PROGRAM

13:00: Opening by the Moderator Prof. Thomas Graven-Nielsen

13:05: PhD lecture by Luisina Gregoret

13:50: Break

14:00: Questions and comments from the Committee

15:30: Questions and comments from the audience at the Moderator’s discretion

16:00 Conclusion of the session by the Moderator

EVALUATION COMMITTEE

The Faculty Council has appointed the following adjudication committee to evaluate the thesis and the associated lecture: 

Prof. Nadine Attal, PUPH de thérapeutique médecine de la douleur INSERM U 987 et CETDCHU Ambroise Paré, France
Prof. Massimiliano Valeriani, Director of Developmental Neurology Unit, Ospedale Pediatrico Bambino Gesù, Italy
Dr. Andrew Stevenson, HST, Aalborg University, Denmark (Chairman).
Moderator: Prof. Thomas Graven-Nielsen, Health Science and Technology, Aalborg University

ABSTRACT

Chronic pain affects to approximately 1 every 5 adults worldwide impacting directly on their physical, mental, and social well-being. Given that the assessment and treatment of pain disorders is challenging when co-morbidities are involved, surrogate models of prolonged pain are central to understand the time course and degree of sensitization during pain progression, its link to baseline pain-free states and the response to potential therapeutical interventions.­­

One of the most frequently investigated noninvasive brain stimulation (NIBS) interventions to modulate pain-induced plasticity is transcranial direct current stimulation (tDCS). Classical single site tDCS of the motor cortex (M1) reveals, however, mild therapeutical effects and sparse pain relief. Since brain regions do not operate isolated but interact with other regions through various excitatory and inhibitory projections, an arising research venue targets brain networks through multifocal tDCS. Multifocal tDCS stimulates multiple and distant areas over the scalp simultaneously to potentially promote advantageous plasticity for substantial recovery. Specifically, following multifocal tDCS of the motor network (network-tDCS), it has been reported a higher modulatory effect on corticomotor output in comparison to classical tDCS montages. The neurophysiological and psychophysical effects of this montage are, however, not fully studied.

The main objective of this PhD project is therefore to study and characterize the time course of cortical excitability and psychophysical responses after multifocal tDCS of the motor network while experimental pain progresses over the course of 24 hours.

The results of the first study indicate that prolonged pain reduces conditioned pain modulation expression and corticomotor output while active network-tDCS normalizes such responses, compared to sham. The results of the second and third study show that prolonged pain inhibits the amplitude of sensory evoked potentials and the frequency of alpha oscillations, respectively, whereas active network-tDCS increases such cortical reorganization, compared to sham.

In conclusion, the results of this PhD work display that network-tDCS can modulate the consequences of prolonged pain on neurophysiological outcomes and the descending pain inhibitory function otherwise reduced after 24-hour experimental pain