Neuroscience 2005 Abstract
| Presentation Number: | 454.3 |
|---|---|
| Abstract Title: | Mapping a cortical-subcortical loop <i>in vivo</i> using manganese-enhanced magnetic resonance imaging in monkey. |
| Authors: |
Simmons, J. M.*1
; Lizak, M. J.2
; Ortiz, M.1
; Koretsky, A. P.3
; Richmond, B. J.1
1Lab. of Neuropsych., NIMH, NIH, Bethesda, MD 2NIH MRI Res. Facility, NINDS, NIH, Bethesda, MD 3Lab. of Functional & Mol. Imaging, NINDS, NIH, Bethesda, MD |
| Primary Theme and Topics |
Techniques in Neuroscience - Staining, Tracing, and Imaging Techniques |
| Secondary Theme and Topics | Cognition and Behavior<br />- Motivation and Emotion<br />-- Reward |
| Session: |
454. Imaging by MRI and PET I Poster |
| Presentation Time: | Monday, November 14, 2005 10:00 AM-11:00 AM |
| Location: | Washington Convention Center - Hall A-C, Board # VV46 |
| Keywords: | Orbitofrontal Cortex, Basal Ganglia, Thalamus, Rhesus |
The development of manganese as a transneuronally-transported, MRI-visible tract tracer has made in vivo identification of multi-stage anatomical pathways feasible. Using this technique, we can localize sites to which groups of neurons project, and target neuronal recordings from directly connected regions. Because manganese is a known neurotoxin, however, we need to determine to what extent intracerebral injections of this tracer result in neuronal damage. We injected manganese chloride (MnCl2, 0.5uL, 800mM) into the orbitofrontal cortex (OFC) of a rhesus monkey. We obtained high-resolution 3D MR images of the brain at 4.7T, with contrast optimized for Mn. We recorded single neurons in OFC while the monkey performed a color detection task before and after Mn injections. Finally, we processed the brain tissue histochemically for Nissl substance, tyrosine hydroxylase, and parvalbumin. Manganese injection sites were centered in area 13 of OFC. On post-injection day 4, we observed enhancements due to Mn transport throughout the orbitofrontal-basal ganglia-thalamic loop. Striatal enhancements were greatest in ventrolateral caudate, ventromedial putamen, and ventral striatum. Mn also labeled the basal ganglia output nuclei, including internal globus pallidus, ventral pallidum, and substantia nigra. Thalamic enhancements were localized to the mediodorsal and habenular nuclei. Neurons in area 13 responded to color cues and reward delivery in the color detection task. Neuronal response properties appeared similar before and after manganese infusion, suggesting that Mn injections left orbitofrontal tissue intact. However, these hyperosmolar injections caused cytotoxic lesions at the injection sites. No tissue damage appeared at the sites of Mn transport. Full exploitation of this technique requires overcoming Mn toxicity, perhaps by lowering MnCl2 concentration.
Supported by NIMH Intramural Research Program and NARSAD Young Investigator Award (JMS)
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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