Reference Section
•
119
Outward Current
Current that flows from the inside to the outside surface of the cell.
Membrane Potential
The potential inside the cell minus the potential outside the cell:
V
m
= V
in
– V
out
.
Depolarization
A positive shift in V
m
(
e.g.
from –60 mV to +80 mV) caused by a flow of
inward current.
Hyperpolarization
A negative shift in V
m
.
MultiClamp Polarity Conventions
The conventions described here apply to all amplifiers manufactured by Axon
Instruments.
To prevent confusion, Axon always uses current and voltage conventions based on
the instrument's perspective. That is, the current is defined with respect to the
direction of flow into or out of the headstage. Axon amplifiers do not have
switches that reverse the current or the voltage command polarities. This prevents
forgetting to move the switch to the correct position. The data are recorded
unambiguously and the correct polarity can be determined during subsequent data
analysis.
Positive Current
Current that flows
out
of the headstage into the electrode and out of the
electrode tip into the cell.
Chapter 5
