LISBON, PORTUGAL – Scientists in Lisbon, Portugal, have made a fascinating discovery while studying learning processes in mice. They have stumbled upon “zombie neurons” in the brain, which are cells that exhibit abnormal behavior despite being functionally alive. This accidental find sheds new light on how the brain learns.
The researchers from Portugal were investigating how the cerebellum, a part of the brain responsible for processing sensory information related to motor movements, learns from the environment. The cerebellum plays a crucial role in tasks such as walking down a crowded street or picking up objects without spilling them.
Utilizing optogenetics, a technique that manipulates cells using light, the scientists conducted experiments with mice to understand the role of climbing fibers in the cerebellum. These climbing fibers were found to be essential for associative learning, as the mice learned to blink in response to visual cues after consistent stimulation of these fibers.
Interestingly, the researchers observed that introducing a light-sensitive protein called Channelrhodopsin-2 (ChR2) as part of the optogenetics manipulation resulted in the zombification of climbing fiber cells. While these zombie neurons remained active, they failed to transmit messages to other neural circuits, impairing the mice’s ability to learn effectively.
The study provides significant insights into the mechanisms of cerebellar learning and emphasizes the importance of climbing fiber signals in the process. The findings could have implications for understanding how similar processes might occur in the human brain, given the similarities between mouse and human brains.
Neuroscientist Megan Carey from the Champalimaud Center for the Unknown highlighted the importance of further research to unravel why ChR2 expression leads to the ‘zombification’ of neurons and whether these findings apply to other forms of cerebellar learning. The research has been published in Nature Neuroscience, offering compelling evidence of the role of climbing fiber signals in associative learning.