Neurocognitive mechanisms of task representation reorganization during task learning

Project Summary/Abstract Humans possess extraordinary flexibility in our behavior: Given the same environmental input, we can act differently depending on our goals and the context. For example, when facing the same data, we can process them differently depending on our goals (e.g., visualize the data to obtain a figure, perform statistical analysis to test a prediction, or even delete the data if the goal is to free storage space). To date, research on this topic has focused on how such flexible behavior is implemented via cognitive control, which is a set of cognitive mechanisms supporting goal-directed and top-down modulation on information processing in the brain. In other words, much research has been conducted to study how a task is executed. However, less is known about where such task knowledge is from, that is, the mnemonic mechanisms that encode, reinforce, and generalize the neural representations of task knowledge. Understanding these mechanisms is crucial to fully understand human intelligence, as the remarkable abilities of learning and retaining task knowledge promptly and efficiently distinguish humans from other animals and artificial intelligent agents and make us adaptive to this ever-changing world. Furthermore, filling the knowledge gap of how we learn and remember task knowledge is also key to understand, detect and treat task learning deficits that are common in mental disorders such as schizophrenia and attention-deficit / hyperactivity disorder (ADHD). In this project, we will focus on the hippocampus, a central brain structure for learning and memory. To achieve the objective of uncovering the hippocampal contributions to task learning, six experiments are proposed using a combination of behavioral methods and human functional magnetic resonance imaging. Specifically, Aim 1 will identify hippocampal contribution to constructing a task representation by assembling task information and experiences to build a task model. Aim 2 will identify how the hippocampus encodes a new task representation into a memory network of existing representations. Aim 3 will identify how the hippocampus reshapes existing task representations when they become associated with other tasks via compositional relations. This work is expected to identify how the human hippocampus constructs key content of task representations (Aim 1) and organizes multiple task representations in relation to each other (Aim 2 and 3). These findings will further our understanding of how the hippocampus contributes to task learning, cognitive control and adaptive behavior. This work will also have clinical impact in bridging the gap between hippocampal abnormality and task learning deficits, which were separately observed in mental disorders such as schizophrenia and ADHD. Ultimately, this work will have a broad impact in helping detect and treat task learning deficits.