Assessing neuronal synchronization properties using spike time response methods

Synchronous neuronal activity is prominent in mammalian hippocampal formation, and is believed to be necessary for the structure\´s role in episodic memory (memory about events). We are studying the "rules" by which synchronization occurs in the hippocampal formation, using approaches that focus on how controlled synaptic inputs affect spike timing in postsynaptic neurons. We measure these spike time response (STR) relationships and use them to predict whether a mutually-coupled population of such neurons would be expected to phase lock, and if so, at what phase. We show that STR relationships are consistent for identified cell types. We verify predicted phase relationships from STR measurements in hybrid neuronal networks, composed of one or more biological neurons, coupled with each other or with in silicon counterparts. The degree to which predictions from STR methods can be generalized depends on a number of simplifications (e.g., the degree of linearity of STRs). Preliminary results indicate that STRs are linear, and thus that our predictions can be generalized to a host of conditions.