Why do falls rise with age? Study points to cerebellar neuron firing

A new study from McGill University has found a direct link between age-related declines in neuron activity in the cerebellum and declines in motor skills such as walking, balance and agility. It is well known that these abilities decline with age, but this is the first study to show precisely how changes in Purkinje cells, an important type of cerebellar neuron, cause this decline, leading to measurable changes in behavior and physical function.

“By demonstrating what changes occur, Purkinje cells “This offers new hope for extending the healthy lifespan of older adults and ultimately improving their quality of life and independence,” explained Eviter Fields, lead author of the study and a McGill doctoral student in the Integrated Neuroscience Program.

The results of this study have important implications for public health measures such as fall prevention. It may also help understand why similar neurological deficits occur in Alzheimer’s disease and other neurodegenerative diseases.

The research was carried out in collaboration with Professor Alanna Watt’s laboratory in the Department of Biology.

connection between mind and body

Purkinje cells process sensory input and internal signals from the body and send corrective messages that fine-tune movement. However, unlike other neurons, they can also fire electrical signals spontaneously. To test how aging affects this activity, the researchers examined motor coordination in mice from young adults (2 months old) to older adults (18 to 24 months old). Older mice performed worse in some ways Adjustment taskreflecting reduced human motor skills, such as crossing high beams or staying on a rotating rod (rotarod).

The researchers then recorded the electrical activity of Purkinje cells and found that the firing rate was significantly lower in older mice. To determine whether this was the cause of the behavioral decline, the researchers used a gene-targeted tool called DREADD, a type of designer receptor that increases or decreases the excitability of neurons when activated.

“We found that when we turned on DREADD in young mice, causing Purkinje cells to fire at a lower rate to mimic older Purkinje cells, they jumped off the rotarod faster than young mice without DREADD,” Professor Fields explained. The reverse was also true: when the researchers stimulated the firing of neurons in older mice, the mice stayed on the rotarod longer, suggesting improved motor coordination.

“We showed that the spontaneous firing rate of older Purkinje cells is reduced, and reversing this increases coordination, indicating that this change plays a direct role in the age-related decline in motor coordination,” Fields said.

A second test yielded similar results. When the older mice were trained to pull a 1-meter string as a reward for cereal, they made more mistakes than the younger mice. But when the researchers increased the firing of Purkinje cells in older mice, the older mice made significantly fewer errors than before.

Professor Watt, a co-author of the study, noted that ongoing research in this area is needed to support the aging population.

“Motor coordination is understudied in the field of aging. It is important to study this because when coordination declines, falls become more common and can have a devastating impact on quality of life,” she said.

Research is published in diary Proceedings of the National Academy of Sciences.