Brain Development and Plasticity

Question 1

Maturation of the Vertebrate Brain - Age of Formation

Answer 1

2 week old embryo

Question 2

Maturation of the Vertebrate Brain - Process

Answer 2

Thickening of the dorsal surface

Formation of lips to create the neural tube surrounding a fluid filled cavity which will later form the ventricles

Forward end of the tube differentiates to form the hindbrain, midbran and forebrain

Question 3

Stages of Neuron Development

Answer 3

Proliferation, Migration, Differentiation, Myelination, Synaptogenesis

Question 4

Stages of Neuron Development - Proliferation

Answer 4

Production of new cells by the division of stem cells into neurons and glia

Question 5

Stages of Neuron Development - Migration

Answer 5

Movements of cells to their target distination

May be radially or tangentically, guided by radial glia, immunoglobins and chemokines

Question 6

Stages of Neuron Development - Differentiation

Answer 6

Cells differentiate to form neurons or glia

Neurons from axons and dendrites

Axon path-finding occurs

Question 7

Stages of Neuron Development - Myelination

Answer 7

Glia (Oligodendrocytes / Schwann cells) produce myelin to speed up transmission of impulses along the axon

Continues throughout life

Question 8

Stages of Neuron Development - Synaptogenesis

Answer 8

Formation of new synapes

Continues throughout life during learning and memory trace formation

Question 9

Maturation - Grey Matter Volume

Answer 9

Decreases with age

First year of life +185%
Adulthood +20-30%

Question 10

Fine-tuning

Answer 10

Brain has limited capacity to recognise itself

Gaining or losing synapses indicates change in connections and information processing

Question 11

Axon-pathfinding

Answer 11

Process by which neurons send out axons to reach the correct targets

Question 12

Axon-pathfinding - Weiss 1924

Answer 12

Found eveidence that axons find their own way to their target destinations

Question 13

Axon-pathfinding - Sperry 1943

Answer 13

Removed, rotated and replaced the eyes of frogs

Severed axons found their way back to their origins and targets, not the location of where they are expected to be

Suggests the involvement of monitoring marker to track where their target is

Question 14

Axon-pathfinding - Chemical

Answer 14

Axons regenerate in their original position by following cell-surface molecules

Trial synapses are formed and tested - if stimulated they are strenghtend, if no stimulated they are eliminated

Question 15

Axon-pathfinding - Neural Competition

Answer 15

Growth and survival of neurons is dependent on nerve growth factor

Competition over nerve growth factor occurs - neurons which receive this are kept, those that do not are eliminated

Question 16

Axon-pathfinding - Nerve Growth Factor

Answer 16

Neurotrophin released by muscles

Enables neural competition which improves efficiency of neurons by allowing the number of incoming axons to match the number of receiving cells

Question 17

Vulnerable Brains - When

Answer 17

During embryonic development

Question 18

Vulnerable Brains - Causes and Effects

Answer 18

Fever impairs proliferation

Low glucose consumption impairs development

Fetal alcohol syndrome impairs development

Question 19

Vulnerable Brains - Causes and Effects, Fetal alcohol syndrome

Answer 19

Dendrites are short with fewer branches resulting in impairments in learning, memory, language and attention

Alcohol suppresses glutamate and enhances GABA so neurons are excited and stimulated less, receiving less Nerve Growth Factor resulting in synapse elimination and neuron apoptosis

Question 20

Effects of Experience - Enriched Environments

Answer 20

Those in enriched environments have thicker cerebral cortex, increased dendritic branches and improved learning due to the strengthening of more synapses and creation of more traces

Question 21

Effects of Experience - Reorganisation

Answer 21

Practice reorganises the brain the maximise performance

Question 22

Effects of Experience - Reorganisation and Plasticity, Sadato et al 1998

Answer 22

The brains of individuals that have been blind since infancy show reorganisation

Visual cortex is active during tactile discrimination tasks, indicating brain plasticity

Question 23

Language Learning - Chomsky

Answer 23

A critical period after which it becomes much harder to acquire language exists

Question 24

Language Learning - Mechelli et al 2004

Answer 24

Bilingualism results in changes of grey matter, especially in languge-related areas indicating how learning and pratice alters brain organisation

Question 25

Lateralisation of Function - Right body

Answer 25

Controlled by left side of the brain

Question 26

Lateralisation of Function - Left body

Answer 26

Controlled by right side of the brain

Question 27

Lateralisation of Function - Right brain

Answer 27

Controls left side of the body

Involved in facial recognition, emotion, music, tactuality, non-verbal memory and spatial processing

Question 28

Lateralisation of Function - Left brain

Answer 28

Controls right side of the body

Involed in visual and auditory language, speech and verbal memory

Question 29

Lateralisation of Function - Language

Answer 29

Evidence from Broca and Wernicke area damage suggest double dissociation of language abilities and localisation of brain function

Question 30

Lateralisation of Function - Language, Broca’s Area

Answer 30

Located in the frontal lobe

Controls langauge production

Aphasia results in inability to produce fluent language

Question 31

Lateralisation of Function - Language, Wernicke’s Area

Answer 31

Located in temporal lobe

Controls language comprehension

Aphasia results in incomprehensible yet fluent language producution

Question 32

Plasticity

Answer 32

Ability for the brain to reorganise and structure functions to compromise for damaged areas or loss of function

Question 33

Plasticity - Causes

Answer 33

Tumour, infection, exposure to toxins, degenerative disease, closed head injury, stroke

Question 34

Plasticity - Diaschasis

Answer 34

Decreased activity of surviving neurons after damage to other brain regions

Disrupts usual stimulation patterns

Question 35

Plasticity - Mechanisms

Answer 35

Regrowth and Remyelination

Collateral sprouting

Reorganisation of Sensory Representations

Change in Neuron Sensitivity

Question 36

Plasticity - Mechanisms, Reorganisation of Sensory Representations

Answer 36

e.g. Sodato et al 2008

Limb amputations result in changes in somatosensory cortex mapping to accommodate for the area no longer assigned to the limb

Question 37

Plasticity - Mechanisms, Change in Neuron Sensitivity

Answer 37

Denervation or Disuse changes

Question 38

Plasticity - Mechanisms, Change in Neuron Sensitivity, Denervation

Answer 38

Heightened sensitivity after destruction of an incoming axon in order to attempt to receive suffient stimulation

Question 39

Plasticity - Mechanisms, Change in Neuron Sensitivity, Disuse

Answer 39

Heightened sensitivity due to inactivy to make use of any slight activity / stimulation