Memory and Cognition Flashcards
what is cognition?
it is the highest order of the brain function and describes the integration of all sensory information to make sense of a situation
what does making sense require?
an ability to remember events and learn from them- learning and memory required motivation
what is neuronal plasticity?
the ability of central neurone to adapt their neuronal connections in responses to learning experiences
what are the 3 key required components of learning and memory?
hippocampus= formation of memories cortex= storage of memories thalamus= searches and accesses memories
what is the limbic system?
where memories are formed and gives events emotional significance which is essential for memory
what are the 4 areas of the limbic system?
hypothalamus= emotion and ANS responses
hippocampus= learning and memory
cingulate gyrus= emotion
amygdala= emotion and memory
how is motivation driven?
seeking reward or avoiding punishment from instinctive behaviours like hunger, sex etc
what happens to experiences that are neither rewarding or punishing?
these are deemed insignificant experiences and are barely remembered so the brain only gives attention to experiences it deems significant
what part of the brain decides significance and where does sensory information then pass?
the frontal cortex and its association with reward/punishment centres in the limbic system - through the hippocampus which relays it to other limbic structures
what would bilateral damage to the hippocampus cause?
immediate (sensory) memory (seconds in length) and intact long-term memory (from time before damage) but unable to form new long-term memories, reflexive memory (motor skills) remain intact
how long are sensory memories normally held in the brain?
a few seconds but varies depending on the sensory modality- visual memories decay fastest (<1s) and auditory ones the slowest (<4s)
describe a short term memory.
lasts seconds to hours and is used for short term tasks like dialling a phone number or reading a sentence, it is an electrical phenomenon which depends on maintained excitation from reverberating circuits
what are reverberating circuits?
keep the brief short-term memory alive by constantly refreshing it
what happens if the memory is deemed significant?
the memory is consolidated into a long-term memory and stored
what happens if the memory is deemed insignificant?
the reverberation faces and no consolidation occurs
what is amnesia?
if reverberation is disrupted eg by head injury or infection then memory is lost
what are the 2 types of amnesia?
anterograde= cannot form new memories retrograde= cannot access (more recent) old memories
describe anterograde amnesia.
inability to recall events happening after the injury, depending on. the severity of the injury can be short lived or permanent (eg destruction of the hippocampus)
when would retrograde amnesia be seen?
if only the thalamus is damaged and the hippocampus is spared which suggests that the thalamus is required for searching our existing memory back
describe immediate long-term memory.
lasts hours to weeks eg what you did last week and is associated with chemical adaptation at the presynaptic terminal- increasing Ca++ entry to presynaptic terminals increases neurotransmitter release which increases excitation of post-synaptic neurones
describe long-term memory.
can be lifelong eg where you grew up and is associated with structural changes in synaptic connections= increase in NT release sites on presynaptic membrane, increase in number of NT vesicles stored and released and increase in number of postsynaptic terminals
what is long-term potentiation?
at the same time as the structural changes the amplitude in the graded membrane potential (EPSP) in the post-synaptic cells increases which strengthens the synapse
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, rule and language (semantic memory) and relies heavily on the hippocampus
what is procedural/reflexive/implicit memory?
acquired slowly through repetition, includes motor memory for acquired motor skilll and rules-based learning and thinking about these skills often impair performance and is mainly based in the cerebellum
what happens to new memories?
there are coded in the sensory and assocaition areas of the cortex where they are stored alongside other existing memories the brain deems similar
what happens if an experience is considered useful?
the frontal cortex ‘gates” the so-called Paper circuit: cingulate gyrus- hipoocampus- anterior thalamus- mammillary bodies and the reverterbrating activity continues between the paper circuit, frontal Cortex, sensory and association areas until consolidation is complete
for example where would the visual component of memory be stored?
the visual cortex as different components of memory are laid down in the relevant parts of the cortex
what is Korsakoff’s syndrome?
related to chronic alcoholism and is vitamin B1 deficiency which leads to damage of the limbic system structures and so ability to consolidate memory is impaired
what happens in Alzheimers disease?
severe loss of cholinergic neurones throughout the brain including the hippocampus causing gross impairment of memory
why is REM sleep important for memory?
dreaming may enable memory consolidation and reinforce weak circuits as subject deprived of REM sleep show significant impairment of memory consolidation for complex cognitive tasks
