EEG (electroencephalography) Exam
Questions and Answers
EEG pros - Answers -Excellent time resolution
- Cognitive, perceptual, linguistic, emotional processes are fast and dynamic
- For example, consider theta band (4-8 Hz), a slow rhythm but quite fast for our
conscious experience
- Or consider gamma (30 -80 Hz)
Direct indicator of neuronal activity
Multidimensional (time, space, frequency, power, phase, connectivity etc)
Portability (observing brain in action)
Relatively inexpensive
EEG cons - Answers -It is not well-suited for precise functional localisation
It is not well-suited for measuring deep brain structures (e.g., putamen, thalamus,
nucleus accumbens)--> Sub-optimal method: where in the brain does process X occur
or is information Y stored
It is also not very well-suited to study very slowly fluctuating process with uncertain and
variable time course
EEG reflects the ___________ of electrical potential overtime, created by the current
flows originating from neuronal populations - Answers -differences
Two types of neuronal electrical activity: - Answers -(i) action potential (AP)
(ii) postsynaptic potential (PSP)
Propagation of the Action Potential - Answers -[see image]
Chemical synapses - Answers -cause local changes in postsynaptic membrane
potentials, through neurotransmitters.
Information transmits with some delay on the order of a millisecond.
electrical synapses (gap junctions) - Answers -Ions flow directly through large channels
into adjacent cells, with no time delay
, Post-Synaptic Potential (PSP) - Answers -An electrical potential initiated at a
postsynpatic site that can vary in amplitude and spreads passively across the cell
membrane, decreasing in strength with time and distance
Generation of PSP - Answers -1. When AP reaches presynaptic axon end, a
neurotransmitter is released into the synaptic cleft
2. The neurotransmitter binds to the receptor of the postsynaptic neuron by opening or
closing an ion channels
3. This leads to a graded change in membrane potential
Two types of PSP - Answers -Excitatory PSP (for excitatory synapse)
Inhibitory PSP (for inhibitor synapse)
Recording Postsynaptic Potentials - Answers -[see image]
Neurons perform ____________________ to integrate synaptic inputs. - Answers -
information processing
A postsynaptic neuron will fire an action potential if a depolarisation that exceeds
threshold reaches its ______ _______ - Answers -axon hillock
Generally the combined effect of many _______________ synapses is required for a
post-synaptic neuron to fire - Answers -excitatory
Spatial Summation in a Postsynaptic Cell [1] - Answers -Threshold reached, AP
triggered
Spatial Summation in a Postsynaptic Cell [2] - Answers -Inhibition counteracts
excitation, no AP
Two Types of Summations - Answers -Spatial summation
Temporal summation
Spatial summation - Answers -the summing of potentials that come from different parts
of the cell. (caused by many presynaptic neuron)
If the overall sum - of EPSPs and IPSPs - can depolarize the cell at the axon hillock, an
action potential will occur.
Temporal summation - Answers -the summing of potentials that arrive at the axon
hillock at different times. (caused by one presynaptic neuron)
Questions and Answers
EEG pros - Answers -Excellent time resolution
- Cognitive, perceptual, linguistic, emotional processes are fast and dynamic
- For example, consider theta band (4-8 Hz), a slow rhythm but quite fast for our
conscious experience
- Or consider gamma (30 -80 Hz)
Direct indicator of neuronal activity
Multidimensional (time, space, frequency, power, phase, connectivity etc)
Portability (observing brain in action)
Relatively inexpensive
EEG cons - Answers -It is not well-suited for precise functional localisation
It is not well-suited for measuring deep brain structures (e.g., putamen, thalamus,
nucleus accumbens)--> Sub-optimal method: where in the brain does process X occur
or is information Y stored
It is also not very well-suited to study very slowly fluctuating process with uncertain and
variable time course
EEG reflects the ___________ of electrical potential overtime, created by the current
flows originating from neuronal populations - Answers -differences
Two types of neuronal electrical activity: - Answers -(i) action potential (AP)
(ii) postsynaptic potential (PSP)
Propagation of the Action Potential - Answers -[see image]
Chemical synapses - Answers -cause local changes in postsynaptic membrane
potentials, through neurotransmitters.
Information transmits with some delay on the order of a millisecond.
electrical synapses (gap junctions) - Answers -Ions flow directly through large channels
into adjacent cells, with no time delay
, Post-Synaptic Potential (PSP) - Answers -An electrical potential initiated at a
postsynpatic site that can vary in amplitude and spreads passively across the cell
membrane, decreasing in strength with time and distance
Generation of PSP - Answers -1. When AP reaches presynaptic axon end, a
neurotransmitter is released into the synaptic cleft
2. The neurotransmitter binds to the receptor of the postsynaptic neuron by opening or
closing an ion channels
3. This leads to a graded change in membrane potential
Two types of PSP - Answers -Excitatory PSP (for excitatory synapse)
Inhibitory PSP (for inhibitor synapse)
Recording Postsynaptic Potentials - Answers -[see image]
Neurons perform ____________________ to integrate synaptic inputs. - Answers -
information processing
A postsynaptic neuron will fire an action potential if a depolarisation that exceeds
threshold reaches its ______ _______ - Answers -axon hillock
Generally the combined effect of many _______________ synapses is required for a
post-synaptic neuron to fire - Answers -excitatory
Spatial Summation in a Postsynaptic Cell [1] - Answers -Threshold reached, AP
triggered
Spatial Summation in a Postsynaptic Cell [2] - Answers -Inhibition counteracts
excitation, no AP
Two Types of Summations - Answers -Spatial summation
Temporal summation
Spatial summation - Answers -the summing of potentials that come from different parts
of the cell. (caused by many presynaptic neuron)
If the overall sum - of EPSPs and IPSPs - can depolarize the cell at the axon hillock, an
action potential will occur.
Temporal summation - Answers -the summing of potentials that arrive at the axon
hillock at different times. (caused by one presynaptic neuron)
