (r = 0.00, F[1, 25] < 1, p = 0.99, Figure 2C) or production (r < 0, Figure 2D) of syntax, nor did FA in the UF correlate with either comprehension (r < 0, Figure 2E) or production (r < 0, Figure 2F) measures. These findings suggest that syntactic processing relies primarily on dorsal, and not ventral, tracts. PPA is typically characterized by degeneration of the left hemisphere, but the right hemisphere is often affected

to a lesser extent. In our sample, FA values in the left and right SLF/Arcuate were correlated (r = 0.57, F[1, 25] = 12.17, p = 0.0018). To assess whether the right SLF/Arcuate might also click here be predictive of syntactic deficits, we included both the left and right SLF/Arcuate as independent variables. Only the left SLF/Arcuate predicted comprehension (partial r = 0.50, F[1, 24] = 7.92, p = 0.0096) and production (partial r = 0.60, F[1, 24] = 13.81, p = 0.0011). The right SLF/Arcuate did not predict either syntactic comprehension (partial r = 0.10, F[1, 24] = 0.27, p = 0.61) or production (partial r = 0.23, F[1, 24] = 1.28, p = 0.27). This suggests that syntactic processing depends on the left but not the right SLF/Arcuate. Therefore,

we considered only left hemisphere tracts in the remainder of our analyses. The 27 patients varied in several important respects. First, PPA patients can be sub-classified into nonfluent, semantic and logopenic variants based on clinical and speech-language features (Gorno-Tempini et al., 2011), and all three variants were represented in our sample. Second, patients varied in terms of severity, which we quantified with Mini Mental Status Examination (MMSE) score. Third, some PPA patients had executive impairments (which

we quantified Resminostat with a modified Trail-Making Test and a test of Design Fluency), and many nonfluent variant PPA patients had concomitant motor speech deficits (which we quantified with an apraxia of speech rating) in addition to agrammatism. Deficits such as these may contribute to syntactic processing deficits. Indeed, all of these measures were significantly associated with syntactic comprehension and/or production scores, and several, such as the apraxia of speech rating, were correlated with FA in the left SLF/Arcuate (see Supplemental Text available online). To ensure that the relationship between left SLF/Arcuate integrity and syntax was not secondary to any of these factors, we included all of these factors as covariates separately (see Supplemental Text) and simultaneously. In the full models with all potential mediating factors included, FA in the SLF/Arcuate continued to predict syntactic comprehension (partial r = 0.63, F[1, 17] = 10.29, p = 0.0052) and production (partial r = 0.54, F[1, 17] = 8.52, p = 0.