CORTICAL PROCESSING OF NATURALISTIC EXPERIENCES
Unlike real-life experiences, cortical processes are investigated too often with the application of context-free single and brief stimuli. Our research on naturalistic experiences comprises two important areas: pain processing and reading. A headache usually lasts much longer than a few seconds and a word is generally embedded into a sentence, a paragraph or an entire book. What matters to the individual is that we might be pleased with sentences that we master to read without difficulties, and we are also pleased with decreasing pain.
We are using neuroimaging (MRI) and neurophysiology (EEG) to study the neuronal processes involved in the domains of pain and reading.
- Which cortical processes generate a subjects’ individual and stable percept of pain; we aim to find the cortical processes that represent different levels of pain intensity. Gamma oscillations have been suggested to contribute to the experience of long-lasting pain but does that apply to all pain patients and to all healthy subjects?
- We are worried when pain starts to intensify and we are relieved when pain declines. These processes demand particular attention. Which brain processes represent pain relief? These are the processes that might be targeted in future therapeutic interventions.
- To investigate long-lasting pain, we developed a new software controller that regulates the intensity of subjective pain. We avoid habituation and sensitisation and deliver the right amount of pain throughout the time course of the experiment.
- In real life, we read to extract meaning from text. However, some words are difficult to read. The context can help to better recognise the words from the universe of existings words. Brain imaging can reveal the bottleneck of reading fluency. Where in the brain are the processes that make reading slower?
- Individuals with reading impairment are worried about the lack of reading proficiency that hampers to acquire much needed information, e.g. from books. These processes can be unique for an individual. No wonder there is a number of competing theories on reading impairment.
Neurofeedback (NFB) training is a particularly promising and innovative approach to self-management that aims at attenuating the suffering from pain. Using NFB, one learns from one’s own brain activity how to modulate future brain activity.
- We aim to develop an individually tailored neurofeedback training for chronic pain patients. Our current project on the stability of pain measures is the first step toward this direction. Besides the investigation of cortical processes that are common to all patients, a particular focus should be placed on the unique neuronal processes of each individual.
- This aspect is tightly connected to the idea that each individual has a unique pattern of brain activities involved in the processing of pain, i.e different brain regions (fMRI) or frequency bands (EEG). Related to the concept of the “individual signature for pain”, those processes are hypothesised to be stronger and more reliably assessed on the individual level than on group level.
Video by courtasy of Dr Enriquez-Geppert
ARTEFACT CORRECTION OF EEG DATA
Muscle artefacts are a major problem for the analysis and interpretation of neuronal oscillations.
- Particularly for the analysis of brief painful stimuli muscle twitches as a “response” to the painful stimulation have been misinterpreted and published as neuronal activity. Inspired by Judith Nottage from UCL, we developed our own method to deal with muscle artefacts.
- The biggest challenge is to detect the spikes but it’s much easier in ICA data; a removal of the many spikes is now relatively easy with the help of Gabor functions but needs some computational power.
In this example, the IC is mainly driven by the signal from electrode FT7. The muscle spikes are removed with razor-sharp precision.