1
Q
the limbic system is ….
A
an anatomical concept
2
Q
Describe the anatomy of the limbic system
A
- It includes a group of cortical and subcortical nuclei found on the medial aspect of the frontal, parietal and temporal lobes.
- these cortical areas are interconnected by corticosteroids-cortical pathway
- made out of the orbito-frontal cortex, cingulate cortex and limbic cortex
3
Q
What lobes is the limbic system found on
A
- It includes a group of cortical and subcortical nuclei found on the medial aspect of the frontal, parietal and temporal lobes.
4
Q
describe the blood supply of the limbic system
A
- The limbic cortex in the frontal and parietal lobes is supplied by blood from the ANTERIOR cerebral artery.
- Limbic cortex in the temporal lobe is supplied by the POSTERIOR cerebral artery,
- although the tip of the temporal lobe & orbital cortex may be supplied by the middle cerebral artery
5
Q
What are the three parts of the limbic system
A
- orbito-frontal cortex and the cingulate cortex make up the limbic cortex in the frontal and parietal lobe
- parahippocampal cortex is the third part of the limbic cortex, it lies in the medial temporal lobe
6
Q
What affect do strokes in the anterior cerebral arteries have on the limbic system
A
- they affect the anterior part of the limbic system which effects what the limbic system does with personality moods and emotions
7
Q
What affect do strokes affecting the posterior cerebral arteries have on the limbic system
A
Strokes of the posterior cerebral artery affect the temporal part of the limbic cortex which can affect memory
8
Q
What does the limbic system do
A
The limbic system is involved in emotion, memory and learning.
It is linked to rewards and punishments for actions.
9
Q
What else is the limbic system connected to
A
- the limbic system is connected to the olfactory sensory system
- allows animals to experience good memories when they smell nutrias food and bad memories when they smell food that made them sick
10
Q
What is the anterior cingulate cortex made out of
A
- Made out of the rostral and caudal anterior cingulate cortex
11
Q
Where is the anterior cingulate cortex
A
- it goes over the front of the corpus callous
12
Q
When does the anterior cingulate cortex become active
A
- it becomes active when someone is suffering and in pain as well as during depression
13
Q
Describe how pain is linked to the anterior cingulate cortex
A
- nociceptive (pain) information travels up the lateral spinothalamic tract. From there it goes a) via the parabrachial nucleus (PB) to the amygdala (AMY) and b) via the anterior thalamic nucleus to the anterior cingulate cortex (ACC) and insula
14
Q
What is the difference between the anterior cingulate cortex and the prefrontal cortex
A
- the anterior cingulate cortex appears to be the cortical area responsible for the ‘unpleasantness’ of pain and its depressing emotional consequences. The prefrontal cortex is activated to “do something” about the pain.
15
Q
What is the difference between the caudal and rostral anterior cingulate cortex
A
Caudal Anterior Cingulate:
Registers the quality of the pain, how bad it is.
Rostral Anterior Cingulate:
Decides upon the action in response to the pain.
Merges into the orbitofrontal cortex, the frontal lobe is responsible for actions.
This planning of future actions helps to avoid pain.
16
Q
in what area do OCD patients may have excessive brain activity
A
Prolonged exposure to make impossible choices causes extreme stress, and has been
linked to the development of OCD.
OCD patients may have excessive activity in this brain area.
= Orbitofrotnal cortex
17
Q
What is a cingulotomy and what does it do
A
- a cingulotomy is the procedure of cutting the anterior cingulate gyrus which disrupts fibres that pass through it
- this reduces the emotional distress of pain
- in patients in which this has happened they reported a decrease in the level of pain and no longer required pain killers
18
Q
what is the orbitofrontal cortex involved in
A
- Involved in actions to avoid pain or injury in the future
19
Q
the anterior part of the cingulate merges into…
A
the orbitofrontal cortex
20
Q
What happens when you have to make a difficult decision
A
- person may not be a able to chose between actions and freeze
- these decisions cause extreme stress and cause the release of stress hormones such as cortisol and adrenaline
- this leads to a sense of hopelessness and then depression
- this happens to patients with OCD
21
Q
What is the posterior cingulate cortex linked to
A
- The posterior cingulate cortex (PCC) has been shown by fMRI to display intense activity when memories with emotional significance such as those concerning friends and family are recalled successfully.
- therefore It has been suggested that the PCC codes or is responsible for the emotional content or significance of memories.
22
Q
if there is dysfunction in the posterior cingulate cortex what is it linked to
A
Loss of function correlates with the disorientation seen in Alzheimer patients.
23
Q
Where is the parahippocampal gyrus
A
- lies medially and inferiorly in the temporal lobe
24
Q
what is the parahippocampal gyrus responsible for
A
- in the acquisition of new memories
25
What are the subcortical parts of the limbic system made out of
- hippocampus
| - amygdala
26
what is the parahippocampal gyrus closely connected to
- It is closely connected to the subcortical parts of the limbic system which are inside the temporal lobe
27
Where are the subcortical parts of the limbic system
- made out of the hippocampus and amygdala
| They lie around the walls of the inferior horn of the lateral ventricles in the temporal lobe
28
Where is the hippocampus
- The hippocampus lies along the medial wall of the inferior horn of the lateral ventricle
29
What do the output fibres of the hippocampus form
; its output fibres form the fornix which curves upwards and round the over the top of the third ventricle
30
describe the structure of the lateral ventricle
- has an anterior horn, posterior horn and inferior horn
31
describe how the hippocampus merges into the fornix
- at the anterior part of the hippocampus it is mostly cells and then as it moves backwards it becomes axons this is called the fornix
- the fornix goes in a 3D curve and ends up in the hypothalamus
32
describe the structure of the fornix
The anterior end of the fornix folds down almost vertically at the front of the third ventricle and ends up in the hypothalamus
The septum reaches down to the anterior pole of the hypothalamus
33
Where do the fornix axons end in
- they end in the septal nuclei and mammillary body of the hypothalamus
34
What happens in the hippocampus is damaged
Loss of the hippocampus causes failure to create experiences into memories.
Anterograde amnesia = Loss of ability to store new experiences.
35
Describe the neuronal connections in the limbic system
1. Information goesfrom the cingulate cortex to the parahippocampal gyrus
2. Information goes from the parahippocampal cortex to the hippocampus
3. Information goes from the hippocampus along the fornix to the mamillary bodies of the hypothalamus
4. Information goes from the hypothalamus to the anterior thalamus
5. Information goes from the anterior thalamus back to the cingulate cortex
36
what is anterograde memory
could not make new memory but can remember the past
37
What is retrograde memory
cannot get past memories but can make new memory
38
What does the hippocampus do to memory
- it is needed for memory storage as it puts a place and date stamp on the experience
- without this information you are not able to store the memory
39
Where are memories stored
= in the cortex
40
What does damage of the hippocampus not affect
• Damage to the hippocampus does not affect some types of memory, such as the ability to learn new motor skills (playing a musical instrument,).
= This fact suggests that such abilities depend on different brain regions (probably the cerebellum).
41
What is the fornix attached to near the lateral ventricle
septum pellucidum.
42
what is kluver bucy syndrome and what are the symptoms
- this is when the subject loses all sense of fear
symptoms
- Psychic blindness (inability to process information).
- Oral tendencies.
- Hypermetamorphism; grabbing objects in view and appropriately using them-
but not at appropriate times.
- Altered sexual behaviour.
- Emotional changes.
43
What is kluver bucy syndrome due to
Bilateral loss of the amygdala
44
Where is the amygdala
The amygdala is embedded in the entorhinal (olfactory) cortex in the anterior medial temporal lobe.
45
what does electrical stimulation of the amygdala produce
- creates fear or anxiety
46
What does the amygdala do
It activates the fight or flight response of the sympathetic NS.
47
describe the structure of the amygdala
- it is made out of many sub nuclei with different connections and thus different functions
48
Describe the pathway of the amygdala
- Septal nuclei is a sensory mechanism, which connects to the reticular formation.
- The RF forwards the signal to the ventral striatum (nucleus accumbens).
- The signal is sent to the amygdala where it can activate fight or flight.
- The commands are sent to the hypothalamus, which is then sent again to the RF.
- The reticulospinal tracts can then be activated and a response triggered.
49
where are the septal nuclei
The septal nuclei lie at the base of the septum pellucidum
50
What does the septal nuclei merge with
merge into the basal nucleus (of Meynert)
51
What do the septal nuclei and the nucleus accumbens form together
ventral striatum
52
the nucleus accumbens is anatomically,,,
Thus it is anatomically part of the basal ganglia but functionally is part of the limbic system
- this is because it is the ventral most part of the anterior striatum where the caudate and putamen merge
53
what does the nucleus accumbes receive dopaminergic fibres from
It receives dopaminergic fibres as part of the mesolimbic dopamine pathway.
54
Describe what the amygdala does to memory
The amygdala tells us whether it is pleasant or frightening
55
What is the mesolimbic pathway
The mesolimbic pathway is a set of dopamine neurones that project from the
brainstem to the accumbens nucleus.
56
What is the ventral striatum involved in
The ventral striatum is involved in the initiation of termination of behaviours that
trigger reward pathways.
57
Describe how the ventral striatum leads to reward pathways
Septal nuclei send axons down to the brainstem and activate dopaminergic
neurones, these then go up to the dorsal and ventral striatum to release dopamine.
The dopamine input to the accumbens nucleus is necessary for the pleasurable
behaviour to take place.
The release of dopamine in the accumbens is what makes you feel good, but it also
enforces the behaviour.
Dopamine motivates you to do things to increase your sense of award.
58
What happens if you block the nucleus accummbens from releasing dopamine
Thus, blocking dopamine receptors in the accumbens may help stop motor actions
associated with addictive behaviours.
However, by blocking dopamine it will cause Parkinson-like effects.
Brain and Behaviour Year 2
flashcards
Decks in class (36)
# Cards
-
CAL 162
-
CAL 283
-
CAL 398
-
CAL 4125
-
Anatomy Practical147
-
Anatomy Practical 289
-
Anatomy Practical 365
-
Introduction to BB28
-
Basal Ganglia53
-
Pharmacology of Movement35
-
Motor System II78
-
Learning and Conditioning27
-
Cerebellum47
-
Anatomy and Physiology of Pain58
-
Pharmacology of Pain46
-
Epilepsy48
-
Pain Mechanism and Management27
-
Blood Supply to the Brain66
-
Vestibular System29
-
Headaches and Migraine44
-
Depression and Antidepressants49
-
Addiction26
-
Drug Dependence45
-
Deep Brain Stimulation27
-
Limbic system58
-
Dementia57
-
Memory and Amnesia22
-
Schizophrenia41
-
Symptoms of the Mind22
-
Persistent vegetative state56
-
Head Injury30
-
Anxiety63
-
Sleep and Arousal64
-
Stroke36
-
Multiple Sclerosis36
-
Before the Exam141
