Cortical oscillations
Cortical oscillations (med. Cortical, starting from the cerebral cortex), (from the Latin oscillare “to swing”, “to sway”, “to rock”) are rhythmic electrical potentials in the brain areas that have to synchronize in order to exchange information. They are involved in the perception of music and language, and in the recognition of sequences and processes.
Functions
The cortical oscillations are mainly used to process external stimuli, i. General Sounds, language, etc. Such rhythms in the brain are very precisely synchronized with language in order to make it possible to understand a continuous flow of language. Such cortical oscillations also play an important role when processing complex sound patterns such as music. According to studies, the vibrations are also subject to learning processes because they differ between musicians and non-musicians. The musicians managed to adapt to the tone structure of the music much better. They achieved harmony much faster than the non-musician test subjects.
- The study, which appeared in the journal Proceedings of the National Academy of Sciences (PNAS), sheds new light on the importance of cortical oscillation for the recognition of musical sequences. They were able to isolate the rhythms in the brain that matched the tempo in the music they were listening to. The findings showed that the presence of these rhythms improved our perception of music and changes in pitch. It was found that musicians have more pronounced oscillations than non-musicians. This shows that one can train to use the auditory perception system more efficiently. Previous studies have already shown that rhythms in the brain are very precisely synchronized with language and thus help us to understand a continuous flow of language. The resonance ensures that we can perceive syllables, words and sentences as such in the spoken language. Even if they are not separated from one another by spaces or punctuation marks, as in the written form. So far, however, it was not known what role these rhythms play in the brain in processing other complex sounds such as music. To answer this, magnetoencephalography was used. It measured tiny magnetic fields that are generated by brain activity. Study participants were asked to identify small changes in pitch. Those that could be heard in 13-second long excerpts from classical piano pieces (Bach, Beethoven, Brahms) and that differed in terms of tempo, from half a note to eight notes per second. The scientists divided the participants into musicians (at least six years of musical training and actively practicing) and non-musicians. For music that consisted of more than one note per second, both musicians and non-musicians showed cortical oscillations that synchronized with the speed of the notes in the piece being heard. From this, the scientists conclude that these oscillations ensured that all participants processed the sounds they heard. However, there were differences, as the musicians came in tune with the beat of the music much faster and especially with unusually slow pieces. The neural rhythm of the brain seems to play a role in the analysis of sound currents and their division into larger units, which are then perceived as language or music.
- In further investigations of the auditory memory, using magnetoencephalographic auscultation, the procedures suggested that in the auditory system, similar to the visual system, spatial and pattern-related information is processed in separate dorsal and ventral paths. A number of studies have shown that changes in the position of a noise source lead to increased oscillatory activity. In the gamma band (approx. 30–100 Hz), a higher stress on the parietal regions was measured. Whereas changes in acoustic patterns, over the temporal lobe, and lower prefrontal cortex were accompanied. Spatial and pattern-related short-term memory studies were carried out as a result of questions relating to memory in certain brain regions. Healthy test subjects each had to assess the identity of two acoustic stimuli (S1 and S2) with an interval of 0.8 seconds. When S1 sound position impressing was claimed, gamma-band activity was increased over the left posterior parietal lobe. If, on the other hand, the patterns of syllables were noticed, increased oscillatory activity occurred in the lower prefrontal cortex. In addition, prefrontal networks were activated in both studies. The best temporal representation of the retention of information in memory was the synchronization between the auditory parts and the prefrontal cortex. These findings showed that retention in short-term memory goes hand in hand with dynamic links between sensory areas and frontal executive networks.
Studies
- Eberhard Karls University
- Max Planck Institute for Empirical Aesthetics
