Learning and Memory Flashcards
What is learning?
an attempt to create a memory that lasts
What is memory?
how you encode, store, and retrieve information
What is an engram?
the physical basis of memory - a pathway of cells/memory trace
How are memories established?
the formation of neuronal interconnections, susceptible to change
Distinguish between anterograde amnesia and retrograde amnesia
Anterograde - failure to store memories after trauma
Retrograde - failure to recall memories before trauma
What are the 3 stages of memory?
- Encoding
- Storage
- Retrieval
What is plasticity?
the brain’s ability to adjust its structure to reflect life’s experiences
Describe the process of neurogenesis (4)
- nerve cells form more synapses
- blood capillaries increase in the brain
- glial cells increase in size and number
- myelin sheath increases
Define neurogenesis
the process by which new neurons are formed in the brain
How does learning occur according to Pavlov and Skinner? (2)
Pavlov - classical conditioning (involuntary responses)
Skinner - operant conditioning (voluntary responses)
Describe classical conditioning (2)
conditioned stimulus is paired with an unconditioned stimulus to produce an unconditioned response
after several pairings, the conditioned stimulus alone produces a conditioned response
Describe operant conditioning
Responses are followed by reinforcement or punishment to strengthen or weaken behaviour respectively
Distinguish between positive and negative reinforcement, and punishment (3)
Positive - addition of positive stimuli to strengthen a behaviour
Negative - removal of negative stimuli to strengthen a behaviour
Punishment - addition of negative stimuli to weaken a behaviour
What was Lashley’s 1st hypothesis? (2)
Was it true or false?
learning depends on new/strengthened connections between 2 brain areas
hence, a cut somewhere in the brain interrupts that connection and destroys the learned response
Result: false
What was Lashley’s 2nd hypothesis? (2)
Was it true or false? Explain
certain portions of the cerebral cortex are more important than other for learning
hence, removing chunks of the cerebral cortex impairs learning
Result: false
Explanation: amount of tissue removed mattered, not from where it was removed
What did Lashley’s studies conclude? (2)
Learning and memory do not depend only on connections
Learning doesn’t depend only on one area
Explain Lashley’s principle of equipotentiality? (3)
all parts of the cortex contribute equally to learning
hence one part of the cortex can take over the function of another part
therefore, to destroy 1 function, the whole area must be destroyed
Explain Lashley’s principle of mass action (2)
the cortex works as a whole
hence if cortical tissue is destroyed after learning a complex task, deterioration of performance is determined by the amount of tissue destroyed
Where is engram found according to Thompson?
in the lateral interpositus nucleus of the cerebellum
Explain Thompson’s experiment regarding the LIP (3)
Classical conditioning:
tone (CS) + airpuff (UCS) –> eyeblink (UCR)
learnt response:
tone (CS) –> eyeblink (CR)
Pathway taken to the LIP:
facial nucleus –> red nucleus –> LIP
What results did Thompson’s experiment yield? (2)
Temporary inactivation of LIP blocked learning completely
Temporary inactivation of red nucleus blocked learning only during inactivation
What are the 3 types of memory?
Short term memory
Working memory
Long term memory
Define working memory
memory for temporary information required for carrying out cognitive tasks (e.g., learning)
What are the 2 types of long term memory?
Declarative (explicit) memory
Procedural (implicit) memory
What are the 2 types of declarative memory?
Episodic memory
Semantic memory
What are the 2 types of procedural memory?
Skills
Habits
Describe episodic memory
autobiographical memories - things that have happened to you
Describe semantic memory
the conscious recollection of factual information and general knowledge
Describe procedural memory
Give an example
memory of skills and procedures that can be used without conscious thought
e.g., playing an instrument
What is the hippocampus responsible for? (4)
formation of long term declarative memories, especially episodic memories
spatial memory
context association
memory consolidation
What are 2 properties of the hippocampus?
located in medial temporal lobe
shaped like a seahorse
What 2 regions is the hippocampus made up of?
Dentate gyrus
Cornu ammonis
What results from the removal of the hippocampus? (3)
moderate retrograde amnesia
severe anterograde amnesia
better procedural/implicit memory than declarative/explicit memory
Which brain structures are associated with procedural (implicit) (3) and declarative (explicit) memory?
Procedural: amygdala, medial temporal lobe, basal ganglia
Declarative: hippocampus
Compare the learning functions of the basal ganglia and the hippocampus (2)
Basal ganglia:
produces habits
learns on reinforcement/punishment
Hippocampus:
produces flexible responses
learns through making connections
What is the hippocampus’s role in context association?
binding information to context by synchronizing the many brain areas a memory is spread across
What is the hippocampus’s role in memory consolidation
guides the reorganization of information stored in the neocortex, so that it becomes independent of the hippocampus
What are 2 types of brain damage that result in amnesia?
Korsakoff’s syndrome
Alzheimer’s disease
What is Korsakoff’s syndrome caused by? (2)
Thiamine deficiency
Chronic alcohol consumption
Distinguish between Wernicke’s encephalopathy and Korsakoff’s syndrome
Wernicke’s encephalopathy - reversible
Korsakoff’s syndrome - non-reversible
How does Korsakoff’s syndrome lead to amnesia?
the brain needs thiamine to metabolize glucose - without thiamine, there is decreased energy, leading to loss or shrinkage of brain neurons
Which brain area is most affected by Korsakoff’s syndrome?
thalamus
What are symptoms of of Korsakoff’s syndrome? (5)
apathy
retrograde amnesia
anterograde amnesia
ataxic gait (cerebellar dysfunction)
confabulation
What is confabulation?
wild guessing mixed with correct information to hide memory gaps
Distinguish between dementia and Alzheimer’s (2)
Dementia - umbrella term
Alzheimer’s - disease that falls under dementia
Therefore, not every type of dementia is Alzheimer’s, but every case of Alzheimer’s is dementia
Describe the 3 stages of Alzheimer’s? (9)
Mild - getting lost, taking longer to complete daily tasks, repeating questions
Moderate - problems recognizing family, inability to learn new things, paranoia
Severe - cannot communicate, bedridden, dependent on others
What is found in the brain of people with Alzheimer’s? (3)
amyloid plaques (outside neurons)
neurofibrillary tangles (inside neurons)
broken neural connections
What causes amyloid plaques and neurofibrillary tangles?
Amyloid plaques: accumulation of amyloid beta protein 42
Neurofibrillary tangles: altered tau function - destabilization of microtubules
What is the treatment for Alzheimer’s? (2)
Donepezil - inhibits acetylcholinesterase - prevents breakdown of acetylcholine
Memantine - blocks NMDA receptors - prevents Calcification
Explain the hypothesis of synaptic plasticity (2)
when we learn something, we create specific physical changes in our brain
these changes are modifications of synaptic connections and strength - making synapses more efficient
Explain the Hebbian Synapse mechanism (2)
neuron A repeatedly excites neuron B - causing a growth process to take place in one/both cells
as a result neuron A is then more able to excite neuron B
Define habituation
a decrease in response to a stimulus that is presented REPEATEDLY and accompanied by NO CHANGE in other stimuli
Describe habituation in an aplysia (2)
the aplysia’s siphon is stimulated, causing the sensory neuron to release normal amounts of neurotransmitter
when habituation occurs, the release of neurotransmitter by the sensory neuron decreases
Define sensitization
an increase in response to a mild stimulus as a result of EXPOSURE to a more INTENSE stimulus
Describe sensitization in an aplysia
a strong stimulus on an aplysia’s skin intensifies a later withdrawal response to touch
What is long term potentiation? (LTP)
What does it depend on? (3)
the major cellular mechanism that moves memories into long term storage
changes at synapses
long lasting enhancement of synaptic strength
modification in signal transmission
What changes does LTP involve? (2)
physical change in neuron structure
strengthening of neural connections
How does LTP occur? (2)
- one or more axons bombard a dendrite with stimulation
- the burst of stimulation leaves the synapse potentiated for a period of time - making the neuron more responsive for minutes/days/weeks
What are 3 properties of LTP? Explain them.
Specificity - only active synapses are strengthened
Cooperativity - simultaneous stimulation by 2 or more axons produces LTP more strongly than repeated stimulation by 1 axon
Associativity - pairing weak input with strong input enhances later responses to weak input
What do the biochemical mechanisms of LTP depend on?
changes at glutamate synapses - involving AMPA and NMDA receptors
What type of receptors are AMPA and NMDA?
Ionotropic - allows ions into postsynaptic neuron when stimulated
Describe the process of LTP (4)
- repeated glutamate excitation of AMPA receptors strongly depolarizes the membrane
- depolarization removes Mg ions blocking NMDA receptors - allowing glutamate to excite them
- Ca ions enter the neuron, triggering the activation of the protein CaMK2
- More AMPA receptors are built and dendritic branching increases - resulting in increased responsiveness to glutamate
What occurs when CaMK2 is activated? (3)
- CaMK2 sets in motion a series of reactions resulting in the release of another protein: CREB
- CREB goes to the nucleus of cell regulating gene expression
- CaMK2 and CREB propagate into the dendrites, triggering the release of BDNF
What are the functions of BDNF (3)?
prevents cell death
induces neurogenesis
maintains neurons’ survival
What changes occur in the presynaptic neuron after LTP? (2)
- postsynaptic neuron releases retrograde neurotransmitter - which gets absorbed by the presynaptic neuron
- retrograde neurotransmitter modifies and regulates neurotransmission - creating a stronger link between neurons
What is long term depression? (LTD)
processes selectively weaken specific sets of synapses in order to make synaptic strengthening useful - occurs after LTP
