Over the last year, several research studies have emerged from New York University, Abu Dhabi that partially or exclusively relied on the Siemens MRI Scanner MAGNETOM Prisma 3T. Here, we present three studies focusing on vision and language processing in the human brain.
White Matter Retinotopy of the Optic Radiation Tract
A central aim of cognitive and clinical neuroscience is to map structure to function, which will enable the prediction of functional deﬁcits from structural damage. In clinical practice, evidence from post neurosurgical evaluations has underscored the importance of minimizing damage to white matter structures in the brain during tumor resections. For example, damage to the optic radiation (OR) tract can result in serious visual ﬁeld defects. The OR carries visual ﬁeld information from the lateral geniculate nucleus (LGN) to primary visual cortex (V1). An important gap in our knowledge is understanding the relationship between individual ﬁber bundles within the OR and information about speciﬁc parts of the visual ﬁeld.
Diffusion-MRI (dMRI) has emerged as a non-invasive modality for tracing and virtually dissecting major white matter bundles in the living brain. Several studies highlighted the utility of dMRI for predicting post-surgical damage of the OR in individual patients. However, due to variability of the location and trajectory of the OR between subjects, this technology has not been widely adopted. In this study, we combined retinotopic mapping of the visual cortex obtained from functional magnetic resonance imaging (fMRI) to guide dMRI ﬁber tracking algorithms of the OR in young healthy male and female adults. The fMRI data was collected during visual stimulation with high contrast sweeping bar and expanding ring stimuli. We employed a population receptive ﬁeld (pRF) approach, which assigned each voxel a receptive ﬁeld center and size. The aggregate maps were used to draw visual regions of interest and determine polar angle and eccentricity maps, consistent with standard retinotopic mapping procedures.
The fMRI-generated maps in V1 were used in turn to classify speciﬁc white matter bundles in the OR (LGN to V1)
according to their terminating points in V1, which provided white matter retinotopic dissection of the visual ﬁeld.
Shows the white matter OR bundle color coded with eccentricity, polar angle, and with combined polar and eccentricity measurements discretized to 8 locations in the visual ﬁeld. Retinotopic-based color-coding of the OR bundle shows that the ventral-anterior bundle (or the Meyer’s loop) carries the upper peripheral visual quadrant information, whereas the dorsal bundle carries the the lower peripheral quadrant information, and the central bundle of the OR carries the information from central visual ﬁeld.The combination of fMRI and dMRI to assign speciﬁc functional roles to white matter tracts represents a potentially valuable tool both for basic science and as a guide for neurosurgeries conducted under general anesthesia.
Language Production with MEG/MRI and Realtime MRI of Modern Standard Arabic
Shows recordings of resting state (i), Arabic /t/ "ت" (ii), Arabic /t / "ط" (iii), Arabic /k/ "ك" (iv), and Arabic /q/ "ق" (v). Visible in (i) is a resting state with the locations of speech articulators: lips, teeth, alveolar ridge, palate, velum, uvula, tongue, pharynx, and vocal folds. The following four images demonstrate the production of the four selected sounds: (ii) shows the production of the sound /t/ with a primary tongue constriction in the dento-alveolar region; (iii) shows the production of the sound /t / with both a primary tongue constriction in the dento-alveolar region and a secondary tongue constriction in the pharynx; (iv) shows the production of the sound /k/ with a primary tongue constriction in the velar region; and, (v) shows the production of the sound /q/ with a primary tongue constriction in the uvular region.
Future studies in collaboration with Siemens Healthineers and local hospitals are underway to adapt some of the advanced imaging and post-processing technologies at NYUAD to beneﬁt the local community in the United Arab Emirates in particular and the Gulf region in general.