Anatomy and function of the Limbic system

Question 1

What is the Limbic system involved in

Answer 1

Emotions

Reward driven activity: feeding and sex

Motivation

Social behaviours: friend and foe

Memory of environment and experience

Question 2

How does the limbic system function

Answer 2

Links to other key brain regions

Output to hypothalamus, sensory and motor and frontal regions to achieve survival

Question 3

What is the Limbic system transitional between

Answer 3

Subcortical nuclei and Neo-cortex

Question 4

What are the subfields of the hippocampus

Answer 4

Dentate gyrus
CA3
CA1
Subicular cortex

Question 5

What is the basic circuit of the hippocampus

Answer 5

1) sensory information from multiple cortical areas
2) flows to Entorhinal cortex
3) Then Dentate gyrus
4) Then CA3
5) Then CA1
6) Then Subiculum
7) Then back to Entorhinal cortex

Question 6

What allows memory formation in the hippocampus

Answer 6

There are connections between the inhibitory and excitatory neurons in the hippocampus

Question 7

What is the function of the septal nuclei (which is connected to the hippocampus)

Answer 7

Have a role in the theta rhythm of the hippocampus which plays a role in behaviour

Question 8

Where does sensory information enter the hippocampus and where does it go

Answer 8

From throughout cortex via entorhinal cortex> perforate path to dentate gyrus

Question 9

What are the outputs of the hippocampus

Answer 9

Via Subiculum and entorhinal cortex to neocortex

Via fornix to

• septal region
• mamillary bodies
• hypothalamus
• median forebrain bundle

Question 10

Non pharmacological treatment for severe or treatment resistant depression

Answer 10

Electroconvulsive therapy
-General anaesthetic and muscle relaxant, electricity given to produce a controlled generalised epileptic seizure. Course of up to 12 treatments

-It is vagal nerve stimulation and deep brain stimulation

Question 11

Another non-pharmacological treatment for depression

Answer 11

Transcranial magnetic stimulation
-Magnets focussed byt do not penetrate far into brain so can be targeted at front-limbic circuits implicated in depression

Question 12

What is cognitive behaviour therapy

Answer 12

Tackles reasons why depression or anxiety are still present, not what caused them

Question 13

How to use CBT in thinking patterns in depression

Answer 13

Tackle:

• Nagative automatic thoughts- based on unhelpful thinking styles e..g. black and white thinking
• Assumptions ‘if something happens then I am good/bad/unloved etc’
• rigid beliefs

Question 14

How to use CBT in behaviour in depression

Answer 14

Set tasks to increase confidence and interest each day

Question 15

How to use CBT in problem solving in depression

Answer 15

Define a spefici problem into one or more solvable problems

Question 16

Inputs Of hippocampus

Answer 16

Sensory info from throughout cortex via entorhinal cortex > perforate pathway to dentate gyrus

Modulatory inputs from septal nuclei, brainstem nuclei influence the overall functioning

Question 17

What are other important connections of hippocampus

Answer 17

Amygdala and thalamus

Question 18

What are the two types of Declarative memory

Answer 18

Semantic: the Eiffel towel is in Paris (fact)

Episodic: I kissed my lover under the Eiffel tower

Question 19

What type of memory is associated with the hippocampus

Answer 19

Episodic memory

Question 20

What does removal of hippocampus lead to

Answer 20

Profound deficit in episodic memory

Preserved procedural memory

Preserved memory of events before surgery

Question 21

What can damage to hippocampus lead to

Answer 21

Temporal lobe epilepsy

Question 22

What are the inputs of the amygdala

Answer 22

Olfactory bulb

Prefrontal cortex
Hippocampus and

Entorhinal cortex

Sensory thalamus and cortex

Viscerosensory cortex

Question 23

How can the effector region of the amygdala generate an autonomic response for fear

Answer 23

via Sympathetic and parasympathetic NS

Question 24

How can the effector region of the amygdala generate hormonal responses to fear

Answer 24

Through HPA axis

Question 25

How can the effector region of the amygdala generate a modulatory response

Answer 25

via modulatory systems using NE 5-HT DA ACh

Question 26

What does the basal nucleus of the amygdala have a role in

Answer 26

regulation via prefrontal cortex reward behaviours via ventral striatum

Question 27

What is the lateral nucleus in amygdala responsible for

Answer 27

Sensory information

Question 28

Where is the effects of most of the outputs of the amygdala from

Answer 28

central nucleus

Question 29

How do the outputs of the amygdala reach the brainstem

Answer 29

Stria terminalis > hypothalamus > brainstem > BNST > accumbens

Question 30

What is an example of a fear conditioning pathway

Answer 30

e.g. If a rat was exposed to a noise when it is electrocuted, it would eventually show a fear response even with just a noise (no electric shock necessary)

Question 31

Mechanism behind the fear conditioning pathway

Answer 31

The stimulus and the fearful thing pathways eventually become linked in the central nucleus so therefore only one is needed to make a fear response

Question 32

What is Kluver-Bucy syndrome What are the symptoms

Answer 32

Large bilateral anterior temporal love resections removing amygdala, hippocampus and surrounding temporal lobe Very docile-no longer aggressive towards keepers - Indiscriminant sexual activity - Lost ability to visually discriminate edible from inedible - A breakdown of visual input to channeling drives

Question 33

What is Urbach Wiethe disease

Answer 33

Bilateral amygdala lesions -Normal ability to recognise familiar faces, happy, sad, angry, surprise, disgust face - Unable to recognise fear face - No fear of other things - Cannot learn fearful associations

Question 34

What do specialised circuits linking sensory input to in amygdala

Answer 34

Link sensory input with their emotional value

Question 35

What do the outputs of the amygdala use to cause behaviour

Answer 35

brainstem and hypothalamic mechanisms

Question 36

What is the neurotransmitter involved in the reward circuit

Answer 36

Dopaminergic neurons

Question 37

*Where is the reward circuit

Answer 37

Ventral tegmental area to nucleus accumbens

Question 38

Where is the Nucleus accumbens

Answer 38

Ventral area of nucleus accumbens

Question 39

When do midbrain dopaminergic neurons show brief bursts of activity

Answer 39

After rewarding stimuli like food or sex Stimuli which PREDICTS reward (such as smelling food)

Question 40

Is the midbrain dopaminergic neurons correlated with 'liking' or 'wanting'

Answer 40

Wanting, not liking

Question 41

When do midbrain dopaminergic neurons show Tonic (base level firing)

Answer 41

Motivation

Question 42

What receptors are involved in reward pathway

Answer 42

D1

Question 43

What does an absence of reward after stimulus predicting a reward produce

Answer 43

A drop in DA neural firing

Question 44

Where are pleasure hotspots

Answer 44

IN nucleus accumbens and Orbitofrontal cortex

Question 45

Where is the dopaminergic circuit

Answer 45

From the Substantial Nigra to the Dorsal Striatum (caudate and putamen)

Question 46

What is the ventral striato-pallidal circuit involved in

Answer 46

Reward

Question 47

What is the route of ventral striato-pallidal circuit

Answer 47

VTA - ->Ventral Striatum - ->Ventral Pallidum - -> Thalamus MD - -> LImbic and prefrontal cortex

Question 48

When is the Cingulate cortex arisen When is there an over activity in OCD

Answer 48

Handline conflicting information (such as the word RED written in green) Monitoring error Arousal -Over activity in OCD

Question 49

What dysfunction is seen in depression

Answer 49

Complex network of limbic-striatum-frontal cortex

Question 50

What are the different components of depression and which part of the brain is responsible for these

Answer 50

Amygdala-anxiety Hippocampus- memory deficits Reward circuits- anhedonia and motivation Frontal lobe- motivation, decision making Striatum- motor slowing

Question 51

What is the Meso-Limbic DA circuit Where does it receive inputs from

Answer 51

key motivation and reward pathway Inputs from VTA to Nucleus accumbens and basal forebrain

Question 52

What is pre-frontal cortex important in What disorders are associated with it

Answer 52

Decisions about reward and appetite Motivation and regulation of behaviour Disorders can include psychiatric and personality disorders

Question 53

What does the septal nuclei connected to the hippocampus have a role in

Answer 53

Producing theta rhythm