LECTURE 7 - Memory Systems

Question 1

what surgery did patient HM have?

Answer 1

• medial temporal lobectomy
• included the anterior hippocampus
• also included parts of the amygdala
• entorhinal cortex on both sides, structure that connects hippocampus to the rest of the cortex, important for memory consolidation

Question 2

what were the effects of patient HM’s surgery?

Answer 2

• anterograde amnesia: could not learn or retain new information (declarative memories) after the surgery
• but, he could learn new visuomotor tasks (but no declarative memory of it happening)
• some memories from before the surgery were retained
• still had short-term memory, could hold items in memory by rehearsing them but could not consolidate or store them
• preserved episodic memory (how to ride a bike)
• no cognitive/intellectual decline, normal perceptual and motor abilities, no change in personality

Question 3

what could patient HM’s inability to consolidate memories be attributed to?

Answer 3

• loss of the entorhinal cortex in both hemispheres resulted in a disconnection of the remaining hippocampus
• there is more than one kind of memory in the brain and the hippocampus is not the only relevant memory structure

Question 4

what is explicit memory?

Answer 4

• declarative, or conscious memory
• responsible for ability to recall facts, events, and connections
• when we say we forget something, it means we cannot retrieve the information from explicit memory

Question 5

what are the different types of explicit memory?

Answer 5

• episodic: recalling specific experiences and events that happened in your life
• semantic: recalling facts and knowledge that can be recounted over time and that accumulates over time
• autobiographical: includes both episodic and semantic components

Question 6

what is implicit memory?

Answer 6

• non-declarative, non-conscious memory
• refers to skills or habits that are learned over time, but are not subject to conscious recall of how such skills or habits were learned
• revealed through performance rather than recollection

Question 7

how was patient HM’s implicit memory impacted by the surgery? why was it impacted differently from his explicit memory?

Answer 7

• his implicit memory was intact
• he was able to improve on the mirror-tracing task, but could not remember learning it
• implicit memory is also less susceptible to dementia and resilient to impairment than explicit memory
• could be because it relies on a more expansive set of brain areas than explicit memory

Question 8

what are the different types of implicit memory?

Answer 8

• procedural learning: acquisition of skills/habits, applies to any procedure that requires repetition to master
• motor sequence learning: learning a series of actions in a sequence, participants react faster when they have to type out a repeated sequence rather than a random onewh

Question 9

what is priming? is priming still present in patients with amnesia?

Answer 9

• refers to how prior exposure to some stimulus or action enhances a perception, thought, or response to a similar stimulus or action
• a form of implicit, non-declarative memory
• amnesic patients show normal priming even when they cannot recognize repeated pictures as familiar
• evidence that perceptual priming relies on perceptual brain areas, not necessarily memory areas

Question 10

what is repetition priming?

Answer 10

• priming that occurs because of direct repetition
• participants respond faster to repeated than to new items

Question 11

what is associative priming?

Answer 11

• priming that occurs for related items
• when presented with the word “nurse”, participants are faster responding to the word “doctor” than “farmer”

Question 12

what is perceptual priming?

Answer 12

• repeated exposure to perceptual features improves perception
• seeing the word “map” improves subsequent recognition of the word “mop” because they share perceptual features

Question 13

what is conceptual priming?

Answer 13

• repeated exposure to meaningful features improves perception
• “cat” evokes “dog” event though they are perceptually different

Question 14

what is statistical learning?

Answer 14

• known regularities about our world, stable
  and predictable features of an environment, object, or task enable us to predict probable future events
• application in language acquisition: learners know statistically common words and patterns, for example, when learning word boundaries
• “pri tee bay bee” is heard as “pretty baby”, because we have learned that syllables “pri” and “tee” are statistically more likely to go together than “tee” and “bay”

Question 15

what is contextual cueing?

Answer 15

• refers to learning where to attend and what to expect based on certain statistical regularities in our environment
• if asked to search for a phone in an apartment, your first impulse would be to search the desk, but not the refrigerator

Question 16

how is contextual cueing studied in the lab?

Answer 16

• it is studied using a visual search task with repeated and new displays
• goal is to find the target as quickly/accurately as possible
• repeated displays → reaction times decrease more rapidly
• new displays → reaction times improve a little but then level off

Question 17

what type of implicit memory is based on predictions?
a. procedural learning
b. statistical learning
c. priming

Answer 17

b. statistical learning

Question 18

what is the primacy/recency effect? how does it represent long-term and short-term memory?

Answer 18

• primacy effect - we have better memory for items at the beginning of a list
• represents long-term memory, we have more time to rehearse so there is better encoding
• recency effect - we have better memory for items at the end of a list
• represents short-term memory, close to the time of recall so there is less distraction

Question 19

what is the serial position curve?

Answer 19

• shows how well people remember items based on their position in a list
• primacy and recency effects take place
• recall is the worst for items in the middle of the list
• delay or interference can interrupt short-term memory

Question 20

where are long-term memories stored?

Answer 20

• long-term memories are stored in the neocortex in a distributed manner
• in the same cortical areas that did the initial processing
• reactivation: activity in the brain when remembering something is similar to what it looked like during first encoding

Question 21

how do the neocortex and hippocampal system work together for memory?

Answer 21

• hippocampus and medial temporal lobe are active during initial encoding and also during retrieval
• initial learning depends on them
• during retrieval, hippocampus/MTL reactivate pieces of info from around the neocortex
• connections in cortical regions gradually strengthen to the point where cortical memories can be accessed without involving the hippocampus/MTL
• hippocampal system helps to associate items and their contexts across different brain areas
• all the info is integrated and linked together and can then activate each other

Question 22

what is the benefit of having two systems for memory, the hippocampus and the neocortex?

Answer 22

• encoding and retrieval of new information depends on the hippocampal system
• allows for quick, one-shot learning
• once fully consolidated, memories can be retrieved via reactivation from neocortex without the hippocampus
• learning is slower, more organized, stabilizes and maintains knowledge

Question 23

what is consolidation? how does it work in the brain?

Answer 23

• the act of stabilizing memories
• occurs when the connection between synapses is strengthened
• synaptic connections are strengthened and activity is increased through experience
• mechanism behind this rule is LTP

Question 24

a professor learns the names and faces of all the students in her course. this is an example of…
a. semantic memory
b. explicit memory
c. implicit memory
d. contextual learning
e. perceptual learning

Answer 24

a. semantic memory