Researchers from the Salk Institute have discovered how the human brain processes colours and shapes using overlapping visual circuits.
The researchers used imaging technology and genetically expressed sensors to study how thousands of individual brain neurons process colours and shapes using overlapping visual circuits in the primary visual cortex. They found that visual neurons selectively respond to colours and shapes along a continuum and while some neurons are only activated by either a specific colour or shape, other neurons are responsive to a particular colour and shape simultaneously.
Edward Callaway, author and professor in Salk’s Systems Neurobiology Laboratory, said: “New genetic sensors and imaging technologies have allowed us to more thoroughly test the link between visual circuits that process colour and shape. These findings provide valuable insight about how visual circuits are connected and organised in the brain.”
How does the brain process colours and shapes using overlapping visual circuits?
The researchers note that, similarly to a digital camera sensor, photoreceptor cells in the eye detect light wavelengths and the information travels through the optic nerve to neurons in the visual cortex.
Peichao Li, co-first author and postdoctoral fellow, explained how the overlapping visual circuits work: “Our brain encodes visual information efficiently using circuits that are smartly designed. Contrary to what is taught in the classroom-that colour and form are processed separately in the early visual cortex and then integrated later by unknown mechanisms-the brain encodes colour and form together in a systematic way.”
Further research on neurons in the visual cortex
Callaway commented: “For the last 20 years, I have wanted to know how the visual system processes colour, so this finding is truly exciting for me. This discovery lays a foundation for understanding how neural circuits make the computations that lead to colour vision. We look forward to building on these findings to determine how the neurons in the visual cortex work together to extract colours and shapes.”