Moreover, two recent studies have demonstrated remarkable consistency between patterns of RSFC in the human brain and maps of anatomical connectivity derived from experimental tracer studies in the macaque monkey (Vincent et al., 2007; Margulies et al., 2009). Here we examine the hypothesis that the patterns of RSFC between areas 6, 44 and 45 and posterior parietal and temporal regions in the human brain are comparable with patterns of anatomical connectivity between the homologues of these areas in the macaque monkey, established in a recent autoradiographic study (Petrides & Pandya, 2009). In order to test this overarching hypothesis, we performed a seed-based RSFC analysis

in which the placement of seed regions-of-interest was determined on an individual basis according to sulcal LY2157299 and gyral morphology. We thus aimed to adopt a level of rigor similar to that exemplified by autoradiographic anatomical studies, albeit limited

by the spatial resolution permitted by functional magnetic resonance imaging (fMRI). We followed this primary examination with a data-driven spectral clustering analysis to verify distinctions emerging from the seed-based analysis. Thirty-six healthy right-handed adult subjects, aged 20–52 years (19 females, 17 males, mean age = 28.1 ± 7.9), participated in this study. All subjects were free of psychiatric disorders or history of head trauma. Participants signed informed consent after the experimental procedures were explained and received monetary compensation. The study complied with the Code of Ethics of the World Medical Association (Declaration of Helsinki) and was approved by the Institutional Review Boards PDK4 at New Histone Acetyltransferase inhibitor York University and the NYU School of Medicine. Data from these participants have been included in previously published studies (e.g. Margulies et al., 2007; Di Martino et al., 2008; Shehzad et al., 2009).

Images were acquired on a Siemens Allegra 3-T scanner using an EPI gradient echo sequence (TR = 2000 ms; TE = 25 ms; Flip angle = 90°, 39 slices, matrix 64 × 64; FOV = 192mm; acquisition voxel size 3 × 3 × 3 mm, 197 volumes, duration = 6 min 38 s) while subjects rested with eyes open. A T1-weighted anatomical image was also acquired for registration purposes (MP-RAGE, TR = 2500 ms; TE = 4.35 ms; TI = 900 ms; Flip angle = 8°; 176 slices; FOV = 256 mm, acquisition voxel size 1 × 1 × 1 mm). Slice timing correction (for interleaved acquisition), motion correction, despiking, temporal band pass filtering (0.009–0.1 Hz) and quadratic detrending using linear least squares were performed using AFNI (Cox, 1996). Further image preprocessing steps were completed using FSL (http://www.fmrib.ox.ac.uk/fsl), and comprised spatial smoothing [using a Gaussian kernel of full width at half maximum (FWHM) 6 mm] and mean-based intensity normalization of all volumes by the same factor [each subject’s entire four-dimensional (4-D) dataset was scaled by its global mean].