Currently we have 2 research programs.
Do fluctuations serve a purpose?
Investigating the fluctuations in intracellular membrane potential of neurons during functional network activity. In the spectrogram figure is shown a sample trace of the spectral content of a motoneuron during a motor task.
We have found that these intense fluctuations are due to a concurrent excitatory and inhibitory input (see Berg 2007)- which came as a surprise to us since it is metabolically expensive and it is not in accordance with conventional wisdom. However, preliminary data suggest that this concurrent input serves an important role in adjusting the integration time of the neuron (see Berg et al 2008) as well as the input-output gain.
Cell-Assemblies and population coding.
Little is know about how populations of neurons produce an appropriate function, such as scratching and locomotion for example. Further, though the number of neurons may seem astronomical it is still small compared with the many types of functions that the nervous system can perform. A cell devoted to an assembly performing one function may later participate in another assembly performing another function. To what extend do assemblies share neurons with other assemblies and how flexible are the assemblies? We intend to address these and other issues with multi-unit recording from spinal cord.