This is a well-rounded lecture summary of "How do neurons communicate information?” lecture in the First Teaching Block in the Brain and Behaviour module, Year 1.
The collection of notes form both the slides provided before the lecture and the actual lecture. It contains all the key points ne...
2. How do neurons communicate information?
1. Descartes – brain communicates with body via fluids – fluids signal down muscles – fill down and
muscles get bigger
2. Electrical signals – discovered by Luigi Galvanni (Bologna) -> muscles of frogs twitched cause of
lightning (electricity)
o Bando Mitsugoro VIII – kabuki actor - ate livers of pufferfish (poisonous) – full of tetrodotoxin –
which interferes with electrical signalling in the brain - blocks voltage gated sodium channels
(crucial for signalling)
o Neurone doctrine = the brain is made up of individual nerve cells, neurones
3. The whole body is made up of cells:
o Nerve cells (neurons) – generate and propagate electrical signals –
information is transmitted in the form of these electrical signals is the basis
of sensation, behavior and physiological processes in all animals -> also
source of cognitive abilities
o Neuroglial cells (glia) – support and hold together nervous tissues – not
capable of electrical signaling – some types have a crucial effect on the
speed at which a neuron’s electrical signal travel
o Each nerve cell – cell body containing a nucleus and organelles - they
communicate intercellular – distinctive feature -> neural circuits
Neural circuits components:
- Afferent neurons – nerve cells that carry info centrally (toward
any neural processing structure – brain or spinal cord)
- Efferent neurons – nerve cells that carry info peripherally (away from central nervous
system)
- Interneurons (local circuit neurons) - nerve cells that participate only in
local aspects of circuit
o The neurons connect to transport information – through the axon hillock -> whole
mechanism of carrying signals = action potential
o Proteins in neuronal membrane:
ion channels (inserted in neuron membrane, allow ion to diffuse down
concentration gradient – only let selective ions to come through – ions from
outside to inside or from inside to outside, move down their concentration
gradients and electrical gradient will come along)
ion transporters/pumps (they move ions from inside to outside or from
outside to inside, work against concentration and electrical gradients, require energy) – support
action potential propagation + create an electrical
charge
o Dentrites – receiving - Axon – sending
4. Forces that connect ion movement:
o Diffusion force -> high to low -> positive to negative
o Electrical force -> reverse
5. Resting membrane potential & Na+/K+ pump
o Sodium (Na+) Potassium(K+) pump – electrogenic – crucial to get the imbalance
of ions across the membrane that allow us to get an electrical arresting membrane
potential - moves K ions from outside to inside and Na ions from inside to outside
o For every 2K ions it moves 3Na ions out -> the inside is negatively charged
6. Voltage-gated ion channels
o Neuron -> put electrode in it to stimulate (inject either positive or negative
current)
o Insert microelectrode (recording) in the resting membrane potential (imbalance between Na and K
on either side of neuronal membrane) -> driven almost exclusively by K
because the only ion channels open are the K ion channels (leak ion
channels)
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