Cognition and Memory Flashcards
What is meant by “Neuronal plasticity”?
The ability of central neurones to adapt their neuronal connections in response to “learning” experiences
Where are memories formed and stored?
Formed in the limbic system but stored in the cortex
Which structures make up the limbic system?
Cingulate gyrus - located in the medial side of the brain next to the corpus callosum
Hypothalamus - located just below the thalamus on both sides of the third ventricle
Hippocampus - located deep in the temporal lobe on each side
Amygdala - located in the temporal lobe on each sisde
What role does the limbic system play in memory?
the limbic system selects which experiences are to be stored in memory by assigning significance based on the degree of reward or punishment gained from the experience
Name four types of memory
Immediate (/Sensory) memory
Short term memory (aka “working” memory)
Intermediate long term memory
Long term memory
Describe the physiological basis of each type of memory
Immediate memory - based on sensory modalities such as vision and auditory sense (only last a few seconds)
Short-term memory - reverberating circuits
Intermediate long-term memory - Chemical adaptations at the presynaptic terminal
Long-term memory - structural changes in synaptic connections
What sort of changes take place in synapses to store long-term memories?
Increase in number of neurotransmitter release sites on the presynaptic membrane
Increase in number of neurotransmitter vesicles stored and released
Increase in number of presynaptic terminals
Why are reverberating circuits necessary for short term memory?
Short term memory is a chemical phenomenon and so depends on maintained excitation from reverberating circuits
What type of synapses are present in reverberating circuits?
Excitatory synapses only
Define two types of amnesia
Anterograde amnesia; inability to recall events that follow an injury
Retrograde amnesia; inability to recall events that lead up to an injury (long term memory is usually unaffected)
What happens if the hippocampus is damaged/destroyed?
Permenant anterograde amnesia due to inability to form new memories
What happens if the thalamus is damaged but the hippocampus is spared? What does this suggest about the role of the thalamus in memory?
Only retrograde amnesia is seen; this suggests that the thalamus is important for “searching” the memory bank
Describe how long-term memory is classified
Declarative (explicit) memory; “knowing what”, is based mainly in the hippocampus and has a conscious component. Can be further classified into Episodic memory (events) and Semantic memory (facts e.g. words, rules, language).
Non-declarative (implicit) memory; “knowing how”, is based mainly in the cerebellum, independent of the hippocampus and does not have a conscious component. Includes motor learning and rule-based learning (i.e. skills and habits)
How are short term memories transferred to long term memory?
Consolidation using the Papez circuit.
Selective strengthening of synaptic connections through repetition - requires attention
Frontal cortex associates with limbic system to assess significance
Where are new memories stored?
Sensory and association areas of the cortex
