Electrical activity is the foundation of the neural system. Coding theories that describe neural electrical activity by the roles of action potential timing or frequency have been thoroughly studied. However, an alternative method to study coding questions is the energy method, which is more global and economical. In this study, we clearly defined and calculated neural energy supply and consumption based on the Hodgkin-Huxley model, during firing action potentials and subthreshold activities using ion-counting and power-integral model. Furthermore, we analyzed energy properties of each ion channel and found that, under the two circumstances, power synchronization of ion channels and energy utilization ratio have significant differences. This is particularly true of the energy utilization ratio, which can rise to above 100% during subthreshold activity, revealing an overdraft property of energy use. These findings demonstrate the distinct status of the energy properties during neuronal firings and subthreshold activities. Meanwhile, after introducing a synapse energy model, this research can be generalized to energy calculation of a neural network. This is potentially important for understanding the relationship between dynamical network activities and cognitive behaviors.

Place cells are important elements in the spatial representation system of the brain. A considerable amount of experimental data and classical models are achieved in this area. However, an important question has not been addressed, which is how the three dimensional space is represented by the place cells. This question is preliminarily surveyed by energy coding method in this research. Energy coding method argues that neural information can be expressed by neural energy and it is convenient to model and compute for neural systems due to the global and linearly addable properties of neural energy. Nevertheless, the models of functional neural networks based on energy coding method have not been established. In this work, we construct a place cell network model to represent three dimensional space on an energy level. Then we define the place field and place field center and test the locating performance in three dimensional space. The results imply that the model successfully simulates the basic properties of place cells. The individual place cell obtains unique spatial selectivity. The place fields in three dimensional space vary in size and energy consumption. Furthermore, the locating error is limited to a certain level and the simulated place field agrees to the experimental results. In conclusion, this is an effective model to represent three dimensional space by energy method. The research verifies the energy efficiency principle of the brain during the neural coding for three dimensional spatial information. It is the first step to complete the three dimensional spatial representing system of the brain, and helps us further understand how the energy efficiency principle directs the locating, navigating, and path planning function of the brain.

The aim of the present study was to investigate the roles of the co-culture of human umbilical cord Wharton’s jelly-derived mesenchymal stem cells (hUC-MSCs) with rat pancreatic cells in the treatment of rats with diabetes mellitus. hUC-MSCs were isolated and passaged, followed by Transwell co-culture with rat pancreatic cells. The induced islet-like cell clusters were transplanted into the renal capsule in rats with streptozotocin (STZ)-induced diabetes mellitus. The effects of co-culture on blood glucose levels in rats were observed. The isolated hUC-MSCs expressed the specific surface markers, including cluster of differentiation 44 (CD44) (91.4%), CD29 (91.3%) and CD105 (99.2%). Following co-culture with hUC-MSCs for 7 and 10 days, the rat pancreatic cells were strongly stained by pancreatic and duodenal homeobox-1 and human insulin. The insulin and C-peptide concentrations were increased significantly compared to the pure culture group. One week following the transplantation of induced islet-like cells into the renal capsule, the blood glucose level of rats in the STZ experimental group was significantly lower than that of the STZ control group. There were notable 5-bromo-2′-deoxyuridine-positive nuclei and insulin-positive cytoplasm in the renal capsule following cell transplantation. Therefore, co-culture of hUC-MSCs with rat pancreatic cells can lower the blood glucose levels in rats with diabetes mellitus.

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