Memory and Cognition Flashcards
What is cognition?
Relates to the highest order of brain function and the behaviour that deals with thought processing
Extremely complex
Describes the integration of all sensory information to make sense of a situation
What does making sense of a situation require?
Ability to remember evens and learn from them
What does learning and remembering require?
Motivation
What is neuronal plasticity?
Ability of central neurons to adapt their neuronal connections in response to learning experiences
What is most of the cerebrum made up of?
Association areas which integrate information from multiple sources rather than being concerned with one specific function
What lobe is are the visual association areas and visual cortex found in?
Occipital lobe
What lobe is the primary somatic sensory cortex and sensory association area found in?
Parietal lobe
What lobe is the primary motor cortex and motor association area (premotor cortex) found in?
Frontal lobe
What lobe is the auditory association area and auditory cortex found in?
Temporal lobe
What are the 3 key components of learning and memory?
Formation of memories (hippocampus)
Storage of memories (cortex)
Searching and accessing memories (thalamus)
What is the hippocampus responsible for in terms of memories?
Formation of memories
What is the cortex responsible for in terms of memories?
Storage of memories
What is the thalamus responsible for in terms of memories?
Searching and accessing memories
In what system are memories formed?
Limbic system
What does the limbic system represent?
‘Old’ cortex but has important connections with the ‘neo’ cortex, in particular the temporal and frontal lobes which allow us to make sense of situations through learning
Gives events emotional significance which is essential for memory
What is the most primitive part of the cortex?
Limbic system
What are the 4 distinct areas of the limbic system?
Hypothalamus
Hippocampus
Cingulate gyrus
Amygdala
What is the hypothalamus associated with?
ANS response
What is the hippocampus associated with?
Memory
What is the cingulate gyrus associated with?
Emotion
What is the amygdala associated with?
Emotion
Collectively, what are the 4 distinct areas of the limbic system responsible for?
Instinctive behaviours such as thirst, sex, hunger and emotive behaviour which is driven by seeking reward or avoiding punishment
What does electrical stimulation of certain areas of the limbic system in conscious patients cause?
Intense feelings of well being
Euphoria
Sexual arousal
this means these areas are reward areas
Other nearby areas elicit fear/terror, anger or pain so are punishment areas
What forms the “affective components” of the sensory experience?
Reward and punishment areas, which are central aspects to learning
What does motivation to learn come from?
Gaining a reward or avoiding a punishment, which gives tasks significance
What happens to experiences that are neither rewarding or punishing (insignificant experiences)?
Barely remembered as your brain naturally gives attention to experiences it deems significant
What assesses the significance of an event?
Frontal cortex and its association with the reward/punishment centres in the limbic system
Limbic system is responsible for selecting what experiences are stored in memory
What part of the limbic system does almost all sensory information go through?
Hippocampus, which in turn relays information to other limbic structures
What happens to people with bilateral hippocampal damage?
Immediate (sensory) memory (seconds in length) and intact long-term memory (from time before damage), but are unable to form new long-term memories
Reflexive memory (motor skills) remain intact
What is an example of an infection that can cause bilateral hippocampal destruction?
Herpres simplex infection
What can memory be divided into?
Immediate or sensory memory
Short term memory
Immediate long-term memory
Long term memory
How long is immediate or sensory memory?
A few seconds
What is immediate or sensory memory
Describes the ability to hold experiences in the mind for a few seconds
For immediate or sensory memory. do visual memories or auditory memories delay fastest?
Visual memories decay fastest (less than 1s), auditory ones slowest (less than 4s)
How long is short term memory?
Seconds to hours
What is short term memory often called?
Working memory
What is short term memory used for?
Tasks such as dialling a phone number, mentla arithmetic, reading a sentence
How long is immediate long-term memory?
Hours to weeks
What is an example of immediate long-term memory?
What you did last weekend
What is short term memory associated with?
Reverberating circuits
What is immediate long-term memory associated with?
Chemical adaptation at the presynaptic terminal
How long is long term memory?
Can be lifelong
What is an example of long term memory?
Where you grew up
Childhood friends
What is long term memory associated with?
Structural changes in synaptic connections
What does short term memory depend on?
Maintained excitation from reverberating circuits (ie they need to be constantly refreshed)
Is an electrical phenomenon
What is a reverberating circuit?
Neural circuit in which nerve impulses that were initially activated in response to stimuli are more or less continuous reactivated so that retrieval of information on demand is possible
Explain the process of short term memory?
1) Each synapse in reverberating circuit is excitatory so brief stimulus at A causes long lasting neuronal activity at B as the circuit continues to excite all neurons in pathway
2) Keeps short term memory alive, if it is deemed significant eventually results in consolidation of the memory in long-term memory storage
3) If reverberation is disrupted, such as following head injury, memory loss normally results (amnesia)
What is the medical term for memory loss?
Amnesia
What are the 2 types of amnesia?
Anterograde
Retrograde
What is anterograde amnesia?
Cannot form new memories
Depending on severity can be short lived or permanent
Destruction of what results in permanent inability to form new memories?
Hippocampus
What is retrograde amnesia?
Cannot access (more recent) old memories
Recall of events that happened a long time ago are usually unaffected
Damage to what results in retrograde amnesia?
If only thalamus is damaged and the hippocampus is spared
(suggests thalamus is required for ‘searching’ our existing memory bank
What chemical changes does immediate long-term memory involve?
Increasing Ca2+ entry to presynaptic terminals, increases neurotransmitter release
What is the process of intermediate long-term memory?
1) Electrical stimulation (membrane depolarisation)
2) Voltage gated Ca2+ channel opens
3) Ca2+ flows in and increases concentration inside the perminal
4) Neurotransmitter release
What structural changes are involved in long term memory?
Increase in neurotransmitter (NT) release sites on presynaptic membrane
Increase in number of NT vesicles stored and released
Increase in number of presynaptic terminals
Increased amplitude in graded membrane potential (EPSP) in post-synaptic cell often observed
What is the term used to describe the structural changes of long term memory?
Long term potentiation (LTP)
What does LTP stand for?
Long term potentiation
What is long term potentiation (LTP)?
Basicallt a well-established, well-rehearded pattern of neuronal firing unique to a particular memory
What are the 2 types of long term memory?
Declarative or explicit memory
Procedural/reflexive/implicit memory
What is declarative or explicit memory?
Abstract memory for events (episodic memory) and for words, rules and language (semantic memory)
What is the abstract memory for events called?
Episodic memory
What is the memory for words, rules and language called?
Semantic memory
What does declarative or explicit memory rely heavily on?
Hippocampus
What is procedural/reflexive/implicit memory?
Acquired slowly through repetition, includes motor memory for acquired motor skills such as playing tennis and rules-based learning such as always driving on the left
Thinking about these skills (memories) often impairs performance
What is procedural/reflexive/implicit memory based mainly and independent of?
Based mainly in the cerebellum, is independent of the hippocampus
What is the process called where short term memory is converted to long term memory?
Consolidation
What does consolidation involve?
Selective stregthening of synaptic connections through repetition (for minutes to hours)
Similar process occurs in the cerebellum during motor learning
During the process memory simply exists as electrical activity and is vulnerable to being wiped out
What does memory recall depend on?
Significance of an event, events deemed significant by the frontal cortex and its association centres with the reward/punishment centres of the limbic system are coded and then stored in the sensory and association areas of the cortex
What does coding new memories result in?
New memories being stored alongside other existing memories the brain deems similar
Explain the process of creating new memories?
1) Sensory input to sensory and association areas
2) Frontal cortex asseses “significance” with the limbic system reward and punishment areas
3) If deemed significant the frontal cortex “gates” the Papaz circuit (limbic system reward and punishment)
4) If still deemed significant the frontal cortex instructives the sensory and association areas to write into long-term memory
5) Papez circuit is “gated” again by the sensory and association ares
6) If still significant the frontal cortex instructs sensory and association areas to keep writing into long term memory
7) Keeps Papez circuit open, this continues until consolidation is complete
What are the components of the Papaz circuit?
Where are different components of a memory laid down during consolidation?
In different parts of the cortex, such as visual component in the visual cortex and auditory component in the auditory cortex
What is a consequence of different components of memory being laid down in different areas of the cortex?
Recall can be evoked by multipled associations
Many memories have a strong emotional connections with them that can be pleasant or unpleasant
What is Korsakoff’s syndrome also known as?
Chronic alcoholism
How does Korsakoff’s syndrome impact memory?
Vitamin B deficiency leads to damage of limbic system structures
Ability to consolidate memory is impared
How does Alzheimer’s disease impact memory?
Severe loss of cholinergic neurons throughout the brain including the hippocampus
Gross impairment of memory
What does evidence suggest about being born with memories?
We are born with some inherited memories essential for survival
What does evidence think the relation between dreaming and memory is?
Dreaming may be to tidy up memory stores so the same information can be packaged more compactly, may also help us forget memories that are no longer useful
What stage of sleep is important for memory?
REM sleep
(subjects deprived of REM sleep show significant impairment of memory consolidation for complex cognitive tasks)
(dreaming may enable memory consolidation, reinforce weak circuits
Why do patients with Korsakoff’s syndrome or Alzheimer’s disease have greatly reduced REM sleep?
Cholinergic neurons responsible for REM
