PSYC 3610 Lecture Notes - Lecture 10: Temporal Lobe, Anterograde Amnesia, Temporal Lobe Epilepsy
20 Jun 2018
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CHAPTER 10 MEMORY DISORDERS
Living with Alzheimer’s and Dementia (video)
• Decline in speed of processing and retaining information – comes with normal
aging
• Dementia – loss of cognitive function to the point where it affects daily life
activities
o Alzheimer’s
o Vascular
o Lewy body
o Frontotemporal
• Damage to brain cells – interfere with normal communication
o Hippocampus – memory loss
o Frontal lobe – loss of emotional control
o Temporal lobe – retrieving the right words
• Aging is the primary risk factor.
• Race and ethnicity
o Hispanic and African Americans – more likely than Caucasian to be
affected by dementia
What is Amnesia?
• Amnesia: any impairment of memory abilities beyond normal forgetting
• In most cases, amnesia refers to an acquired condition brought about by
trauma to the brain.
• A whole host of different disorders can be classified as amnesia.
o The most common form of amnesia is associated with Alzheimer’s
disease.
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• The major deficit in most cases is in encoding new information into episodic
memory.
o But some amnesias affect retrieval from episodic memory, access to
semantic memory, access to working memory, and executive control
of memory.
• Neurological amnesias – amnesias that result from physical destruction of
different regions of the brain
• Psychogenic amnesias – quite uncommon; do not result directly from brain
damage but seem to be elicited by psychological trauma
Case Studies of Amnesia
Patient HM
• In 1953, neurosurgeon William Scoville removed HM’s hippocampi as a
treatment for epilepsy.
o Decreased seizures
o IQ increased
o Working memory was normal
o Ability to speak, understand, read, and write were not impaired
o Able to remember much of his life from before the surgery – no
retrograde amnesia
• The effect on HM’s ability to encode new information was devastating.
o HM never learned anything new in a direct and conscious manner.
o Anterograde amnesia
• Implicit memory was largely intact.
o Procedural memory
• Anterograde amnesia was originally attributed to deficits in the hippocampus
and surrounding temporal lobe areas.
• However, more recent MRI on HM also showed damage to other areas of the
brain, including the amygdala.
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Clive Wearing
• Wearing contracted viral encephalitis, which causes massive swelling of the
brain.
• It caused massive damage to his brain, including to his medial temporal lobes
and prefrontal lobes.
• Wearing has severe anterograde amnesia, and he also has severe retrograde
amnesia – global amnesia.
o As such, he lives in a perpetual present.
o Can maintain information for about 10 seconds
• His amnesia does not extend to lexical memory, nor to procedural memory.
Anterograde Amnesia
• Anterograde amnesia: an inability to form new memories following brain
damage
• Mild impairment – a person simple requires more time to encode information
than normal individuals do
o May be able to compensate for their deficit (compensatory devices)
o In some cases, can even resume careers
• Severe impairment – a person may remember little of anything new
o In need of round-the-clock supervision
o May forget where they live if they have moved since their injury
• In all cases, there is difficulty in learning new information, whether that
information is episodic or semantic in nature.
• Damage in the brain tends to be in the hippocampus (learning and memory)
and medial temporal lobes (cortical area in the temporal lobe associated with
learning and memory).
• A second locus in the brain also causes the amnesic syndrome – the
mamillary bodies of the diencephalon (subcortical region associated with
learning).
• Damage to the adjacent fornix can also induce anterograde amnesia.
