Unit 2-Introducing the Brain

Question 1

What is a neuron? What are its three main components?

Answer 1

A cell type that makes up the nervous system and supports cognitive functions

Soma (cell body), dendrites, and axon

Question 2

What does the cell body (soma) contain?

Answer 2

The nucleus, which contains genetic code and is involved in protein synthesis

Other organelles

Question 2

What are dendrites?

Answer 2

Branching structures that extend away from the cell body to receive information from other neurons in close proximity

Question 3

What is the axon?

Answer 3

Long tail of neuron that is used to propagate action potentials that send information to nearby neurons

Question 3

How many dendrites and how many axons does a neuron have?

Answer 3

One axon, many dendrites

Question 4

What is a synapse? What is it formed by?

Answer 4

A small gap between neurons that permits signalling

The presynaptic and postsynaptic neurons

Question 5

What is an action potential? When is the action potential propagated in the axon? What happens when the action potential reaches the axon terminal?

Answer 5

A sudden change in the electric properties of the axon membrane, which forms the basis for how neurons code information

When the presynaptic neuron is active

Neurotransmitters are released

Question 5

What are neurotransmitters? What do they bind to on the postsynaptic neuron? What is their impact on the postsynaptic neuron?

Answer 5

Chemical signals released by one neuron that affect other neurons

Receptors on the dendrites or cell body

Create synaptic potential

Question 6

What is synaptic potential? How is it conducted? When does it cause an actional potential?

Answer 6

A change in a neuron’s membrane potential due to the binding of neurotransmitters released from another neuron

Passively, without creating action potential

When the sum of passive currents increases above a certain threshold in the axon hillock

Question 7

What is the axon hillock?

Answer 7

The region of the neuron’s cell body where the axon begins and where the sum of passive currents is calculated to initiate an action potential

Question 7

What are the five phases in action potential?

Answer 7

Resting
Depolarisation
Repolarisation
Hyperpolarization
Refractory Period

Question 8

What happens during the Depolarisation phase? What type of ions rush into the neuron to make the inside more positive? What gate is opened to allow for this?

Answer 8

A sufficiently strong stimulus causes the membrane potential to increase

Sodium ions

Sodium gates

Question 8

What is the resting membrane potential in the Resting phase?

Answer 8

Around -70 millivolts

Question 9

What happens during the repolarization phase? What type of channels open up and what type of channels close? What does this cause? At around what potential does this happen?

Answer 9

The negative charge is restored

Potassium channels open and sodium channels close

Potassium ions leaving and sodium ions no longer entering the neuron

-50 mV

Question 10

What happens during the refractory period phase?

Answer 10

The neuron is temporarily unable to fire another action potential due to the inactivation of voltage-gated ion channels

Question 10

What happens during the hyperpolarization phase? What is the purpose of this?

Answer 10

The membrane potential briefly becomes more negative than the resting potential before returning to its resting state

Preventing the action potential from travelling backwards

Question 11

What is myelin? What is another function of it?

Answer 11

A fatty substance around axons that speeds conduction

Blocking sodium and potassium transfer in normal conditions

Question 12

What are the three types of effects of neurotransmitters? Explain all of them. Give some examples of neurotransmitters causing each of them:

Answer 12

Inhibitory - making the neuron less likely to fire (e.g., GABA)

Exhibitory - making the neuron more likely to fire (e.g., glutamate)

Modulatory functions (e.g., serotonin, dopamine)

Question 13

What is the primary way through which neurons code information?

Answer 13

Through their spiking rate, i.e., the number of action potentials is propagated per second

Question 14

How can one determine the type of information coded by a neuron?

Answer 14

By the inputs and outputs of the neurons, i.e., where the information comes from and where it goes

Question 15

What does grey matter primarily consist of?

Answer 15

Neuronal cell bodies

Question 16

What does white matter primarily consist of?

Answer 16

Axons and glia

Question 17

What are glia?

Answer 17

Support cells involved in forming myelin and repairing tissues

Question 18

What is the cerebral cortex? What type of matter does it consist of? What comes under it? What comes under this?

Answer 18

The outermost layer of the brain

Grey matter

White matter fibres

Subcortex

Question 19

What is the function of white matter tracts? What are the three kinds of white matter tracts?

Answer 19

They connect different regions of the brain to each other Association tracts, commissures, and projection tracts

Question 20

What is the subcortex made up of?

Answer 20

Grey matter

Question 21

What is the hierarchical view of the central nervous system?

Answer 21

Older structures are not replaced with newer ones Newer structures are added onto older ones Older pathways still contribute to brain functionality

Question 21

What is a ventricle?

Answer 21

A hollow chamber in the brain containing cerebrospinal fluid (CSF)

Question 22

What do association tracts connect? How about commissures? How about projection tracts?

Answer 22

Cortical regions within the same hemisphere Cortical regions in different hemispheres Cortical and subcortical structures

Question 23

What is cerebrospinal fluid? What are its three primary functions?

Answer 23

A fluid filling the ventricles in the brain Carries waste, transfer messenger signals (hormones) and provides cushioning for the brain

Question 24

What are the four ventricles of the brain?

Answer 24

The left lateral ventricle, right lateral ventricle, central ventricle and brainstem/hindbrain ventricle

Question 25

What do the terms anterior/rostral and posterior/caudal refer to?

Answer 25

Anterior/rostral refers to the front of the brain Posterior/caudal refers to the back of the brain

Question 26

What do the terms superior/dorsal and inferior/ventral refer to?

Answer 26

Superior/dorsal refers to the top of the brain Inferior/ventral refers to the bottom of the brain

Question 27

What do the terms lateral and medial refer to?

Answer 27

Lateral refers to the outer surface of the brain Medial refers to the inner part of the brain

Question 28

What is a sagittal slice?

Answer 28

A vertical slice that divides one of the brain’s hemispheres into two

Question 29

What is a coronal slice?

Answer 29

A vertical slice that divides the brain into front and back parts (from ear to ear)

Question 30

What is a midline slice?

Answer 30

A midline slice is a vertical slice dividing the brain into the two hemispheres

Question 31

What is an axial slice?

Answer 31

A horizontal slice that divides the brain into upper and lower parts

Question 31

What are gyri?

Answer 31

The ridges or folds on the surface of the cerebral cortex

Question 32

What are sulci?

Answer 32

The grooves or furrows that separate gyri

Question 33

What does the cerebral cortex consist of? Why is it structured with gyri and sulci?

Answer 33

Two folded sheets of grey matter organised into two hemispheres To create a higher surface area

Question 34

What are the three layers of the cerebral cortex?

Answer 34

The neocortex, mesocortex, and allocortex

Question 35

What is the neocortex? What is it involved in?

Answer 35

The largest part of the cerebral cortex in humans and other mammals Higher-order brain functions

Question 36

What is the mesocortex? What are its primary functions?

Answer 36

A transitional region of the cerebral cortex bridging the neocortex and allocortex Emotional processing, autonomic functions, and awareness of bodily sensations

Question 37

What are the four main ways in which the regions of the cerebral cortex can be divided by?

Answer 37

By the pattern of gyri and sulci By Brodmann’s areas By function (e.g., by sensory vs motor) By connectivity profiles (which brain regions are connected to what region)

Question 37

What is the allocortex? What are the primary structures that it includes? What are its most crucial functions?

Answer 37

The evolutionarily older part of the cerebral cortex The primary olfactory cortex and the hippocampus Smell and memory formation

Question 38

What are the four lobes of the lateral surface of the cortex?

Answer 38

The frontal, parietal, temporal and occipital

Question 39

What are Brodmann’s areas?

Answer 39

Divide the cortex into approximately 52 areas based on relative distributions of cell types

Question 40

What are the three primary systems in the subcortex?

Answer 40

The basal ganglia The limbic system The diencephalon

Question 41

What is the primary function of the thalamus?

Answer 41

A sensory relay for all senses except smell

Question 42

What is the limbic system’s primary function? What are its primary components, and what is the function of each?

Answer 42

The detection and expression of emotional responses The Amygdala (fear, threatening stimuli) Cingulate Gyrus (emotional and cognitive conflicts), Hippocampus (learning and memory), Mammillary bodies (memory), Olfactory Bulbs (smelling)

Question 43

What is the basal ganglia? Where are they located in the brain? What are their two primary functions?

Answer 43

Two large rounded masses, one in each hemisphere In the centre of the brain, around the thalamus Regulating motor activity, Learning of rewards, skills and habits

Question 44

What two structures does the diencephalon consist of?

Answer 44

The thalamus and hypothalamus

Question 45

What are the two main components of the midbrain?

Answer 45

Superior and inferior colliculi

Question 46

What is the primary function of the hypothalamus?

Answer 46

Deals with homeostasis, i.e., temperature, hunger, thirst, sexual activity, body, growth, etc.

Question 47

What are the two primary functions of the superior colliculi?

Answer 47

Integrating information from several senses Programming fast eye movements

Question 48

What is the primary function of the inferior colliculi?

Answer 48

Auditory processing

Question 49

What is the implication of the midbrain and hindbrain providing older pathways for some senses?

Answer 49

Allow for reflex actions to certain stimuli

Question 50

What are the two main functions of the cerebellum?

Answer 50

Ensuring smooth execution of movement Integrating motor commands with sensory feedback

Question 51

What are the three main components of the hindbrain?

Answer 51

The cerebellum, pons, and medulla oblongata

Question 52

What is the function of the pons?

Answer 52

Connecting the cerebellum and cerebrum, in the forebrain, and responsible for higher cognitive functions such as thinking, perception, planning, and voluntary movement

Question 53

What is the primary function of the medulla oblongata?

Answer 53

Regulating vital functions such as breathing, swallowing, heart rate, and the wake-sleep cycle