Behavioural neurosciences
Basic brain anatomy – An introduction and Optimize your learning and
memory performance
The four lobes
The human brain has 4 lobes
- Frontal lobe
- Parietal lobe → processing information related to the
body
- Occipital lobe → processing visual information
o You look with your brain, so you can see things that aren’t there.
- Temporal lobe → the area for learning and memory
o Hippocampus
Gyrus → hill parts
Sulcus → grooves
This folding will allow you to have more of this surface area in a certain volume. The more of the
folding you have, the more information is being processed and probably the more intelligent a
species is. You can’t say that about individuals. Fissures are places where the brain separates a bit
Shape of skull and brain
There is also a frontal, parietal, temporal and occipital bone. This tells you that there is a close
relationship between the skull and the brain. Because the frontal bone is becoming higher, we
interpret that that there is more volume behind the frontal bone. This is maybe the increasing of the
prefrontal cortex.
Broca and Wernicke : localized function in the cerebrum
Motor aphasia (Broca); if you cannot speak properly. Patients with this
disturbance usually have problems speaking, also repeating words or sentences
which they just heard. A language disturbance in which a person has difficulty
speaking or repeating words but can understand language; also known as motor or nonfluent
aphasia.
Sensory aphasia (Wernicke); if you do not understand language (dyslexia). Spoken language of
Wernicke patients ususally sounds fluently, but lacks meaning (it doesn’t make sense). symptoms
such as poor auditory comprehension, relatively intact repetition, and fluent speech with semantic
paraphasias present.
Brain imaging
- CT scan (computerized tomography) → you don’t see
much but anomalies.
- MRI scan (magnetic resonance imaging) → you see the
structure
, - PET scan (positron emission tomography) → you see
action, white and red are very active, dark blue is inactive.
The researcher is setting a threshold.
- fMRI scan (functional magnetic resonance imaging) → you
use MRI together with activity in the brain. The patient
makes a movement or has to remind something, you can
see what places in the brain are involved. fMRI is more
easily to localize the changes than PET.
In a study by Neuroscientist Dr. James Fallon, it was revealed that
while a normal brain shows patches of yellow and red when scanned,
a psychopath’s brain has dark patches, which suggest low activity in
the orbital cortex, an area of the brain responsible for moral decision
making. An inactive orbital cortex cannot control the amygdala, which
dictates aggression.
Sections through the human brain
Global similarities between human and rat brain
If we want to understand the human brain we still need animal brains.
There is an overall comparable organization. The olfactory bulb in rats is
way bigger than in humans. The folding in the human brain is not there
in rats so the amount of cortical tissue that is needed to perform
optimally in the environmental setting of the rat does not require more
tissue.
White matter is all the axons with myelin sheaths. Grey matter is the cell
body and the dendrites. The bigger a brain is, the more you have to invest in
white matter to connect to enough other neurons.
Neuronal organization of the cerebrum (cortex)
The cortex is organized not only in columns but also in layers. 6 layers is what
we call the neocortex. During evolution layers were added. There are also
glial cells in the brain. They are as important as neurons, they support the
neuronal system. The Schwann cells (peripheral) and
oligodendrocytes (central) make myelin sheaths. In the CNS
we also have astrocytes, part of the blood-brain barrier and
part of synapses. There are also astrocytic end feed, they are
very critical for synapses. Microglia are critically involved in
neuroinflammation. There is no brain disorder without
,neuroinflammation → issues with the microglia. Ependymal cells are the barriers between
compartments like walls of ventricles.
The cells in the ventricle produces cerebrospinal fluid (CSF), about 500ml/day. The volume of the
ventricles about 150ml. Replacement of CSF about 3 times a day. When the brain wants to get rid of
compounds, it needs to enter the ventricle system and will be removed to the outside of the brain
and be taken up by blood vessels. For signaling also compounds enter
the ventricle system so it will spread quickly.
The cerebral aqueduct can be blocked, then you get a
waterhead. If that happens in early days after birth this
can influence the shape of the brain. It can built op a
pressure and tissue can be pushed to the side. That has to be medically cured, that can be done by
draining the fluid to the heart or abdominal cavity.
Here you see that the lateral ventricles are enlarged. If you loose tissue
around the ventricles there will become space available. Because of the
pressure in the ventricle, the ventricle will enlarge.
Analysis of brain material: Nissl staining (Franz Nissl)
Where there are a lot of proteins, there is a darker stain than where there are
less proteins. If you stain tissue it always shrinks a bit, that’s the white stains
around the colored things.
Golgi staining (Camillo Golgi)
Golgi added a substance taken up by the neurons. Then you see nicely the cell
body and the dendrites etc. Axons are more difficult to see. He found out cell
bodies and dendrites belong to the same cell structure.
Spines are little mushroom shaped structures on dendrites. The shape of the
spines tells you how well the brain works and how well the neurons function.
Axons
Axon-collaterals → the branching of the axons. Axons and
dendrites are collectively called neurites. If the neuron
starts to fire it will send an electric stimulus through the
fiber that then causes the release of neurotransmitters
from these vesicles, these are picked up by receptors.
, The red things you see are not part of the shown neuron but the result of the incoming axons. The
shape of dendritic tree determines the type of neurons
Glia cells (astrocytes): 2x as many as neurons
Glial cells and their processes often fill the space not occupied by neurons or
blood vessels; nevertheless the neuron is viewed as the most important
functional unit in the brain: they directly dictate behavior. Microglia can move
around. They migrate through brain scanning everything, when something is
wrong, they go there and become activated and solve the problem.
Employ your memory to the best
1. Maximize the use of short-term and long-term memory
(STM and LTM)
a. Pay attention to what has to be learned; what is
key in the slide/lecture. Focus! Use brief periods,
for example 15-20 minutes. Use breaks several
times. A bit of stress is OK. Give yourself a
(small) reward after a focused period.
2. Facilitate the transition from STM to LTM (and vice versa)
a. Try to sleep well (and enough). Look at (a part) of the study material a few hours
before you go to sleep.
3. Optimize memory retrieval
a. Provide a context; do you have concepts to use as an
anchor point? By having these, larger brain networks
can be formed during learning. These networks can
strengthen each other. It provides more possibilities
to form associations, which make the chance of
getting the retrieval process started bigger.
4. Reduce unwanted/undesirable forgetting
a. Repeat the study material; by doing so,
it enhances the chance that newly
formed but weak synapses become
stronger and survive
Learning and memory
Henri Gustav Molaison (H.M) is probably the most studied patient in
neuroscience. He fell as a kid and cracked his skull. He started to develop
seizures, black outs and loss of bodily functions. They didn’t know the
function of the hippocampus yet. H.M. had his hippocampus removed.
There were some consequences.
The good:
- No more seizures
- No change in personality
- I.Q. improved
The bad
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