New York University
Hosted by John Huguenard
The dominant model posits that biological neural networks can represent information in the collective action potential discharge of neurons, and store that information amongst the synaptic connections between the neurons that both comprise the network and govern its function. Indeed, the strength and organization of synaptic connections adjust during learning as a function of their use. However, mammalian life is replete with both useful task-relevant information and an abundance of distracting task-irrelevant information, requiring cognitive control to judiciously process the relevant at the expense of distraction. Instead of parallel discrete for-purpose neural activity or circuits, we observe that rodent hippocampal action potential discharge alternates with cognitive control and between transient and discrete memory functions like encoding current information and recollecting past information. This lecture will first summarize our investigations of the molecular and biochemical mechanisms that change synaptic function to persistently store spatial memory in the rodent hippocampus. I will then report on how entorhinal cortex-hippocampus circuit function changes during cognitive training that creates memory, as well as learning to learn in mice. I will describe that the hippocampus system operates like a competitive winner-take-all network, that, based on the dominance of its current inputs, self organizes into either encoding or recollection information-processing modes. We find no evidence that distinct cells are dedicated to those two distinct functions, rather activation of the hippocampus information processing mode is controlled by a subset of dentate spike events within the network of learning-modified, entorhinal-hippocampus excitatory and inhibitory synapses.