This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Long after playing a game of squash or reading this abstract, the memory of playing and reading continues to be processed by the brain. These "off-line" processes improve game performance and understanding of this abstract, and more generally, enhance adaptive behavior. These off-line processes have, for at least the last 100 years, been recognized to play a critical role in determining subsequent recall of facts, events and skills. Yet, the mechanisms engaged to support off-line processing are very poorly understood, and there remains considerable debate over multiple competing models. With support from the National Science Foundation, Dr. Edwin Robertson and colleagues at Harvard Medical School will distinguish amongst these models by determining which brain areas are vital to off-line memory processing over sleep and wakefulness. According to one model, largely supported by functional imaging work, the same brain areas support off-line processing over wakefulness and sleep (Uniform Model). In contrast, recent behavioral studies have shown that different types of processing occur over wakefulness and sleep (Differential Model). Finally, there may be a mixture of these two models with some brain areas being engaged regardless of brain state; whereas others areas may be engaged only over sleep or wakefulness (Hybrid Model). In a set of experiments, Dr. Robertson and colleagues will use Transcranial Magnetic Stimulation (TMS), a non-invasive technique for stimulating small regions of the brain, to establish those brain areas that are critical to off-line processing over wakefulness and sleep. These experiments will reconcile the contrasting perspectives offered by contemporary models and so provide novel insights into off-line processing, which is critical for the retention, and sometimes the enhancement of recently acquired memories.
Work from this project will provide a unified conceptual foundation that bridges the gulf between viewing off-line memory processing as requiring time, independent of brain state (i.e. sleep vs. wakefulness), and the alternative in which brain state alters the mechanisms engaged to support off-line processing. A greater understanding of off-line processing may translate into novel therapeutic strategies to improve the recovery of motor skills lost following brain damage such as a stroke (for example by modulating brain areas or brain states). Funding from this award will strengthen ties across several collaborating laboratories, providing a rich substrate for undergraduate and graduate students' training over a wide selection of disciplines from cognitive psychology to chronobiology.
