Zusammenfassung der Ressource
Synapses and Neural Pathways
- How do we measure communication between neurons?
- Electrically: neurophysiology
- Branch of physiology that
deals with the flow of ions
- Electroencephalogram (EEG)
- Advantages
- Non-invasive
- High temporal resolution
- Disadvantages
- Low spatial resolution
- Only record from cortex
- Multiple unit recording
- Records brain rhythms
- Synchronous firing produces
measurable waves of activity
- Advantages
- Average spatial resolution
- Average temporal resolution
- Disadvantages
- Only records
groups of neurons
- Invasive - mostly used on animals
- Single unit extracellular
- Advantages
- Very high spatial resolution
(multiple single neurons)
- High temporal resolution
(action potentials)
- Disadvantages
- Invasive
- No knowledge of intracellular events
- Intracellular
- Advantages
- Very high spatial resolution
- Examine sub-cellular processes
- Disadvantages
- Fragile electrodes
- One cell at a time
- Only in anaesthetised animals
- Chemically: microdialysis
- Invasive procedure
- Slow - sample every few minutes
- Communication between neurons
- Frequency is important, not size
- If the stimulus is weak, only a few action potentials will be fired.
- Spike timing
- Rhythms occur when a lot of neurons
fire action potentials at the same time.
- Timing of an action potential relative to a
rhythm can change the information it carries
- Neurotransmitters work on
post-synaptic receptors on dendrites
- Ionotropic receptors
- Transmit info quickly
- Simple mechanism
- Metabotropic receptors
- Slow-acting and long lasting
- Complex mechanism
- Two types of neurotransmitter
- Excitatory
- Causes depolarisation
- Glutamate
- Inhibitory
- Causes hyperpolarisation; stops
action potentials from being generated
- GABA
- Excitation/inhibition caused
by open ion channels
- Four types
- Autoreceptors
- Bind to neurotransmitters released by
the neuron on which they are situated
- Can be anywhere on cell membrane; usually
inhibitory; help self-regulate neurons