Stability of individually unique signatures of chronic pain encoding in the human brain

• Applicant: Dr. Enrico Schulz, Ph.D.
• Subject Area: Clinical Neurology; Neurosurgery and Neuroradiology
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 332807080

Chronic pain develops into a complex disease that is often associated with a variety of emotional, social, physical and cognitive conditions. The complexity of symptoms and individual suffering is reflected by a maladaptive pattern of neuronal activity in the human brain. Besides the administration of drugs, active self-management strategies can increase the capability to cope with many aspects of the pain disease. One of these self-management strategies, neurofeedback (NFB) training, has also been applied to influence the maladaptive neuronal pattern in chronic pain. NFB training with means of or real-time functional Magnetic Resonance Imaging (fMRI) or Electroencephalography (EEG) aims to modulate brain activity by providing a patient with the quantified signal of its own cortical processes. However, previous studies to alleviate pain with NFB were lacking a solid theoretical foundation, could not replicate their findings or were just not able to reduce pain intensity. In order to make real progress in alleviating pain we must overcome the disadvantages of the previous attempts.To generate a useful feedback signal, it is required to explore a subject's entire pattern of pain-related brain activity. However, due to the low signal-to-noise ratio (SNR) of the current techniques to measure brain activity, the assessment of cortical processing of a single subject is prone to false positive results and may also neglect potentially important processes. A NFB intervention would require to tackle rather stable and reliable processes.The objective of the present study is to characterise these subject-specific and reliable patterns of neuronal activity that relate to the encoding of chronic pain intensity. The relevant neuro-oscillatory (EEG) or neuro-metabolic (MRI) processes that encode the experience of pain for a single pain patient will be determined in repeated sessions. Besides the investigation of cortical processes that are common to all patients, a particular focus is intended to be placed on the unique neuronal processes of each individual. The encoding of pain intensity in the human brain for a single subject in a future assessment is hypothesised to have a tighter relationship to their own previous data rather than to results obtained by group statistics. Also, the within-group variability is assumed to be larger than the variability between the groups of pain patients.We will illuminate those pain-related cortical processes that are usually neglected by group statistics. By weighing and integrating all processes that are important for an individual, a pilot NFB study will be conducted by means of the technique that promises utmost success (EEG or fMRI). The assessment of individually unique cortical processes that encode the intensity of endogenous pain will provide a suitable foundation for a future NFB study.

• DFG Programme: Research Grants