Lecture 7 Study Guide

Question 1

the neuron doctrine

Answer 1

the neuron is the basic
cellular unit for processing information.

Basic structure of neurons:
– Cell body (Soma)
– Dendrites
– Axon (or nerve fiber)

Question 2

the doctrine of specific nerve energies in the context of sensory modularity.

Answer 2

• Johannes Müller, in 1842, proposed that perception is based on the “nerve energies” received in the brain.
• This suggested that specific perceptions and their
  qualities/features depended on which neurons were stimulated.

• So, it wasn’t the (distal) stimulus per se, but rather the activation of 
the neuron (by any means necessary) that was responsible for the sensation. 

– This was one of the earliest examples of separating brain
responses by discrete neural function.

– Later made more specific, stating that the activation of the
target area in cortex was the critical element of the sensory
experience.

Question 3

how neurons propagate signals via action potentials

Answer 3

are the primary means of transmitting signals to other
neurons. They are the voltage changes that travel the length of the neuron to the terminal button, where a neurotransmitter is released – possibly causing an action potential in the next neuron(s).

Question 4

how we measure action potentials

Answer 4

single-unit recording = Microelectrodes are used to record from single neurons.

Question 5

how IPSPs and EPSPs can influence the firing rate of target

neurons.

Answer 5

An influx of positively charged ions (e.g. Na+) pushes the neuron toward depolarization (EPSP)

An efflux of positively charged ions (e.g. K+) makes the neuron more polarized (hyperpolarized) (IPSP)

EPSPs and IPSPs can
summate on the same neuron.

An action potential is only 
triggered if the EPSPs can 
push the neuron to 
depolarization faster than 
the IPSPs pull it toward 
hyperpolarization.

This becomes critical for the formation of receptive fields.

Question 6

IPSPs & EPSPs and receptive fields

Answer 6

d