Wei Wang

Tuesday 29th May 2018

Time:4.00pm

Ground Floor Seminar Room

25 Howland Street, London, W1T 4JG

Cortical integration from V1 into V4 along the object-processing hierarchy

Human and non‐human primates effortlessly see both global and local features of objects in great detail. However, how the cortex integrates local visual cues to form global representations along visual hierarchies remains mysterious, particularly considering a long-standing paradox in vision as neurally encoded complexity increases along the visual hierarchy, the known acuity or resolving power dramatically decreases. Putting it simply, how do we simultaneously recognize the face of our child, while still resolving the individual hairs of her or his eyelashes? Many models of visual processing follow the idea that low-level resolution and position information is discarded to yield high-level representations (including cutting edge deep learning models). These are themes that are fundamental to conceiving how the brain does sensory transformation, and current ideas require hypothetical complicated recurrent loops to connect global and local information across the visual hierarchy.

Combining large-scale imaging of high spatial resolution to record the transformation of information across three visual areas simultaneously (V1, V2, and V4) with electrophysiological multi-site laminar recordings, we found a bottom-up cascade of cortical integration of local visual cues as general cortical mechanisms for global representations in primate ventral and dorsal streams. The integrated time window and neural response are dependent on the sizes and preferences of their receptive fields. Recently, we reveal an unexpected neural clustering preserving visual acuity from V1 into V4, enabling a detailed spatiotemporal separation of local and global features along the object-processing hierarchy, suggesting that higher acuities are retained to later stages where more detailed cognitive behaviour occurs. The study reinforces the point that neurons in V4 (and most likely also in infero-temporal cortex) do not necessarily need to have only low visual acuity, which may begin to resolve the long-standing paradox concerning fine visual discrimination. Thus, our research will prompt further studies to probe how preservation of low-level information is useful for higher-level vision and provide new ideas to inspire the next generation of deep neural network architectures.

Short CV of Dr. Wei Wang:
Dr. Wang obtained his MS and PhD degrees at University of Science & Technology of China (USTC) with Professor Tiande Shou in Hefei (Anhui Province, China) from 1990 to 1998. After the completion of his PhD study, Dr. Wang worked with Professor Adam Sillito at UCL as a Postdoc Research Fellow from 1998 to 2004. He went to University of Manchester to work with Dr. Niall McLoughlin as a Senior Research Fellow in 2004. Dr. Wang was awarded as the Wellcome Trust career development fellowship in 2006. In the end of 2008, He joined Institute of Neuroscience (ION) with the support of Chinese Academy of Sciences’ 100 talents’ Program and established the Laboratory of visual perceptual mechanisms. Dr. Wang has published frequently in high visible Journals including Nature Neuroscience, Neuron, and Journal of Neuroscience.