You can picture the long-ago scene perfectly: The waiter opens your bottle of champagne with the familiar — yet always startling — pop. The bubbles tickle your nose as you sniff the effervescent liquid. You raise your glass as you look into the eyes of your spouse. You see pupils dilate as those eyes look at you in return. “Happy anniversary,” you say, “to the love of my life.” This is episodic memory in action.
Episodic memory allows you to mentally time-travel back to an episode of your life and relive it in vivid detail. You also use episodic memory to remember the name of someone you recently met at a party. It enables you to remember to take a detour because there is construction along your usual route. In fact, most of the time when you speak about “memory,” you are referring to episodic memory, which involves several parts of the brain.
The hippocampus is crucial for episodic memory
If you drew a line between your ears you would pass through the most critical structure for episodic memory. The hippocampus looks somewhat like a seahorse with a head, body, and tail. It is always turned on, recording thoughts, feelings, perceptions, and sensations that arise from other regions of the brain. One part of the hippocampus binds these disparate aspects of experience into a coherent whole. Another part tags it with an index that will allow the memory to be retrieved minutes, hours, days, or years later.
Learning and retrieving information: the frontal lobes
What you pay attention to determines what you will remember. If you are watching your favorite television show and your spouse walks in and gives you a verbal to-do list, you will have difficulty remembering the list if your attention was focused on the television. You can, however, use your frontal lobes to focus your attention. Located behind your forehead, the frontal lobes also enable us to voluntarily retrieve memories. In fact, when you are searching for a specific memory, it is your frontal lobes that are doing the searching.
Trying to remember whether you learned that medical information from a Harvard Health Blog post or a supermarket tabloid? The frontal lobes also help you remember the source and context of information that you learn.
Providing context: the parietal lobes
Have you had the “aha!” experience where you suddenly recall the information you’re looking for — such as the name of a friend who is walking toward you? The conscious recollection of episodic memory comes from the parietal lobes, located in the top, back part of the brain.
Episodic memory: left brain versus right brain
You have two hippocampi, frontal lobes, and parietal lobes, one on each side. The left-brain system is specialized for words and language. The right-brain system is particularly good at remembering non-linguistic information including images, body language, and tone of voice. So, when you recall a conversation with your friend, your left hippocampus remembers the words that were spoken, and your right hippocampus remembers how they were spoken, your friend’s face, and the emotion conveyed.
Aspects of episodic memory decline in normal aging
One reason it is useful to know about the different parts of the episodic memory system is that frontal lobe functions — such as learning, searching, and ability to recall source — tend to decline in normal aging. For this reason, it’s normal for people to notice three changes in episodic memory as they age:
- Because learning diminishes, information may need to be repeated a couple of times in order to get it into the hippocampus so it can be remembered.
- Because the search process slows, it may take more time or a hint or a cue to retrieve a memory.
- Because the ability to judge source declines, it may be more common to experience trouble recalling where we learned information.
In normal aging, however, once information is learned, a person should be able to retrieve it — even if it takes a bit of time, or a hint or cue. By contrast, if a person cannot retrieve learned information, this suggests some problem in addition to normal aging is present. In future blogs I will discuss what happens to episodic memory in disorders of aging, such as Alzheimer’s disease.
Bible verses for today’s meditation and inspiration: Matthew E. McLaren
2 Corinthians 2:14 But thanks be to God, who always leads us in triumph in Christ, and manifests through us the sweet aroma of the knowledge of Him in every place.
Romans 6:17 But thanks be to God that though you were slaves of sin, you became obedient from the heart to that form of teaching to which you were committed,
2 Thessalonians 1:3 We ought always to give thanks to God for you, brethren, as is only fitting, because your faith is greatly enlarged, and the love of each one of you toward one another grows ever greater;
1 Corinthians 1:4 I thank my God always concerning you for the grace of God which was given you in Christ Jesus,
Philippians 1:3-5 I thank my God in all my remembrance of you, always offering prayer with joy in my every prayer for you all, in view of your participation in the gospel from the first day until now.
Colossians 1:3-6 We give thanks to God, the Father of our Lord Jesus Christ, praying always for you, since we heard of your faith in Christ Jesus and the love which you have for all the saints; because of the hope laid up for you in heaven, of which you previously heard in the word of truth, the gospel.
2 Corinthians 8:16 But thanks be to God who puts the same earnestness on your behalf in the heart of Titus.
Psalm 75:1 We give thanks to You, O God, we give thanks, For Your name is near; Men declare Your wondrous works.
2 Chronicles 29:6-14 “For our fathers have been unfaithful and have done evil in the sight of the LORD our God, and have forsaken Him and turned their faces away from the dwelling place of the LORD, and have turned their backs. “They have also shut the doors of the porch and put out the lamps, and have not burned incense or offered burnt offerings in the holy place to the God of Israel.
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