Good sleep can do us so much good. But you might not know that while you sleep and go into something called sleep spindle periods, our hard working brain keeps working on all the data we absorb during the day to be filed away in memory. Sometimes referred to as “sigma waves,” sleep spindles typify duration’s where the brain is suppressing activity to keep the sleeper in a tranquil state. Combined with K-complexes they are tell tale characteristics of, and signal the onset of, stage 2 sleep. Sleep spindle activity has been correlated with the transition of new information into existing knowledge along with the management of recollecting and forgetting. Trying to remember the name of an actor for example and waking up and knowing the answer is a great example of the management of recollection that occurs during sleep.
Scientists at the Center for Cognition and Sociality have completed the first study to show that manipulating sleep spindle oscillations at the right time affects memory (at least in mice). The experiments, carried out in alliance with the University of Tüebingen, focused on slow wave deep sleep associated with memory formation, instead of REM sleep, which is connected with dreaming. The researchers focused on spindles because it has been demonstrated that the amount of spindles rises following a day packed with studying and diminishes in the aged, and in patients with mental disorders like schizophrenia. This is the first study to show that simulated thalamic spindles affect memory, if dispensed concurrently with slow oscillations.
The details of the experiment were a bit on the cruel side involving giving mice a mild electric shock after hearing a tonal noise. Placing the mice in the same setting, the researchers tested whether the mice remembered the tone confirmed by them being frozen in fear to get a memory baseline. By escalating or reducing the number of overnight spindles it was possible to manipulate mice to remember or forget their traumatic experience.
The research team concludes in the paper published in the journal Neuron, that the thalamus seems to negotiate the data exchange between hippocampus and cortex. The hippocampus is like a station, where bundles of information are filed correctly within the brain. The destination of this filed information is often the cortex where information is filed away as long-term memory. While many questions remain on whether this technique will be useful in targeting forgetting specific memories for example, it could potentially help people with poor memory issues if this research can be translated to humans.
- Tamminen, J.; Payne, J.D.; Stickgold, R.; Wamsley, E.J.; Gareth Gaskell, M. (2010). Sleep spindle activity is associated with the integration of new memories and existing knowledge. The Journal of Neuroscience, 30(43), 14356–60
- Saletin, J.M.; Goldstein, A.N.; Walker, M.P (2011). The Role of Sleep in Directed Forgetting and Remembering of Human memories. Cerebral Cortex, 21, 2534–2541