Abstract
The human visual system is capable of processing visual information from fovea to the far peripheral visual field. Recent fMRI studies have shown a full and detailed retinotopic map in area prostriata, located ventro-dorsally and anterior to the calcarine sulcus along the parieto-occipital sulcus with strong preference for peripheral and wide-field stimulation. Here, we report the anatomical pattern of white matter connections between area prostriata and the thalamus encompassing the lateral geniculate nucleus (LGN). To this end, we developed and utilized an automated pipeline comprising a series of Apps that run openly on the cloud computing platform brainlife.io to analyse 139 subjects of the Human Connectome Project (HCP). We observe a continuous and extended bundle of white matter fibers from which two subcomponents can be extracted: one passing ventrally parallel to the optic radiations (OR) and another passing dorsally circumventing the lateral ventricle. Interestingly, the loop travelling dorsally connects the thalamus with the central visual field representation of prostriata located anteriorly, while the other loop travelling more ventrally connects the LGN with the more peripheral visual field representation located posteriorly. We then analyse an additional cohort of 10 HCP subjects using a manual plane extraction method outside brainlife.io to study the relationship between the two extracted white matter subcomponents and eccentricity, myelin and cortical thickness gradients within prostriata. Our results are consistent with a retinotopic segregation recently demonstrated in the OR, connecting the LGN and V1 in humans and reveal for the first time a retinotopic segregation regarding the trajectory of a fiber bundle between the thalamus and an associative visual area.
Highlights
Mikellidou et al (2017b) described for the first time the functional properties of area prostriata in humans using a novel wide-field visual stimulation system (Greco et al 2016)
The aim of this study was to explore the structural connectivity of area prostriata in the human brain with the thalamus using diffusion tractography and freely available datasets from the Human Connectome Project (HCP)
We observe a white matter bundle connecting area prostriata with the lateral geniculate nucleus (LGN) from which two subcomponents can be extracted; one that follows a similar route to the optic radiations and another one that bends around the lateral ventricle and reaches the LGN from a superior direction
Summary
Mikellidou et al (2017b) described for the first time the functional properties of area prostriata in humans using a novel wide-field visual stimulation system (Greco et al 2016). Area prostriata is located at the junction between the calcarine and parieto-occipital (POS) sulci, adjacent to the far peripheral representation of V1 and ventral V2 (Mikellidou et al 2017b). Area prostriata preferentially responds to very fast motion, greater than 500 °/s, and has a complete representation of the visual field, clearly distinct from the adjacent area V1. The functional properties of area prostriata suggest that the area may serve to alert the brain about fast visual events, in the peripheral visual field and it could subserve as a critical node for transient attention (Liu et al 2005)
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