Working memory is our ability to hold information in mind, for short periods of time. It can be disrupted by almost any brain problem. It has been difficult to pinpoint where and how such immediate memories are held.
We study short-term visual memories, measuring our memory capacity, how memories decay, and are disrupted by irrelevant information.
- Recently we have developed a neural model of working memory, proposing a very simple network. It is unlike previously proposed mechanisms, because it suggests that the patterns of brain activity do not correspond to what we are remembering. Rather, rapid interference leads to highly variable — but predictable — codes in prefrontal cortex. “Neural mechanisms of attending to items in working memory”, Manohar et al., Neuroscience and Biobehavioral Reviews (2019). Recordings from single neurons in prefrontal cortex show signatures consistent with this variable coding. “Neural signature of flexible coding in prefrontal cortex” Bocincova et al. PNAS 2022. This same network model can, without any modification, perform visual search! “A common neural network architecture for visual working search and working memory”, Bocincova et al. Visual Cognition (2020).
- We have shown that motivation can improve some aspects of memory performance, but the capacity itself appears to be strictly limited. “Motivation improves working memory by two processes: Prioritisation and retrieval thresholds”, Grogan et al. Cognitive Psychology 2022.
- Working memory may be important for keeping information online when we perform reinforcement learning. “Working memory as a representational template for reinforcement learning”, Shibata et al. Scientific reports 2024.
- Attention in working memory can be improved by increasing acetylcholine in patients with Lewy body disease. “Effects of cholinesterase inhibition on attention and working memory in Lewy body dementias”, Fallon et al. Brain Comms 2023. In contrast, dopamine alters our ability to change information we are already holding in memory. “Mechanisms underlying corruption of working memory in Parkinson’s disease”, Fallon et al, J. Neuropsychology 2023
- Patients with a rare antibody that disrupts NMDA receptors have specific impairments in combining information in working memory “N-methyl-D-aspartate receptor-antibody encephalitis impairs maintenance of attention to items in working memory” Dor et al. J. Neuroscience 2024. We can characterise these patients using the profile of psychiatric symptoms. “The psychopathology of NMDAR-antibody encephalitis in adults: a systematic review and phenotypic analysis of individual patient data”, Al Diwani et al. Lancet Psychiatry 2021