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Improving memory with magnetism


So the main topic of this study is to
understand the causal relationship between brain oscillations that are rhythmic
fluctuations of brain activity and behavior. To the same we have started
to identify these oscillatory markers in the human brain and those markers that
are related to a certain task. We use the spatial and temporal resolution of the
energy to localize during the retention period of the task the brain areas that
were involved in this in the behavior and task performance and more
particularly this parietal region that seemed to be involved and showed
activity in the five Hertz range which was both the target for anatomy and for
rhythmic stimulation with TMS. In the first stations we were doing the MEG-EEG recording. So by combining those two methods we had access to the brain
marker so the oscillations but also the network of interest where those
oscillations match. To define the network of interest we use two different paths I can show you here. One is a simple task where participants listen to
two melodies, so first melody, a silence and a second melody. We have to say
the melodies are the same editions. In the second part the participants were
stimulated with TMS while recording the EEG as well and this
combination allowed us to explore whether the TMS with the untrained brain
oscillation if we boost those oscillations so the amplitude and also the phase of
those oscillations with the stimulation so it produces a manner of controlling and
the effects of the stimulation. Then we observe that theta activity for 5 hertz during the redemption period when you are manipulating information in
memory emerges more in the manipulation tasks
and in comparison to the simple task but what was really interesting is that
this theta activities predicts participant behaviour and performance. Meaning that the more Theta
the brain is generating during this retention period the
better the participants are doing the task. In terms of behaviour we made the
link because a link between those theta oscillations and behavior
with the stimulation by showing that the stimulation, rhythmic or arrhythmic, did
not change anything for the simple task where you don’t have to manipulate
information. But for the manipulation task
the benefits in terms of performance was observed mainly for the rhythmic
stimulation and only for this one. So it makes a link between ongoing oscillations that are already present and if you are able to entrain those oscillations we can specifically boost participants
performance on the given task. Another important aspect is that
the link between this entrainment and the behavior was that the better the
brain was entrained are compared to the first day the better the behavioral benefit. The bigger was the behavioural benefit. The key insight here is not only that we
can modulate memory circuits via the stimulation but also that we are
beginning to understand how that modulation works so not only will be
able to demonstrate the improvement in the capacity to retain auditory
information for a few seconds but also we saw that there were changes in the
brain oscillations that accompanied that enhanced ability. So that tells us
something about the underlying mechanism it tells us something about how it is
that the brain stimulation actually causes people to enhance their working
memory capacity.

Glenn Chapman

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