| 1. Dept Biomath, 2. Dept Neurosci., 3. CNIC, Mount Sinai Sch of Med, New York, NY, USA |
| 4. Dept. Psychiatry, Boston Univ., Boston, MA, USA |
| 5. Applied Math, UNSW, Sydney, Australia |
Poster presentation:Tuesday, Oct. 26, 9:00 AM - 10:00 AM
Location:T20
| CNFA 2004 SfN Abstracts |
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| MORPHOLOGIC CHANGES IN DENDRITIC STRUCTURE AND SPINE DENSITIES MAY ACCOUNT FOR AGE-RELATED INCREASES IN ACTION POTENTIAL FIRING RATES | |||
| D.M.Kabaso1,3*; J.I.Luebke4; B.I.Henry5; P.R.Hof2,3; S.L.Wearne1,2,3 | |||
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| Recent in vitro electrophysiological studies of neocortical pyramidal neurons in monkey prefrontal cortex (PFC) show increased input resistance and action potential (AP) firing rates with age. Using a variant of 3D Sholl analysis, we characterized global neuronal mass distribution (DM) in pyramidal neurons from macaque monkey PFC. DM was decomposed into scaling exponents representing global dendritic tapering (DT) and global branching (DN). The mass scaling exponent was significantly larger with age (p<0.05), due primarily to a significant decrease in global tapering with age (p<0.05). Proximal regions of the apical trunk were also significantly thinner (p<0.05), and spine densities significantly reduced with age. To determine the contribution of these age-related morphologic changes to the observed electrophysiological changes, neurons were electrophysiologically characterized, filled intracellularly with biocytin, digitized in 3D, and simulated using compartment modeling. Model neurons were constrained with recorded passive parameters. Ion channel conductances and distributions were adjusted to fit the recorded AP data. To isolate the effect of dendritic morphology, all other parameters were held constant between modeled neurons. Without spines, the aged dendritic morphologies produced significantly higher simulated AP firing rates (p<0.05). Addition of spines to the compartment models further increased the age-related increase in AP firing rates (p<0.01). We conclude that morphologic changes in dendritic structure and spine densities can be a major determinant of increased AP firing rates with age. Supported by ARC, NIH grants MH58911, MH60734, DC05669, AG05138, AG00001, RR16754. | |||
| Program No. 638.18 Poster presentation:Tuesday, Oct. 26, 9:00 AM - 10:00 AM Location:T20 |
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