Foundations of Cognition I Notes PDF

2024-10-10 Foundations of cognition I PSYC-2014 FAO – Week 05 Last class: Short-term memory Working memory Today: Long-term memory  2024-10-10 Long-term Memory Recall that working memory interfaces with long-term...

2024-10-10 Foundations of cognition I PSYC-2014 FAO – Week 05 Last class: Short-term memory Working memory Today: Long-term memory  2024-10-10 Long-term Memory Recall that working memory interfaces with long-term memory I.e., You can use information from long-term storage to manipulate information held in working memory E.g., To do math Today, we will focus on long-term memory Long Term Memory Early Model: Atkinson & Shiffrin (1968) Long-Term Memory (LTM): Memory that has no capacity limits and lasts from minutes to an entire lifetime Two key advantages: Seemingly unlimited storage Seemingly unlimited duration Unlike STM, LTM does not rapidly undergo forgetting  2024-10-10 Early Model: Atkinson & Shiffrin (1968) Atkinson & Shiffrin envisioned LTM as a single long-term storage Proposed control processes: Strategies that a person uses to facilitate learning (i.e., strategies that determine how information is processed) Rehearsal Coding Imaging Early Model: Atkinson & Shiffrin (1968) (1) Rehearsal: Repeating verbal information to keep it in active short-term memory Involves the phonological loop A form of Rote Learning: Learning by repetition, rather than through understanding (i.e., memorization) Early Model: Atkinson & Shiffrin (1968) (2) Coding: Semantic elaboration of information to make it easier to remember Attempts to place the to-be-learned information in the context of easily- retrievable information Makes information easier to remember  2024-10-10 Early Model: Atkinson & Shiffrin (1968) Example of Coding: Mnemonics Mnemonic: a memory aid that makes it easier to remember information by linking it to something more memorable. These are strategies to link more complex, harder-to-remember information in some way to simpler, easier-to-remember information Example: Mnemonics Mnemonics can be used to make very complex information retrievable E.g., Classification of star temperatures are represented by “OBAFGKM” We can learn relatively complex information (e.g., stellar classification system) very quickly using mnemonics Example: Mnemonics Remember: Oh Boy, Another F's Gonna Kill Me  2024-10-10 Example: Mnemonics What are the star spectral classes? Early Model: Atkinson & Shiffrin (1968) (3) Imaging: Creating visual images to make material easier to remember Involves the visuospatial sketchpad at the time of encoding E.g., Mentally visualizing places, things, etc. Serves as a mental reminder for associated information Imagery: Example Imagery ties together visual imagery and information The Bactrian camel is shaped like the letter B The Dromedary camel is shaped like the letter D  2024-10-10 Which type of camel is this? Which type of camel is this? Rundus (1971): Serial Position Effect Rundus (1971) tested the probability of successfully recalling words from a list Found that recall depended on the position of words in the list Memory was strongest for the words at the beginning and end …..but weakest for words in the middle of a list  2024-10-10 Rundus (1971): Serial Position Effect This is called the serial position effect Serial position effect: The ability to recall words from a list is better for words at the beginning and end of the list Two components: (1) Primacy (2) Recency Rundus (1971): Serial Position Effect Primacy effect: The better recall of words at the beginning of a list Recency effect: The better recall of words at the end of a list There are possibly different mechanisms for these two effects Rundus (1971): Serial Position Effect Why does this happen? Primacy effect: Words early in a list tend to have been rehearsed more, leading to storage in LTM Recency effect: Words latest in the list may not have yet been forgotten from STM These two combine to cause better recall for early and late words in a rehearsed list  2024-10-10 Stages of Long-Term Memory Stages of LTM (1) Acquisition: Storage of information in LTM When memories are first attained (2) Retention: Maintenance of information in LTM Initial encoding, consolidation (strengthening) (3) Retrieval: Recalling information from LTM Consolidation After being acquired, memories are consolidated which supports long-term retention Consolidation: The process of stabilizing a memory trace following initial acquisition Occurs over time; transfer for memories to long-term storage  2024-10-10 Sleep & memory Memories from the day are also later strengthened during sleep This is thought to be one of the primary functions of sleep Many studies have shown that targeted memory reactivation (cues presented during sleep to ‘remind’ participants of learned information from the day) can enhance memory Smith & Weeden (1990): Clock Experiment Participants asked to learn a complex logic task Two groups of subjects: (1) Learned the task with a constant clock ticking noise in the background (cued groups) (2) Simply learned the task with no sound in the background (non cued) Participants then went to sleep in the lab Smith & Weeden (1990): Clock Experiment During the night, while participants were asleep… During REM sleep, a clock ticking noise was played In the morning, groups were re-tested on the same complex logic task Which group performed better?  2024-10-10 Smith & Weeden (1990): Clock Experiment The cued group showed significantly better task improvement up to one week later Suggests that targeted memory reactivation during sleep can cue memory consolidation Consolidation Hebbian Learning: synaptic connections between neurons are strengthened when one neuron's activity is consistently paired with another neuron's activity “Neurons the fire together wire together” Donald Hebb – Canadian Psychologist from Nova Scotia  2024-10-10 Consolidation The biological mechanism for this is called Long-Term Potentiation This is thought to be one mechanism by which new memories are acquired and maintained LTP is a long-term change in neuron activity that supports long-term memory formation Bliss & Lømo (1973): Long-Term Potentation Timothy Bliss & Terje Lomo are credited with the discovery of Long-Term Potentiation Long-Term Potentiation: a lasting increase in synaptic strength following repeated stimulation Strengthens the connection between two neurons after they repeatedly fire together (one sending, and one receiving)  2024-10-10 Consolidation NMDA receptors are channels on neurons that are normally blocked by a magnesium ion Opening the channel makes it more likely that a neuron will fire an action potential (electrical potential) Consolidation Opening the channel requires two conditions: (1) The receiving neuron must fire an action potential (2) Glutamate (a neurotransmitter) must activate the channel The result is that, when two neurons fire together, the channels open Makes the neuron more likely to fire when stimulated again later Connection becomes strengthened Memory Engrams An Engram (or memory trace) is a unit of information imprinted in a physical substance (e.g., cells, brain tissue) Theorized to be the means by which memories are stored The Physical representation of memories in the brain LTP is thought to be one mechanism for engrams  2024-10-10 Eric Kandel: Non-associative learning While LTP had been discovered in the late 1960s, it was not known that this was a mechanism for learning Bliss & Lomo were studying the hippocampus That LTP specifically supports learning was later shown by Eric Kandel We will come back to this at the end Types of Long-Term Memory Types of Long-Term Memory Atkinson & Shiffrin (1968) conceptualized LTM as a single long- term memory store We now know that this is not the case Long-term memory is not a single memory type  2024-10-10 Types of Long-Term Memory There are declarative long-term memories and procedural long-term memories Within these, there are types of memories that depend on different brain networks Memory Types We have already discussed sensory memory and short-term memory/working memory Long-term memories are either Declarative or Non-Declarative Memory Types Declarative Memory: Memory that requires conscious recall Includes episodic and semantic memories These types of memories require conscious recall E.g., “What is the largest city in Canada?”  2024-10-10 Memory Types Non-Declarative Memory: Types of memory that do not require conscious recall There are many different types of memory which do not require conscious recall for us to perform We will discuss the first three today (1) Declarative Long- Term Memory Declarative Memory Stores facts and concepts Can be summarized as “knowledge and experiences” Two main components: Episodic Memory: memory for events, including when and where they occurred Things you “remember” Semantic Memory: General knowledge not associated with a particular context Things you “know”  2024-10-10 Episodic Memory Stores specific events Context-dependent Where, when something happened Deals with specific names of places, etc. Episodic Memory We know this is the case because of Place cells Place cells: neurons in the hippocampus that activate when an individual is in a specific location, aiding in the brain's spatial mapping Hippocampal Place Cell recorded over 50 minutes  2024-10-10 10 Hippocampal Place Cells recorded over 50 minutes Semantic Memory Stores facts and concepts Can be summarized as “knowledge and experiences” Two main components: Episodic Memory: memory for events, including when and where they occurred Things you “remember” Semantic Memory: General knowledge not associated with a particular context Things you “know” Is a potato a fruit, or a vegetable?  2024-10-10 Semantic Memory Semantic memory deals with global knowledge/general knowledge Is not associated with any particular place/context Knowledge of facts and information: Language Categorical knowledge (e.g., you know that an apple is a fruit) Conceptual knowledge (e.g., understanding what “freedom” is) Biographical, cultural, and historical information Memory Storage Where are declarative memories stored? It is thought that storage is distributed There is no known single “ semantic memory” center in the brain Different types of semantic memories are likely stored with their association areas (e.g., Language with language regions, etc.) Some of our understanding of memory storage comes from amnesia Patient H.M. (Henry Molaison) Patient H.M. was a famous case in neuroscience H.M. underwent brain surgery in 1953 to treat epilepsy The surgery removed parts of the temporal lobe, including pathways to the hippocampus This was thought to potentially reduce the frequency/severity of his seizures  2024-10-10 Patient H.M. (Henry Molaison) After his surgery, H.M. experienced severe anterograde amnesia He could not form new long-term memories after the surgery His short-term memory and general intelligence remained intact H.M.'s case highlighted the importance of the hippocampus in memory formation Patient H.M. (Henry Molaison) Amnesia is memory loss, temporary or permanent, resulting from various cause. Two main types: (1) Retrograde Amnesia: partial loss of previous memories. (2) Anterograde Amnesia: inability to form new memories. Temporally-Graded Amnesia However: H.M. Did not lose all of his older memories Many amnesiacs actually have access to older memories, but not recent more ones This phenomenon is called Temporally Graded Amnesia Temporally-Graded Amnesia: a type of memory loss where recent events are forgotten more than older memories  2024-10-10 Standard Model of Declarative Memory Why does this happen? Suggests storage of recent memories is somehow different from storage of older memories Initially: Hippocampus encodes information about declarative memory, including when/where events took place (place cells) Standard Model of Declarative Memory The Standard Model of Declarative Memory Suggests that over time, consolidation transfers memories from the hippocampus to the cortex Over time, memories become less and less dependent on hippocampus Fully consolidated memories are stored in the cortex only Multiple Trace Theory Key Observation: Sometimes people can remember details of an object, but not what the object itself is I.e., “I can picture her face, but I can’t remember her name!” Suggests these are two different memory engrams  2024-10-10 Multiple Trace Theory A second approach that explains this is Multiple Trace Theory Multiple Trace Theory: Proposes that every time a memory is retrieved, a new "trace" is formed in the brain As a result, hippocampus is always involved in the retrieval of memories Even for older memories Multiple Trace Theory Also suggests that each time memories are recalled, they are potentially altered as a new trace is created This process is called ‘reconsolidation’ Occurs when older memories are recalled Episodic Memory Reconsolidation: restabilizing a memory that has been destabilized through memory retrieval Rather than simply strengthened over time, memories are also altered and updated Useful mnemonic: Memories are “Unboxed” and must be repackaged for long-term storage  2024-10-10 Ongoing Debate There is currently no definitive answer as to which (if any) of these theories is correct Not all amnesiacs have temporally graded amnesia Evidence exists for both (2) Non-Declarative Long-Term Memory *Note: We will leave priming for a future class. Procedural memory  2024-10-10 When you came in today, did you have to think about how to turn the door handle? Procedural Memories Some learned information is not verbal, visual, or contextual This includes actions, skills, operations (e.g., tying one’s shoes) These are things that you “do” rather than things you “know” We refer to these types of memories are procedural memories Procedural memory: Memory for actions, skills, and operations. Procedural Memories Procedural memories are largely associated with the striatum and cerebellum Striatum: part of the Basal ganglia Basal Ganglia: a group of brain structures involved in controlling movement. Includes the striatum, globus pallidus, substantia nigra, and subthalamic nucleus.  2024-10-10 Procedural Memories Damage to these networks results in loss of ability to perform procedural tasks Disorders like Parkinson’s and Huntington’s disease Associative Memory Associative Memory Associative Memory: a type of memory that allows for the retrieval of information based on related cues or associations E.g., Classical conditioning You can learn to like fear something neutral if it frequently occurs with something scary  2024-10-10 Associative Memory This is Emotional Associative Memory Largely dependent on Amygdala Like other types of memory, other types of (non-emotional) associative learning are distributed throughout the brain Non-Associative Memory Associative Memory Some learning can also occur without any association These are primarily things like Habituation and Sensitization Habituation: A decrease in response to a repeated, neutral stimulus over time. Sensitization: An increased response to a stimulus following exposure to a strong or intense stimulus.  2024-10-10 Eric Kandel: Gill Withdrawal Reflex Eric Kandel: Showed that LTP is the foundation of memory formation for simple reflexes Aplysia (Marine Snail): Will reflexively withdraw its gill when the siphon is touched (See next slide) Non-Associative Learning This is habituation Repeated prompting of the siphon causes the gill reflex to stop This type of learning is thought to occur locally within the network that triggers the gill response (not in the brain or elsewhere)