25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Power and altruistic helping in organizations: roles of psychological closeness, workplace design, and relational self-construal

University of Minnesota Ph.D. dissertation. September 2013. Major: Human Resources and Industrial Relations. Advisor: Joyce E. Bono. 1 computer file (PDF); viii, 238 pages, appendices A-H.I tested a model wherein psychological closeness mediated the negative relationship between power and altruistic helping. I also proposed two moderators--physical distance and relational self-construal--to moderate this relationship, specifically by interacting with power to influence psychological closeness. First of all, this study did not support the proposition that power was negatively related to helping. Power was not associated with helping in the lab setting; perceptions of power measures were positively associated with helping whereas most of the measures of status and relative power were not associated with helping. Second, I did not find support for the model wherein psychological closeness mediated the negative relationship between power and helping in both the lab setting and the field setting. Third, neither physical distance nor relational self-construal was a significant moderator of the relationship between power and psychological closeness. Therefore, the association between power and helping via psychological closeness did not vary by either of the moderators

Wnt Modulators in the Aqueous Humor Are Associated With Outer Retinal Damage Severity in Patients With Neovascular Age-Related Macular Degeneration

Citation: Park KH, Choi AJ, Yoon J, et al. Wnt modulators in the aqueous humor are associated with outer retinal damage severity in patients with neovascular age-related macular degeneration. Invest Ophthalmol Vis Sci. 2014;55:5522-5530. DOI: 10.1167/iovs.14-14566 PURPOSE. To investigate the associations of the Wnt modulators Wnt inhibitory factor 1 (WIF-1) and Dickkopf 3 (DKK-3) in the aqueous humor with neovascular age-related macular degeneration (nAMD) and to determine their clinical implications. METHODS. Seventy-four nAMD patients initially treated with an intravitreal injection of ranibizumab (IVR) and 74 age-and sex-matched controls were studied. Aqueous humor WIF-1 and DKK-3 levels were measured by Western blotting and an ELISA before and 1 month after two consecutive IVRs (pre-and post-IVR). Visual acuity assessments and spectral domain optical coherence tomography were performed pre-and post-IVR. RESULTS. Western blotting showed increased WIF-1 and DKK-3 in 12 nAMD patients compared with 12 controls. The ELISA analysis demonstrated elevated WIF-1 (pre) and DKK-3 (pre) in 62 patients compared with 62 controls (54.7 vs. 23.0 and 114.3 vs. 93.0 ng/mL, respectively). In multivariate analyses, high WIF-1 (pre) levels were associated with increased disruption in the photoreceptor junction's inner and outer segments (IS/OS) (pre and post) and high WIF-1 (post) levels. Interestingly, WIF-1 (pre) levels were significantly higher in type 3 neovascularization (NV) patients than in type 1 or 2 NV (90.5 6 36.7 vs. 48.3 6 22.5 and 41.3 6 28.8 ng/mL, respectively). However, choroidal thickness was not correlated with WIF-1 levels. CONCLUSIONS. We report, for the first time, the possibility of phenotypic, anatomic, and ocular proteomic correlations, demonstrating correlated WIF-1 and DKK-3 upregulation in nAMD patients' aqueous humor. Secreted WIF-1, reflecting the degree of retinal structure damage, may be a new biomarker for the retina's healthy and disease states