The vermis plays a central role in maintaining posture and balance. It integrates information from the vestibular system (the balance organ) and proprioception (body awareness) and generates motor commands that keep us stable and coordinated, even in dynamic or unexpected situations.
A recent review in the Journal of Neuroscience
https://pubmed.ncbi.nlm.nih.gov/40399043/
provides exciting insights into how different regions of the vermis contribute to postural control, and puts forward intriguing hypotheses:
1. Anterior vermis
- Likely particularly active during voluntary movements (e.g., walking)
- Purkinje cells in this region may suppress balance reflexes that would otherwise interfere with goal-directed movements
- They may help transform sensory information from a head-centered to a body-centered reference frame—crucial for posture and coordination
👉 Example: While walking, constant reflexive corrections would disrupt the flow of movement. The anterior vermis may suppress these reflexes, enabling efficient, goal-directed locomotion.
2. Posterior vermis (nodulus and uvula)
- Receives afferent input from both otolith organs and semicircular canals
- Likely contributes to continuous monitoring of body orientation relative to gravity — regardless of whether the movement is voluntary or unexpected
- In contrast to the anterior vermis, Purkinje cells here probably do not suppress reflexes, but instead provide a stable internal model of spatial orientation
👉 Example: Imagine standing in a swaying train. Even without moving voluntarily, your brain must know in which direction your body is tilting—this information is likely supplied by the posterior vermis.
Conclusion
- The authors propose a functional differentiation:
- The anterior vermis may selectively inhibit balance reflexes during voluntary movements to allow goal-directed motor control.
- The posterior vermis may provide a continuous, reference-stable orientation in space, independent of movement type.
These hypotheses could help explain how the cerebellum ensures both stability and mobility at the same time. An exciting area for future research.