Allen Institute Openscope - Barcoding

Some visual neurons have been shown to respond to white noise flicker visual stimuli with high temporal precision, particularly retinal ganglion cells and LGN relay cells. Responses to white noise stimulation are useful for a variety of analyses, including information theoretic measures and generative models of precise spike timing. However the literature was lacking data on responses to white noise in cortical visual areas, or in the visual stream flowing through the superior colliculus.

This experiment used the OpenScope Neuropixels passive viewing protocol, and displayed visual stimuli modulated in time by a short, repeated white noise sequence. The visual stimulus was either a spatially uniform field whose luminance was modulated in time (Full Field Flicker), or a standing sinusoidal grating whose contrast was modulated in time (Static Gratings). Perhaps surprisingly, most cortical visual neurons responded well to full-field flicker white noise. To obtain large populations of neurons in subcortical areas, roughly half of the mice were recorded in a novel electrode configuration.

When white noise visual stimuli are presented repeatedly and the neural responses displayed as spike rasters, the rasters look remarkably like UPC codes or bar codes. The same bar-code-like patterns have been found in neurons recorded in different individual animals, and even neurons in different species. We speculated that these barcodes could be used as identifiers of discrete cell types. The Temporal Barcode Dataset provides "barcodes" for visually responsive neurons throughout the mouse brain, enabling a test of this hypothesis.