Lecture 6 - Learning & Memory Flashcards
What’s amnesia ?
The loss of memory or the inability to form new memories
What can cause amnesia ?
- Surgery
- Traumatic brain injury
- Infections of the brain (herpes simplex encephalitis)
- Alzheimer’s disease
- Korsakoff syndrome
- Concussion
What are the different types of memory ?
- ST memory : working memory, sequence learning, planning
- LT memory : explicit, implicit & emotional memory
What are the different types of amnesia ?
- Retrograde
- Anterograde
- Autobiographical
What’s the difference between retrograde & anterograde amnesia ?
- Retrograde : inability to retrieve old memories (entorhinal damage)
- Anterograde : inability to form new memories (hippocampal damage)
What’s memory ?
The ability to recall previous experiences
To what part of the brain is linked explicit memory ?
(Temporal/Frontal) Cortex & Hippocampus
To what part of the brain is linked implicit memory ?
Basal Ganglia
To what part of the brain is linked emotional memory ?
Amygdala
To what part of the brain is linked ST memory ?
Prefrontal Cortex/DLPFC
What’s ST memory ?
It involves the neural record of events & their order for a brief period of time (movements, locations, verbal & visual information)
What is the role of the ventral stream in ST memory ?
Memory of objects
What is the role of the DLPFC in ST memory?
Integrates information from dorsal & ventral stream
Where are located the lesions that can cause different ST memory problems ?
- Lateral & medial PFC
- L/R temporal lobe
What aspect of ST memory can be affected by lesions in the parietal association areas ?
- Location
- Memory within specific visual field
What causes modality-specific ST memory problems ?
Temporal association area lesions
What aspects of ST memory can be affected by frontal lesions ?
- Working memory
- Memory of order
What role does the hippocampus play in memory retention ?
Retaining memory within a restricted period after learning
What connections does the fornix provide from the hippocampus ?
Connections to :
- Thalamus
- Basal ganglia
- PFC
What connections does the perforant pathway provide ?
Connections to :
- Temporal & parietal cortex : memory of objects, sounds, smell & locations
What are the components of the hippocampal formation ?
- Hippocampus
- Amygdala
- Enthorinal cortex
What is the function of the hippocampal formation ?
Consolidation of new information for storage in LT memory
What brainstem inputs are necessary for memory, and how do they affect it ?
Inputs : acetylcholine, serotonin & noradrenaline
Effects : poor memory when depressed (low serotonin), better memory in stressful situations (high noradrenaline)
In what is involved the CA1 region in the hippocampal formation ?
- LT potentiation
- Consolidation of new information
How does Alzheimer’s disease affect memory systems in the brain ?
Loss of neurons in cholinergic, serotonergic & noradrenergic systems leading to memory deficits
What are the 2 subcomponents of explicit memory ?
Episodic (personal & autobiographical) & Semantic (facts & knowledge) memory
Where is semantic memory stored in the brain ?
- Temporal cortex : facts/objects
- Frontal cortex : expected value & associations
What do rhinal lesions have an impact on ?
Affect the ability to associate objects with rewards
What do hippocampal & frontal lesions have an impact on ?
Affect memory-updating & temporal memory
Which brain lesion affects information that depends on temporal context ?
Ventral PFC lesions
What type of material are L & R temporal cortex involved in recognizing ?
L : verbal material (stories, words, numbers)
R : nonverbal material (faces, objects, geometrical figures)
What is the connection between temporal & frontal lobe critical for ?
Autobiographical memory
What is the function of the L orbitofrontal cortex (OFC) in memory ?
Encoding or acquisition of semantic & episodic memory
What is the function of the R-DLPFC in memory?
Episodic memory retrieval
What is working memory ?
The ability to hold information online for several minutes
Which brain lesions affect temporal memory for objects and sounds ?
Ventral PFC lesions
Which cortical areas are involved in implicit memory ?
Premotor & motor cortex
What role does the cerebellum play in implicit memory ?
Classical conditioning of non-emotional motor responses
How does the brain stem contribute to implicit memory ?
Involved in basic motor function & autonomic functions
What is emotional memory ?
Memory for the affective properties of stimuli or events
What are the symptoms of Urbach-Wiethe disease ?
- Amygdala damage
- Abolishes emotional memory (e.g. no automatic fear responses)
- No effect on implicit & explicit memory
What causes Korsakoff syndrome ?
Vitamin B1 (thiamine) deficiency due to chronic alcoholism
Which brain areas are damaged in Korsakoff syndrome ?
- Mammillary bodies
- Medial thalamic nucleus
- Cerebellum
-> progress toward general cerebral atrophy
What are the symptoms of Korsakoff syndrome ?
- Complete anterograde amnesia
- Increasing retrograde amnesia
- Confabulation
- Apathy, indifference
- Ataxia
Which brain areas are involved in autobiographical amnesia ?
- Hippocampus
- Temporal lobe/entorhinal cortex
- (sometimes) Frontal lobe
How does the extent of hippocampal lesions affect retrograde amnesia ?
Period of memory loss depends on the extent of lesions within & around hippocampus
What are the early symptoms of Alzheimer’s Disease affecting the medial temporal lobe ?
- Retrograde amnesia
- Difficulty remembering recently learned facts
- Inability to acquire new information
- Orientation issues
What are the symptoms of Alzheimer’s Disease in the middle to severe stages ?
- Further loss of episodic memory
- Recognition issues with relatives
- Problems with recall & ST memory
- Difficulties with complex motor sequences
- Emotional disturbance
- Adopting a fetal position
What are the effects of herpes simplex encephalitis on the temporal lobe ?
- Serious retrograde amnesia (lateral temporal cortex & insula)
- Anterograde amnesia (medial temporal lobe : hippocampus & paralimbic cortex)
