? ? Recent developments in imaging (i.e. functional MRI) have endowed researchers with the ability to visualize brain activity in real time. However, many of these imaging techniques 1) are expensive and timeconsuming to use; 2) do not allow subjects to fully interact with their environment; and 3) do not allow for truly simultaneous electrical measurements. Dynamic Near-infrared Optical Tomography (DYNOT) is a new non-invasive imaging technology that allows the researcher to explore hemodynamic changes in the brain in real time. Hb changes can be correlated to brain activity using current theories on the physiologic requirements for brain function, similar to the Blood-Oxygen Level Dependent (BOLD) response obtained with fMRI. The technology is economical, can be made portable, and allows for combination with other physiological monitoring technologies, namely EEC and associated single-cell electrical recordings. This project aims to combine the latest version of DYNOT technology, functional imaging in freely moving animals, with multi and intra-cellular neural recordings of various brain regions, in rats undergoing pre-established learning tasks that elicit a specific response in one of three brain regions. Both DYNOT & EEC/single cell recordings can be simultaneously measured from probes/electrodes attached to the animal's head, allowing for study of the switching among memory systems as tasks are performed. Furthermore, the experimental setup is well suited for an emerging signal processing methodology in neuroscience, called synchrony index, which is capable of measuring the phase-locking between a set of intracellular recordings within the hippocampus. Synchrony index calculations on sets of EEG/intracellular recordings from the three brain regions to be studied will allow us to demonstrate communication between the neurons in these regions. The combined recordings with synchrony index calculations will permit the study of learning and memory storage, as well as interconnections between a variety of brain regions in real time, all while the subject is free to interact with all aspects of the environment. Successful demonstration of this integrated approach will set the stage for the exploration of a spectrum of other normal brain functions and pathologies involving real-world stimuli, learning, and memory storage/recall. In the future, this work can have applications in the study of ADHD, epilepsy, Alzheimer's Disease, stroke, brain edema, and meningeal hemorrhages. ? ? ?
