Host: Prof. Zhong-Lin Lu, NYU Shanghai
Abstract:
In this talk, I will first briefly describe evidence for plaid-selective neurons and multiple types of contrast response functions, illustrating the advantages of two-photon imaging for large-scale, relatively unbiased neuronal sampling at single-neuron resolution. I will then present ongoing studies examining how V1 populations represent orientation and spatial frequency (SF) (and ocular dominance). First, their functional maps do not exhibit the orthogonal organization as hypothesized by Hubel and Wiesel and others. At the cellular level, map intersection angles are broadly distributed without consistent orthogonal alignment. Second, however, these features form near-orthogonal geometries in population activity space. Thus, orthogonality emerges in population responses rather than cortical layout. Third, the geometric separation does not ensure independent orientation and SF coding, as shared trial-to-trial variability couples orientation and SF decoding errors and reduces coding efficiency. Fourth, a transformer decoder revealed that joint recovery of orientation and SF depends on stimulus SF. During readout, low-SF stimuli show SF-first or concurrent recovery, whereas intermediate-SF stimuli show orientation-first recovery followed by SF refinement. These patterns are linked to the geometry of the underlying population representation. Together, these studies reveal how the geometry and variability of V1 population activity shape the representation and readout of visual features.
Biography:
I received BA degree in psychology from East China Normal University in Shanghai in 1981 and Ph.D. from University of Louisville in 1985. Then I did two postdocs from 1985-2003, first at University of Houston College of Optometry and later at UC Berkeley School of Optometry. I set up my own vision lab at the Institute of Neuroscience, Chinese Academy of Sciences in Shanghai in 2003, and moved the lab later to Beijing, first at Beijing Normal University Institute of Cognitive Neuroscience and Learning (2006-2011) and then at Peking University School of Psychological and Cognitive Sciences (2012-2025). I joined in Zhejiang University Department of Psychology and Behavioral Sciences at the end of 2025.
This event is open to the NYU Shanghai, East China Normal University, and Neuroscience community.