Cerebellum Stimulation Boosts Older Adults’ Episodic Memory

New research shows how noninvasive neurostimulation of the right cerebellum improves episodic memory and may offset age-related cognitive decline.

For centuries, the cerebellum was considered a motor-function-only brain region that coordinated smooth and accurate muscle movements but didn't play a role in cognition. Most neuroscientists didn't think the cerebellum played a role in nonmotor brain functions or cognition until the late 1990s, after Jeremy Schmahmann identified and coined the term cerebellar cognitive affective syndrome in 1998.
Before 1998, damage to the cerebellum was primarily associated with motor syndromes like cerebellar ataxia and dysmetria.
Since the early 2000s, accumulating evidence suggests that different microzones within the left and right cerebellar hemispheres play a vital role in optimizing how the whole brain works in concert to facilitate higher executive functions like working memory, linguistic processing, spatial cognition, social mentalizing, and emotion regulation.
Much like the cerebellum coordinates smooth, fluid movements and promotes superfluid athletic performance, different parts of the cerebellum's left and right hemispheres help to coordinate thought processes and may facilitate superfluid thinking.
For years, we've known that damage or deterioration of certain cerebellar regions affects the whole brain's cognitive capacity and can result in what Schmahmann calls "dysmetria of thought." Now, new research suggests that stimulating the right cerebellum enhances the brain's ability to learn and remember.
Stimulating the Right Cerebellum Improves Episodic Memory
A new study (Almeida et al., 2023) into the cerebellum's role in cognitive functions found that stimulating the right cerebellar hemisphere with anodal transcranial direct current stimulation (tDCS) improves episodic memory in older adults over age 60. These findings were recently published in the peer-reviewed journal GeroScience.
"Here, we show that the cerebellum plays a causal role in episodic memory performance and aging-related [cognitive] decline and that age-related episodic memory decline can be reduced in a long-lasting way with neurostimulation to the right cerebellum," the authors explain.
For this 12-day study, first author Jorge Almeida and colleagues randomly assigned study participants to one of four groups. Only one group received anodal tDCS to the right cerebellum for 12 days. Another group received anodal tDCS to the left prefrontal cortex during this time. The remaining groups were used as controls and didn't receive actual tDCS neurostimulation but instead were put on a waitlist or received sham tDCS treatment.
The researchers tested participants' verbal episodic memory using the Free and Cued Selective Reminding Test (FCSRT) at three different time points: before the study began, one day after the 12-day study ended, and four months after the study concluded.
Notably, those who received anodal tDCS to the right cerebellum were the only participants with significantly better FCSRT scores immediately following 12 days of neurostimulation and four months later at a follow-up evaluation.
"Memory performance enhancement greatly outlasts the [12-day] stimulation period," the authors explain. "Moreover, all individuals in the right cerebellum anodal tDCS experimental group showed memory performance improvements at the follow-up evaluation time [four months later]."
Neurostimulation of the Right Cerebellum Enhances Memory-Related Connectivity
Interestingly, Almeida et al. found that subcortical anodal tDCS to the right cerebellum improved its structural and functional connectivity with the hippocampus and other cortical brain regions involved in episodic memory.
As the authors explain, "Immediate effects of tDCS to the right cerebellum on the functional connectivity of the hippocampus were observed over a series of regions that are majorly involved in many of the processes that are central to episodic memory, and thus are important to sustain enhancements of episodic memory performance."
The Main Takeaways From This Study
Stimulating the right cerebellum improves episodic memory in older adults for at least four months after a 12-day treatment. Noninvasive anodal tDCS to the "little brain" also changes the cerebellum's functional and structural connectivity with the hippocampus and other cortical regions in the episodic memory network.
The authors conclude that neuromodulation of the right cerebellum can improve long-term episodic memory. They also posit that these findings demonstrate a "causal role of the cerebellum in high-level cognitive processes—specifically in episodic memory."
In an April 2023 news release, Almeida summarizes the clinical implications of his team's latest findings: "[Our] work opens up the possibility of developing non-pharmacological interventions to ameliorate typical age-related cognitive frailty that induce long-lasting improvements that, at least, outlast the four months tested herein."
Optimizing Connectivity Between All Four Brain Hemispheres
For decades, I've been fascinated with how the right and left cerebellar hemispheres work in concert with the cerebrum's "left brain-right brain." As a young right-handed tennis player, my neuroscientist father taught me that the right cerebellum works with the left cerebral hemisphere to control the right side of the body.
During my years as a professional athlete, I was always intrigued by the crisscrossed connectivity between the cerebral and cerebellar hemispheres as it relates to superfluid coordination and peak performance. (See The Split-Brain: An Ever-Changing Hypothesis.)
In 2009, I drew a brain map (see illustration, left) using some highlighters and Sharpies that showed a birds-eye view of all four brain hemispheres squished down onto a two-dimensional plane. The yellow and green bidirectional arrows form a "Super 8," illustrating how structural and functional connectivity might flow between all four hemispheres in ways that help the whole brain function better.
Looking at this brain map through the lens of Almeida et al.'s latest (2023) research, it seems plausible that targeting the right cerebellum kickstarts a chain reaction that enhances structural connectivity between different hemispheres and, in doing so, helps to optimize whole-brain functionality.

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False Memories and Memory Enhancement: Neuroscience Insights

Factors that contribute to memory errors, and steps to improve memory

Have you ever left your keys in a spot where you were sure you would remember, only to forget and have to retrace your steps? Or, have you ever vividly remembered an event that never actually happened? These everyday experiences highlight the fallibility and reconstructive nature of human memory. Fortunately, new neuroscience research is helping us understand the underlying mechanisms of memory formation and identify ways to enhance memory retention while avoiding the formation of false memories.
False Memory: What Is It?
Human memory is fallible, and people can easily remember events that never occurred or remember them differently from how they happened. A person can produce a false memory when a person to post-event information somewhat consistent with the original memory. For instance, showing a series of photos, participants who viewed a photograph of a stop sign may later falsely recall seeing a yield sign instead. The false memory was instigated when they were told that a yield sign was actually in the images.
Neural Mechanisms Involved in False Memory Formation
The hippocampus is a brain region critical for forming, consolidating, and retrieving memories. Recent research has shown that hippocampal activity can predict false memory formation. For example, St. Jacques, Wittmann, Singh, and Daselaar (2021) used functional magnetic resonance imaging (fMRI) to investigate how neural activity in the hippocampus relates to forming false memories. Participants viewed a series of images and were later given false information about the images. The study found that people with high levels of cross-stage neural pattern similarity in the hippocampus were more likely to form false memories based on inaccurate information.
Shao, Chen, et al.'s (2023) research on predicting false memory derived from post-event inaccurate information using fMRI data showed that the hippocampus plays a central role in forming false memories. Precisely, patterns of neural activity in the hippocampus can predict the likelihood of developing a false memory. Furthermore, this research shows that the hippocampus, a region critical to memory formation, is also a source of memory errors when exposed to post-event information.
Factors Contributing to Memory Distortion
Post-event information can interfere with the original memory and produce a false memory similar to, but not identical to, the event itself. Several factors can influence the extent to which post-event information affects memory. These include:
1.The time delay between the actual event and the post-event information.
2.The degree of similarity between the post-event information and the actual event.
3.Individual factors such as age, personality, and cognitive abilities.

The research provides valuable information on the factors contributing to memory distortion, with conclusions such as time delay and similarity between post-event information and the actual event essential factors influencing memory accuracy. Thus, these factors should be considered when thinking about memory recall and strategies to improve memory retention and retrieval.
Tips for Improving Memory Retention
While false memory can be a frustrating experience, there are several strategies you can use to enhance memory retention and accuracy:
1.Engage in physical exercises, as studies show that it may help improve cognitive abilities and memory functions.
2.Study in short sessions with frequent breaks rather than trying to learn everything in one go.
3.Use mnemonic devices, visualization, and other memory aids to help you remember information effectively.
4.Get adequate sleep each night, as sleep is critical to consolidating memories.
5.Stay focused on the event and give a detailed description of events right after it happened.
The studies above indicate that human memory is a complex and nuanced cognitive ability prone to errors and inaccuracies. The insights offered by these studies are critical to our understanding of how the brain functions and how we can enhance our memory performance, particularly in situations where memory accuracy is essential, such as eyewitness testimony in legal settings. By continuing to explore the neural mechanisms underlying memory formation and conducting further research into strategies for improving memory accuracy, we can better understand the complexities of human memory and develop effective interventions for individuals who suffer from memory deficits.

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