Neuro Ch 9 Memory

memory where info is temporarily maintained in mind while it is being used to perform some task, but is rapidly lost when attention shifts elsewhere

• visuospatial sketchpad: keeps visual images in mind
• phonological loop: keeps words, sentences, and numbers in mind

• encode, store, and retrieve information over long periods of time
• greater capacity than working memory 
• divided into implicit and explicit

• skills and learning that can occur without conscious awareness 
• nondeclarative: can't verbally express these memories (e.g. playing piano or tying shoes)

• implicit memory
• memories for how to perform skills or habits
• acquired through repition and practice

• implicit memory 
• form of unconscious memory in which past experiences can influence a response to a sensory stimulus 
• can be perceptual or conceptual

• implicit memory
• a form of memory in which a previously neutral stimulus gains the ability to elicit a behavioural response, after becoming associated with another stimulus that naturally elicits that response

• implicit memory 
• a form of learning in which a behaviour is made more likely by providing a reinforce (reward) after it occurs or made less likely by providing a punishment after it occurs

• long term strengthening or weakening of a response after repeated exposures to stimulus 
• habituation and sensitisation

• information that can be consciously recalled and expressed 
• declarative: things you know you know, and can be talked about

• explicit memory 
• memories for past events in you life associated with spatial context (where), temporal context (when and sequence), perceptual detail (what things looked like, who was there, how felt)

• recognition memory - ability to tell that you have seen or experienced something before 
• recollection: retrieval of qualitative details realted to previous experience
• familiarity: sense of having seen something before, without an ability to bring to mind qualitative details about the prior experience

• explicit memory memories for facts about the world 
• memories for concepts rather than specific percepts
• semantic memories are independent of any particular sensory modality 
• organised based on meaning

• Alzheimer's disease (episodic memory before semantic memory)
• semantic dementia (semantic before episodic)

• damage to the hippocampus and surrounding medial temporal lobe cortex results in amnesia
• retrograde: inability to retrieve episodic memories for events that occurred prior to brain injury
• anterograde: inability to form new episodic memories after injury

an extensive body of research on the hippocampus comes from non human animal models

were discovered in the rodent hippocampus these are cells that fire when the animal is a particular location in its environment

• memories represented as a pattern of activity in the brain 
• the system of brain regions active when memory is encoded
• hippocampus serves as a pointer to perceptual systems, indexing perceptual features of the memory 
• some parts of the network active during memory encoding reactivated when memory retrieved

• hippocampus critical for all forms of declarative memory 
• hippo has time limited role in memory: involved initially but gradually memories become independent and consolidated into cortical areas

• important for semantic and episodic memory
• only semantic memories become independent of the hippocampus over time
• true episodic memories accompanied by mental time travel always depend on hippocampus
• semantic and semanticised episodic memories gradually become supported by the cortex as a result of repeated retrieval and rehearsal

• the hippocampus is critical for
• recollection: retrieval of specific details about the events of a particular memory, including where and when those events took place
• medial temporal lobe cortex critical for assessing familiarity in absence of recollection

hippocampus critical for storing relations/associations between elements of events in contrast to storing just individual items

• hippocampus evolved to create and store spatial maps for navigation, orientation, finding resources
• this system has been co opted to create and store episodic memories as well (because they're spatial)

patients with amnesia not only have difficulty remembering the past, but also have difficulty imagining new experiences

• network of brain regions linked to episodic memory and imagine, but also active when people are resting quietly 
• default mode involves memory retrieval, introspection, mind wandering, self reflection

• Memory is falliable: we all make errors in remembering even when we are fairly confident
• memory is reconstructive

• unintentional production of false or distorted recollections or narratives, often in the face of contradictory evidence
• may be inability to inhibit currently irrelevant memories in favour of ones that are currently relevant

healthy people, uninjured brains, when they're pressured to remember details of memory beyond their ability to recall it accurately

• generated with no external cues, accompanied by strong conviction, may be acted upon 
• constructed memories containing elements of the past but for the wrong situation at hand

attributing an idea or recollection to the wrong source (wrong time, place, or person)

false memories can be created by providing a fictitious suggestion about a past experience, then encouraging elaboration of that false memory

• cells that fire together wire together
• evidence from synaptic connections can be modified as a result of the activity history of the cells involved

• long lasting increases in synaptic strength that are induced when a presynaptic cell consistently activates along with a postsynaptic cell
• many postsynaptic membranes contains NMDA receptors, which are glutamate receptors

long lasting decreased synaptic sgregnth that are induced when a presynaptic cell and postsynaptic cell are not consistently activated at the same time

• other mechanisms important for memeory formation
• neurogenesis: production of new neurons
• dentritic spines: tiny protrusions from dendrites, which may undergo structural changes with experience