%% ### #todo - [ ] See action points for individual sections below. - [ ] Add references to this note and sub-notes. - [ ] Make sub-notes public and add to Anki. - [ ] Tetzlaff et al. (2021): Time scales of memory, learning, and plasticity - [ ] The most prominent method for survival that living beings have is to sense certain features of their environment and (re)act accordingly. The simplest behavior relies on direct sensorimotor coupling (reaction); more advanced behavior entails making simple sensing predictions (proaction) or even base the method on sophisticated and memorized environ- mental knowledge (planning) built by multisensory experi- ence. - [ ] For the most basic mechanism—reaction—memory is not necessary because a direct connection from sensors to motors suffices (cf. Braitenberg 1984). The second—proaction— involves reaction to stimuli that are expected. Thus, for such a behavior the underlying mechanisms require the collection of stimuli from the past on which predictions for the future are based. The third—planning—relies on remembered stim- uli, combines predictions into a plan, and must memorize the state of the plan while executing it. - [ ] The last two behaviors discussed above rely mainly on two concepts: - [ ] (1)  The first concept consists of an extraction mechanism that condenses information from past experiences and performs refinement processing of the condensed infor- mation so that behaviorally useful predictions of the future can be made. This concept is often referred to as “learning,” and we find mainly three mechanisms for it: (a) correlation learning is based on evaluating statisti- cally significant relations between events in the envi- ronment, (b) reinforcement learning or reward-based learning is based on unspecific good–bad signals, and (c) supervised learning relies on specific error signals. - [ ] (2)  The second concept consists of a bridging mechanism that retains the condensed past and present information for future use. This concept is often referred to as “memory,” and three subcategories of memory have been identified. Working memory processes informa- tion and usually requires attention, and short-term and long-term memory performs long-term storage of infor- mation where the difference between the two concepts lies in duration and capacity. - [ ] https://sites.google.com/view/efratfurst/learning-in-the-brain?authuser=0 - [ ] Review and connect related notes: - [[There are two main types of long-term memory and pathways to store information in long-term memory – declarative (explicit) and procedural (implicit)]] - [[Memory involves reconstruction rather than retrieval of exact copies of encoded mental representations]] - [[Memory evolved in the service of fitness, so we remember information more easily that is relevant for fitness]] - [[Parameters change at many levels to codify learning and memory]] - [[Parameters change at different speeds to codify learning and memory]] - [[The brain manages the tradeoff between stability and plasticity by using different systems with different speeds of learning and distributing memory widely across the biological parts of the body]] - [[The New Theory of Disuse posits that there are two indices of memory strength – storage strength and retrieval strength]] - [[Each memory is represented by alterations to millions of synapses]] %% --- ### Definition *What is memory?* Schacter (2007) offered four different senses of memory: >1. The neurocognitive capacity to encode, store and retrieve information; >2. A hypothetical store in which information is held; >3. The information in that store; and >4. An individual’s phenomenal awareness of remembering something. For the purpose of this note, I'll go with the first definition: **Memory is the capacity to encode, store, and retrieve information**. With respect to learning, memory is the **record of learning**.^[Polk, 2018] ### Benefits *What does memory serve? How does it it support learning?* Memory allows an organism to **learn and adapt from previous experience** — in particular, to use previous experience to support a range of **cognitive functions**, including [[Perception is the organization and interpretation of sensory information|perception]], problem-solving, planning, and creative thinking.^[Budson & Kensinger, 2023; National Academies, 2018; Seel, 2012] Importantly, memory uses past experience in **new ways** and in **novel contexts**.^[Budson & Kensinger, 2023] Memory is an essential component of most, if not all, types of learning.^[National Academies, 2018] It is what allows learning to be **cumulative and progressive**. Without the ability to retain and add up many individual instances of learning, there would be no "forward movement" in learning. [[Learning happens in relation to what you already know (prior knowledge), not in the abstract]]. So learning and memory are intertwined. They are **two sides of the same coin**, where one side (learning) focuses on the acquisition of skills and knowledge, and the other side (memory) on the retention and future application.^[Lieberman, 2021] Learning extracts and distills useful information from previous experience that allows the individual to make behaviorally useful predictions of the future, whereas memory provides a bridge across time so that past and present learning can be applied in the future.^[Tetzlaff et al., 2012] ### Types *What are the different types of memory? How do they work?* Memory isn't a single, unitary ability or process, but a **collection of abilities and processes**. It is composed of several **distinct systems**, each associated with a particular **brain network** that allows different types of information to be remembered over different timescales.^[Budson & Kensinger, 2023] Strong evidence to support this claim comes from the study of people with **amnesia** – that is, people whose memory is impaired as a result of brain damage.^[Lieberman, 2021] The most famous example is patient H.M., who had parts of his brain removed to prevent seizures he was frequently experiencing. After the intervention, the seizures occurred less frequently, but he also wasn't able to form new explicit long-term memories anymore. Interestingly, he was still able to form new implicit long-term memories and to hold information in working memory. This story demonstrated that memory is made up of different systems that depend on different brain structures.^[Polk, 2018] Memory systems or types can be classified in multiple ways:^[Budson & Kensinger, 2023; Lieberman, 2021; Polk, 2018] - By **content** – i.e., the type of information they contain. - By **duration** – i.e., the timeframe in which they operate. - **Short-term memory** lasts only seconds to minutes. - **Long-term memory** lasts minutes to several years. - **Remote memory** lasts many years to decades. - By **temporal direction** – i.e., whether the content to be remembered is in the past or in the future. - **Retrospective memory** involves remembering what happened in the past. - **Prospective memory** involves reminding oneself to do something in the future. - By whether (or to what extent) **conscious awareness** is required for learning and retrieval. - **Explicit memory** requires conscious awareness for learning and retrieval. - **Implicit memory** doesn't require conscious awareness for learning and retrieval, though it can be present. - By **individual vs. collective** – i.e., whether the memory is held by an individual or a group of people. - Probably there are many more useful distinctions depending on the context of consideration. Here, I'll use the duration of memory as the highest-level distinction, and content and the involvement of conscious awareness as secondary classification criteria.^[For the breakdown of long-term memory, I'll follow the account in Lieberman, 2021.] - [[Short-term memory stores a small amount of information for a short period of time]] - [[Sensory memory stores input from the senses for a few seconds to allow time to identify it]] - [[Working memory is a "mental workbench" that temporarily holds a small amount of information readily available for ongoing processing]] - [[Long-term memory stores a large amount of information for a long period of time]] - [[Explicit memory requires conscious awareness for learning and retrieval]] - [[Episodic memory is about personal experiences in one's life]] - [[Semantic memory is about facts and general knowledge]] - [[Implicit memory doesn't require conscious awareness for learning and retrieval, although it can be present]] - [[Perceptual memory is about memory for stimuli]] - [[Procedural memory is about memory for actions]] ### Integration *How do the different types of memory work together?* In real-world situations, **multiple memory systems usually work together** to store and retrieve information in multiple ways and areas of the brain. Also, individual memory systems aren't completely independent. Instead, they **interact with and often depend upon each other**.^[Budson & Kensinger, 2023] Budson and Kensinger (2023, p. 8) use the example of listening to a new song. To summarize their account, this involves forming a sensory memory in the parts that process sound which is then transferred to working memory as you pay attention to the song. An episodic memory forms, including several aspects of the situation in which you listen to the song, such as where you are and what you are doing. As you continue to listen to the song over the next few days, a semantic memory forms, which links the melody of the song to its name. ### Stages *What are the different processes or stages in memory?* See [[Memory involves the stages of encoding, consolidation, and retrieval]] %% ### Phenomena *What are the observable events and characteristics?* - [ ] Kahana et al., 2022: [Laws of Human Memory](https://memory.psych.upenn.edu/files/pubs/KahaEtal22.pdf) - [ ] [[Why We Forget and How to Remember Better]] - [ ] [[How We Learn]]: - [ ] **primacy** Improved recall for items from the beginning of a list compared with items from the middle. - [ ] **recency** Improved recall for items from the end of a list compared with items from the middle. - [ ] … - [ ] [[Psych]]: - Memory is not a veridical recording of the world, stored intact, ready to be recovered through introspection or dreams or hypnosis. Rather, our experience of the past is molded by all sorts of other processes. - We don’t simply absorb sensory data from the world; we don’t simply store what we perceived. Rather, our perception and memory are shaped and informed by intelligent guesses of how the world should be. - Because our interpretations are based on what’s probable, we sometimes get it wrong.== ([Location 3129](https://readwise.io/to_kindle?action=open&asin=B0B2RRP1ZZ&location=3129)) - But in a world of limited and fragmentary information, there might be no better way for the system to work. - [ ] [[Memory involves reconstruction rather than retrieval of exact copies of encoded mental representations]] - [ ] Stability-plasticity dilemma: - [ ] [[Learning faces a tradeoff between stability and plasticity]] – between holding onto old learning and allowing for new learning. This is sometimes called the "stability/plasticity dilemma." - [ ] [[The brain manages the tradeoff between stability and plasticity by using different systems with different speeds of learning and distributing memory widely across the biological parts of the body]] – from neurons all the way to genes. - [ ] Tradeoff between storage size and access speed: - [ ] Add from [[Algorithms to Live By]] (caching) and [[The New Theory of Disuse posits that there are two indices of memory strength – storage strength and retrieval strength]]. - [ ] Memory on an evolutionary timescale: - [ ] [[The brain holds a record of an individual's environment on a short timescale]], whereas [[The genome holds a record of a species' environment on a long timescale]]. - [ ] [[Knowledge integration refers to the process of merging multiple knowledge structures into a single structure by identifying and establishing relationships between pieces of knowledge]] ### Principles *What determines how strongly something will be memorized?* - [ ] Kahana et al., 2022: [Laws of Human Memory](https://memory.psych.upenn.edu/files/pubs/KahaEtal22.pdf) - [ ] [[Why We Forget and How to Remember Better]] - [ ] [[Learning and Memory]], chapter 11: Meaning is at the heart of memory. We remember the abstracted meaning rather than the details of an event or situation. - [ ] [[Principles of Neural Design]] might also have things to say on memory, e.g., "only store what is needed" ### Neural foundations *How is memory represented in the brain?* - [ ] [[Change in synaptic strength is necessary, but may not be sufficient, for learning and memory]]. It’s unclear whether it’s the root mechanism or a consequence. However, the field often concentrates on synapses because that’s what we can most easily measure. - [ ] [[Parameters change at many levels to codify learning and memory]], because [[Biological systems have many degrees of freedom]]. - [ ] [[Parameters change at different speeds to codify learning and memory]]. Instead of looking at the biological parts (above), it can be helpful to look at the timescale on which they operate. Plasticity works on multiple levels at different speeds. Changes at shallow layers happen fast whereas deeper layers change more slowly but also retain information for longer. - [ ] Amer & Davachi: [Neural Mechanisms of Memory](https://psyarxiv.com/32egy/) - [ ] [[Understanding How We Learn]], chapter on memory has a section on neural representation - [ ] Arguably, memory requires involvement of the nervous system. ### Application *How to improve memory in practice?* - [ ] [[Why We Forget and How to Remember Better]]: see the bullet-point lists at the end of each chapter - [ ] Especially chapter 7, but also others %% --- Created: [[2023-04-30]] Type: #permanent Topics: [[Learning (Index)]] Related notes: - [[What are the cognitive mechanisms of learning and how do they work?]]