The Restoring Active Memory (RAM) program aims to mitigate the effects of traumatic brain injury (TBI) in military Service members by developing neurotechnologies to facilitate memory formation and recall in the injured brain. More than 270,000 Service members have been diagnosed with TBI since 20001. The condition frequently results in an impaired ability to retrieve memories formed prior to injury and a reduced capacity to form or retain new memories following injury. Despite the scale of the problem, few effective therapies currently exist to mitigate the long-term consequences of TBI on memory. Enabling restoration of memory function would support military readiness by providing injured personnel the option of returning to duty, and would improve quality of life for wounded veterans.

DARPA’s end goal for the RAM program is to develop and test a wireless, fully implantable neural interface for human clinical use. To achieve that goal, the program blends fundamental research and technology development. Performer teams are building multi-scale computational models with high spatial and temporal resolution that describe how neurons code declarative memories—the well-defined parcels of knowledge that can be consciously recalled and described in words, such as events, times, and places. Teams are also exploring new methods for analyzing and decoding neural signals to understand how targeted stimulation might be applied to help restore function to the injured brain.

Building on this foundational work, researchers are integrating the computational models into new, implantable, closed-loop systems able to deliver targeted neural stimulation to restore normal memory function. Volunteers living with deficits in the encoding and/or retrieval of declarative memories and/or volunteers undergoing neurosurgery for other neurological conditions are taking part in human clinical studies to help test and refine the RAM systems. RAM also supports animal studies to advance the state-of-the-art of quantitative models that account for the encoding and retrieval of complex memories and memory attributes, including their hierarchical associations with one another. This work aims to identify any characteristic neural and behavioral correlates of memories facilitated by therapeutic devices.

The RAM program is informed by independent Ethical, Legal, and Social Implications (ELSI) experts to help DARPA proactively identify potential issues related to memory and neurotechnology. Communications with ELSI experts supplement the standard oversight provided by institutional review boards that govern human clinical studies and animal use.

RAM Replay

RAM Replay aims to support military training and effectiveness by using non-invasive interventions to accelerate and improve the performance of complex, military-relevant skills by healthy individuals. DARPA anticipates that capabilities developed under RAM Replay will directly translate to training of Department of Defense (DoD) operational tasks and could enhance military readiness by reducing the time required to respond to unanticipated threats.

The program is developing new closed-loop, non-invasive systems that leverage the role of neural “replay” in the formation and recall of memory to help individuals better remember specific episodic events and learned skills. Replay is a process in the brain that occurs during waking and sleep to consolidate memory. In the RAM Replay effort, systems are designed to detect, model, and facilitate real-time correlates of replay in humans, leveraging neurophysiology and other factors including physiological state and external elements in the surrounding environment. The novel intervention strategies under development help investigators determine not only which neural, physiological, and environmental components matter for memory formation and recall, but also how much they matter.

To facilitate transition of RAM Replay neurotechnologies, performer teams validate their assessments and intervention strategies using simulated DoD-relevant tasks instead of the conventional behavioral paradigms commonly used to assess memory in laboratory settings.

Footnote: 1Source: Faul M, Xu L, Wald MM, Coronado VG. Traumatic Brain Injury in the United States: Emergency Department Visits, Hospitalizations and Deaths 2002–2006. Atlanta (GA): Centers for Disease Control and Prevention, National Center for Injury Prevention and Control; 2010.