Download The Brain

Topic 8.3


Locate and state the functions of the regions of
the human brain
 Cerebral hemispheres (ability to see, think,
learn and feel emotions),
 Hypothalamus (thermoregulate),
 Cerebellum (coordinate movement) and
 Medulla oblongata (control the heartbeat).
Describe the use of magnetic resonance imaging
(MRI),functional magnetic resonance imaging
(fMRI) and computed tomography (CT) scans in
medical diagnosis and investigating brain
structure and function.
 The
brain is the coordinator of the body:
interprets information from our environment
and controls our internal environment
 Types

of neurones:
Sensory, motor and relay
 Differences

in structure:
Location of cell body, length of dendrites and
axons
 Grey
matter: mainly cell bodies
 White matter: mainly myelinated axons

The cerebral cortex is the largest part of the
brain (2/3rd of total)

It is made up of the left and right hemispheres,
connected by “white matter” – axons in the
corpus callosum.
Hemispheres = “grey matter” – cell
bodies, synapses and dendrites.

Outermost sheet of neural tissue,
highly folded.

 Interactive
Tutorial and Activity 8.10
 Use book to complete Activity 8.10a and
label Fig 8.37
 Q8.32-8.34
 How
do we know what the different regions
do?

Various scans: MRI, CAT, etc.
 Before
this technology, how do you think
neuroscientists were able to work out the
functions of each part of the brain?

Stroke victims, accidents to the brain.
 What

Metal bar through brain
 What

changed?
His personality, he became impatient, foul
mouthed, irresponsible, could not make plans
for the future
 What

kind of accident did he have?
parts of his brain were damaged?
Midbrain and frontal lobe connections
 Can
you explain these changes?

http://news.bbc.co.uk/2/hi/health/860188.stm-
 What

Can’t recognise faces. Called- Prosopagnosia
 What

part of his brain is damaged?
Temporal lobe
 What

problem does he have?
else could cause damage?
Drugs, lack of O2, strokes, tumours, disease,
infection
 Brad
Pitt has this
condition






One symptom which often occurs in stroke victims are
speech problems
Paul Broca studied the brains of such patients after
they died
He found a region of the frontal lobe damaged
Now called the Broca’s area or region
Some patients can recover after a stroke. What does
this show?
 The brain is flexible, neural plasticity
Complete Activity 8.11
 What
does CAT/CT
stand for?
 Which
type of Xray is used? Why?
 What
can CT scans
show?
 What
are its
disadvantages?
 Computerised
axial tomography
 Which type of X-ray is used? Why?

Narrow beam x-rays pass through soft tissues:
these change (reduce in strength) depending on
the density of the material they pass through
 What

Can show frozen moment pictures of soft tissue
such as the brain
 What



can CT scans show?
are the disadvantages?
Don’t show function
Limited resolution
Repeated exposure of X-rays are harmful – 100 to
1000 times higher dose in CT compared to normal
X ray
1.
2.
3.
4.
5.
6.
7.
8.
What does MRI stand for?
What is used to detect soft tissue?
How many magnetic fields are used?
What happens to the H nuclei as a result of these
magnetic fields?
What happens when the magnetic field due to the
radio waves is turned off?
How can a 3D image be produced?
What can a MRI be used for?
What are its advantages and disadvantages when
compared to CAT scans?
1.
Magnetic resonance imaging
2.
Uses radio waves and magnetism.
3.
2 magnetic fields are imposed on the patient.
4.
H nuclei in water change spin due to 2 magnetic fields
5.
The H nuclei return to their original spin and release energy: this energy
is detected.
6.
3D images produced by computer analysis from many sections
7.
MRI can be used for diagnosis of
tumours, strokes, infections. Their size
and location can be identified.
1.
Compared with CAT scans  Better resolution than CAT
 No exposure to harmful radiation
 Takes longer
 More specialist equipment needed
 What
 How
do the letters stand for?
does it work? What does it show?
 Which
areas of the brain have more
oxyhaemoglobin? Why? How is this seen on
the photo?
1. Functional magnetic resonance imaging
2. Shows activity of brain in real time (not frozen
images)when carrying out certain actions
 Patients will have to perform tasks during the scan like
listening, speaking, looking at images, etc.
 Oxyhaemoglobin doesn’t absorb radio waves,
deoxyhaemoglobin does and these appear differently on
scans.
3. Active areas of the brain result in increased blood flow.
 Higher amounts of oxyhaemoglobin indicate increased
blood flow.
 Less signal is absorbed in active areas of the brain and so
they “light up”.

Q 8.36-8.37
Figure 1 fMRI image of the brain at rest.
Each picture shows a different section of
the brain, starting at the top of the brain
on the top left, and going to the bottom
on the lower right-hand picture.
Figure 2 Brain image of someone
completing a thinking task.
Figure 3 Brain image of someone looking
at a colourful patterned image.
Figure 4 Image of the brain of a person who is
performing a motor task, namely jumping up
and down on one leg.
(Note that the stimulation is higher in the brain
than in Figure 5.)
Figure 5 Image of the brain of a person
listening to music (i.e. auditory
stimulation). (Note that music and
language together would stimulate this
position in both cerebral hemispheres.)
Q1
Decide which part of the brain is being used in the PET image
shown in Figure 8. State a reason why that area of the brain is active
Figure 8 PET image of the brain of someone memorising where they
are leaving their car in an airport car park before they fly off for a
holiday.
 Read
page 233
 What energy change occurs within the eye?

Light  electrical impulses
 Which

2

3

part of the eye is light sensitive?
The retina
types of light sensitive cells in the retina?
Cones and rods
layers within the retina?
Photoreceptors, bipolar and ganglion
 Which
part of the brain routes sensory
information to the correct part of the brain?

Thalamus
 Which
part of the brain processes visual
information?

Occipital lobe
 Where

is this located?
In the cerebral cortex at the back of the brain
 retina
> optic nerve > thalamus > occipital
lobe
 Info from the right side of _______ eyes is
processed by the ______ hemisphere and info
from the left by the ______ hemisphere.


Locate and state the functions of the regions of
the human brain’s
 Cerebral hemispheres (ability to see, think,
learn and feel emotions),
 Hypothalamus (thermoregulate),
 Cerebellum (coordinate movement) and
 Medulla oblongata (control the heartbeat).
Describe the use of magnetic resonance imaging
(MRI),functional magnetic resonance imaging
(fMRI) and computed tomography (CT) scans in
medical diagnosis and investigating brain
structure and function.