Queensland Brain Institute researchers have shown the size and structure of inhibitory synapses connecting our brain cells during learning.
Associate Professor Victor Anggono explained that this study is one of the first to show how the inhibitory synapses adjust after learning, expanding our knowledge of neuronal plasticity, connectivity and refinement.
“Most of our neurons are excitatory—when their synapses fire, they activate other neurons, propelling electrical signals through our nervous system—and so most research focuses on the excitatory synapses,” Associate Professor Anggono said.
“The inhibitory synapses that restrain or inhibit neuronal communication are as important, and that’s what our study focused on.
“We used an innovative labelling method to visualise the inhibitory synapses in healthy, adult mice before and after a motor learning activity.
“By zooming in on the inhibitory synapses, we have shown that, like excitatory synapses, they also get bigger during learning.”
Postdoctoral Research Fellow in the Anggono lab, Dr Nishita Bhembre, said the team proposed two possible explanations for the remodelling of the inhibitory synapses.
“The first hypothesis is that it changes to maintain homeostasis or balance neuronal firing, ensuring that the inhibitory synapse can control excitation to avoid abhorrent firing and preserve learned information,” Dr Bhembre said.
“The second hypothesis is disinhibition – whereby the brain’s learning circuit is ready to go, like an automatic car that’s idling, and when learning occurs, the inhibitory synapse expands, effectively releasing the brake to communication between neurons.”
The research team measured this effect after one day of accelerated learning, so further research is required to establish if the changes occur over multiple days and to gain more insight into the structural plasticity of inhibitory synapses.
The Anggono lab continues to research how neurons dynamically modulate their synaptic strength, aiming to understand how dysregulation of these processes contributes to dementia and neurodegenerative diseases.
This research was published in Open Biology
