The paper by Ben-Yishai, Lev Bar-Or, and Sompolinsky explores the mechanisms underlying orientation selectivity in the visual cortex. They use a neural network model to investigate how intrinsic cortical connections influence the processing of visual stimuli and the generation of behavioral outputs. The model incorporates orientation-selective inputs from the lateral geniculate nucleus (LGN) and orientation-specific cortical interactions. Depending on the model parameters, the network exhibits orientation selectivity that originates from within the cortex through a symmetry-breaking mechanism. This mechanism allows for sharp orientation tuning even when LGN inputs are only weakly anisotropic. The authors derive several experimental consequences of this cortical mechanism, including the independence of tuning width on contrast and angular anisotropy of the visual stimulus. They also describe a transient population response to changes in stimulus orientation, characterized by a slow "virtual rotation." Additionally, they calculate neuronal cross-correlations, which exhibit long-time tails whose sign depends on the preferred orientations of the cells and the stimulus orientation. The study highlights the importance of cortical circuitry in shaping orientation tuning and suggests that neuronal cross-correlations can provide valuable insights into the cooperativity among cortical neurons. The findings have implications for understanding the mechanisms of mental rotation and other cognitive processes in the visual cortex.The paper by Ben-Yishai, Lev Bar-Or, and Sompolinsky explores the mechanisms underlying orientation selectivity in the visual cortex. They use a neural network model to investigate how intrinsic cortical connections influence the processing of visual stimuli and the generation of behavioral outputs. The model incorporates orientation-selective inputs from the lateral geniculate nucleus (LGN) and orientation-specific cortical interactions. Depending on the model parameters, the network exhibits orientation selectivity that originates from within the cortex through a symmetry-breaking mechanism. This mechanism allows for sharp orientation tuning even when LGN inputs are only weakly anisotropic. The authors derive several experimental consequences of this cortical mechanism, including the independence of tuning width on contrast and angular anisotropy of the visual stimulus. They also describe a transient population response to changes in stimulus orientation, characterized by a slow "virtual rotation." Additionally, they calculate neuronal cross-correlations, which exhibit long-time tails whose sign depends on the preferred orientations of the cells and the stimulus orientation. The study highlights the importance of cortical circuitry in shaping orientation tuning and suggests that neuronal cross-correlations can provide valuable insights into the cooperativity among cortical neurons. The findings have implications for understanding the mechanisms of mental rotation and other cognitive processes in the visual cortex.