Week 7 Discussion: Aging And The Brain Memory

4week 7 Discussion Ageing And The Brain Memorystudents Nameinstructor

Memory resides in a region of the brain called the hippocampus, and recent studies have implicated two distinct but related functions for this region: pattern separation and pattern completion (Freberg, 2019). Pattern completion refers to the capacity to recall previously visited locations after some time has passed, even if certain specifics have changed, while pattern separation involves keeping different interactions from various visits distinct. These processes are crucial for effective memory function; however, aging significantly impairs them, primarily due to structural and biochemical changes in the hippocampus.

The hippocampus experiences a decline of about 5 percent of its nerve cells per decade after the age of 20, resulting in diminished capacity for memory processing. Importantly, aging affects the inhibitory neurons within the hippocampus, especially in the hilum of the dentate gyrus. Both memory-impaired (AI) and unimpaired (AU) elderly brains demonstrate a decrease in inhibitory neurons, particularly in the dentate gyrus and proximal CA3 regions, which are essential for pattern separation calculations (Fraundorf et al., 2019). The balance between excitation and inhibition within these hippocampal circuits is fundamental to preserving memory function, and disruptions due to neuronal loss impair this dynamic.

These neural changes manifest in detectable cognitive declines, such as reduced working memory capacity, slower response times, diminished ability to form new episodic memories, and decreased blood flow in areas involved in cognition. Brain structure and chemistry reflect these declines: there is less lateralization of functions critical for memory and cognition, and regions that are typically highly active show reduced activity with age (Freberg, 2019). One underlying factor involves the difficulty in clearing extracellular adenosine, which suppresses memory-related signaling pathways, thereby impairing memory consolidation.

Additional neurochemical alterations include decreased white matter integrity and poorer sleep quality in older adults. Changes in monoaminergic systems, particularly the serotonergic pathway, also contribute to cognitive aging. Serotonin influences numerous processes, including mood regulation, sleep, appetite, and learning. As individuals age, both serotonin receptor density and transporter availability decrease in key brain regions such as the frontal cortex, putamen, caudate nucleus, thalamus, and midbrain (Pluvinage & Wyss-Coray, 2020). These reductions further impair cognitive functions and behavioral regulation, underscoring the interconnectedness of neurochemical health and cognitive performance.

The physical structure of the aging brain also undergoes notable changes: volume reduction and cortical thinning occur due to neuronal loss and morphological alterations. Dendritic retraction and decreased neuron size, stemming from myelin degradation, contribute to decreased neural connectivity. Loss of synapses hampers the brain's capacity for learning and memory. Notably, the reduced presence of S1 receptors in the frontal cortex, putamen, and caudate nucleus, alongside decreased serotonin transporter binding, underscores the biochemical and structural alterations that underlie cognitive decline in aging (Pluvinage & Wyss-Coray, 2020).

References

  • Freberg, L. (2019). Discovering Behavioral Neuroscience: An Introduction to Biological Psychology (4th Ed.). Boston, MA: Cengage Learning, Inc.
  • Fraundorf, S. H., Hourihan, K. L., Peters, R. A., & Benjamin, A. S. (2019). Aging and recognition memory: A meta-analysis. Psychological Bulletin, 145(4), 339-365.
  • Pluvinage, J. V., & Wyss-Coray, T. (2020). Systemic factors as mediators of brain homeostasis, aging and neurodegeneration. Nature Reviews Neuroscience, 21(2), 93-102.
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  • Roberts, E., & Mednick, S. C. (2017). Sleep deprivation and cognitive decline in aging: An integrative review. Sleep Medicine Reviews, 32, 13-23.
  • Lieberman, A. P., & Patterson, D. (2015). Neurochemical changes in the aging brain. Neurobiology of Aging, 36(4), 1593-1604.
  • Gage, F. H., & Kempermann, G. (2019). Adult neurogenesis: What's responsible for its decline in aging? Cell Stem Cell, 24(2), 172–175.

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