Principles Of Neuroscience Lecture 29 Disorders of the Nervous System II

Question 0

What irreversible deficits come about due to abuse induced trauma?

Answer 0

Social behaviour
Neuro cognitive impairment
Fearful, timid, withdrawn

Question 1

What are some examples of abuse/trauma?

Answer 1

Neglect
Physical
Sexual
Psychological

Question 2

Give some examples of studies connecting abuse and trauma (3)

Answer 2

a. Time spent in orphanage vs. incidence of neuro cognitive impairment
b. Harlowe’s monkeys: reared in isolation –> fearful, timid withdrawn monkeys
c. MRI tractography of deprived children: reduced connection between PFC and the rest of the brain

Question 3

What are the requirements for the critical period?

Answer 3

Tactile based attachment

Nurturing

Question 4

Describe how the analogy of vision can be used for critical periods

Answer 4

There is a critical period for development of the occular dominance columns and stereoscopic vision.

If one eye is covered during this time, normal vision can never be regained

Question 5

Describe the study in which cats eyes were sutured

Answer 5

Normal cat: most neurons in V1 receive input from both eyes, some receive input from only one eye
Eye sutured shut during critical period: every when reopened, the neurons in the V1 only receive input from neurons from one eye
Eye sutured after critical period: once reopened, the neurons in V1 can regain the normal input patterns

Question 6

What does the sutured eye experiments in cats tell us about critical periods?

Answer 6

There is a critical time during which all the important things occurin terms of organisation of the system.

This can be used as an analogy for normal social behaviour. If a child does not receive the correct care during this time, it will never acquire normal social behaviour

Question 7

What is stereopsis?

Answer 7

This is normal 3D and depth vision

Question 8

What is strabismus?

Answer 8

This is abnormal stereoscopic vision. The depth of objects can no be seen

Question 9

Monocular deprivation can lead to …

How long must the monocular deprivation last?

Answer 9

Strabismus

3 days is sufficient to generate biasing to one eye
6 days: there will be complete biasing to one eye

Question 10

How do inputs into neurons in layer IV in the visual cortex establish dominance?

Answer 10

The input neuron that correlates most with the activity of the neuron it is inputting into will have its connection strengthened

Question 11

Describe the three eyed frog experiment

Answer 11

Normally, the input from each eye in frogs goes to separate parts of the brain.

Attaching a third eye results in occular dominance columns in the brain, because the inputs from the two eyes compete for space in the visual cortex

Question 12

What were the conclusions of the three eyed frog experiment?

Answer 12

Competition for space results in ocular dominance columns

Question 13

What is the hyper plastic state, and why is it important?

Answer 13

This is a state when also the connections and organisation of the neural circuits are made

It is important because if the individual does not get the right stimuli during this time, the function may never be properly developed

Question 14

What are some examples of processes that are set up in the hyper plastic state?

What are some common molecules?

Answer 14

Neuromuscular junctions
Ocular dominance
Language
Stress

NMDA
GABA
CREB

Question 15

Describe the mechanism of growth of neurons and establishment of circuits

Answer 15

Stimulus: ligand binding
Increase in intracellular calcium
Activation by phosphorylation of proteins
Activation of transcription factors
Gene expression

Question 16

Describe the stress response

Which systems are important for the stress response?

Answer 16

Sensory input
Amygdala
Hypothalamus -> HPA, autonomic nervous system
Avoidance behaviour
Diffuse neuromodulatory systems -> noradrenaline, increased vigilance

Question 17

Describe the Stress (HPA) axis.

Answer 17

Amygdala activates the HPA which releases cortisol

The hippocampus inhibits the release of cortisol from the HPA

Question 18

Compare the function of the HPA axis in normal development and in children who are abused/ experience unrelenting stress

Answer 18

Normal: inhibition of too much cortisol by action of the hippocampus

Unrelenting stress: lots of cortisol in the system, which is toxic to the hippocampus. The cells in the hippocampus die and now the HPA is no longer inhibited. There is overactivity of HPA and too much release of cortisol

Question 19

Studies of the HPA axis in depressed individuals reveals that …

Answer 19

The HPA axis is over active

Question 20

Studies of the brain in abused individuals reveals that …

This is due to …

Answer 20

There is reduced volume of the PFC and the hippocampus

This is due to the toxic effects of cortisol

Question 21

What is the relationship between abuse and neurodevelopment?

Answer 21

The relationship is unclear.

We don’t know whether or not it is a linear relationship, or if there is a threshold, above which development is normal

Question 22

What does it mean when we say that we only know this relationships at extremes?

Answer 22

We only really know the effect or chronic abuse and complete neglect

Question 23

What is the effect of an ultra-enriched environment?

Answer 23

We don’t know