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Summary - Brain and Behaviour (NWI-BB085C)
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This summary contains all information of the lectures 1-7 off the course Brain and Behaviour (NWI-BB085C)
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Brain & Behaviour – Lecture NotesContents
Lecture 1 – Introduction....................................................................................................................1
Lecture 2 – Genes & Molecules.........................................................................................................5
Genes & Behaviour........................................................................................................................6
Lecture 3 – Membrane potential.......................................................................................................6
Lecture 4 – Action potential.............................................................................................................11
Lecture 5 – Sensing..........................................................................................................................16
Lecture 6 – Muscle actuation...........................................................................................................22
Lecture 7 – Brain development (pre-natal)......................................................................................29
Lecture 1 – Introduction
Goal of neuroscience : relate neural activity to behaviour and cognition.
,A major organising principle of the brain different functions are supported by different parts of
the brain.
Functional specialisation of the brain :
1. An overview CSN can be divided into 7 structures :
o Spinal cord
o Medulla oblongata
o Pons
o Cerebrum
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
o Midbrain
o Diencephalon
o Cerebellum
2. Phrenology : based on the (misguided) idea that the more you exercise a brain region the
bigger it becomes size of a brain region will affect the shape of the skull.
3. Language :
- Language deficits which result from a lesion to Broca’s area : Broca’s aphasia.
○ Broca’s area : the left posterior region of
the frontal lobe.
- Wernicke’s aphasia : no understanding of language
but can still form words as a result of lesions in the
left posterior part of the cortex.
4. Brodmann areas : 52 anatomically and functionally distinct
areas in the human cerebral cortex.
5. Cortical homunculus : areas with high sensitivity (tongue/fingers) are over-represented in
the sensory map.
- Over-representation of certain limbs development of homunculus.
fMRI : measures the small changes in blood flow that occur with brain activity.
Behaviour and cognition arise as a result of nerve cells ( = neurons ) becoming active diversity in
neuronal connectivity leads to behavioral diversity.
CNS also contains glial cells.
Most neurons have 4 morphologically defined regions :
1. Cell body (= soma)
2. Dendrites
3. Axon
4. Pre-synaptic terminals
Action potentials : signals that allow the brain to receive, analyse and convey information.
- All-or-nothing events.
, - Speed of transmission is aided by myelin.
- Speed of potential is constant as it is regenerated at regular intervals along the axon.
Golgi stain : method that stains small minority of neurons visualisation different types of
neurons could be identified and connections with other neurons delineated.
Dynamic polarisation : electrical signals in neuron travel in 1 direction.
Connectional specificity : neurons do not connect at random with other neurons, but rather a
neuron makes specific connections with certain post-synaptic cells.
3 types of neurons :
○ Unipolar neurons
- Contain single primary process.
- Process gives rise to different branches.
- 1 branch is the axons others are dendrites.
- Occur in nervous system of invertebrates.
○ Bipolar neurons
- Contain oval zone that gives rise to 2 processes;
1. Dendrites which receives signals from the periphery.
2. Axon that carries information to the CNS.
- Many sensory cells are bipolar.
- Pseudo-unipolar cells : neurons conveying information about touch, pain and
pressure.
○ Multipolar neurons
- Predominate in vertebrate nervous system.
- Typically a single axon but multiple dendritic structures can emanate from
multiple points on the soma.
- Vary in shape + length of axon + complexity of dendritic branching.
- Number of dendrites correlates with how many synaptic contacts they receive.
Glia : most numerous cell type in the brain.
- Do not have dendrites and axon.
- Not directly involved in electrical signalling.
1. Microglia
2. Macroglia : enhance signal conduction by segregating voltage-sensitive ion channels into
distinct axonal domains ( = node of Ranvier )
a. Schwann cells (CNS)
, b. Oligodendrocytes (CNS)
c. Astrocytes (PNS)
Derive name from shape and number of processes.
End-feet that make contact with capillaries and arterioles in the
brain + neurons.
Function is unknown.
○ Protoplasmic : in gray matter.
○ Fibrous : white matter.
Knee-jerk reflex : …
Signalling :
1. Excitatory
2. Inhibitory
a. Feed-forward inhibition (ex. knee-jerk reflex).
b. Feedback inhibition.
All neural transmission contains 4 steps :
1) Receptive component
- Neuronal signaling is initiated by input to receptors located on dendrites of cell receptor
potential.
graded (depend on size and duration of input)
to have effect in CNS it must cause an action potential.
Axon initial segment : trigger zone for action potential.
2) Summing/integrative component
3) Long-range signaling component
4) Secretory component
Confined to 4 separate anatomical regions on the cell.
All signalling components depend in part on the electrical properties of the cell’s membrane
membrane potential changes are initiated via the activation of dendritic receptors + can be
depolarising (less negative) causing excitation, or hyperpolarising (more negative) leading to
inhibition.
Sudden and dramatic change in the membrane potential action potential.
- Amplitude and duration is always the same.
- When reached neuron’s terminal it stimulates the release of neurotransmitters the
neuron’s output signal.
- After release neurotransmitter defuses across the synaptic cleft and binds to receptors on
the post-synaptic cell leads to synaptic potential.
Action potentials can differ in frequency determined by intensity and duration of stimulus.
- Has direct impact on the magnitude of the output signal.
- Action potential frequency carries intensity important information.
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