Systems Neuroscience

Question 1

Give some examples of teh level of description and understanding that encompasses Systems Neuroscience

Answer 1

Basal ganglia thalamocortical system

Visual system

Question 2

What what systems neuroscience can be quoted from Zeki 2003?

Answer 2

No evidence that single cells/molecules are a ‘neural correlate of consciousness

Question 3

Describe the predicate of systems neuroscience

Answer 3

Abnormal behaviour and sybjective experiences linked to abnormal functioning of brain systems

There are direct correlations, and can in some cases predict subjective experience

Question 4

Describe the predicate of biological psychiatry

Answer 4

The brain is the organ that generates, sustains and supports mental function, and modern psychiatry seeks the biological basis of mental illness

Question 5

Systems neurosciene generates models fo brain function to link with descision making

Give two examples of how this is achieved

Answer 5

(1) Computational Neuroscience
- Computational psychiatry - Montague 2012
- Neuroeconomics in psychiatry - Hasler 2012
(2) Animal Model
- 5-HT and mechanisms of defence - Deaken & Graeff 2013
- Drug addiction, allostasis and reward, neurobiology of addiction (Koob & Volkow 2010)

Question 6

Describe Koob’s Allostasis theory of addicition

Answer 6

Brain changes that occur in the development of addiction explain the persistence of vulnerability to relapse

Addiction is a spiralling dysregulation of brain reward systems

Progressively increasing to cause loss of control

Counteradaptive processes (such as opponent-process) fail to return to normal homeostatic state, forming an allostatic state

Allostasis represents a chronic deviation from reward set point norms

Driven by dysregulation of reward circuits and endocrine stress responses

Question 7

Describe the spiral progression of the stages in Koob’s Allostasis model of addicition (3)

Answer 7

Binge Intoxication

Withdrawal/ Negative affect

Proccupation / Anticipation

Question 8

Who proposed the ‘opponent process’ model of addiction, which Koob extended into allostasis?

Answer 8

Solomon & Corbit 1974

Question 9

Describe the evidence for 5-HT function in depression which pre-dated Deakin’s theory

Answer 9

Evidence that dopamine was involved in reward

Serotonin thought to have a complementary role

5-HT had an inhibitory effect on behaviour and may have anxiogenic properties

5-HT neurones mediate the effects of punishment behaviour

(still debated whether 5-HT mediates aversive motivational state)

Question 10

What did Deakin and Graeff propose?

Answer 10

DRN neurones fucntion in opposite to dopaminergic neurones

Function as a ‘stop’ or negative reinforcement signal, guiding away from threatsm, toward dopamine cues

MRN neurones mediate an ‘unlearning’ function during punishment or instrumental learning.

Linked to evidence on 5-HT1a agonists impairing memory and projections to hippocampus

Suggested that MRN neruones prevent consolidation of aversive memories, tolerating adversity (resilience)

Question 11

According to Deakin’s theory, what two roless does 5-HT appear to have in anxiety?

Answer 11

Aversion toProximal threats

Aversion to Distal threats

Question 12

In Deakin’s theory, what role does the brainstem play in the Depression and anxiety?

Answer 12

Brain stem - responding to aversive threats

Amygdala - m, hypothalamus - PAG

This system is modulated in different ways be 5-HT

Question 13

In Deakin’s theory, what role does the Amygdala play in Anxiety and Depression?

Answer 13

Amygdala - distal threats

Receives cortical afferents with complex stimuli information

Question 14

In Deakin’s theory, what role does the PAG play?

Answer 14

PAG - Proximal threats

Mediates flight/fight behaviour

Hard-wired, unconditioned reflexive response to proximal threat (imminent death!)

Touch / pain / suffocation (hypoxia)

‘Painic attacks’ can be triggered by CO2

Question 15

Why might 5-HT be activated in punishment, yet inhibit PAG fight / flight mechanism?

Answer 15

When threats perceived at a distance by amygdala, PAG outputs for autonomic and respiratory function activated

Fight / flight component is inhibited from premature activation by 5-HT release from DRN neurones

This enables learned avoidance strategies to guide away from threat

Implies that anticipatory anxiety inhibits panic attacks (clinical evidence: pain attacks made worse by relaxation therapy)

Question 16

Deakin’s theory has numerous implications. How does it explain ‘learned helplessness’? (animal model of depressive illness)

Answer 16

-Increased anxiety and impaired escape behaviour

Both mediated by profound activation of DRN (fMRI)

Medial frontal cortex detects when punishment is controllable and inhibits DRN

Question 17

Deakin’s theory has numerous implications. How does it explain fear processing?

Answer 17

Proposed that effects of the DRN on amygdala and in dopaminergic structures, are mediated by high concentrations of 5-HT2c receptors

Question 18

Deakin’s theory has numerous implications. How does it explain depression and resilience?

Answer 18

MRN projection to the hippocampus mediate behavioural adaption to chronic or repeated aversive experiences

• systemic/hippocampal 5HT1a agonist/anti-depessants prevent anxiety
• SSRIs may correct an ipairment of 5HT1a neurotransmission

Predicts that recovery from depression associated with increased MRN activity, and reduced hippocampal activity