PSYC 304 Chapter Notes - Chapter 11: Protein Synthesis Inhibitor, Anterograde Amnesia, Rhinal Cortex
Learning & Memory 2013-01-18 2:02:00 AM
Mnemonists
- “.R. Luria studied a man, who’s known as S. for 30 years.
• S is talented in mnemonics, and has a profound memory.
• But suffered from synaesthesia (words have images and numbers have
personalities), because the associations were too overwhelming for him to
understand.
• Method of loci – place items you want to remember in locations
Amnesics
- Bilateral medial temporal lobectomy
• H.M. received a bilateral temporal lobectomy – the removal of the medial
portions of both temporal lobes, including most of the hippocampus,
amygdala, and adjacent cortex.
• Significant in memory storage: medial temporal lobe, medial diencephalon
• H.M. had a normal short-term anterograde memory (digit span was six)
• H.M. had global amnesia – amnesia for information presented in all sensory
modalities.
- Retrograde amnesia
• Inability to retrieve memories prior to that time at which the brain damage
occurred.
• Temporally graded: gradient of memory loss from most severe to most mild.
Most distant memories were lease affected.
- Anterograde amnesia
• Inability to form memories of events occurring after the time at which the
brain damage occurred.
• Has to determine whether effected memories are long-term or short-term or
both
• H.M. couldn’t make episodic memories, total inability.
- H.M.’s case also illustrates the difference between explicit and implicit memory.
• Explicit (Declarative)
o Semantic – Memory for facts
o Episodic – Memory for particular events or episodes in life
• Implicit (Procedural, non-declarative)
o But his improvement in mirror-drawing test indicated an
improvement even though he has no recollection of learning
- Rhinal cortex
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• Associated with object recognition memory, spatial navigation, learning,
memory, temporal order of events
• H.M.’s deficits were initially attributed solely to hippocampal damage, but it
has since come to light that much of it was due to adjacent rhinal cortex
damages.
- Korsakoff’s Syndrome
• Attributable to the brain damage that results from severe thiamine deficiency;
thiamine deficiency often accompanies heavy alcohol consumption.
• Often results in severe anterograde amnesia, and mild retrograde amnesia.
Also involves dementia.
• Used to be called Beri Beri. In the early 20th century, people were forced to
only eat white rice, which does not contain high thiamine and resulted in Beri
Beri.
• Lesions to medial thalamus and mammillary bodies.
Hebb’s First Postulate
- When an axon of cell “ is near enough to excite a cell ” and repeatedly or
persistently takes part in firing it, some growth process or metabolic change takes
place in one or both cells such that “’s efficiency, as one of the cells firing ” is
increased.
Hebb’s Second Postulate
- Groups of neurons that tend to fire together form a cell assembly whose activity can
persist after the triggering even and serves to present it.
Consolidation
- How memory is formed and written in your brain
- Reconsolidation
• Conditioning Phase:
o Regular conditioning
• Reminder Phase:
o One group receives Conditioned Stimuli with protein synthesis
inhibitor
▪ Protein synthesis have known to be impair learning
o One group receives Conditioned Stimuli with saline
• Test Phase:
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o Both groups are presented with one Conditioned Stimuli
o Group with protein synthesis inhibitor shows impaired learning
• Even after 100 days of consolidation, the presence of protein synthesis still
destabilize the learned task, causing impaired learning afterwards. By
disrupting the reconsolidation, you disrupt the original memory.
Systems-Level Consolidation
- Standard (aka dual trace) consolidation theory
• Involves trace both in hippocampus and cortex
• Reverbratory activity between hippocampus and cortex, leading to more
permanent writing in the cortex. Therefore, lesions in hippocampus only
result in damage in recent memories.
• Problem – not always a temporal gradient of loss – sometimes retrograde
amnesiacs lose everything, not just recent memories.
- Multiple trace theory
• Hippocampus is involved in the memory for the life of the memory.
• First serves to write the memory to cortex, and then later the hippocampus
acts as an referring index of memories. Therefore, lesions in hippocampus can
result in total retrograde amnesia.
Concept Cells
- Network of cells with a receptive field for a particular concept in the medial
temporal lobe/hippocampus Jennifer “niston cells
• Images of Luke Skywalker, someone saying LS, and any related concepts will
elicit optimal firing of the cells.
• Long latency period – many synapses being traversed before cell’s RF is
stimulated.
Kindling
- Long-term potentiation – Replaced kindling as the popular model of research of
memory
Planaria
- T-maze for planaria: trained them to go to the light side, then cut them in half and
test them on retention – they have equal retention before and after cut in half!
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Document Summary
Inability to retrieve memories prior to that time at which the brain damage occurred: temporally graded: gradient of memory loss from most severe to most mild. Inability to form memories of events occurring after the time at which the brain damage occurred: has to determine whether effected memories are long-term or short-term or both, h. m. couldn"t make episodic memories, total inability. H. m. "s case also illustrates the difference between explicit and implicit memory: explicit (declarative, semantic memory for facts, episodic memory for particular events or episodes in life. Implicit (procedural, non-declarative: but his improvement in mirror-drawing test indicated an improvement even though he has no recollection of learning. Korsakoff"s syndrome: attributable to the brain damage that results from severe thiamine deficiency; thiamine deficiency often accompanies heavy alcohol consumption, often results in severe anterograde amnesia, and mild retrograde amnesia. Also involves dementia: used to be called beri beri.
