Papers for the month of September 2013

" The role of human ventral visual cortex in motion perception."
Brain, 136:2784-2798

Mouse over here for a brief summary or click to open article in a new tab.Visual motion perception has long been associated with the dorsal (parietal) pathway and the involvement of the ventral ‘form’ (temporal) visual pathway has not been considered critical for normal motion perception. Here, we evaluated this view by examining whether circumscribed damage to ventral visual cortex impaired motion perception. Patients with a right, but not with a left, ventral visual lesion displayed widespread impairments in central motion perception even for non-form motion, for both slow and for fast speeds, and this held true independent of the integrity of areas MT/V5, V3A or parietal regions. In contrast with the traditional view in which only the dorsal visual stream is critical for motion perception, these novel findings implicate a more distributed circuit in which the integrity of the right ventral visual pathway is also necessary even for the perception of non-form motion.

"The development of hub architecture in the human functional brain network."
Cerebral Cortex, 23(10):2380-93

Mouse over here for a brief summary or click to open article in a new tab.Functional hubs are brain regions that play a crucial role in facilitating communication among parallel, distributed brain networks. The developmental emergence and stability of hubs, however, is not well understood. The current study used measures of network topology drawn from graph theory to investigate the development of functional hubs in 99 participants, 10-20 years of age. We found that hub architecture was evident in late childhood and was stable from adolescence to early adulthood. Connectivity between hub and non-hub ("spoke") regions, however, changed with development. From childhood to adolescence, the strength of connections between frontal hubs and cortical and subcortical spoke regions increased. From adolescence to adulthood, hub-spoke connections with frontal hubs were stable, whereas connectivity between cerebellar hubs and cortical spoke regions increased. Our findings suggest that a developmentally stable functional hub architecture provides the foundation of information flow in the brain, whereas connections between hubs and spokes continue to develop, possibly supporting mature cognitive function.

"Reprogramming of G protein-coupled receptor recycling and signaling by a kinase switch."
Proc Natl Acad Sci U S A., 110:15289-94

Mouse over here for a brief summary or click to open article in a new tab.Why is it that the trafficking of many neurotransmitter receptors is subject to multiple sequence requirements, considering that many other proteins can traffic without any such requirements? Our results suggest that these requirements provide biochemical switches that can be used by cells to rapidly redirect receptor trafficking. They can, therefore, act as control points for cells to reprogram their sensitivity to signals and adapt to changes in the environment.

"He who is well prepared has half won the battle: an fMRI study of task preparation"
Cerebral Cortex, in press:in press

Mouse over here for a brief summary or click to open article in a new tab.This paper examines the neural mechanism underlying preparation for tasks that vary in difficulty. The results suggest dynamic involvement of the working memory network not only during working memory task performance but also during task preparation.

"Ventral and Dorsal Visual Stream Contributions to the Perception of Object Shape and Object Location. "
Journal of Cognitive Neuroscience, Sept 3. :Epub Ahead of print

Mouse over here for a brief summary or click to open article in a new tab.Growing evidence suggests that the functional specialization of the two cortical visual pathways may not be as distinct as originally proposed. Here, using functional neuroimaging, we explore possible contributions of the dorsal “where/how” visual stream to shape perception and conversely, contributions of the ventral “what” visual stream to location perception in human adults. We conclude that both ventral and dorsal visual streams contribute to shape perception, but that the representation of spatial location appears to be solely within the purview of the dorsal visual pathway.