How the brain filters out irrelevant information
New York, Sep 21 Have you ever wondered how our brain enables us to read a book even in a noisy cafe by filtering out the irrelevant stimuli coming through ears and "gating" in the relevant ones in our vision -- words on a page? It is possible due to the inhibitory neurons that the brain employs in such situations, new research suggests.
The inhibitory neurons are brain's traffic cops that help ensure proper neurological responses to incoming stimuli by suppressing other neurons and working to balance excitatory neurons, which aim to stimulate neuronal activity, said the study.
"Our computational model shows that inhibitory neurons can enable a neural circuit to gate in specific pathways of information while filtering out the rest," said senior author Xiao-Jing Wang, Professor at New York University.
Of particular interest to the team was a specific subtype of inhibitory neurons that targets the excitatory neurons' dendrites -- components of a neuron where inputs from other neurons are located.
These dendrite-targeting inhibitory neurons are labeled by a biological marker called somatostatin and can be studied selectively by experimentalists.
The researchers proposed that they not only control the overall inputs to a neuron, but also the inputs from individual pathways -- for example, the visual or auditory pathways converging onto a neuron.
"This was thought to be difficult because the connections from inhibitory neurons to excitatory neurons appeared dense and unstructured," Guangyu Robert Yang, a doctoral candidate in Wang's lab, observed.
"Thus a surprising finding from our study is that the precision required for pathway-specific gating can be realised by inhibitory neurons," Yang noted.
The study's authors used computational models to show that even with the seemingly random connections, these dendrite-targeting neurons can gate individual pathways by aligning with excitatory inputs.
In the study published in the journal Nature Communications, they showed that this alignment can be realised through synaptic plasticity -- a brain mechanism for learning through experience.