psych 345 lecture 22 - amnesia and generalized cognitive disorders

what type of amnesia did patient HM have?

both retrograde and anterograde amnesia, anterograde being more severe while retrograde was temporary and childhood memories were spared

what memory abilities were spared in HM

his procedural memory was normal despite his profound explicit memory defecits

why was HM’s anterograde amnesia so severe?

this was becuase the removal of his medial temporal lobes (MTL, including hippocampi) disrupted his encoding and consolidation of new episodic memories

what is the most common cause of basal forebrain amnesia?

aneurysm of the anterior communicating artery (ACoA)

what were the 4 memory profile characteristics of basal forebrain amnesia?

1. severe anterograde amnesia

2. variable retrograde amnesia

3. spared procedural memory

4. prominent confabulation

confabulation; what does this reflect?

the production of false memories without awareness that they are false; this reflects impaired self-monitoring and frontal dysfunction

what is the dual-lesion hypothesis?

confabulation in basal forebrain amnesia arises from BOTH

1. a basal forebrain amnesia-producing lesion

2. frontal lobe damage

what strucutres compose the diencephalon?

1. thalamus

2. hypothalamus

what condition is the classic cause of diencephalic amnesia?

korsakoff’s syndrome, caused by chronic alcoholism and a deficiency in thiamine, associated with confabulation

true or false: korsakoff’s syndrome is irreversible

false! it is reversible in early stages as it is a vitamin deficiency in thiamine — can be fixed with vitamin rehabilitation when caught early

what 5 memory impairments characterize medial thalamus amnesia?

1. severe anterograde amnesia

2. retrograde amnesia with temporal gradient

3. material specificity depending on lesion location

4. confabulation when frontal lobes are involved

what is material specificity in diencephalic amnesia

1. left lesion —> memory deficits

2. right lesion —> visuospatial memory deficits

3. bilateral —> global amnesia

what do amnesia syndromes reveal about memory storage?

memory is distributed, not just in one area, multiple regions form an extended memory circuit

why do different lesions produce similar amnesic profiles?

because the memory circuit is interconnected so damaging any major component will disrupt episodic memory

what accounts for differences between amnesic syndromes?

1. neighborhood effects

2. lesion laterality

3. extent of damage

what is a generalized/nonspecific cognitive disorder

a condition where cognitive decline is not limited to one domain; multiple abilities all decline concurrently

name 4 causes of generalized cognitive deficits

1. closed head injuries

2. degenerative diseases

3. demyelinating diseases

4. toxins

what is an effect of generalized disorders on the brain

diffuse (not focal) brain damage —> widespread cognitive impairement

dementia

progressive decline in cognitive abilities that interferes with daily life and often results in personality changes

what categorizes the different types of dementia?

the location of brain damage

what are the 3 types of dementia?

1. cortical dementia (language/memory)

2. subcortical dementia (speed of thinking, ability to organize, motor control)

3. vascular dementia (a small vessel disease)

what characterizes cortical dementia

• affect memory/language

• early symptoms of memory loss, disorientation, naming problems, personality change

what are 2 examples of cortical dementia

alzheimers and frontotemporal dementia

what characterizes subcortical dementia?

• motor symptoms

• cognitive slowing and attention lapses

• impaired recall

what is preserved in subcorticla dementia?

• memory storage

• language

2 examples of subcortical dementia

1. parkinsons disease

2. huntingtons disease

what characterizes vascular dementia

• due to strokes/multi-infarcts

• second most common dementia

• sudden or stepwise onset

• high variable and dependent on stroke location

what are 3 disorders that vacular dementia may include?

1. aphasia

2. amnesia

3. agnosia

true or false: lewy body and creutzfeldt-jakob diseases can be subcortical or cortical

true! they can be present in both cortical and subcortical features

what is the most common dementia in people over 65

alzheimers disease

list the key features of alzheimer’s

1. severe anterograde amnesia

2. progressive memory loss

3. decline in language, visuo-spatial skills, judgment, and abstract-thinking

true or false: alzheimers is most prevalent in men

false! women

what brain region is primarily affected in parkinsons

the basal ganglia — especially dopamine-producing cells

name the 4 key motor symptoms of parkinsons

1. bradykinesia

2. tremor at rest

3. postural instability

4. rigidity/stiffness

name the 4 cognitive defects of parkinsons

1. bradyphrenia (slowed thinking)

2. executive dysfunction

3. intact storage but impaired retrieval

4. poor reward based learning

5. reduced visuospatial abilities