21/09/2020
Lecture 3: Bioelectricity
1. The Study of Bioelectricity: from Galvani to optical recording
Mapping a neural connectome of an animal (golgi technique, new techniques) lets you
understand all of the pathways for information flowing in nervous system
- it’s a framework for understanding hoe the nervous system works
- it reveals all pf the potential the avenues for information to flow through neural
circuits.
- 30 years ago, electron microscopy reconstruction was used to sliced through a
nematode worm and imaged each one of those slices to map the entire
connectome (302 neurons) where the neurons were at the synaptic level.
o We’ve known exactly how the nervous system works, but you’d think after
years of research we should understand the nervous system and behaviourits not that simple, its complex! THeres more we need to do to understand
how it operates.
- WE must understand both the connectivity and mechanism for the information flow
in the neural circuit (the electrical properties)
o Chemical (neurotransmitter at synapse, neuromodulators)
 Ex chemical synapses- the retina and how neurons communicate with
each other. WE have a pre-synaptic terminal with various vesicles
packed with various types of excitatory neurotransmitter (ex glutamate
tends to open up ion channels and excite post synaptic cell) and
inhibitory ones (GABA open up chloride channel). That is the chemical
form of cellular communication across the synapse.
o There are also electrical components graded potential, Action potential,
electrical synapse)
 Graded potential
 ion channels open when neurotransmitters bind to them.
 AN excitatory nerurotrasnmitter will conduct a positive cation
current into the cell that causes depolarizes. The voltage will go
up for a bit, but it will dissipate over time as the charges spread
and dilute themselves.