Neural mechanisms for coordinating the sampling of environmental information and internally stored information - PROJECT SUMMARY Daily activities, such as driving a car, require selective processing of external information that is present in the environment (i.e., during selective attention) and internal information that is stored within the mind (i.e., during working memory). Previous research has shown that the sampling of external information and the maintenance and sampling of internal information are associated with shared neural resources in frontal, parietal, and sensory cortices. Shared neural resources might lead to competitive interactions between these processes during tasks that require both external and internal sampling. Here, we will investigate the neural mechanisms through which the brain coordinates the sampling of external and internal information to avoid competitive interference. There are two specific aims. In Aim 1, we will test whether the same neurons or different neurons represent and sample external and internal information under different task conditions. We will intracranially record from macaque frontal, parietal, and sensory cortices while the animals complete a task that requires (i) only external sampling, (ii) only internal sampling, or (iii) both external and internal sampling. We predict that during trials that require both external and internal sampling (i.e., during dual-task trials), there will be a shift toward functional segregation, with neurons (and perhaps brain regions) specializing for external or internal sampling. In Aim 2, we will use the same data to test whether the competition between external and internal sampling—for shared neural resources—leads to the separation of functionally specific neural activity over time. That is, we will test whether external and internal sampling are temporally coordinated on a sub-second timescale, consistent with previous evidence that competing neural processes can be coordinated by theta- rhythmic neural activity (3–8 Hz). Our findings will provide critical insight into how the brain flexibly accomplishes selective processing during tasks that require both environmental information and internally stored information. It will also provide cross-species translation between humans and macaques, given that we are building on a human EEG project that used the same behavioral task. Finally, the proposed experiments will address several ongoing debates in cognitive neuroscience, including (i) the extent to which selective attention and working memory utilize a shared sampling process, (ii) whether higher order (i.e., frontal and parietal) cortices engage visual cortex to help represent to-be-remembered information (i.e., during working memory), and (iii) whether the theta-rhythmic coordination of neural activity provides a general mechanism for avoiding functional conflicts during cognitive processes. Dysfunctions of attention and working memory are markers of common disorders, such as attention-deficit/hyperactivity disorder (ADHD). By investigating how the brain typically balances the sampling of information from the environment and internal memory stores, we will provide important insights to help the development of effective treatments for these disorders.
