Memory Flashcards
Name some different kinds of memory
- autobiographical episodic memory
- factual memory
- conditioned reflexes
What is an autobiographical episodic memory?
Memories that pertain to your own actual lived experiences
What is amnesia?
The loss of one or more component of memory
What does amnesia demonstrate?
That there are different types of memories
Define a memory?
It is the group of mechanisms or processes by which experience shapes us, changing our brains and behaviour
What is the critical structure related to memory?
The hippocampus
What does unilateral damage to the hippocampus cause?
Material specific memory disorders
How can we subdivide memory impairment?
- anterograde amnesia
2. retrograde amnesia
What is anterograde amnesia?
The impairment of learning new information after the onset of amnesia (loss of memory AFTER brain injury)
What is retrograde amnesia?
The impairment of memories that were made prior to amnesia (loss of memory BEFORE brain injury)
What was H.M. the first to indicate about amnesia?
That amnesia results from extensive damage to the regions of the MEDIAL TEMPORAL LOBE, including the HIPPOCAMPUS, DENTATE GYRUS, SUBICULUM, AMYGDALA and NEIGHBOURING AREAS
What is crucial for identifying that amnesia is memory specific?
The fact that it is global; the modality and material generality of amnesia is crucial for identifying the disorder as specifically a memory disorder and not a perceptual, linguistic, or cognitive deficit
Define learning.
The process of acquiring new information
Define memory. More specifically, what is it?
Memory is the persistence of learning that can be demonstrated later in time
- memory is the brain’s ability to store the learned effect of its experiences
What two subcategories does explicit (aka. declarative) memory contain?
- facts (semantic memory)
2. events (episodic memory)
What subcategories does implicit (aka. non-declarative) memory contain?
- skills and habits
- priming
- classical conditioning
- non-associative learning
Describe explicit memories?
they are conscious, relational (i.e. they make links between things), flexible (in that they can add info)
Describe implicit memories?
Unconscious retrieval
- includes procedural memory (less flexible)
Which brain structure(s) is/are crucial to declarative memory?
The hippocampal system and related systems, and midline diencephalic regions
What other brain structures are involved in memory in general?
- amygdala
- fornix
- inferior temporal cortex
- putamen
- globus pallidus
- dorsolateral prefrontal cortex
What did patient HM have a lesion to?
He had a bilateral mesial temporal lobectomy
What kind of amnesia did HM suffer from?
anterograde amnesia (mild retrograde amnesia approximately extending to two years prior to the surgery) - he was amnesic for autobiographical and public information (his brain was fossilized in time such that, when asked who the president was, he named Eisenhower, president in the 50s)
What is explicit memory?
Declarative memory (information that you can share with someone) - includes semantic and episodic memories
What is working memory?
The manipulation of learned information, exercised temporarily to accomplish a goal before it is stored
How was HM’s memory affected? In other words, which abilities did he lose? Which did he retain?
HM was impaired in his demonstration of explicit learning, but his implicit memory remained intact (ex. picture drawing mirror task)
How did HM contribute to science?
- he demonstrated that medial temporal lobes play a crucial role in declarative memory
- that there is a difference between long term and short term memories
- that there is a difference between declarative and procedural memories
What is relational learning?
Conjunctions between modules and integration of different sensory experiences
What are medial temporal areas involved in?
Declarative and anterograde memory
What brain systems are involved in the hippocampal formation?
- the hippocampus
- the dentate gyrus
- the subiculum
What does the hippocampal formation receive input from?
From each of the higher order processing areas in the cortex (via the entorhinal cortex)
Where is long term memory stored?
In the same cortical areas where the stimulus took place (at the secondary or tertiary level)
What is the left hippocampus generally involved in?
Verbal learning and memory
What is the right hippocampus generally involved in?
non-verbal and spatial memory
What is the role of the hippocampus?
To synchronize the individual cortical memories of an event, to integrate them to form a cohesive memory (like a choreographer)
- once the “dance” has been learned, we might not need the “choreographer”
What are the two important roles of the medial temporal areas?
- crucial for rapid acquisition of new information about facts and events
- cells that fire together wire together (long term potentiation)
- temporary, implicit memory is separate
- uses NMDA and glutamate - crucial for remembering the environment
Describe the Morris water maze task.
Rats were placed in a pool with opaque water
- they needed to find a platform to stand on
after several trials, the rats learned where the platform was based on spatial cues in the room they were in
When do hippocampal place cells activate?
When seeing a particular location (this is the basis of a spatial map)
What did the study with taxi drivers in London find?
That taxi drivers in this city had bigger right hippocampi compared to control (because London has so many twists and turns, the spatial memory of taxi drivers needs to be very accurate)
What are the parahippocampal cortices important for?
- long term memory
What do the rhinal cortices consist of?
The entorhinal and perirhinal cortices
Where does most of the input to the entorhinal cortex come from?
The perirhinal and parahippocampal cortices (approximately responsible for 2/3 of input)
- not required for implicit memory
What does the amygdala serve to do?
It adds salience to a memory
Which non-hippocampal regions are responsible for memory?
long term memory is stored in the medial temporal lobe (consolidation); the secondary cortex and association sensory cortex
Which area degenerates first in Alzheimer’s disease?
The hippocampus
What role do the secondary sensory cortices play in memory?
These areas activate in memory retrieval
- some respond specifically to faces, and prefer specific orientations and eye gaze (in the infero temporal cortex)
- cells can learn to prefer other stimuli
What are hippocampal place cells?
These fire relative to the location (to learn where A is relative to B)
What are grid cells?
These fire when in a specific location
What are time cells?
These fire depending on the timing of a stimulus (relative to location but in time, not space)
What is the perforant pathway responsible for?
It is the major efferent projection to the hippocampus and the dentate gyrus
Describe semantic dementia?
The inability to retain semantic information
What kind of memory is semantic memory?
Long term memory
What is semantic memory mediated by?
The posterior parietal cortex
What are some other areas important in learning and memory?
- the cerebellum
2. the basal ganglia
What are the cerebellum and basal ganglia’s role in memory?
They are involved in procedural (implicit) memory
- skill learning (basal ganglia)
- involved in rewards (due to dopamine)
What area of memory do Huntington’s and Parkinson’s diseases affect?
Impaired implicit learning (ex. rain and sun task challenges probabilistic learning)
- what we learn is based on trial and error
What is the difference between remembering and knowing?
Remembering is episodic in nature; it pertains to your actual lived experiences…knowing is based in familiarity but does not necessarily mean having experience
- ex. remembering a friend vs. knowing you saw someone somewhere but not sure where
What kind of synapses does the basal ganglia contain?
Dopaminergic synapses
When is there an increase/decrease in dopamine release?
Dopamine is released more when a reward is not predicted but is granted; less dopamine is released when a reward is predicted but not granted (this is the basis of error-driven learning, which tends to be implicit)
What is the hippocampal system responsible for?
Declarative and episodic memory
What is the amygdala responsible for in memory?
Adds emotional salience to a memory
What is the striatum and basal ganglia responsible for in memory?
Procedural and implicit memory
What is the dorsolateral prefrontal cortex responsible for in memory?
Involved in working memory and manipulation of stored memory
What is the anterior temporal lobe responsible for in memory?
Semantic memory
Why do we need two types of learning? (i.e. implicit and explicit memory)
Because the goals of each type are mutually incompatible
- generalized learning (basal ganglia) = the best place to park your car
- specific episodes (hippocampal system) = where you actually parked the car
Define a skill.
An increase in performance due to a large amount of exposure and practise
What is error-driven learning?
When the prediction of outcome and actual outcome are at odds
