Neural Mechanisms of the Representation, Prioritization, and Manipulation of Visual Working Memory

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In order to perform many everyday tasks, such as driving down a busy street, it is necessary to hold information in mind “on-line” when it is no longer in view. The cognitive process responsible for holding information in memory for short periods of time is referred to as visual working memory. This ability is extremely limited, however; it is not possible to hold an unlimited amount of information in visual working memory. Consequently, previous studies have demonstrated that when you hold more information on-line, the quality of the information maintained becomes quite variable: that is, while some memories are very detailed, others have very low-resolution. Our past work has established that selectively attending to some items predicts how well people will remember that information. Attention “biases” memory, and this biasing of memory by attention appears to provide an explanation for why memory performance decreases when more items have to be remembered: when many items have to be remembered, attention is split across all items, and memory performance suffers. The current proposal builds on our previous research, and aims to identify the neural mechanisms that support the top-down biasing of visual working memory by attention. In particular, we are using fMRI and EEG and measure neural activity while healthy young adults perform visual working memory tasks, in order to understand how the brain can use attention to select and enhance the memories for some visual objects. We are also using TMS to causally disrupt brain functioning in areas thought to support this process, so that we can more accurately identify their role in this behaviour. Finally, we are also going to examine whether the process of selecting and enhancing some items in memory is similar to the processes involved when performing manipulations on the contents of memory (e.g., if you have to rotate an object in your mind). This research is important to people who study the brain, such as psychologists, neuroscientists and neurologists, as it will better help us understand how the brain supports short-term memory for visual objects. In particular, because this process is so limited, it will help to clarify how the brain manages to cope with these limits on information processing. By better understanding how the brain works, this research may help inform how behavioural interventions can support individuals who may suffer from short-term memory impairments.