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)
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)
