Flow stimuli reveal ecologically appropriate responses in mouse visual cortex

Abstract

Assessments of the mouse visual system based on spatial-frequency analysis imply that its visual capacity is low, with few neurons responding to spatial frequencies greater than 0.5 cycles per degree. However, visually mediated behaviors, such as prey capture, suggest that the mouse visual system is more precise. We introduce a stimulus class—visual flow patterns—that is more like what the mouse would encounter in the natural world than are sine-wave gratings but is more tractable for analysis than are natural images. We used 128-site silicon microelectrodes to measure the simultaneous responses of single neurons in the primary visual cortex (V1) of alert mice. While holding temporal-frequency content fixed, we explored a class of drifting patterns of black or white dots that have energy only at higher spatial frequencies. These flow stimuli evoke strong visually mediated responses well beyond those predicted by spatial-frequency analysis. Flow responses predominate in higher spatial-frequency ranges (0.15–1.6 cycles per degree), many are orientation or direction selective, and flow responses of many neurons depend strongly on sign of contrast. Many cells exhibit distributed responses across our stimulus ensemble. Together, these results challenge conventional linear approaches to visual processing and expand our understanding of the mouse’s visual capacity to behaviorally relevant ranges.

Training deep neural density estimators to identify mechanistic models of neural dynamics

“…For this challenging estimation problem with high-dimensional summary features, an SMC-ABC algorithm with the same simulation-budget failed to identify the correct receptive fields ( Figure 2g ) and posterior distributions ( Appendix 1—figure 5 ). We also applied this approach to electrophysiological data from a V1 cell ( Dyballa et al, 2018 ), identifying a sine-shaped Gabor receptive field consistent with the original spike-triggered average ( Figure 2i ; posterior distribution in Appendix 1—figure 6 ).…”

“…As a more challenging problem, we inferred the receptive field of a neuron in primary visual cortex (V1) ( Niell and Stryker, 2008 ; Dyballa et al, 2018 ). Using a model composed of a bias (related to the spontaneous firing rate) and a Gabor function with eight parameters ( Jones and Palmer, 1987 ) describing the receptive field’s location, shape and strength, we simulated responses to 5 min random noise movies of 41 × 41 pixels, such that the STA is high-dimensional, with a total of 1681 dimensions ( Figure 2e ).…”

“…We applied this approach to extracelullar recordings from primary visual cortex of alert mice obtained using silicon microelectrodes in response to colored-noise visual stimulation. Experimental methods are described in Dyballa et al, 2018 .…”

Efficient Temporal Coding in the Early Visual System: Existing Evidence and Future Directions

“…Many cells were unresponsive to entire classes of visual stimuli, such as natural scenes, while responding robustly to other classes, like drifting gratings. A related example comes from a study in Michael Stryker’s lab ( Dyballa et al, 2018 ). Dyballa et al analyzed the responses of V1 neurons to flow-like videos designed to imitate a mouse’s motion through grass and found robust visual responsiveness to spatial frequencies as high as about 1.5 cycles per degree, significantly greater than traditional visual acuity estimates of ∼0.5 cycles per degree measured using sinusoidal gratings ( Porciatti et al, 1999 ; Prusky et al, 2000 ; Niell and Stryker, 2008 ).…”

Existing function in primary visual cortex is not perturbed by new skill acquisition of a non-matched sensory task

“…Next we considered whether BCI training may have altered the strength of responsiveness. Changes in the response amplitude for all responsive neurons, including neurons that were not well-fit by the Gaussian function, in other words not necessarily tuned by classic metrics, were considered 48 . The average amplitude of the stimulus response that elicited the maximum response was compared between the two conditions.…”