Seeing my uncle like this was disheartening but spending time with him was eye-opening. I didn\u2019t say much, and was all too eager to simply say my hellos and spectate. The nurse wheeled him into a room so he could sit with us, and then promptly took off. My dad, eyes heavy, took the first step and said the first words. \u201cBrother, how are you feeling today?\u201d is the closest approximation I can recall\u2014their conversation was in Urdu. My uncle took his time to respond, glassy-eyed with stuttering lips, but he slowly pulled out a haphazard response resembling \u201cby Allah\u2019s grace, I am fine.\u201d My dad then proceeded to ask more effortful questions, such as \u201cdo you remember me?\u201d Or \u201cdo you remember your kids?\u201d Or \u201cthis is my son, wife, and daughter, do you remember them?\u201d My uncle just stared at my dad as he asked these things, eyes faraway with an uncertain smile as he replied in a hoarse voice \u201cOnly you, no one else.\u201d A beat of silence passed, and then my brother stepped forward. \u201cTayabbu<\/em>, I heard you liked to write so I brought you a notebook and pen,\u201d my brother said, then gently handed said items to my uncle, who muttered a shaky \u201cthank you\u201d before opening the notebook, uncapping the pen, and attempting to write. He could not. His hand shook uncontrollably, and he was not able to write out a single word, leaving instead only a squiggly, long line slashed across the lined page.<\/p>\n\n\n\n He remembered no one from the past twenty years of his life. He could barely speak and could no longer write. From stories my aunt told me, he also forgot how to use the bathroom and swallow food.<\/p>\n\n\n\n So how is it that, as my family began reciting prayers, my uncle, too, remembered every single one? How is it that my uncle, who forgot so much, could barely speak, could no longer write, and could not perform daily functions, somehow remembered litanies of Arabic scripture? At fifteen, I chalked it up to God\u2019s miracles, and, while even now I don\u2019t doubt God\u2019s role, I also know that what happened to my uncle can also be explained using cognitive psychology. My uncle\u2019s formal diagnosis was vascular dementia<\/a>, or vascular cognitive impairment (VCI). For my uncle, vascular dementia was an aftereffect of multiple minor strokes. In a stroke, the brain\u2019s blood vessels are blocked, leading to brain damage and changes in how the brain functions. Vascular dementia aftereffects can range from mild to severe, depending on how badly blood vessels are damaged and where within the brain they ruptured. <\/p>\n\n\n\n Using the umbrella of my uncle\u2019s experiences as context, I want to explore memory\u2014specifically long-term memory, and, if we want to get even more specific, long-term semantic memory. The specifics matter here, because \u201cmemory\u201d is a very broad term. There are many different stages of memory, and there are many different types of memories. We will discuss the memory stages shortly, but first, I want to briefly highlight the three main areas of long-term memory: episodic, procedural, and semantic. Episodic memory is contextual, everyday memory. We use episodic memory to recall life events or autobiographical information. Examples of episodic memory include remembering what you ate last night or recalling the events of your high school graduation. Flashbulb memories <\/a>are a particularly interesting branch of episodic memory, encompassing our emotionally-charged memories. Episodic memories are subjective and biographical, and they are explicit <\/a>memories, meaning they have to be consciously recalled. Procedural memory <\/a>is about skills or \u201cprocedures,\u201d and encompasses how to complete tasks. Procedural memories are implicit<\/a>, meaning they are retrieved subconsciously, or automatically. An example of procedural memory would be in how to ride a bike or brush your teeth\u2014you don’t think about how to do these tasks, you just do them. Semantic memory is the memory of acquired knowledge\u2014memorized facts or information. An example of semantic memory would be remembering the capital of Cuba. Semantic memories don\u2019t require context, making them objective. Like episodic memories, semantic memories are also explicit and require conscious recall. <\/p>\n\n\n\n Thinking back to my uncle\u2019s post-stroke condition now knowing these types of memories, it\u2019s clear now that both his episodic and procedural memories had been damaged. In not being able to remember the past twenty years of his life, he exhibited episodic memory decline, and in being unable to perform daily tasks such as swallowing or using the bathroom, he exhibited procedural memory decline. I even spoke with his doctor recently, who is a family friend, and she confirmed this. She also confirmed my final hunch: that his miraculous memory of all those Arabic prayers was his semantic memory, and that it was, for the most part, still intact. Upon realizing this, I got very, very curious about how semantic memory worked\u2014how it was organized, and what the neural mechanisms (fancy brain stuff) were. And honestly, what I found is that when people say, \u201cit\u2019s all just semantics,\u201d they probably don\u2019t realize how right they are.<\/p>\n\n\n\n The first, perhaps most important thing to note is that our long-term memory is organized semantically. The brain groups together similar concepts based on their \u201csemantics,\u201d or meaning. In the realm of cognitive psychology, semantic memory is both decontextualized knowledge and meaning-based information. The concepts and ideas we already have stored in our minds are decontextualized knowledge that fuels our top-down processes, and the meaning-based characteristics we take in from our environment fuel our bottom-up processes. Those are a lot of big words. Let\u2019s take a step back for a second. A top-down process is basically just how we use prior knowledge to interpret surroundings, and a bottom-up process is how we use new sensory information to form an idea or interpretation. These two processes usually work together, and simultaneously. All semantic memory is meaning-based. In memory models, before information can be moved into long-term memory, it undergoes stages. I told you we would be talking about those. Atkinson and Shiffrin\u2019s Modal Model of memory, for example, mentions sensory memory, short-term memory, and then finally, long-term memory. Sensory memory is when we take in information from the environment, and most of it is lost immediately if we ignore it. What we do pay attention to goes to short-term memory, where it is reviewed and processed if we keep paying attention to it. Finally, once the information has been rehearsed and processed enough, it\u2019s transferred into long-term memory where it is filed into a semantically relevant place. Semantic memories go through a very rigorous encoding process before reaching long-term memory, because it takes more effort to remember things based on their meaning. This meaningful processing is called deep processing. Once semantic information is deeply processed, it\u2019s transferred into long-term memory storage\u2014which is stored all over the brain. While information is organized semantically in the brain, there is no specific region for semantic memory, so it\u2019s kind of all over the place. Additionally, semantic memory in our brain can almost be thought of as a web of concepts and categories. In cognitive psychology, categories are groups of objects with things in common, and concepts are our mental representations of those objects. <\/p>\n\n\n\n However, just because semantic memory is stored everywhere, doesn\u2019t mean there aren\u2019t specific brain regions worth mentioning. Semantic memory formulation relies primarily on three regions: the frontal cortex, the temporal cortex, and the hippocampus. The frontal cortex is used for executive functions, like attention and memory formation. The temporal cortex is responsible for pattern recognition and helps us assign meaning to visual and auditory stimuli. If \u201cassigning meaning\u201d sounds familiar at all, it\u2019s because this has to do with deeply processing something semantically! This is what the temporal cortex helps us do, along with creating long-term memories. As for the hippocampus, researchers wondered if the hippocampus was as important for semantic memory as it was for episodic memory for a long time. The hippocampus is a brain region known for processing memory.<\/p>\n\n\n\n In a paper<\/a> published by Duff and colleagues, the semantic memory and hippocampus link is explored. The research on Patient HM\u2019s<\/a> memory loss was a critical point in cognitive memory studies, and in part, the data showed that, even with a damaged hippocampus, new semantic learning was possible. However, when looking over this famous case, researchers noted there was no control group, and that only baseline levels of semantic learning were detected\u2014that is, semantic memory levels were nowhere near optimal. Researchers now agree that for semantic memory to work properly and effectively, it requires a functioning, intact hippocampus.<\/p>\n\n\n\n![\"\"](\"https:\/\/web.colby.edu\/cogblog\/files\/2022\/04\/psych-image-2.jpg\")
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