looking at a complex landscape, the eye needs to focus in on important
details without losing the big picture—a charging lion in a jungle, for
example. Now, a new study by Salk scientists shows how inhibitory
neurons play a critical role in this process.
The study, published May 25, 2021, in the journal Cell Reports, shows that inhibitory neurons do more than just inhibit neuron activity like
an off-switch; paradoxically, they actually increase the amount of
information transmitted through the nervous system when it needs to be
flexible. To make this possible, inhibitory neurons need to be
integrated into the circuit in a specific way. These observations could
help scientists better understand and treat disorders involving our
ability to focus and modulate signals based on the bigger picture, which
are altered in conditions such as anxiety and attention deficit
work points to a new role for inhibitory neurons, which are usually
just thought to be suppressors and organizers of activity," says
Professor Tatyana Sharpee, who led the study. "The role of inhibitory
neurons extends much further. By targeting only the most sparsely
responding neurons, inhibitory neurons make it possible for the whole
circuit to function well. That's completely new."
new work was motivated by unanswered questions from a previous study of
the diversity of response rates among neurons in the retina. The retina
is a part of the eye that converts lights to electrical signals to be
sent to the brain. "Remarkably, when we looked at retina cells that were
not responding very much, their rates of information transfer actually
increased in the presence of modulation," says first author Wei-Mien
Hsu, a postdoctoral fellow in the Sharpee lab. "The trick for making
this unexpected phenomenon possible is to apply the modulation signal
via inhibitory neurons."
the researchers tested the theory in neurons involved in vision, the
findings could apply widely to neurons found throughout the brain and nervous system, adds Sharpee, who holds the Edwin K. Hunter Chair at Salk.
The next step in this line of research is to study how the phenomenon works in large sets of neurons.
More information: Wei-Mien M. Hsu et al, How inhibitory neurons increase information transmission under threshold modulation, Cell Reports (2021). DOI: 10.1016/j.celrep.2021.109158