RT Journal Article
SR Electronic
T1 Propagating Activation during Oscillations and Evoked Responses in Neocortical Slices
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 5005
OP 5015
DO 10.1523/JNEUROSCI.19-12-05005.1999
VO 19
IS 12
A1 Wu, Jian-young
A1 Guan, Li
A1 Tsau, Yang
YR 1999
UL http://www.jneurosci.org/content/19/12/5005.abstract
AB Population activity in the cortex is poorly understood. In this report we use voltage-sensitive dye imaging to examine the spatiotemporal patterns of a 7–10 Hz oscillation in neocortical slices from rat somatosensory areas. This oscillation appeared as a component of spontaneous epochs when the preparation was bathed in low [Mg] artificial CSF (ACSF) (Silva et al., 1991). Each epoch started with a synchronized spike, and 3–200 cycles of oscillation emerged afterward. Voltage-sensitive dye imaging revealed that the oscillations in the local field potential recordings were actually caused by a propagating population activation. This activation propagated in a relatively uniform size (not expanding). We call this confined, propagating activation a “dynamic ensemble.” During each oscillation cycle, one (occasionally two) dynamic ensemble(s) appeared in the slice and was sustained for 60–200 msec. Dynamic ensembles propagated at ∼30 mm/sec; the activity could propagate in both directions in cortical slices. The propagation consisted in part of “jumps,” the locations of which were not fixed. Dynamic ensembles were distinguishable from the epileptiform spikes that occurred in low [Mg] ACSF. Population events similar to dynamic ensembles were also evoked under conditions of unaltered excitability (slice in normal ACSF) by electrical stimulation that activated a low density of neurons in a large area. Our data suggest that self-sustained, spatially confined, and propagating dynamic ensembles might be related to the epoch oscillations in somatosensory cortex seen in vivo(Nicolelis et al., 1995) and thus resemble one form of population activation in the neocortex.