A new study by Michelmann et al. (Hanslmayr lab) published in PLoS Biology reveals the neural mechanisms that enable our brains to replay videos and sounds experienced in the past. In their study, Michelmann et al let subjects encode short video and sound clips and asked them to mentally replay these later. Using temporal pattern similarity analysis the authors show that the phase at 8 Hz carries a temporal signature of the replayed stimulus. This replay is linked to a decrease in power (i.e. desynchronization) in the same frequency range. This study is the first to reveal a domain general neural mechanism which underlies the replay of dynamic memories.
A new study from the Hanslmayr lab published in the Journal of Neuroscience has shown that retrieving memories of events from our past may take place quicker than we previously thought – and it is possible to interfere with that process. The process of retrieving episodic memory, personal experiences that require revisiting sensory information received in the past, was believed to be a relatively slow process in the brain – taking around half a second. Using electroencephalography (EEG), which monitors neural activity with a high time resolution, the team showed that episodic retrieval starts with a very rapid reactivation of sensory brain areas. The findings provide the first neural evidence for this early sensory activation, and show that it actually takes between 0.1 and 0.2 seconds to recall the event. Furthermore, the initial activation of sensory brain areas was shown, for the first time, to be causally relevant for conscious remembering using TMS.
How does the brain transform brief experiences into lasting memory traces? Dr. Staresina has been awarded the prestigious Sir Henry Dale Fellowship, conjointly funded by the Royal Society and the Wellcome Trust, to investigate episodic memory processes during post-learning offline periods. These time windows (entailing both sleep and awake rest) appear to constitute a critical period for new memory traces to solidify. Dr. Staresina’s research will employ intracranial Electroencephalography (iEEG), high-field functional magnetic resonance imaging (fMRI) and transcranial electrical stimulation (tES) to systematically elucidate how the hippocampus, a key region for intact memory, processes previous experiences during offline periods and re-distributes them throughout the brain in the service of successful memory formation.
Dr Sarah Aldred attended the Cell symposia meeting in Amsterdam this week where Henriette van Praag spoke about Exercise, adult hippocampal neurogenesis and spatial memory.
It was an excellent presentation where Henriette reminded us all that exercise stimulates neurogenesis. She presented wonderful data showing how her work has evaluated the neurogenesis in the medial and lateral entorhinal cortex and the impact this has on spatial memory.
Kobilo T1, Liu QR, Gandhi K, Mughal M, Shaham Y, van Praag H. Running is the neurogenic and neurotrophic stimulus in environmental enrichment. . Learn Mem. 2011 Aug 30;18(9):605-9. doi: 10.1101/lm.2283011.
Dr Jonathan Lee has recently begun a new £605k grant funded by the Medical Research Council. The focus of the project will be on instrumental cocaine memory reconsolidation. We will be building on our recent work showing that instrumental sucrose memories (the memories that support a rat pressing a lever for a sucrose reward) do undergo reconsolidation, and so can be impaired to reduce reward-seeking. The new project will seek to translate these findings to models of cocaine addiction, in order to test whether such an approach can reduce relapse to cocaine seeking. Dr Marc Exton-McGuinness has returned to Birmingham in order to lead the research on this project.