Song of the Cerebellum

Rachel Gross shares her personal story of experiencing a stroke caused by a bleed in her cerebellum, a part of the brain traditionally understood as primarily involved in motor control. The episode begins with her karaoke mishap, which serves as a narrative entry point into her health crisis. After her stroke diagnosis and surgical removal of part of her cerebellum, she faces persistent challenges with speech, coordination, and self-perception, prompting her to explore the new science behind the cerebellum.

The episode delves into the history and anatomy of the cerebellum, revealing how its function has been historically misunderstood as merely controlling movement. Recent scientific discoveries suggest that the cerebellum also plays a crucial role in cognitive, emotional, and social functions. This shift in understanding is supported by research showing extensive neural circuit connections between the cerebellum and the 'upstairs' brain regions involved in higher cognitive functions.

Research indicates that during primate evolution, the cerebellum has expanded significantly, especially in humans, with a large proportion of brain neurons residing there. This expansion correlates with complex cognitive functions and possibly human evolution itself. The episode emphasizes that the cerebellum's interconnectedness with the cerebral cortex suggests it is integral to why humans are capable of advanced thinking, language, and emotional regulation.

Science is increasingly recognizing the cerebellum's role beyond motor control, including organizing thoughts, language, and emotional responses. Rachel discusses cases of cerebellar damage leading to difficulty with speech, planning, personality changes, and emotional regulation. The cerebellum appears to act as an 'invisible conductor,' coordinating the timing and sequencing of both physical movements and cognitive processes, thus shaping our sense of self and social interactions.

The episode explores how the new understanding of the cerebellum challenges traditional dualist views separating mind and body, suggesting instead that thinking and feeling are deeply rooted in brain circuitry involving the cerebellum. Rachel’s personal journey highlights the importance of this paradigm shift in neuroscience, emphasizing that a better grasp of the cerebellum’s functions could deepen our understanding of what it means to be ourselves, especially after injury.