Researchers at the University of Freiburg Medical School, Germany, have discovered that a part of the brain called the “zone of uncertainty” (zona incerta) functions in unconventional ways to control memory formation and has additional brain functions.
The brain’s neocortex, the largest and most complex part of the brain, considered the site of storage for long-term memories is now known to be influenced by the zona incerta.
Led by Dr. Johannes Letzkus and the Max Planck Institute for Brain, this research yields a mechanistic understanding of memory with broad implications, including the treatment of memory and anxiety disorders, the development of artificial intelligence, and efficient hardware and software design. To form memories, the brain must make connections between sensory signals from the environment and internally generated signals that convey information about past experiences and current goals. These latter signals are a central focus of current research.
“Long-range inhibitory pathways are much sparser and less numerous, but mounting evidence suggests that they can still have powerful effects on network function and behavior,” says Prof. Dr. Johannes Letzkus, Professor at the University of Freiburg and former Research Group Leader at the Max Planck Institute for Brain. “We set out to determine whether such inputs might be present in neocortex, and if so, how they might uniquely contribute to memory,” Letzkus says, in a statement.
Dr. Anna Schroeder, postdoctoral researcher in the Letzkus lab, focuses on the zona incerta for study. Her early findings indicated that the zona incerta sends inhibitory projections into an area of the neocortex known to be important for learning.
“The results were striking,” recalls Schroeder. “While about half of the synapses developed stronger positive responses during learning, the other half did exactly the opposite. In effect, what we observed was thus a complete redistribution of inhibition within the system due to learning.”
“This connectivity implies that an activation of the zona incerta should result in a net excitation of neocortical circuits,” explains Schroeder. “However, combining this with the redistribution of inhibition that we see with learning shows that this pathway likely has even richer computational consequences for neocortical processing.”
This work is published in Neuron.