Functional organisation of the brain and brain plasticity

Question 1

What is a neuron?

Answer 1

The elementary unit of the nervous system. Basic signalling units. They receive, integrate and transmit signals

Question 2

What is the soma?

Answer 2

Cell body. Contains the cell’s nucleus and DNA

Question 3

What are dendrites?

Answer 3

They receive input. They are the branches of the neuron that pick up signals carried adjacent neurons

Question 4

What are axons? (& myelin)

Answer 4

(Output). The fatty sheath that covers an axon is made up of myelin which speeds up conduction of nerve impulses

Question 5

What are glial cells?

Answer 5

• They provide supportive functions - housekeepers of CNS
• They do not generate signals themselves
• ~10x more glial cells in the brain than neurons
• Without them neurons would not function properly and may die (e.g. multiple sclerosis

Question 6

What are the 2 main types/locations of neural signalling?

Answer 6

Within the neuron and between neurons

Question 7

What is a synapse?

Answer 7

The space between neurons where communication happens.

Presynaptic neuron –> synapse –> post synaptic neuron

Question 8

What does chemical transmission happen between?

Answer 8

Cell-to-cell

Question 9

What is the brain and what does it do (in broad, non-specific terms)?

Answer 9

• Provide knowledge about how the brain works and understanding the consequences of brain damage
• Helps understand how cognition is created/implemented
• Knowledge about brain structure and function can inform and constrain psychological theories (integration)
• There is a strong association between the brain, the mind and behaviour
• We are reverse engineering something already ‘designed by nature’ to understand these relationships

Question 10

What does medial versus lateral mean?

Answer 10

Middle versus to the side

Question 11

What does superior versus inferior mean?

Answer 11

Superior versus below

Question 12

What does anterior versus posterior mean?

Answer 12

Front versus back

Question 13

What does dorsal versus ventral mean?

Answer 13

Back versus abdomen

Question 14

What does ventromedial prefrontal cortex versus dorsolateral prefrontal cortex mean?

Answer 14

vmPFC (just above your eyes) means low and in the middle whereas dlPFC means higher up and on the side

Question 15

What is grey matter?

Answer 15

On the outside of the brain. Contains the cell bodies of neurons

Question 16

What does cortex mean?

Answer 16

Bark. Large thin layer of neurons covering the brain. Roughly 3mm thick

Question 17

What significance does the folding of the cortex have?

Answer 17

It is many bumps and grooves, meaning it is highly folded. It is folded to maintain a high SA to volume ratio (save space), to bring the neurons closer together (improves communication) and the regions closer together (improve efficiency of communication)

Question 18

How does cortical folding develop?

Answer 18

• Cortical folding also changes dramatically across development
• Folding peaks in around the 66th-80th week of life (birth = 40 weeks), remaining high in adults

Question 19

What does GI stand for?

Answer 19

Gyrification index, a way of measuring extent of folding

Question 20

What is white matter?

Answer 20

• Like the motorways or roads between the cities (grey matter)
• Make up connections between regions
• Appears while because of fatty myelin covering axons

Question 21

What are tracts?

Answer 21

• Bundles of neuronal fibres connecting brain regions (motorway analogy)
• Studied using DTI methods

Question 22

What are DTI methods?

Answer 22

Diffusion tensor imaging, an imaging method based on measuring the movement of water molecules in the brain

Question 23

What are the 3 types of white matter pathways?

Answer 23

• Projection tracts: Connect ‘higher’ and ‘lower’ brain regions, and brain to spinal cord (e.g., corticospinal)
• Association tracts: Connect regions within same hemisphere (IFOF)
  Commissural tracts: Links L and R hemispheres (e.g., corpus callosum)

Question 24

What are gyri (si: gyrus)?

Answer 24

A ridge or protruding surface of the brain (pink bit)

Question 25

What are sulci (si: sulcus)?

Answer 25

A depression, groove, crevice in brain surface (black bits)

Question 26

What are the 4 lobes?

Answer 26

Temporal, parietal, Frontal, Occipital

Question 27

What is the temporal lobe responsible for?

Answer 27

Hearing, language and memory

Question 28

What is the parietal lobe responsible for?

Answer 28

Movement, spatial processing, somatosensory processing

Question 29

What is the cerebellum responsible for?

Answer 29

Balance, fine motor movements, timing

Question 30

What is the dorsal portion frontal lobe?

Answer 30

Primary motor cortex

Question 31

What is the motor cortex?

Answer 31

Area at the back of the frontal lobes that controls voluntary movements

Question 32

What does stimulation to specific parts of the motor cortex in left or right hemisphere do?

Answer 32

makes specific body parts move on the opposite (contralateral) side of the body

Question 33

What is the homunculus?

Answer 33

(little man) Body regions represented in the ‘homunculus’, with ordered point-to-point relationship (e.g., toes next to ankle representation) - Size of each body part relates roughly to size of cortical region that controls muscles in that body part - except face & hands (much larger cortical representation because they are extremely important to functioning, more nerve fibres than in other parts of the body) - So, face & hands are over-represented as they have more fine muscles & therefore muscle control – more receptors

Question 34

What is located in the parietal lobe?

Answer 34

Primary somatosensory cortex

Question 35

What is the primary sensory cortex?

Answer 35

o an area at the front of the parietal lobes - It registers and processes body sensations - Stimulate this area and the person reports being touched - The more sensitive a body region, the greater area of sensory cortex devoted to it - Contralateral organisation

Question 36

What is the occipital lobe?

Answer 36

Also known as the 'visual cortex' - A blow to back of the head might cause you to go blind - If stimulated there, you may see flashes of colour/light

Question 37

What is the temporal lobe?

Answer 37

Contains the auditory cortex - If stimulated there, you might hear something that isn’t real - fMRI data from people with schizophrenia reveal that auditory areas are active during hallucinations

Question 38

What is the association area?

Answer 38

- Makes humans different - Most of the rest of cortex made up of brain areas not involved in primary motor or sensory functions (e.g. vision, audition etc.)

Question 39

What is cortical cytoarchitecture?

Answer 39

- Cell structure and organisation - Brodmann (1909) - Original drawings of ~52 different brain areas - He categorised these neural regions according to their distinctive: - Cell morphology - Cell organisation (e.g. layers) (not overly modern but must be showing something so it’s still in use today) - System still in common use today (e.g., fMRI findings) - Numbering often done rather randomly

Question 40

What are subcortical structures?

Answer 40

- Below the cortex are older, more primitive areas of the brain – with more basic functions (breathing, temperature, hormones, sleep, fight/flight, etc...) - E.g. Amygdala, hippocampus, hypothalamus

Question 41

What is plasticity?

Answer 41

The brain's capacity for modification - Evident in brain reorganisation following damage - Especially in children (younger = more plastic)

Question 42

What have experiments on the effects of experience on brain development revealed?

Answer 42

- Most severed neurons will not regenerate - However, neurons can reorganise in response to damage - And new neurons are growing all the time

Question 43

What is phantom limb?

Answer 43

Sensations of an arm or leg that has been lost or removed. The limb still lingers in their minds and is painful

Question 44

What is the main theoretical reasoning behind phantom limb?

Answer 44

It emerged from sensitive nerve endings

Question 45

What sis Ramachandran find while studying phantom limbs?

Answer 45

- Hypothesised that the missing lower arm area of the sensory cortex might have reorganised due to missing the normal sensory input - The face and upper arm areas are on either side of arm area, they would be most likely to take over the cortex that is lacking normal innervation by arm - Found that stimulating the patient’s face led to ‘sensations’ in their phantom limb and so face-area did innervate the arm area! - Same finding with the upper arm area - 2 representations for missing arm: one on the face & one on upper limb - The ‘hand area’ in brain no longer being stimulated (no hand!), so the neighbouring face and arm areas ‘took over’ this region

Question 46

What was found by Maguire (2000) studying taxi drivers with MRIs?

Answer 46

- The hippocampus is a brain area involved in spatial navigation/maps - Study with London taxi drivers showed they had a larger hippocampus than controls - Shows more experience in spatial navigation is associated with a larger hippocampus - Furthermore, the amount of time learning to be and working as a taxi driver was correlated with size of hippocampus

Question 47

How can brain organisation change with experience?

Answer 47

The brain is not as ‘hard-wired’ as once thought - This can happen due to experience or damage, such that brain areas may reorganize themselves over time - This means that everyone’s brain is unique and is constantly being sculpted by experience