Saur et al. (2008) PNAS Ventral and dorsal pathways for language (14 authors!) Hickok & Poeppel’s (2004, 2008) Model –Dual-streams for auditory language processing Like visual system? –Visually guided “where/how” system = dorsal –Object recognition “what” system = ventral Motor-articulatory system (dorsal?) Conceptual system (ventral?)

Two Language Tasks Repetition –60 German words –60 phonotactically legal nonwords –Repeat each one –2 blocks, 30 trials/block Comprehension –90 well-formed German sentences –90 pseudo-sentences comprised of phonotactically legal pseudo-words –Listen carefully and push button at end of sentence –3 blocks, 30 trials/block

fMRI Data Collection 3T magnet Event-related design –W/in block, real and pseudo-stimuli randomly ordered –ISI varied 6-11 sec 33 native German-speaking participants –11 F / 22 M, mean age 34 –18 RH / 15 LH No info on familial handedness

Diffusion Tensor Imaging & Tractography Same subjects as fMRI study Diffusion-weighted data collection Only Left Hemisphere imaged fMRI data used as seeds for tractography –Anatomical activity at 5 highest activity peaks used as seeds Used a different tractography algorithm than Glasser & Rilling (2008)

fMRI Activation Results Real vs Pseudo Contrasts Auditory Repetition TaskAuditory Sent Comp Task 5 peaks used as seeds FOP = deep frontal operculum F3op = IFG pars opercularis PMd = dorsal premotor cortex T1a = anterior STG T1p = posterior STG 5 peaks used as seeds F3orb = IFG pars orbitalis F3tri = IFG pars triangularis T2a = anterior MTG T2p = posterior STG FUS = fusiform gyrus

fMRI activation on sagittal slices through the DTI seed locations Blue = Repetition Red = Comprehension

3D Reconstruction of Probable Tracts Repetition Sent Comp

Probable Dorsal & Ventral Tracts PFC = Prefrontal Cortex = Ventral PMC = Premotor Cortex = Dorsal Blue = Repetition Red = Sent Comp “Superior temporal and premotor regions, activated during repetition, interact via a dorsal pathway along the Arcuate Fasciculus/ superior Longitudinal Fascicle. In contrast, middle and inferior temporal regions and the ventrolateral prefrontal cortex, activated during auditory comprehension, interact via a ventral pathway that runs through the Extreme Capsule.” (p ) “Thus, it seems that language, for All its human uniqueness and sophistication, adheres to the same anatomical principles that govern brain functions in other domains.” (p )