Recording neuronal behavior during behavior with experimental microstimulation
J.W. Gnadt1 and S.D. Echols2
1Department of Neurobiology and Behavior, Stony
Brook University, Stony Brook, New York, USA
2Riverbend Instruments, Inc., Birmingham, Alabama, USA
Over 100 years ago, Fritsch and Hitzig, Ferrier and other experimental
biologists demonstrated the utility of using systematic electrical stimulation
to reveal the working mechanisms of the nervous system in large vertebrates.
Roughly 50 years later Lorente de No introduced the use of fine needle
electrodes to record neuronal action potentials from individual neurons
in vivo. By the early 1970s, neurophysiologists like Evarts, Hyvärinen,
Mountcastle and Asanuma had perfected techniques of chronic, in vivo neurophysiology
and micro-stimulation to study neural function during highly
trained behaviors in nonhuman primates. By 1990, Newsome and colleagues
demonstrated that in vivo brain stimulation could be used to bias behavioral
responses in monkeys behaviorally trained to report their introspective
perception. However, because electrical stimulation pulses corrupt the
neural recordings with large artifacts, neural action potentials that
fall within the time course of the artifacts are completely obscured or
badly corrupted, making them difficult to detect by conventional techniques.
Until recently, this difficulty has presented an intractable limitation
for the field of behavioral neurophysiology. The experimental electrophysiologist
has been unable to reliably record neural activity simultaneously with
experimental stimulation of the neural tissue.
Using an adaptive noise cancellation technique, we present a real-time
method for recording neural activity during experimental microstimulation
in actively behaving monkeys. This allows the simultaneous measurement
of neural and animal behavior while using microstimulation to activate
or perturb ongoing behaviors in intact, trained subjects. The adaptive
filter uses a combination of one-shot and iterative learning to quickly
cancel the spectral content of the corrupting artifact waveform that is
time-locked to a triggered stimulation pulse, without interfering with
spectral content of the underlying neural recording. Even during complete
corruption of the neural recording during prolonged, repetitive microstimulation,
we demonstrate accurate recovery of action potentials during stimulation-induced
behaviors in real-time, regardless of the size, shape, or timing between
action potentials and stimulation artifacts. Signal detection reliability
for recovery of action potentials can achieve better than one error in
104. Because the noise cancellation is stimulus-event triggered, even
stimulation artifacts with identical shapes as action potentials are accurately
rejected.
Paper presented
at Measuring Behavior 2005
, 5th International Conference on Methods and Techniques
in Behavioral Research, 30 August - 2 September 2005, Wageningen, The
Netherlands.
© 2005 Noldus
Information Technology bv
|