PYSC20006 JA's Lectures (Memory) Flashcards
What is the biochemical basis of epileptic seizures?
Not enough GABA. Excitatory synapses fire too often due to lack of GABA inhibition.
What is the most common cause of TL Epilepsy?
Hippocampal sclerosis
What are other aetiologies of TLE?
infections, tumours and vascular malformations
What did HM teach us about different types of memory?
That declarative memory and procedural memory are anatomically different
What memory impairment did HM experience post surgery?
Severe impairment of his declarative memory (but not procedural memory)
What is the Medial Temporal Lobe essential for?
Learning and the consolidation of memories
What is Declarative Memory?
The ability to consciously access previously learned information
What is procedural memory?
Automatically remembering learned behaviour (eg. how to play piano)
What functional asymmetry does the Medial Temporal Lobe Have?
Left - verbal memory
Right - non-verbal/ visual memory
What kind of memory is MTL essential for?
Formation of Anterograde Memories (not retrograde memory). So involved in consolidation and retrieval of new memories.
What does Consolidation Theory suggest?
After a period of consolidation information can be retrieved independently of hippocampal involvement.
What does Multiple Trace Theory (MTT) suggest?
That retrieval of autobiographical/episodic memory always involved the hippocampal system
What kind of memory tasks is the hippocampus especially important for?
Relational memory tasks (eg. paired associate learning tasks where picture and word need to be linked)
The hippocampus has what memory function?
learning and retrieval of arbitrarily related info & learning semantic information
The Perirhinal Cortex has what memory function?
item recognition based on familiarity (and poss. semantically associated learning)
The Parahippocampal Cortex has what memory function?
learning of spaces and association of object-locations
The Inferolateral Neocortex has what memory function?
learning & retrieval of semantically related information
What is synaptic plasticity?
The biochemistry of synapses changes to alter
the effect on post-synaptic neuron
Mnemonic for Papez’s Circuit
He Man Ate a F’ing Cat (H = hippocampus; M = mamillary body; A = anterior thalamic nucleus, F = fornix; C = cyngulate gyrus)
What is Papez’s Circuit + Amygdala?
The limbic system
What type of memory is most affected by lesions to Papez’s circuit?
Declarative memory (poor relational memory & encoding)
Damage to what structures within Papez’s Circuit most reliably lead to declarative memory impairment?
Anterior Thalamic Nucleus (ATN) and Hippocampus
What role do the frontal lobes play in memory?
They are involved in developing and implementing strategies for memory encoding and retrieval
What memory deficits are associated with damage to Dorsolateral Prefrontal Cortex?
Difficulty remembering contextual details (eg. sources of info/ chronological order of memories)
What memory deficits are associated with damage to Prefrontal Cortex?
Confabulation (caused by difficulty monitoring truth and veracity of own statements/reasoning)
What comprises the Diencephalon?
Thalamus and Hypothalamus
What memory problems are associated with damage to the Frontal Lobes?
Impaired ability to organise encoding, retrieval and maintenance of memories
What memory problems are associated with damage to the Thalamic nuclei?
reduced mental flexibility and inappropriate selection of information retrieval
What is Hebbs Rule?
That the cellular basis of learning involves the strengthening of a synapse that is repeatedly active when the postsynaptic neuron fires
What causes increased synaptic strength between neurone during LTP?
By insertion of additional AMPA receptors into post-synaptic membrane of dendritic spine.
More AMPA receptors = more glutamate = larger excitatory postsynaptic potential = stronger synaptic connection
What synaptic changes occur during long lasting LTP?
- Insertion of AMPA receptors in postsynaptic neuron = more glutamate uptake
- Increased amount of glutamate released by pre-synaptic neuron
- Protein synthesis in post-synaptic neuron
- Changes in physical structure of synapses/dendritic spines
- Most long term LTP also involves dopamine (not short term)
According to Raymond, there are 3 types of LTP. What are these?
- LTP that lasts for an hour or 2 (insertion of AMPA receptors in post synaptic neuron)
- Longer LTP (AMPA receptors & protein synthesis)
- Longest LTP (also incl. structural changes and dopamine)
What is Long Term Depression (LTD)?
A long term decrease in the excitability of a neuron to a particular synaptic input caused by stimulation of terminal button when postsynaptic membrane is hyper polarised or only slightly polarised
What is perceptual learning?
Learning to recognise new stimuli (or changes to familiar stimuli)
What is the biological basis of perceptual learning?
Changes in synaptic connections within the sensory association cortex
What areas of the brain are involved in perceptual short term memory?
Sensory association cortex, visual association cortex (visual memories), and prefrontal cortex
What is the biological basis of Classical Conditioning?
NMDA mediated LTP in the amygdala (conditioned emotional responses)
What is instrumental conditioning (operant conditioning)?
Strengthening of connections between neural circuits that detect stimuli and neural circuits that produce responses.
What area of the brain is focal in instrumental conditioning?
Basal Ganglia
What aspects of instrumental conditioning involve the basal ganglia?
learning of automated and routine behaviours
What neurotransmitter is especially important in reinforcement (instrumental conditioning)?
Dopamine (dopaminergic neruons in ventral tegmental area project into the nucleus accumbens, prefrontal cortex & amygdala)
What is anterograde amnesia?
Inability to form new memories following a brain injury/insult
What is retrograde amnesia?
Inability to remember events that occurred prior to a brain injury/insult.
What is declarative memory?
Memories that are explicitly available to conscious awareness. Memories that can be verbally expressed.
What is non-declarative memory
Memories that don’t require us to be consciously aware of them.
What are 3 types of non-declarative learning?
- Perceptual learning (perceiving stimuli)
- Motor Learning
- Stimulus/Response Learning
What type of memory is impaired in patients with anterograde amnesia?
Declarative memory
What types of memory is not impaired when suffering anterograde amnesia
Non-Declarative memory
What are 3 types of declarative memory?
- Episodic memory (memories of events)
- Semantic memory (knowledge of facts about world)
- Autobiographical/remote memory (personal memories?)
What are two examples of declarative memory task?
- Remembering past experiences
2. Finding your way in a new environment
What are 4 examples of perceptual learning (non-declarative)
- Learning to recognise broken drawings (elephant & umbrella)
- Learning to recognise pictures/objects
- Learning to recognise faces
- Learning to recognise melodies
What are 2 examples of stimulus-response learning?
- Classical Conditioning (eye blink)
2. Instrumental Conditioning (operant conditioning)
What is an example of motor learning?
Learning sequence of button presses or how to draw a star in a mirror
What three structures make up the limbic cortex of the medial temporal lobe?
entorhinal cortex, perirhinal cortex & parahippocampal cortex
What role does the hippocampus play in long term memory formation?
The consolidation and retrieval of declarative memory
What are the three aspects of memory need to be assessed when assessing episodic memory?
- Encoding
- Consolidation/Retention
- Retrieval
What aspect of episodic memory is assessed through learning tasks?
Encoding
What aspect of episodic memory is assessed through delayed recall tasks?
Consolidation/Retention and Retrieval
What aspect of episodic memory is assessed by recognition tasks?
Retrieval
What does poor performance on recall and recognition tasks indicate?
Problem with consolidation/retention but could also have difficulty with retrieval (can’t tell if only one impaired or both)
What does poor recall performance but good recognition indicate?
Problems are with retrieval (not consolidation). Shows the memory is their but prompt required to retrieve it
What is not effected by semantic dementia (initially at least)?
- Normal Working Memory
- Preserved Anterograde Episodic Memory (verbal & non-verbal)
- May have poor retrograde episodic memory (older memories deteriorate first in reverse temporal gradient)
- Phonology & syntax intact
- No topographical disorientation
- No visuo-spatial defecits
- Intact organisational and planning skills
What deficits are present in semantic dementia?
1st symptom: Anomia (unable to think of correct word for object)
2nd Symptom: Impaired Word Comprehension
3. Effects verbal and visual domains
What is a category dissociation in semantic dementia?
Loss of semantic knowledge is a discrete category of semantic memory (eg. faces, body parts, number, natural objects vs man-made objects, abstract vs concrete)
What is modality dissociation in semantic dementia?
Intact verbal semantic memory but impaired visual memory (and vice versa)
What tests are used to assess semantic memory?
- Word Definitions
- Picture Drawing
- Picture Naming
- Word-picture matching
- Famous faces test
- Category fluency (name as many xxx as you can)
- Colour selection for picture (eg. red for tomato)
- Sorting words/pictures into categories
What is Ribolt’s Law?
That there is a temporal gradient in amnesic patients in which the distant past is remembered better than the recent past
What temporal gradient is associated with medial temporal lobe lesions (eg Alzheimers)?
Temporal Gradient (older memories go later, recent memories go first)
What temporal gradient is associated with lateral temporal lobe lesions (eg. Semantic Dementia)?
Reverse temporal gradient (older memories go first)
What temporal gradient is associated with frontal lobe lesions?
No Temporal Gradient
