Dean Mobbs - US grants

Abstract Not Provided.

Abstract Not Provided.

This NSF Major Research Instrumentation (MRI) Award will enable a three-year grant to purchase a major upgrade to the magnetic resonance imaging scanner used for studying the function and structure of the human brain by neuroscience researchers at the California Institute of Technology and their national and international collaborators. The award will support the upgrade of the existing Siemens Tim Trio 3T scanner at the Caltech Brain Imaging Center to the latest Siemens Prisma platform. The upgraded scanner will provide clearer and more detailed images of the human brain. Such an improvement in imaging capabilities will enable Caltech researchers to address fundamental problems such as how the brain learns from experience, how the brain makes decisions and how brains support the ability to learn from and interact with other people in social contexts. This new equipment will ultimately help Caltech researchers obtain a better understanding of how the brain works, how it is wired up, and how it may dysfunction in disease. That knowledge, in turn, will contribute to efforts to build artificially intelligent systems. The grant will also enable students and post-docs to obtain experience in using state-of-the-art brain imaging equipment, through classes taught at Caltech that offer hands-on-experience as well as through the participation of trainees in research projects that utilize the equipment. Taken together, the cutting-edge science enabled by the new equipment, and the training of the next generation of young scientists on it, will contribute substantially to cognitive, decision and social neuroscience at Caltech, in the US and worldwide.

To advance understanding about how the brain supports the capacity of humans to learn, make decisions and mediate social interactions it will be necessary to make progress in three distinct domains. First, there is a need to develop a much more detailed circuit-level understanding of the neural mechanisms underlying these various computational processes by resolving the functional properties of discrete neuroanatomical sub-divisions within each of the relevant brain areas of interest such as the amygdala, ventromedial prefrontal cortex, striatum and midbrain. Second, it is necessary to address how the various sub-processes that are implemented in these distinct sub-systems are ultimately integrated together at the systems level to drive complex behavior. Third, it will be important to characterize how the various computations and neural implementations differ across time, tasks and individuals. The Siemens Prisma scanner provides technical capabilities that are uniquely suited to advance progress in each of these three domains at the California Institute of Technology. The new platform will offer significant improvements in the quality of high resolution fMRI scans obtained from brain structures of interest, by minimizing dropout and geometric distortion, and by increasing signal-to-noise. These capabilities will also enhance the stability of the images obtained and hence improve test-retest reliability, while the improved gradient set will offer major gains in the quality of diffusion weighted imaging, and of functional connectivity data.

Project 3. Project Summary. This Project 3 derives from Project 3 in our current Conte Center. It has the only new PI in our Conte Center, new faculty at Caltech Dean Mobbs (moving from Columbia University in summer, 2016), together with senior Co-PI Colin Camerer. Its overarching goal is to understand how social inference and context guide social decisions under threat, a counterpart to Project 2, which investigates how these processes instead guide prosocial altruistic decisions. There are four Aims, which trace this theme from the buffering safety value of other people, through investigations of social versus nonsocial threat, to investigations of how we behave when other people block our goals (closely related to the RDoC construct of ?frustrative non-reward?). The last Aim, as in Projects 1 and 2, investigates individual differences. As with the other Projects, there are close links to Aims investigated with different approaches. For instance, Aim 1 under Project 4 will use single-unit recordings from the amygdala to investigate neuronal responses to specific types of threat, from basic to social. These links are also reflected in the personnel of Project 3, which includes PIs Adolphs and Hutcherson (from Project 2), O'Doherty (Project 1), and Rutishauser (Project 4, for the single-unit recording link), as well as several shared post-docs and students. The Aims leverage the expertise of PI Mobbs in constructing more ecologically valid protocols that can be used in the fMRI environment, have quantifiable parameters, but capture ecological contexts related to social threat in the real world. It will test 60 healthy participants recruited through Cores 2 and 3 in six fMRI experiments. Aim 1 investigates how the competence and reputation of other people can serve as a buffer against physical threats (electric shock). Aim 2 investigates dynamic decision-making in a virtual foraging task, to understand how people's choices trade reward probabilies against social or nonsocial threats. Aim 3 investigates frustrative nonreward in a social setting: what responses are elicited when other people block our goals-- and how this may vary depending on whether or not the other person has an excuse or is blocking us intentionally. Taken together, Projects 1, 2 and 3 build from a very computational framework with very quantitative tasks, to a more standard social neuroscience framework, to a framework maximizing ecological validity. They all involve fMRI studies in healthy people, and they all have links to Aims under Projects 4 and/or 5 that extend the investigation to single-unit studies or lesion studies.