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Week 7 Discussion Ageing and the brain memory

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Ageing and the Brain Memory

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). One definition of pattern completeness is the capacity to recall previously visited locations after a period has passed, even if some of the specifics have changed. However, pattern separation entails keeping separate the various interactions that took place throughout several visits. In particular, the parts of the brain responsible for memory decline rapidly with age. The hippocampus, a brain region, loses around 5 percent of its nerve cells per decade after age 20 (Freberg, 2019). As people become older, the hippocampus loses inhibitory neurons. It has been demonstrated both in the memory-unimpaired (AU) and memory-impaired (AI) elderly brain that the number of inhibitory neurons in the hilum of the dentate gyrus decreases, albeit the number of inhibitory neurons in other hippocampal sub-regions decreases as well (Fraundorf et al., 2019). The dentate gyrus and proximal CA3 are two important sub-regions for pattern separation calculations, and their intricate feedforward and feedback linkages are notable. A key factor in the dynamics of a network is the equilibrium between excitation and inhibition.

Age-related declines in working memory skills, the capacity to build new episodic memories, response speed, eye-blink conditioning, and reduced blood flow in memory- and cognition-related regions of the brain were among those emphasized by Freberg. Brain structure and chemistry mirror these changes in cognitive performance. When we reach the middle of our lives, our brains undergo a series of gradual but observable changes. Less lateralization in certain processes essential for memory and cognition, and in regions of enhanced activity, are indications of this remodeling in the brain. According to Freberg (2019), the explanation lies in the fact that the aging brain has a harder time clearing extracellular adenosine, which in turn influences memory consolidation. To be sure, adenosine suppresses a memory-related signaling pathway. A decline in white matter and worse sleep quality are also mentioned as reasons of these age-related cognitive declines. There are also some further monoamine alterations that occur in the brain. Freberg says that the serotonergic pathway oversees a wide range of cognitive functions and behaviors, including waking up and staying awake, regulating emotions and moods, controlling aggressiveness, maintaining a healthy weight, and maintaining a balanced energy level. Appetite, sleep, memory, learning, body temperature, mood, muscular contraction, and the cardiovascular and endocrine systems are all directly influenced by these processes and behaviors. Both serotonin receptors and transporters become less abundant as we become older.

The aging brain undergoes both volume reduction and cortical thinning, both of which are influenced by changes at the level of individual neurons. Dendrites are retracted and neuron sizes are reduced due to the breakdown of the fatty myelin sheath that protects the axons. Loss of synapses, or connections, between brain cells may also impair cognitive functions including learning and remembering. In addition, less S1 receptors are present in the frontal cortex, putamen, and caudate nucleus (Pluvinage & Wyss-Coray, 2020). Additionally, serotonin transporter binding ability is decreased in the thalamus and midbrain.

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.

Pluvinage, J. V., & Wyss-Coray, T. (2020). Systemic factors as mediators of brain homeostasis, ageing and neurodegeneration.  Nature Reviews Neuroscience,  21(2), 93-102.