Neuroscience 2004 Abstract
| Presentation Number: | 227.17 |
|---|---|
| Abstract Title: | Uncovering the functional neuroanatomy of absence epilepsy with manganese enhanced MRI. |
| Authors: |
Tenney, J. R.*1
; Bhagavatheeshwaran, G.1
; Messenger, T. L.1
; Ferris, C. F.1
1Ctr. for Comparative Neuroimaging, Univ Massachusetts Med Sch, Worcester, MA |
| Primary Theme and Topics |
Neurological and Psychiatric Conditions - Epilepsy -- Basic mechanisms |
| Secondary Theme and Topics | Techniques in Neuroscience<br />- Staining, tracing and imaging techniques |
| Session: |
227. Epilepsy: Basic Mechanisms I Poster |
| Presentation Time: | Sunday, October 24, 2004 8:00 AM-9:00 AM |
| Location: | San Diego Convention Center - Hall A-H, Board # YY16 |
| Keywords: | imaging, seizure |
Absence seizures are impairments of consciousness with 3 Hz spike-wave discharges (SWD) on EEG. To elucidate the neuroanatomy responsible for these behavioral and EEG effects, manganese enhanced MRI (MEMRI) was completed. Mn2+ is a Ca2+ analog and MR contrast agent that has been used to non-invasively visualize Ca2+-dependent neural activity. A unique property of Mn2+ is that once internalized it is transported transynaptically via functional connections of neurons. This study was designed to uncover the functional neuroanatomical circuit causing absence epilepsy. Rats were stereotaxically implanted with a cannula in the somatosensory cortex (peri-oral area). Rats were then given an i.p. injection of vehicle or γ-butyrolactone (GBL, used to induce the absence seizure). Five minutes after GBL/vehicle administration rats were microinjected with 100nl of 100mM MnCl2 into the somatosensory cortex. The SWDs characterizing the seizure were maintained for 8 hours by repeated injections of GBL to allow sufficient transport of the Mn2+. Rats were then transcardially perfused with formaldehyde and brains removed for imaging. All images were acquired using a 9.4T small-bore magnet. T1-weighted images were acquired using a spin echo sequence (TR=150ms;TE=4.5ms;256x512;FOV=22x22mm;averages=46). Images were registered to a digital rat atlas and the contrast was thresholded and displayed within a 3-D reconstructed rat brain. Signal intensity measurements show Mn2+ contrast was found specifically in the fronto-parietal cortex, thalamic nuclei (bilateral), and hippocampus. Microinjection of manganese into a cortical area critical for SWD generation represents a feasible way to uncover the neural circuitry underlying absence seizures. Comparing MEMRI images of seizure circuitry with BOLD functional maps may further our understanding of the aberrant thalamocortical connections underlying absence epilepsy.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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