L2/L3

Question 1

What is the brain made of?

Answer 1

• neurons account for only about 10% of our brain cells.

* Glial cells account for about 90% of our brain cells, but their role is mainly supportive.

Question 2

what does communication between neurons in the brain enables

Answer 2

• Communication between neurons in the brain enables our behaviours and thoughts.

Question 3

what does cognition depend on

Answer 3

• Cognition depends on the activity of neurons as well as the transmission of information between
neurons.

Question 4

what is the role of neurons

Answer 4

• Neurons are the basic signalling unit.

* Neurons receive information, process it, and then transmit the output to other neurons.

Question 5

what is the function of neurons

Answer 5

• Function: Communication via electrical and chemical signals

Question 6

how are neurons distinguished

Answer 6

• Neurons are distinguished by their function, location, and interconnectivity.

Question 7

describe the structure of neurons

Answer 7

• Structure:
– Dendrites
– Soma (or cell body)
– Axon
– Axon terminals

Question 8

describe dendrites

Answer 8

• Dendrites extend from the cell body.

* Dendrites are (usually) treelike processes that receive inputs from other neurons.

Question 9

what is the central part of the neuron

Answer 9

• The soma is the central part of the neuron.

Question 10

describe the soma and its function

Answer 10

• The soma contains metabolic machinery that maintains the neuron; this machinery is suspended in fluid and surrounded by the cell membrane.

Question 11

what is the axon

Answer 11

• The axon extends from the cell body.

Question 12

what is the function of the axon

Answer 12

• The axon functions like a telegraph wire, sending electrical impulses to distant sites in the nervous system.

Question 13

describe axons

Answer 13

• The axon extends from the cell body.
• Axons vary in length from less than a
millimetre to over a metre.
• Some axons are covered in myelin.
• Axons often branch

Question 14

in the CNS what is myelin formed by

Answer 14

• Myelin is formed by oligodendrocytes.

Question 15

what is myelin

Answer 15

• Myelin is a fatty substance that surrounds and insulates nerve fibres (i.e., axons). therefore it appears white.

Question 16

what is the function of myelin

Answer 16

• Myelin facilitates the conduction of nerve impulses (i.e., speeds up the signal).

Question 17

what is the relationship between myelin and MS

Answer 17

• The importance of myelin becomes obvious when you consider the pathology and symptoms of
multiple sclerosis (MS).
• The pathology associated with multiple sclerosis causes the destruction of myelin.

Question 18

describe a synapps

Answer 18

• The synapse is where the axon terminal of one neuron contacts another neuron in order to transmit information.
• The synapse has two sides: presynaptic and postsynaptic (information flows from the presynaptic neuron to the postsynaptic neuron).

Question 19

describe the terms pre and postsynaptic

Answer 19

• Presynaptic = before the synapse, with respect to the flow of information (e.g., axon terminals are presynaptic because they are positioned before the synapse)
• Postsynaptic = after the synapse, with respect to the flow of information (e.g., dendrites are postsynaptic because they are positioned after the synapse)

Question 20

At most synapses, information in the form of electrical impulses travelling down the axon is converted
in the axon terminal into a chemical signal that crosses the synaptic cleft.

what s this chemical signal called

Answer 20

a neurotransmitter.

Question 21

what happens on the postsynaptic membrane when it receives the chemical signal

Answer 21

• On the postsynaptic membrane, this chemical signal is converted back into an electrical signal.

Question 22

describe neurotransmitters

Answer 22

• Neurotransmitters are stored in and released from synaptic vesicles within the axon terminal.
• Different neurotransmitters are used by different types of neurons.

Question 23

glial cells account for how much of the brains volume

Answer 23

Glial cells account for more than half of the brain’s volume.

Question 24

what is the role of glia

Answer 24

• Glial cells support neurons.

Question 25

what are the main types of glia

Answer 25

• Main types of glial cells in the CNS: – Astrocytes – Oligodendrocytes – Microglia

Question 26

what is the role of astrocytes

Answer 26

• Astrocytes form a barrier between neuronal tissue | and blood, called the blood-brain barrier (BBB).

Question 27

what is the role of the BBB

Answer 27

• The BBB protects the CNS from some molecules in | the bloodstream.

Question 28

what is the role of oligodendrocytes

Answer 28

• Oligodendrocytes myelinate axons • Oligodendrocytes form myelin by wrapping their cell membranes around the axon during development. • The myelination of one axon requires many oligodendrocytes.

Question 29

what is myelin

Answer 29

(myelin is a fatty substance that surrounds the axons of many neurons and speeds neural communication).

Question 30

what is the role of microglia

Answer 30

• Microglia devour and remove debris left by dead or degenerating brain cells.

Question 31

what happens once microglia have cleaned up by the debris

Answer 31

Once the microglia have cleaned up by the debris you end up with a fluid filled hole much like a ventricle because cells there have died and it becomes filled with CSF

Question 32

what causes an AP to be propagated

Answer 32

• Note that each neuron can receive input from many other neurons and can output to many other neurons. • Sufficient input to the postsynaptic neuron can trigger an action potential, causing the electrical signal to be conducted down the axon.

Question 33

what do AP trigger

Answer 33

• Action potentials trigger synaptic transmission.

Question 34

what is synaptic transmission

Answer 34

• Synaptic Transmission = Neuronal Communication

Question 35

what is a AP

Answer 35

• An action potential is a rapid change in the voltage of the cell’s membrane.

Question 36

What normally causes action potentials?

Answer 36

* Sufficient input can trigger an action potential. | * For example, moving a whisker on a rat can cause somatosensory neurons to fire rapidly.

Question 37

what is a single cell recording

Answer 37

• Single cell recording involves recording action potentials from an individual neuron.

Question 38

what do single cell recording measure

Answer 38

• Using single cell recording, we can measure the activity of an individual cell while different stimuli are viewed.

Question 39

what is a receptive field

Answer 39

All visually sensitive cells only respond to stimuli in a limited region of space. • This region of space is referred to as that cell’s receptive field

Question 40

How many neurons participate in the representation of a single visual image?

Answer 40

• Functional imaging techniques, such as fMRI, provide an opportunity to explore this issue because they allow the simultaneous detection of the entire neuronal population responding to each stimulus. • fMRI is an adaptation of MRI that records changes related to metabolic activity in order to produce a functional view of the brain. • Because the signal from fMRI is approximately proportional to neuronal activity, this method can be used to estimate the number of neurons involved in a specific cognitive process. • Using a complicated calculation, the researchers determined that at least two hundred million neurons in the visual cortex are involved in the representation of a single image.

Question 41

what is the difference between fMRI and MRI

Answer 41

• fMRI is an adaptation of MRI that records changes related to metabolic activity in order to produce a functional view of the brain.

Question 42

what defines the tonotopic map

Answer 42

• In primary auditory cortex, the frequency tuning properties of the cells define a tonotopic map.

Question 43

what is seen when looking at the activity of neurons in the olfactory bulb

Answer 43

* The activity of many neurons in the olfactory bulb was recorded. * Different scents evoked different spatial patterns of neural activation in the olfactory bulb. * The different patterns of activity can account for the ability to discriminate these three scents. * Consider two distinct scents that cannot be distinguished.

Question 44

what are other examples of topographic maps in the brain

Answer 44

• Topographic maps are also seen in primary motor cortex and primary somatosensory cortex.