Lecture Exam 3 Flashcards
Temporal Categories of Memory
Immediate memory
Short-term memory
Long-term memory
Forgetting
Immediate Memory
Fractions of a second-seconds
- The routine ability to hold ongoing experiences in mind for fractions of a second.
- The capacity of immediate memory is very large and each sensory modality (visual, verbal, tactile, and so on) appears to have its own memory register
- Example: While making saccadic eye movements, we are continuously getting new ‘snapshots’ of the visible environment.
- Example: Memory of somebody walking across the room just a second ago and knowing they moved to the right.
Short term memory
Seconds-minutes
- The ability to hold and manipulate information in mind for seconds to minutes while it is used to achieve a behavioral goal.
- Example: Searching for the ketchup bottle in the fridge, you know what you are looking for while looking around
- Asking somebody to repeat numbers 475 or use digit span testing (most people can remember approximately 7-9 digits)
Working memory
Seconds-minutes
- A part of short term memory but introduces a manipulation component.
- Example: Not only asking to repeat numbers 475 but to tell you them backwards.
Long term memory
Days-years
- Retaining information in a more permanent form of storage for days, weeks, or years.
- Important/significant information can enter long term memory (from immediate or short-term) by conscious or unconscious rehearsal or practice.
- Example: I remember my 8th birthday party, where you were on 9/11. Highlights importance of emotional salience which promotes consolidation.
Engram
- The physical embodiment of the long-term memory in neuronal machinery
- “Single memory unit”
- Depends on long-term changes in the efficacy of transmission of the relevant synaptic connections, and/or the actual growth and reording of such connections.
- Example: The memory is represented by protein changes, generation of new proteins or AMPA which will improve strength of synaptic connection; this may be where the memory actually can be.
- Example: We know if hippocampus is damaged you lose memory, so the theory is that they have to be localized somewhere.
Consolidation
- Aspect of long term memory which refers to the progressive stabilization of memories following initial encoding of memory “traces”.
- Requires changes in gene expression, protein synthesis and synaptic plasticity (e.g., AMPA cell phosphoralation)
Engram + Consolidation
Both of these topics are ‘controversial’. No evidence for a physical site of memory storage. Memory is not a one-size-fits-all situation.
2 Forms of Long term Memory
- Semantic/Declaritive/ EXPLICIT
- Skill learning/Nondeclaritive/IMPLICIT
Implicit Memory
Nondeclarative; unconscious recollection of previously learned information. This type of memory is typically manifested in an automatic manner, with little conscious effort of the subject.
-Examples: Priming, Procedural (skills and habits), Associative learning (classic and operant conditioning), Nonassociative learning (habituation and senstization).
Explicit Memory
Declarative; deliberate or conscious retrieval of previous experiences as well as conscious recall of factual knowledge about people, places, facts and events.
Examples: Facts (semantic) and Events (episodic).
Brain systems underlying declarative memory acquisition and storage
Reliant on midline diencephalic and medial temporal lobe structures. Hippocampus in particular.
- Papez/Limbic Circuit
- Prefrontal cortex, forebrain, fornix, thalamus, mamillary bodies, amygdala, rhinal cortex, hippocampus, MMT, corpus callosum, temporal lobe.
Posterior hippocampus and spatial navigation
Together with the entorhinal cortex, the hippocampus has specialized cells with receptive fields that specifically respond to spatial location.
Appreciate that there are cells in the posterior hippocampus that respond to SPATIAL LOCATION and have denser connectivity in this range
Example: study where taxi drivers have increased area of posterior hippocampus than controls.
Rodent models of spatial learning
“Place cells” which fire for being in a very specific location. Was proven with the morris water maze task for rodents.
Rats will learn where pedestal is in water to rest. If you remove the pedestal and everything else stays same “place cells” will activate and they will swim immediately to where platform is. If you damage hippocampus there is no memory for were that platform was.
(CA 1, CA2, CA3, DG, FI)
Patient HM (1926-2008)
- Seminal case for understanding why temporal lobe is important for memory.
- HM suffered from severe epilepsy.
- Dr Scoville, a neurosurgeon, localized the seizures to the R and L medial temporal lobes.
- Dr Scovelle actually removed more than just the hippocampus, HM ended up with a bilateral anterior hippocampal, amygdalar and entorhinal cortical resection.
- HM was mostly cured of his epilepsy by his surgery
- However, he suffered profound ANTEROGRADE AMNESIA. Inability to form new episodic memories.
- Brenda Milner discovered that his working memory and procedural memory were intact (examples: could do mirror drawing test, draw a path through a maze, tower of hanoi game)
Where memory likely is “stored”
Evidence for cerebral cortex as the major long-term repository for many aspects of declarative memory.
Association
- Important for storage
- Ability to remember meaningless information is extremely limited. Must ASSOCIATE things with something else or provide meaning/context.
- Mneumonists assign meaning to number strings to remember them beyond typical 7-9 digit span (Ex: Singling the digits of Pi decimels)
Association Research
- Research on depression indicates those with depression will attend to certain negative memories over good or have a different attending pattern. People who are depressed have rumination and bias to remember negative experiences over positive experiences.
- Storage of information is important for association based cues. For example, when HUNGRY subjects have increased ability to recognize a certain food item or non-food item. When people are SATED they recognize food or non-food items at similar level.
Conditioned learning
-Generation of a novel response elicited by repeatedly PAIRING a novel stimulus with a stimulus that normally elicits a response.
Classical conditioning
Conditioned learning.
Innate reflex is modified by associating normal trigger with an unrelated stimulus (e.g., Pavlovs dogs)
Amnesia
Abnormal forgetting or pathological forgetfullness
The inability to learn new information or to retrieve information that has already been acquired
Retrograde Amnesia
Difficulty retrieving memories established prior to precipitating neuropathology
- More typical of the generalized lesions associated with head trauma
- Also affected by neurodegenrative disorders, such as AD
- This tells us that while the hippocampus/midline diencephalic structures form and consolidate declarative memories, they are ultimately stored elsewhere
Anterograde Amnesia
An inability to establish new memories following neurological insult
Agnosia
Inability to recognize stimuli.
Often misinterpreted as memory deficit, but does not result from memory, attention, language problems or unfamiliarity to the stimuli.
Results from dysfunction of one of the sensory modalities: visual, tactile, auditory.
Visual example: when seeing cup, “its red, its smooth” verse when touching the cup “its a mug”