Limbic System - Constantinidis - Exam 1 Flashcards
Different types of memory are processed differently and in different parts of the brain,. It is possible to lose one type of memory while another is intact depending on lesion location.
- Classified by duration:
- ____-term = seconds
- Synonymous term: “____” memory
- Information in current thought
- Limited capacity, around __ items
- Limited duration of storage, around ___ seconds
- Involves ____ circuit: prefrontal cortex, connections of prefrontal cortex with other cortical areas (superior ____ fasciculus)
- ___-term- information stored permanently, called into consciousness at will
- Can be recent (<2 hours) or remote (hours to years)
- Vast capacity, store millions of items
- Distributed across cerebral cortex
- ___ ___ lobe needed for storing new memories: hippocampus, entorhinal, perirhinal, parahippocampal cortex
- ____-term = seconds
Different types of memory are processed differently and in different parts of the brain,. It is possible to lose one type of memory while another is intact depending on lesion location.
- Classified by duration:
-
short-term = seconds
- Synonymous term: “working” memory
- Information in current thought
- Limited capacity, around 7 items
- Limited duration of storage, around 30 seconds
- Involves fronto-patieal circuit: prefrontal cortex, connections of prefrontal cortex with other cortical areas (superior longitudinal fasciculus)
-
Long-term- information stored permanently, called into consciousness at will
- Can be recent (<2 hours) or remote (hours to years)
- Vast capacity, store millions of items
- Distributed across cerebral cortex
- medial temporal lobe needed for storing new memories: hippocampus, entorhinal, perirhinal, parahippocampal cortex
-
short-term = seconds
Memory is classified by content:
- ___/___ memory – facts and events, requires cognitive effort and attention, can be learned fast (single trial), phylogenetically recent, ontologically late, accessible to conscious recall
- To test, ask “what did you eat for dinner last night?”
- Association cortex, limbic system, medial temporal lobe, diencephalon
- Impaired in amnesia
- ____/____ memory – skills/things you have to practice (ex. driving, riding a bike), learned without paying attention, learned incrementally with practice, phylogenetically primitive, ontogenetically early, inaccessible to conscious recall
- Amygdala, cerebellum, striatum, nucleus accumbens, motor cortex
- Spared in amnesia
Classified by content:
-
Declarative/explicit memory– facts and events, requires cognitive effort and attention, can be learned fast (single trial), phylogenetically recent, ontologically late, accessible to conscious recall
- To test, ask “what did you eat for dinner last night?”
- Association cortex, limbic system, medial temporal lobe, diencephalon
- Impaired in amnesia
-
Non-declarative/implicit memory – skills/things you have to practice (ex. driving, riding a bike), learned without paying attention, learned incrementally with practice, phylogenetically primitive, ontogenetically early, inaccessible to conscious recall
- Amygdala, cerebellum, striatum, nucleus accumbens, motor cortex
- Spared in amnesia
Memory impairments:
___ ____– impairs storage of NEW declarative memory
- Associated w/ __ ___ __ lesions or damage to ___ loop (any part of the loop)
- AA also seen in stroke and Alzheimer’s and other dementia patients
__ ___ —impairs recall of already STORED declarative memory
- Most recently stored memories before lesion appears are often the first to go.For example, people in major vehicle crashes won’t remember the crash or how they got to the hospital
- Associated with cortical and/or white matter damage– since damage can be anywhere it’s not as easy to pinpoint the lesion
__ __ __– difficulty maintaining a train of thought. Very likely to be caused by the pre-frontal cortex or the ___ ___ ___. For example, person goes to kitchen to make a sandwich and then doesn’t remember why went to kitchen when gets there
STM loss is associated with lesions in prefrontal cortex and fronto-parietal connections
Multiple memory systems impairment– example: Alzheimer’s is NOT a memory disease…it is a neurodegenerative disease that affects memory
Alz eventually affects BOTH declarative and non-declarative memory (the most strongly preserved)
____ -- inability to recognize specific stimuli, a “perceptual deficit”
VIsual agnosia– associated with ___ ___ lobe lesion, which may be generalized or specific
Most commonly involves faces (prosopagnosia), letters, or animals
Memory impairments:
Anterograde amnesia– impairs storage of NEW declarative memory
- Associated w/ medial temporal lobe lesions or damage to Papez loop (any part of the loop)
- AA also seen in stroke and Alzheimer’s and other dementia patients
Retrograde amnesia—impairs recall of already STORED declarative memory
- Most recently stored memories before lesion appears are often the first to go.For example, people in major vehicle crashes won’t remember the crash or how they got to the hospital
- Associated with cortical and/or white matter damage– since damage can be anywhere it’s not as easy to pinpoint the lesion
Short-term memory impairment– difficulty maintaining a train of thought. Very likely to be caused by the pre-frontal cortex or the superior longitudinal fascicles. For example, person goes to kitchen to make a sandwich and then doesn’t remember why went to kitchen when gets there
STM loss is associated with lesions in prefrontal cortex and fronto-parietal connections
Multiple memory systems impairment– ex Alzheimer’s is NOT a memory disease… it is a neurodegenerative disease thataffects memory
Alz eventually affects BOTH declarative and non-declarative memory (the most strongly preserved)
Agnosia-- inability to recognize specific stimuli, a “perceptual deficit”
Visual agnosia– associated with inferior temporal lobe lesion, may be generalized or specific
Most commonly involves faces (prosopagnosia), letters, or animals
Short term memory depends on the ___ ___ circuit (primarily the pre-frontal cortex). It also depends on a fiber tract called the ___ ___ ___, which connects the pre-frontal cortex with parietal cortex. If this is severed or damaged in some way, it will also cause __ ___memory problems.
In contrast, LTM is the info that is stored permanantly. LTM has vast capacity. It also has a long duration of storage.
Where is LTM stored? Once it is consolidated, it is not entirely clear where it is. It is thought to be distributed across the ___ ___. So, we have long term memories that are represented in large areas of the cerebral cortex. But, in order to store info into LTM, you need the ___ lobe, __, ento-rhinal (interior to the rhinal sulcus), peri-rhinal and ___ cortex. These are necesarry to store new LTM episodic memories.
Short term memory depends on the fronto-parietal circuit, primarily the pre-frontal cortex. It also depends on a fiber tract called the superior longitudinal fascicles which connects the pre-frontal cortex with parietal cortex. If this is severed or damaged in some way, it will also cause short term memory problems.
In contrast, LTM is the info that is stored permanantly. LTM has vast capacity. It also has a long duration of storage.
Where is LTM stored? Once it is consolidated, it is not entirely clear where it is. It is thought to be distributed across the cerebral cortex So, we have long term memories that are represented in large areas of the cerebral cortex. But, in order to store info into LTM, you need the medial temporal lobe, hippocampus, ento-rhinal (interior to the rhinal sulcus), peri-rhinal and parahippocampal cortex. These are necesarry to store new LTM episodic memories.
MA DL is a mnemonic for all the areas associted with ___ memory (___).
A A M S C is a mnemonic for al lthe areas associated with __ memory (___).
Which one is spared in amnesia?
MA DL is a mnemonic for all the areas associted with declarative memory (explicit).
A A M S C is a mnemonic for al lthe areas associated with non-declarative memory (implicit).
Which one is spared in amnesia? –> non-declarative/implciit memory is spared
Memories A Disney Land - declarative memory (facts or episodes)
Medial temporal lobe
Association cortex
Diencephalon
Limbic System
African-American Music Student’s Concert (because playing is like riding a bike)
Amygdala
N. Accumbens
Motor Cortex
Striatum
Cerebellum
Diagnostic tests:
- Testing ____ memory:
- Time scale = seconds
- Test:
- Ask patient to spell “world” backwards
- Digit span– tell them a series of digits (ex 7 or 8 numbers) and ask them to recite them back in correct order, their “digit span” is how many they could recite back
- Neural substrate: persistent discharges of neurons, prefrontal association cortex
- Testing ____ memory:
- Time scale = 1 min to 2 hours
- Test: 3 term recall after 5 minute delay
- Neural substrate: protein synthesis, phosphorylation, medial temporal lobe
- Testing ___ memory:
- Time scale = hours to years
- Test: ask about historical events, ex when was the Declaration of Independence signed
- Neural substrate: new synapse formation, throughout association cortex
Note– memory recall is __, confidence does NOT imply accuracy!
- People will “remember” details of events that never happened, this is normal (ex will confidently pick out wrong perpetrator in a line up)
- ___– spurious story-making rather than admitting error
Diagnostic tests:
- Testing short term/working memory:
- Time scale = seconds
- Test:
- Ask patient to spell “world” backwards
- Digit span– tell them a series of digits (ex 7 or 8 numbers) and ask them to recite them back in correct order, their “digit span” is how many they could recite back
- Neural substrate: persistent discharges of neurons, prefrontal association cortex
- Testing recall memory:
- Time scale = 1 min to 2 hours
- Test: 3 term recall after 5 minute delay
- Neural substrate: protein synthesis, phosphorylation, medial temporal lobe
- Testing remote memory:
- Time scale = hours to years
- Test: ask about historical events, ex when was the Declaration of Independence signed
- Neural substrate: new synapse formation, throughout association cortex
Note– memory recall is imprecise, confidence does NOT imply accuracy!
- People will “remember” details of events that never happened, this is normal (ex will confidently pick out wrong perpetrator in a line up)
- confabulation -- spurious story-making rather than admitting error
The limbic system is a collection of different areas which reside in different parts of the brain and have different functions.
What are the parts?
HATH
It is a phylogenically ancient system– all the functions an animal needs to assign meaning to stimuli, seek reward, etc.
- Functions related to “value” of stimuli for survival, ex hunting/eating
- Functions?
The limbic system is a collection of different areas which reside in different parts of the brain and have different functions.
What are the parts?
HATH
Hypothalamus, Amygdala, Thalamus, Hippocampus
It is a phylogenically ancient system– all the functions an animal needs to assign meaning to stimuli, seek reward, etc
- Functions related to “value” of stimuli for survival, ex hunting/eating
- Functions:
- Homeostasis– including autonomic and neuroendocrine control
- Olfaction
- Memory
- Emotions and drives– mating, survival, addition, appetite, etc
Structures: limbus = border, portions of the frontal, parietal, and temporal lobes forming the “border cortex” around the __ and ___
Structures within the Limbic System:
Structures: limbus = border, portions of the frontal, parietal, and temporal lobes forming the “border cortex” around the diencephalon and brainstem
Structures within the Limbic System:
Hippocampus
Amygdala
Fornix
Cingulate gyrus
Orbitofrontal cortex
Mammillary bodies
___ – plays important roles in the consolidation of information from short-term to long-term memory and spatial navigation
The local hippocampal loop – creates a ___ feedback loop to give continuously precise information. Every part of the brain that does some action has a similar CLOSED loop design
This loop is called the perforant pathway. It sends info to hippocampus. The hippocampus then sends info back to be compared with results of action and corrects the next action accordingly
Composed of:
Hippocampus – plays important roles in the consolidation of information from short-term to long-term memory and spatial navigation.
Local hippocampal loop– creates a CLOSED feedback loop to give continuously precise information, every part of the brain that does some action has a similar CLOSED loop design.
This loop is called the perforant pathway. It sends info to hippocampus. The hippocampus then sends info back to be compared with results of action and corrects the next action accordingly
Composed of:
The Hippo went to Paris For Dental school.
- Composed of:
- Hippocampus cornu ammonis (“horn of Ammon”)- -CA1-4
- Parahippocampal gyrus
- Fornix
- Dentate gyrus
The circuit of Papez is a pathway within the limbic system that consists of:
The hippocampal formation lies within the parahippocampal gyrus that plays a major role in memory, learning, and recognition of new stimuli.
Bilateral lesions of the hippocampal formation result in __ __.
The __ ___ consists of two groups of nuclei (medial and lateral) that are thought to be important in episodic memory.
Damage in ANY part of the Papez loop will mimic ___ lesions. For ex. a lesion in the mammillary body gives __ ___ just like if damage hippocampus itself
The circuit of Papez is a pathway within the limbic system that consists of:
He Man Ate An Egyptian Cat
Hippocampal formation
Mammillary bodies
Anterior nucleus of the thalamus
Amygdala
Entorhinal cortex
The hippocampal formation lies within the parahippocampal gyrus that plays a major role in memory, learning, and recognition of new stimuli.
Bilateral lesions of the hippocampal formation result in anterograde amnesia.
The mammillary bodies consists of two groups of nuclei (medial and lateral) that are thought to be important in episodic memory.
Damage in ANY part of the Papez loop will mimic hippocampal lesions. For ex. a lesion in the mammillary body gives anterograde amnesia just like if damage hippocampus itself
Cellular substrates of memory – damage to the __ __ __ affects memory.
Explain Long term Potentiation of Synapse:
It is the _____ two neuronal synapses.
For example:
Let’s say it is noon, and you are hungry. There are neurons in the hippocampus that are activated by food. Other neurons in the hippocampus have a spatial map of a building and is activated when you are in the cafeteria. There are neurons in the hippocampus that are activated by the closest restaurant. So, when you are there in that space, and you are hungry, the two events become associated with eachother and the connection of neurons that are connected to each other by these two events is strengthen. This is how memories are stored and how associations are created in the hippocampus – through the strengthening of synapse.
How memories are stored:
- Strengthen associates between specific neurons via ___ strength (long term potentiation of synapse = synapse strengthened)
- ____ neuron must be already activated when a ___ input arrives. The two inputs are then “___”
- Once an association made, the strength of synapse between two neurons will stay increased over long period of time
Cellular substrates of memory – damage to the medial temporal lobe affects memory.
Explain Long term Potentiation of Synapse:
It is the strengthening of two neuronal synapses.
For example:
Let’s say it is noon, and you are hungry. There are neurons in the hippocampus that are activated by food. Other neurons in the hippocampus have a spatial map of a building and is activated when you are in the cafeteria. There are neurons in the hippocampus that are activated by the closest restaurant. So, when you are there in that space, and you are hungry, the two events become associated with eachother and the connection of neurons that are connected to each other by these two events is strengthen. This is how memories are stored and how associations are created in the hippocampus – through the strengthening of synapse.
How memories are stored:
- Strengthen associates between specific neurons via synapse strength (long term potentiation of synapse = synapse strengthened)
- Postsynaptic neurons must be already activated when a presynaptic input arrives. The two inputs are then “associated”
- Once an association made, the strength of synapse between two neurons will stay increased over long period of time
The Amygdala is buried in the __ lobe. It is surrounded by white matter and made up of three nuclei:
temporal
- corticomedial nucleus
- central nucleus
- basolateral nucleus)
Functions and Projections of the Amygdala:
•Emotional Memory Pathway
–___ cortex
–Nucleus ___
–___ lobe
•Endocrine / Autocrine
–____
–Brainstem autonomic nuclei
–Diffuse systems
•Olfaction
–Olfactory structures
–___
–___
Functions and Projections of the Amygdala:
•Emotional Memory Pathway
–orbitofrontal cortex
–Nucleus accumbens
–temporal lobe
•Endocrine / Autocrine
–hypothalamus
–Brainstem autonomic nuclei
–Diffuse systems
•Olfaction
–Olfactory structures
–hypothalamus
–thalamus
Why do smells trigger strong memories?
Neurons in the olfactory epithelium synapse in the olfactory bulb. Neurons from the O.B. terminate directly into the amygdala. The amygdala is essentially ___ synapses away from the olfactory neurons.
This is different from vision. There are many synapses that must happen before vision gets to the amygdala.
Olfaction has preferential access to emotional memory!
- There are only __ synapses between olfactory neurons in nose and the amygdala– this is a direct path and in contrast to other senses have to travel through lot of centers and synapses to get to amygdala
- This is why smells bring back memories much more quickly than vision (ex fresh cookies remind you of your childhood)
Why do smells trigger strong memories?
Neurons in the olfactory epithelium synapse in the olfactory bulb. Neurons from the O.B. terminate directly into the amygdala. The amygdala is essentially two synapses away from the olfactory neurons.
This is different from vision. There are many synapses that must happen before vision gets to the amygdala.
Olfaction has preferential access to emotional memory!
- There are only two synapses between olfactory neurons in nose and the amygdala– this is a direct path, and in contrast to other senses have to travel through lot of centers and synapses to get to amygdala.
- This is why smells bring back memories quickly (ex fresh cookies remind you of your childhood)
B
Classic Korsakoff’s Syndrome
