Commander
Reference
then
be
turned
up
without
the
annoying
offset.
The
M
Ω
value
found
by
Bridge
Balance
is
the
resistance
of
the
electrode,
which
may
be
slightly
higher
than
the
value
in
the
bath
because
of
partial
blockage
of
the
tip
during
penetration.
The
residual
transient
at
the
start
and
finish
of
the
current
step
is
due
to
the
finite
response
speed
of
the
microelectrode,
which
is
determined
in
part
by
the
capacitance
of
the
electrode.
The
transient
can
be
minimized
by
correctly
setting
the
Pipette
Capacitance
Neutralization
control
(see
Capacitance
Neutralization
).
Adjust
Pipette
Capacitance
Neutralization
for
the
most
rapid
decay
without
causing
an
overshoot.
Buzz
The
Buzz
button
and
adjustable
field
for
pulse
duration
are
located
at
the
bottom
of
the
I
‐
Clamp
tab.
In
I
‐
Clamp
mode
only,
Buzz
drives
a
brief,
large
current
oscillation
through
the
micropipette.
The
oscillation
is
achieved
by
increasing
the
Pipette
Capacitance
Neutralization
by
a
small
amount
over
the
currently
set
level.
Therefore,
it
is
essential
that
you
set
Pipette
Capacitance
Neutralization
to
the
correct
level
prior
to
using
Buzz.
If
the
Pipette
Capacitance
Neutralization
level
is
too
low,
Buzz
may
fail
to
activate.
Buzz
duration
can
be
set
to
discrete
values
between
100
μ
s
and
500
ms.
View
the
duration
options
by
right
‐
clicking
the
field.
Depending
on
the
microelectrode
and
the
preparation,
this
method
can
aid
in
clearing
blocked
electrode
tips.
When
used
while
the
tip
of
the
microelectrode
is
pressing
against
the
membrane,
Buzz
may
also
cause
the
micropipette
to
penetrate
the
cell.
The
exact
mechanism
is
unknown,
but
it
may
involve
attraction
between
the
charge
at
the
tip
of
the
electrode
and
bound
charges
on
the
inside
of
the
membrane.
For
some
small
cells
a
long
duration
Buzz
can
be
deadly.
An
appropriate
duration
can
be
found
for
most
cells
that
is
sufficiently
long
to
allow
penetration
of
the
membrane
but
short
enough
that
the
cell
is
not
damaged
after
penetration.
119
