The neural mechanisms of precision in visual working memory



 DESCRIPTION (provided by applicant): Visual working memory (VWM) is essential for our ability to maintain information about stimuli that are no longer in direct view. In daily life, we ely on this skill to maintain relevant information about objects in our environment and to facilitate action planning. Importantly, the complex neural mechanisms that support visual working memory are not yet well characterized, and careful research in this area is critical for understanding how the healthy human brain actively maintains precise visual information in memory. Interestingly, the precision with which visual information can be encoded, maintained, and retrieved from VWM varies considerably between healthy individuals, and even from trial to trial within a single individual. Previous research has shown that the lateral prefrontal cortex (PFC) and higher-order visual areas like the fusiform face area (FFA) are involved in the encoding and maintenance of face stimuli in VWM. However, it remains unclear how these areas interact to support the precise maintenance of VWM representations. Therefore, the goal of the proposed research is to determine how complex visual objects are maintained with high precision in VWM, and to identify potential neural mechanisms responsible for VWM failures and imprecision. Using diverse behavioral, functional magnetic resonance imaging (fMRI), and concurrent transcranial magnetic stimulation - fMRI approaches, the proposed set of experiments will investigate the nature of VWM representations for faces, and the mechanisms by which those representations are maintained with high precision over time. More specifically, the following hypotheses will be tested: (1) a stimulus-selective visual area such as the FFA supports precise VWM by maintaining perception-related activity when a visual stimulus is no longer present, and (2), that the lateral PFC provides top-down inputs to, or engages in interactions with, stimulus-selective areas that aid in sustaining the precision of VWM representations. This research is relevant to public health because it will advance our understanding of the respective roles of temporal visual areas and the frontal lobes in VWM. Many psychiatric and neurological disorders such as schizophrenia, dementia, stroke and traumatic brain injury affect frontal and/or temporal lobe function; and many other conditions such as attention-deficit disorder, substance addiction, and normal aging are proposed to involve selective dysfunction of frontal brain systems. The proposed research will lead to basic knowledge about healthy brain function that can provide valuable insights into the understanding, diagnosis and treatment of a wide range of clinical conditions.