Our mind does a great job of acting as a master control center for our meat sack if you stop and think about it – which calls your mind back. Now researchers have discovered more about how the brain fixes long-term memories in its storage slots.
A new study looks at the ‘zone of uncertainty’ or ‘zona incerta’ inside the brain: we don’t know much about it, but we do know that it seems to handle memory formation in concert with the largest part of the neocortex. Cerebral cortex.
In learning tests in mice, researchers analyzed how the connections between the zona incerta and the neocortex operate, paying particular attention to synapses (connections between neurons) and inhibition (reconnection of neuron activity).
“The results were surprising,” says neuroscientist Anna Schröder of the University of Freiburg in Germany. “While half of the synapses developed strong positive responses during learning, the other half did just the opposite.”
“In fact, what we saw was a complete redistribution of inhibition within the system due to learning in this way.”
When the brain forms memories, it combines ‘bottom-up’ signals from the environment and ‘top-down’ signals that it generates itself; These top-down signals can be influenced by our current goals or past experiences, for example.
The zona incerta carries a less common type of top-down signaling called the long-range inhibitory pathway. Top-down signals typically light up or stimulate neural pathways, while these types are inhibitory, essentially suppressing and blocking these pathways.
Differentiating the strength of synapses and chains of neurons in the brain is essential for making memories, helping the brain to assign value to what is happening to us: everything that happens to us happens somewhere on the memory level.
These tests show that the zona incerta encodes past experiences in a unique bidirectional manner that was not seen before. Additional tests where zona incerta pathways were blocked resulted in learning impairments in rats.
“This connection indicates that activation of the zona incerta results in net stimulation of neocortical circuits,” says Schroeder.
“However, combining this with the redistribution of inhibition that we see with learning suggests that this pathway may have richer computational consequences for neocortical processing.”
This is all relatively high-level neuroscience, but the conclusion is that we now know more about how a mysterious brain region influences memory and learning—and it does so in strange and unexpected ways that are of particular interest to scientists.
As more studies investigate the role of the zona incerta, we are beginning to understand just how much influence it has: it is now linked to sleeping and feeding and pain and anxiety.
Furthermore, this region is routinely targeted in the treatment of Parkinson’s disease, although scientists are still not sure why it helps with symptoms. Future research like this will help solve that mystery and many others.
“Ultimately, this study will inspire other researchers to continue exploring the role of long-range inhibition in the regulation of neocortical function, both from the zona incerta and from additional, as yet unidentified sources,” says neuroscientist Johannes Letzkus. University of Freiburg.
Research has been published in neuron.