Hidden in plain sight – Context controls the activity of sensory neurons
Andreas J Keller is 2021 finalist of the Eppendorf & Science Prize for Neurobiology. This international prize encourages the work of the most outstanding neurobiological research by young scientists.
We congratulate Andreas and his research team for this achievement!
It’s the context that controls our vision
Ever gave up on finding Waldo (or Wally, or Liam, or however the figure was called) in the famous kids’ puzzle-books filled with overcrowded illustrations in which they are embedded? All these figures are seemingly super-easy to spot even if up on the moon, as they wear or carry things with striking features. However, similar patterns surrounding the figures to search for make finding them very challenging for our visual system.
Hidden in plain sight
“Our perception of a visual stimulus is strongly influenced by the scene surrounding the stimulus – the visual context. Depending on its context, the same visual stimulus can stand out or meld into the rest of the visual scene. This is what is making individual patterns of any other figures in such illustrations so hard to spot. If alone, or at least the only one wearing for example a red-and-white–striped shirt, they would be conspicuous and spotted effortlessly”, Andreas J Keller, Head of the IOB Visual Cortex Plasticity Group explains.
Our sensory neurons fill in the gaps
Andreas and his team were able to prove: when there is nothing to see, we see what we expect to see. In other words: Context dominates when something is hidden in plain sight.
When a neuron’s visual information is missing, for example because of obstruction, it’s activity can be driven by context alone. Our sensory neurons fill in the gaps, likely relying upon past visual experience, with information flowing back from higher cortical regions to primary visual cortex.
“To test whether responses to the visual context are driven by activity in higher visual areas in the brain, rather than in the primary visual cortex, we silenced higher visual areas. This virtually abolished the contextual drive. Using optical recordings from axons originating in higher visual areas and projecting to the primary visual cortex, we found that these feedback projections carry the information necessary for contextual drive”, Andreas explains.
The stimulus and the surround
Context gives meaning to sensations. Accordingly, sensory processing of a stimulus is shaped by the context in which the stimulus is embedded. “Our research team set out to understand the neural circuits in the mouse visual cortex responsible for contextual modulation of sensory stimuli. We hypothesized: When stimulus and surround are similar, somatostatin-expressing (SOM) inhibitory neurons are active and suppress excitatory neurons. When stimuli and surround differ, VIP inhibitory neurons (expressing vasoactive intestinal peptide (VIP), the main inhibitor of SOM neurons) are active, suppress SOM neurons, and thereby relieve excitatory neurons from suppression.
Using computational modeling, optical recordings, and optogenetic perturbations, we showed that VIP neurons orchestrate the amount of suppression that SOM neurons provide to other neurons”, Andreas explains.
Read the full essay in Science:
“Hidden in plain sight – Context controls the activity of sensory neurons”
https://www.science.org/doi/10.1126/science.abl7124
About the Prize
The Eppendorf & Science Prize for Neurobiology acknowledges the increasingly active and important role of neurobiology in advancing our understanding of the functioning of the brain and the nervous system—a quest that seems destined for dramatic expansion in the coming decades. This international prize, established in 2002, encourages the work of promising young neurobiologists by providing support in the early stages of their careers. It is awarded annually for the most outstanding neurobiological research by a young scientist, as described in a 1,000-word essay based on research performed during the past three years.