Hippocampal Network Analysis Using a Multi-electrode Array (MEA)Jonathan KarrApril 1, 2004Outline• Goal: To create a neuron level map of the dissociated hippocampal network• Take correlations between stimulated neurons and all other neurons; Use result to assign unidirectional connection strength• Will use spike sorting to connect electrode level to neuron level• First lets see if this correlation makes sense by applying it to an artificial network• Possible applications– Integrating man and machine– Understanding and repairing diseases/damagesToy Network – Step I• 9 Neurons with first order connections, the magnitude of these connections is specified– Any pair of neurons can be connected• Model includes parameters for– Synaptic delay– Refractory Period Length• Benefit of model is infinite signal to noise ratio• Program generates nine “data” sets, each one corresponding to the “stimulation” of one of the neuronsToy Network – Step IIToy Network – Step IIIToy NetworkHippocampal Network – Step IIHipppocampal Network – Step IIISpike Sorting• Goal is to connect level of electrodes to the level of individual neurons• Idea is to attribute spikes to individual neurons by performing convolutions and then look at the correlations between the spike trains of neurons• Method requires the assumption no two neurons at one electrode spike with the same shape• This requires a low neuron density as well as ten different spike shapes randomly distributed among in the culture.Works Cited• Panasonic. (2003). MED64 Systems - Multichannel Multielectrode Array Systems for In-vitro Electro-physiology. Retrieved March 27, 2004, from http://www.med64.com/.• Eversmann B., Jenker M., Hoffman F., et al (2003). A 128x128 CMOS biosensory array for extracellular recording of neural activity. IEEE Journal of Solid State Circuits. 38 (12): 2306-2317.• McAllen R.M. and Trevaks D. (2003). Are pre-ganglionic neurones recruited in a set order? ActaPhysiologica Scandinavica. 177(3): 219-225.• Kerman I.A., Yates B.J., and McAllen R.M. (2000). Anatomic patterning in the expression of vestibulosympathetic reflexes. American Journal of Physiology. Regulatory, Integrative, and Comparative Physiology. 279 (1):R109-R117.• Cambridge Electronic Design. (2003). Spike2, Version 5. Retrieved March 27, 2004, from http://www.ced.co.uk/pru.shtml.• Lewicki M.S. (1998). A review of methods for spike sorting: the detection and classification of neural action potentials. Computational Neural Systems. 9: R53-R78.• Bierer S.M. and Anderson D.J. (1999). Multi-channel spike detection and sorting using an array processing technique. Neurocomputing. 26-27:945-956.• Fee M.S., Mitra P.P., and Kleinfeld D. (1996). Automatic sorting of multiple neuronal signals in the presence of anisotropic and non-Gaussian variability. Journal of Neuroscience Methods. 69:175-188.• Heitler W.J. (2004). Dataview. Retreived March 27, 2004 from