Tutorial 02 Flashcards
Where in the brain is short-term memory?
Prefrontal cortex
Where in the brain is working memory?
The prefrontal cortex, partial lobe, temporal lobe, and hippocampus
What can long-term memory be divided into?
Declarative memory (explicit memory)
Non declarative memory (implicit memory)
Where in the brain is declarative memory?
Hippocampus, the neocortex and the amygdala
Where in the brain is non declarative memory?
Basal ganglia and cerebellum
Where is the hippocampus situated?
In the mesial temporal lobe, within the inferior horn of the lateral ventricle
What does the hippocampus look like and how said that when?
Sea-horse like appearance (arantius 1564)
What are the three parts of the hippocampus and how are the associated axes called?
- head: mesolateral axis
- body: anteroposterior axis
- tail: mesiolateral axis
Where is the LTP happening in rodents?
Pyramidal neurons in hippocampus
What does high-frequency stimulation at a synapse make?
The post-synaptic neuron more responsive to future stimulations at this synapse
How long can the effect of LTP last?
Hours to years
Specificity of LTP
No general increase in responsiveness of the post-synaptic neuron (synapses that are inactive during high-frequency depolarization are not reinforced)
What needs to happen for LTP to arise?
LTP will arise when both the pre-synaptic and the post-synaptic neuron are depolarized in synchrony (i.e. within approx. 100 ms of one another)
What slogan explains LTP very simple?
Cells that fire together, wire together
What happens to the NMDA receptor at depolarization?
Depolarization activates NDMA receptors leading to Ca2+ influx
What happens to NMDA receptors if the postsynaptic cell is not deploarized?
No NMDA receptor activity
What happens after the CA2+ influx (LTP)?
Ca2+ activates proteins that contribute to expression of AMPA receptors on surface, locally amplifying glutamate effect, or activating „silent synapses“ (previously not expressing AMPA receptors)
How do we study memory?
Behavioral experiments, neuroimaging techniques, lesion studies, TMS, pharmacological studies
How do we study memory with behavioral experiments?
Memory Tests: such as recall tasks to measure working and shortterm memory
Eyewitness Memory Studies: to examine how people recall events, often focusing on how memories can change over time or be influenced by suggestion.
How do we study memory with neuroimaging techniques?
fMRI: measures brain activity by detecting changes in blood flow. To see which areas of the brain are activated when people form or recall memories.
PET: measure glucose metabolism in the brain, to see which regions are more active during memory tasks.
EEG: measures electrical activity in the brain
How do we study memory with lesion studies?
Examining people or animals with brain damage to see which parts of the brain are involved in memory. For example, damage to the hippocampus is associated with problems in forming new memories. (Patient HM)
How do we study memory with TMS?
temporarily disrupt or enhance activity in specific areas of the brain. To see how disrupting these areas affects memory performance.
How do we study memory with pharmacological studies?
using drugs to investigate memory processes, testing how different neurotransmitters or receptors affect memory formation. (Drugs that modulate acetylcholine, glutamate, and dopamine systems)
Memory is ….
Reconstructive: Our memory is based on a combination of the original experience and external information. Each time we retrieve a memory, it can be subtly altered and re-stored with new details.
False memories
False memories can be created! People can vividly recall events that never happened, especially when they are given misleading
information or asked leading questions.
Which studies look at how false memory can be and what did they find?
Loftus’s research on how suggestive questioning can lead people to “remember” details that were never part of the original event
What affects memory?
Emotion and Stress
Attention
Age-Related Memory Decline
Neurodegenerative Diseases
Cognitive Biases
Sleep
Drugs
What neuromodulator is used in LTP and LTD?
Dopamine is used as a neuromodulator in both
Can LTP and LTD happen at the same time?
No
Why are both (LTP and LTD) essential?
LTD provides necessary balance for fine-tuning neural signals
LTP alone would result in all synapses becoming maximally strong.
What is the relationship between LTD and forgetting?
LTD can sometimes result in forgetting
Mechanisms in LTD vs Forgetting
LTD: single synaptic mechanism
Forgetting: multiple mechanisms
Time-span of LTD vs Forgetting
LTD: induced within minutes
Forgetting: occurs over minutes to years
Passive forgetting
- natural decay of memories over time
- loss of retrieval cues/context
What are the two mechanisms of active forgetting?
- memory inhibition
- process inhibition
Memory inhibition
Direct suppression of memories
Process inhibition
General suppression of memories
Benefits of forgetting
- emotional resilience
- reduced cognitive conflict
- allows for adaptation to current goals
Practical implications of forgetting
- useful in organizations for training
- clinical applications
- emotional regulation
What is unwanted/pathological forgetting called?
Amnesia (pathological forgetting)
Two different amnesias
Anterograde amnesia and retrograde amnesia
Anterograde amnesia
Difficulty forming new memories
Retrograde amnesia
Difficulty retrieving old memories
Causes of amnesia
Various causes: head injuries, strokes, neurodegenerative diseases
Dementia is more than..
„Normal“ memory loss due to aging
What is dementia characterized by?
Memory loss, decline of other cognitive functions, personality changes
Clinical features of dementia
Executive dysfunction, apraxia, dyslexia, dyscalculia, receptive dysphasia, prosopagnosia, agnosia, episodic memory loss, mood changes, expressive dysphasia, alteration of behavior and personality
Executive dysfunction is …
Difficulty performing complex tasks and planning ahead
Apraxia is …
Impairment of visuospatial and motor abilities
Dyslexia is …
Inability to read
Dyscalculia is …
Deterioration in simple arithmetic
Receptive dysphasia is …
Difficulty comprehending language
Prosopagnosia is …
Inability to recognize familiar faces
Agnosia is …
Difficulty recognizing familiar objects
Episodic memory loss is due to …
Hippocampal atrophy
Mood changes are due to …
Amygdala damage
Expressive dysphasia is …
Problems with expressive aspects of language
Alterations of behavior caused by …
Degeneration of the prefrontal cortex
What is the most common form of dementia (%)?
Alzheimer‘s disease, 60 - 80 %
Early symptoms of Alzheimer’s include
- short-term memory loss, particularly episodic memory
- spatial disorientation
How can alzheimer‘s diagnosis be confirmed?
Only post-mortem
Three pathological changes in alzheimer‘s
- intraneuronal neurofibrillary tangles
- extracellular amyloid plaques
- diffuse loss of neurons
What are characteristic symptoms of lewy body dementia and how much % of dementia cases?
- 20% of dementia cases
- characteristic symptoms include visual hallucinations, fluctuation in cognitive performance, parkinsonism
What are the prominent symptoms of Vascular dementia and how much % of dementia cases?
- 10% of dementia cases
- more prominent mood cahnges
- bigger fluctuation in symptoms
Explain the relationship between LTD, LTP and connections
LTP works to strengthen connections, while LTD makes sure not all connections become too strong
