| DETAILED MULTICOMPARTMENTAL MODELS OF HIPPOCAMPAL
PYRAMIDAL NEURONS BASED ON HIGH-RESOLUTION 3D MORPHOLOGICAL RECONSTRUCTION
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| F.Hamzei-Sichani1*; A.B.Rocher2;
D.B.Ehlenberger3,4; S.R.Young1; P.R.Hof2,3,5;
S.L.Wearne2,3,4; M.G.Stewart1; R.D.Traub1
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| 1. Department of Physiology & Pharmacology, State Univ.
of New York, Downstate Med. Ctr., Brooklyn, NY, USA |
| 2. Department of Neuroscience, 3. Computational Neurobiology
and Imaging Center, 4. Department of Biomathematical Sciences,
5. Advanced Imaging Program, Mount Sinai School of Medicine,
New York, NY, USA |
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We developed multicompartmental models of CA3 and CA1
pyramidal neurons based on submicrometer 3-dimensional (3D) morphological
reconstructions and recent ionic channel data. We loaded CA3 and CA1
pyramidal neurons (Long-Evans (LE) rats, 8-month old male, n = 5;
Sprague-Dawley (SD) rats, 2-month old male, n = 3) with Lucifer Yellow
via iontophoresis in hippocampal transverse slices (350  m thick). Twenty
high quality dye loaded neurons were selected, 10 in CA1 (all from
SD rats) and 10 in CA3a subfields (3 from LE rats and 7 from SD rats)
and imaged at high magnification (60X, 1.4 N.A.) using confocal laser
scanning microscopy. The neuronal morphology and branching tree were
extracted from stacks of scanned images using a custom-designed algorithm
(NeuronStudio3). Morphometric analysis provided unbiased
measurements of both local and global structure of the neurons. The
3D morphological representation was imported into the NEURON
simulation environment and integrated with the electrophysiological
properties of pyramidal neurons (from the literature) in a multicompartmental
model. Although isotropic distribution of the 10 voltage/calcium-gated
conductances in the axonal and somatodendritic compartments of model
neurons gave rise to the well-known spike-burst activity following
brief somatic/dendritic current injections, it did not support single
spike generation seen at higher current injections. Conductance distributions
able to produce such a burst-to-spike activity switch depended on
the neuron s morphology and
had to be tuned for each neuron individually.
Support Contributed By: NIH MH58911, DC05669, RR16754
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