Limbic System: Manaye

Question 1

List the brain structures associated with the limbic system.

Answer 1

• involve motor and nonmotor areas that will integrate your learning, memory, and emotions
• all the animals mate through pheromones
• smell is important to like your food or stay in certain environments

Amygdala
Entorhinal cortex
Hippocampal formation
Cingulate gyrus & cingulum
Hypothalamus
Thalamus
Septum

Question 2

What is the entorhinal cortex and what structures in the brain is it closely related to?

Answer 2

it is part of the limbic system

• located in the anterior part of the parahippocampal gyrus, on the medial surface of the temporal lobe
• transition zone between hippocampus and temporal neocortex
• multiple inputs to the entorhinal cortex, including fibers from the cingulate gyrus, basolateral amygdala, olfactory cortex, and cortical association areas

-entorhinal cortex funnels highly processed cortical information to the hippocampal formation and serves as its major output pathway

Question 3

How are all the limbic structures connected?

Answer 3

through long term potentiation (Allard’s lecture)

Question 4

CA1-4

Answer 4

The hippocampus is composed of two major components, the dentate gyrus and the hippocampus proper – the latter also referred to as Ammon’s horn or cornu Ammonis (CA regions). The Ammon’s horn region is divided into four subregions – area CA4 or the hilus, areas CA3, CA2, and CA1.

Question 5

What is learning and what are the routes in which it occurs?

Answer 5

• is the acquisition of new experiences (information)
• strengthen of receptors and synapses

-can be achieved through plasticity, associative and Non-Associative learning

Question 6

How strong must a stimulus be for an individual to learn?

Answer 6

it depends on the individual and ???

Question 7

What is the function of the limbic system?

Answer 7

It is the system controlling learning, emotion, motivation, and memory in man. It has two parts; cortical and subcortical components.

• drives and rewards, crucial to motivational state
• affects visceral activities central to emotional expression
• influences sensory and associative mechanisms that are critical ingredients of perceptions and perhaps thought

Question 8

Where is the majority of the limbic system located?

Answer 8

around the rim of the lateral ventricle

Question 9

What is the role of the Paul McLean (1949) in the limbic system?

Answer 9

expanded on the Papez circuit in the article “Psychosomatic Brain and the Viscera

Question 10

What is the role of the Papez (1930) in the limbic system?

Answer 10

Linked the structures comprising the “Limbic System” as having a role in emotions.

Question 11

What is the role of the Broca (1878) in the limbic system?

Answer 11

“Le Grande Lobe Limbique” (Grand Limbic Lobe) – this is a reference strictly to anatomical organization

Question 12

What is the rhinencephalon?

Answer 12

part of the brain associated with the olfaction

Question 13

What is the hippocampal formation?

Answer 13

• it is closely associated with the adjacent dentate gyrus and forms an S-shaped structure
• consists of the dentate gyrus, hippocampus proper, and the subiculum
• each of these components have 3 layers of neurons
• embryologically the hippocampal formation is an extension of the medial edge of the temporal lobe

Question 14

Where is the dentate gyrus located?

Answer 14

occupies the interval between the hippocampus and parahippocampal gyrus

Question 15

What is the subiculum?

Answer 15

the part of the parahippocampal gyrus that is in direct continuity with the hippocampus

Question 16

Describe the anatomy of the hippocampal formation.

Answer 16

• part of the limbic system
• located in the temporal lobes
• composed of dentate gyrus, CA1-3, and subiculum
• perforant pathway

Question 17

What is the perforant pathway and what is its function?

Answer 17

• provides a connectional route from the entorhinal cortex to all fields of the hippocampal formation, including the dentate gyrus, all CA fields (including CA1), and the subiculum
• perforant activates the Ca3 neurons in the hippocampus which is important for encoding memory

Question 18

What is the histology of the limbic system? What are the layers of the hippocampus?

Answer 18

• cortical structure of parahippocampal gyrus is six layers
• as the cortex is traced into the hippocampus there’s a gradual transition from a six to three layered arrangement

the hippocampus has:

• outer molecular layer
• middle pyramidal layer
• inferior and inner polymorphic layer (CA1, CA2, CA3, and CA4 (cornu Ammonis)

Question 19

Describe the distribution of hippocampal neurons.

Answer 19

• cluster of neurons entering the dentate gyrus known as CA1-CA4 are pyramidal cells
• neurogenesis only occurs in the dentate gyrus within the limbic system
• most of the neurons in the dentate gyrus are granular cells

Question 20

What is long term potentiation?

Answer 20

• increased excitability during altered chemical state on repeated stimulation of synapses
• is due to augmentation of postsynaptic potentials overtime

Question 21

What is the fundamental postulate of the molecular mechanisms of memory storage?

Answer 21

anatomical connections between neurons

-these mechanisms are set by genetics and the strength and effectiveness of synapses

Question 22

Is memory predetermined?

Answer 22

NO but it can be altered by experiences

Question 23

What are the neural mechanisms of learning?

Answer 23

?????

Question 24

What is learned (where in the brain; organization level?

Answer 24

???

Question 25

What is perceptual learning?

Answer 25

functions to identify objects and situations

Question 26

What is stimulus-response learning?

Answer 26

involves making a response when a particular stimulus is present as - classical conditioning - operant conditioning

Question 27

What is motor learning?

Answer 27

involves forming new circuits in the motor system

Question 28

What is relational learning?

Answer 28

involves identifying connections between stimuli

Question 29

What are associated with associative and non-associative learning?

Answer 29

associative: - classical conditioning - operant conditioning non-associative - habituation, sensitization - perceptual in nature - recognition of objects and situations

Question 30

Which type of learning involves acquisition of new motor behaviors, associations between new stimuli and existing behaviors, and new associations between familiar stimuli and existing responses?

Answer 30

associative learning

Question 31

What is habituation in non-associative learning?

Answer 31

- repeated exposure to a stimulus results in REDUCED responding to that stimulus - generally neutral, non-noxious stimuli

Question 32

What is sensitization in non-associative learning?

Answer 32

- repeated exposure to a stimulus results in INCREASED responding to that stimulus - generally biologically relevant, strong hedonic valence (positive or negative) - also refers to augmentation of responding following exposure to a second stimulus

Question 33

What are the 3 pathways in the hippocampal formation that display long term potentiation?

Answer 33

- perforant pathway (subiculum to dentate gyrus) - Mossy fiber pathway (dentate gyrus to CA3 pyramidal cells) - Schaffer collaterals (CA3 pyramidal cells to CA1 pyramidal cells)

Question 34

What is memory?

Answer 34

an active system that receives information from the senses, organizes, and alters it, stores it away, and then retrieves the information from storage

Question 35

What are the different processes of memory?

Answer 35

encoding: the set of mental operations that people perform on sensory information to convert that information into a form that is usable in the brain storage: holding onto information for some period of time retrieval: getting information is in storage nto a form that can be used

Question 36

What are the 3 gross stages of learning and memory?

Answer 36

- acquisition - storage - retrieval - Incoming sensory information will go to sensory buffers and get encoded - they will then procede to the either be placed in short-term or long-term memory which are both consolidated through repetition or training of your neurons to learn and remember that activity

Question 37

What is the importance of CA1?

Answer 37

it is a target of epileptic seizures

Question 38

CA3 is innervated by what pathway?

Answer 38

perforant pathway

Question 39

Which fibers go to the neocortex?

Answer 39

fornix

Question 40

What are the brains structures involved in memory?

Answer 40

- prefrontal cortex - amygdala - medial temporal gyrus - hippocampus - cerebellum

Question 41

What is the function of the following brain structures in regards to memory? - prefrontal cortex - amygdala - medial temporal gyrus - hippocampus - cerebellum

Answer 41

- prefrontal cortex: memory involving the sequence of events, but not the events themselves - amygdala: encodes emotional aspects of memory - medial temporal gyrus: (not visible) encodes and transfers new explicit memories to long-term memory - hippocampus: encodes and transfers new explicit memories to long-term memory - cerebellum: memory involving movement

Question 42

What brain structure is associated with working memory?

Answer 42

prefrontal cortex

Question 43

What brain structure is associated with explicit memory that involves episodic (remembering events) and semantic (knowing facts) memory?

Answer 43

hippocampus, nearby cortical areas, medial diencephalon

Question 44

What brain structure is associated with implicit memory specifically related to skills and habits? ?

Answer 44

striatum, motor areas of cortex, cerebellum

Question 45

What brain structure is associated with implicit memory specifically related to emotional assoications?

Answer 45

amygdala

Question 46

What brain structure is associated with implicit memory specifically related to conditioned reflexes?

Answer 46

cerebellum

Question 47

What are the two types of declarative long term memory?

Answer 47

declarative: things you know that you can tell others episodic: remembering your first day in school semantic: knowing the capital of France

Question 48

What are the three types of nondeclarative (procedural) long term memory?

Answer 48

nondeclarative (procedural): things you know that you can show by doing - skill learning: knowing how to ride a bicycle - priming: being more likely to use a word you heard recently - conditioning: salivating when you see a favorite food

Question 49

Why do we forget? What is encoding failure and what are the factors that can cause it?

Answer 49

- naturally our brain goes through an unknown process that makes room for new memories - encoding failure- failure to process information into memory Pathologically: - amnesia - dementia

Question 50

What is the difference between anterograde and retrograde amnesia?

Answer 50

anterograde: -inability to establish new memories - loss of relational learning ability - New declarative memories are not formed - Simple stimulus-response, perceptual and motor learning abilities remain intact - Previously formed memories remain intact retrograde: inability to recall past memories - loss of previously formed declarative memories

Question 51

What is infantile amnesia?

Answer 51

Childhood amnesia, also called infantile amnesia, is the inability of adults to retrieve episodic memories (memories of situations or events) before the age of two to four years, as well as the period before the age of ten of which adults retain fewer memories than might otherwise be expected given the passage of time.

Question 52

What is dementia/

Answer 52

Dementia is not a specific disease. It's an overall term that describes a group of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person's ability to perform everyday activities. Alzheimer's disease accounts for 60 to 80 percent of cases.

Question 53

What is the memory deficiency caused by lack of thiamine (vitamin B6) that is often seen in chronic alcoholism? What areas of the brain are affected? What are some of the symptoms of patients suffering from this syndrome?

Answer 53

Korsakoff's syndrome - brain damage occurs in mammillary bodies of the hypothalamus and basal frontal lobes, which produces anterograde amnesia - disconnects the path between the hippocampus anterior thalamic nucleus - causes memory impairment - patient often fabricate imaginary experiences as compensation for loss of memory (confabulate); fill in a gap in memory with a false memory that they fully believe to be true

Question 54

What are some emotions associated with behavioral stress?

Answer 54

approach | withdrawal

Question 55

What are some emotions associated with motivational stress?

Answer 55

``` reward punishment thirst hunger pain craving ```

Question 56

What are some emotions associated with moods and background emotions?

Answer 56

``` depression anxiety mania cheerfulness contentment worry ```

Question 57

What are some emotions associated with emotion systems?

Answer 57

seeking panic anger fear

Question 58

What are some emotions associated with basic emotions?

Answer 58

``` happiness fear rage disgust sadness surprise contempt admiration jealousy ```

Question 59

What are some emotions associated with social emotions?

Answer 59

``` pride embarrassment quilt shame maternal love sexual love infatuation ```

Question 60

What is the feed-forward mechanism that can induce specific emotion?

Answer 60

emotion generates an emotional response in the person via connections to the motor structures, hypothalamus, and brainstem nuclei (where emotional response is generated)

Question 61

The emotional state in the person perceiving the stimulus is through activation of what parts of the brain?

Answer 61

right somatosensory cortices

Question 62

What is the anatomy of the cingulate gyrus?

Answer 62

- the cingulate gyrus wrap around the external border of the corpus callosum, warping around its genu (subcallosal gyrus) - there is a posterior, anterior, and medial part as it is a rim - receives inputs from the thalamus and the neocortex - projects to the entorhinal cortex via cingulum

Question 63

What area of the brain is associated with disgust?

Answer 63

frontal insula

Question 64

What are the functions of the cingulate gyrus?

Answer 64

- emotion formation and processing - memory-learning - related to pain sensory

Question 65

What are disorders related to cingulate gyrus?

Answer 65

- depression | - schizophrenia

Question 66

What are mirror cells? Where do they reside and what is their function?

Answer 66

- A mirror neuron is a neuron that fires both when an animal acts and when the animal observes the same action performed by another. Thus, the neuron "mirrors" the behavior of the other, as though the observer were itself acting. - resides in the insula and anterior cingulate gyrus - mediates empathy: the experience of feeling the emotion of another

Question 67

What are the 6 layers of the neocortex (cortical structures of the limbic system)?

Answer 67

- entorhinal cortex - parahippocampal gyrus - hippocampus - amygdala - cingulate gyrus - olfactory cortex

Question 68

What are the parts of the diencephalon? (subcortical structures of the limbic system)?

Answer 68

- thalamus: anterior nucleus (gets reciprocal input) AND mediodorsal nucleus - hypothalamus: medial and mammillary bodies

Question 69

The limbic cortex consists of what two structures?

Answer 69

cingulate gyrus: dorsal to the corpus callosum and is heavily interconnected with the associated areas of the cerebral cortex; consists of an anterior and posterior cingulate gyrus; involved in planning of info related to pain, anger or sadness; it also involves the premotor cortex for planning parahippocampal gyrus: in the medial temporal lobe and contains several distinct regions, the most important being the entorhinal cortex; consists of a large number of neurons from hippocampal, dentate, and subiculum gyrus

Question 70

What is the difference between anterior and posterior cingulate gyrus?

Answer 70

- anterior receives input from anterior and dorsomedial thalamus and neocortex and projects back to ERC via cingulum and goes through hypothalamus - anterior cingulate gyrus works with amygdala for immediate action to run away from something that you fear??

Question 71

What are the only thalamic nuclei related to emotions?

Answer 71

anterior and dorsomedial thalamic nuclei

Question 72

What is important about the cingulate gyrus?

Answer 72

- is also related to motor - you are so sad that you cannot move your arms - facilitates negative memory (pain, anger, depression) associated with autonomic system (gets projections from lateral hypothalamus and inferior gyrus important for hunger, trust, pain)

Question 73

Explain the relationship between the amygdala and anterior cingulate gyrus.

Answer 73

- they work hand in hand - amygdala is involved in fear perception, ANS response and memory - anterior cingulate gyrus stores that memory and retrieves it whenever necessary (retrieves memories that are unpleasant and painful) - all the noises associated with pain is through the activation of the anterior cingulate gyrus and amygdala -amygdala activation by fearful stimuli and fearful faces

Question 74

The hippocampus layers is comprised of what neurons?

Answer 74

CA1 CA2 CA3 CA4

Question 75

Most of the neurons in the dentate gyrus are what kind of cells?

Answer 75

granular cells

Question 76

What is the difference between neurogenesis and neuroplasticity?

Answer 76

- neurogenesis is born of new cell - neuroplasticity is when a surviving cell is learning how to function like a normal cell and extend its processes and strengthen its synapses

Question 77

Where in the hippocampal formation is there neurogenesis?

Answer 77

dentate gyrus

Question 78

What is the papez circuit?

Answer 78

AKA limbic circuit is a neural circuit for the control of emotional expression hippocampal formation (subiculum)--> fornix---> mamillary bodies ----> mammilothalamic tract----> anterior thalamic nucleus--> cingulum--> hippocampal formation basic neural circiut through -perforant activates the Ca3 neurons in the hippocampus which is important for encoding memory -all the information will be taken up by the Mossy fibers which are glutaminergic and project to subiculum via fornix back to the diencephalon specifically the mammillary bodies and anterior nucleus of the thalamic

Question 79

Why is the Papez circuit important?

Answer 79

learning and emotions involve both motor and higher cortical functions through basal ganglia for motor learning long term potentiation occurs which will stimulate your axons and connectivity circuit is greatly influences by the cerebellum and lesions of the cerebellum can have an inhibitory effect on the circuit