Dynamic Range of Neurofeedback
Neurofeedback (NF) is an operant conditioning that allows subjects to control their brain activity.
Regardless of the abandonment of the first years, recently the scientific community has presented a
renewed interest in NF. One of the technologies most commonly used to perform NF is the
electroencephalogram (EEG), which records electrical fields generated by the synchronous activation
of a neurons population.
NF as been applied as a complementary therapeutic tool in a wide clinical conditions. It has been
also applied in healthy subjects to improve their performances, from sport to music. However,
methodological differences exists between authors.
A better understanding about the working mechanisms of NF is still necessary and this work aims
to explore a new hypothesis through the dynamic range. The dynamic range refers to the variation in
amplitude of brain waves recorded in EEG, i.e., the lowest and highest amplitude possible to achieve.
A complementary goal is the study of the cumulative or cancellation effects of the dynamic range on
behaviour. NF will be used in this work to enhance and to suppress individual alpha band (IAB)
amplitude in the vertex. For that purpose twelve volunteers were randomly divided in two groups. One
group performed a NF protocol to enhance their IAB amplitude followed by a NF protocol to suppress
their IAB amplitude; between each protocol there was a pause of about one month. At the same time,
the other group performed the same protocols but in an inverse order.
The results obtained revealed that both groups were able to perform successfully NF in both
directions. The results of performance tests revealed improvement in mental rotation accuracy in the
first protocol performed by each group. However, only the group that performed first the enhancement
protocol revealed improvement in response time of mental rotation test. After the intervals and after the
opposite protocol, there were no significant changes in tests. This reveals that the improvements were
maintained over time and after the opposite NF training.
In conclusion, the proposed objectives were achieved, nonetheless, further work should be done, in
particular to increase the number of subjects to participate in the experimental study