Spatial Distribution of 4-Aminopyridine-Induced Synchronized Excitation and Inhibition in Neocortical Slices: An Optical Imaging Study.
Abstract number :
3.030
Submission category :
Year :
2001
Submission ID :
1686
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
L.S. Chen, MD, Neurology, Childrens Hospital Los Angeles, Los Angeles, CA; D. Sutoyo, BA, Neurology, Childrens Hospital Los Angeles, Los Angeles, CA
RATIONALE: The convulsant 4-aminopyridine (4-AP) is known to enhance both excitatory and inhibitory synaptic neurotransmission. The spatial distribution of 4-AP-induced synchronized excitation or inhibition in the neocortex is unclear.
METHODS: Neocortical slices (500 [mu]m) were prepared from adult rats, incubated with voltage-sensitive dye di-4-ANEPPS (1 [mu]M), recorded by a CCD camera (250 frames/sec) while bathed in (1) 100 [mu]M 4-AP (22 slices, 137 recordings), (2) 25 [mu]M 4-AP (24 slices, 236 recordings), or (3) 60 [mu]M 4-AP in the presence of 10 [mu]M CNQX and 10 [mu]M CPP (20 slices, 67 recordings).
RESULTS: Four patterns of optical signals were observed: (1) baseline signals (B), (2) progressive depolarization signals (D), propagating from lower to upper cortical layers at an average rate of 0.18 mm/sec, (3) progressive hyperpolarization signals (H), simultaneous over the majority of the image area, and (4) coexisting D and H (D/H). In a total of 33 recordings of D/H, 42% showed multiple columns of H adjacent to D, 24% showed laminar distribution of H in the upper layers with D in the lower layers, and 33% showed one large area of D adjacent to one large area of H. There was a significant difference in the distribution of these 4 patterns between recordings in 100 [mu]M 4-AP vs 25 [mu]M 4-AP (p=0.038).
CONCLUSIONS: The optical imaging data demonstrated that 4-AP-induced excitation or inhibition has specific spatial distribution in the neocortex.[table]