One of the most fascinating characteristics of human nature is our ability to experience ourselves as a self and person. However, because we have no direct access to our brain in experience, the link between brain and self, and thus between mental and neural states, remains unclear. Recent imaging studies suggest that cortical midline structures (CMS) may be involved in the neural processing of self, but the exact physiological and psychological mechanisms required to provide a mental-neural link have yet to be elucidated.
Our prior work focuses on the relationship between CMS, emotional processing, and self-related processing in both healthy and psychiatric subjects using various imaging techniques. In addition, the implications of these findings for philosophical problems such as the mind-brain relation, personal identity, and our brain-based knowledge apparatus have been explored.
Our aim is to investigate the link between mental and neural states, as well as how our brain constitutes the experience of a self. For this purpose, we integrate neuroscientific, neuropsychiatric and neurophilosophical approaches. We investigate the biochemical underpinnings and neurochemical mechanisms underlying neural activity changes during consciousness and the experience of self, and try to link them with observations at the psychological level. This combination of investigative strategies will help lead us the knowledge required to develop diagnostic and therapeutic tools, in particular for depression and schizophrenia.
Neuroscientific approach: The distinct components of subjective emotional experience (attention, feeling, judgment, observation, etc.) and of the experience of self are investigated in imaging studies using fMRI, PET, DTI, EEG, MEG, and TMS. These investigations are combined with neurochemical studies focusing on the measurement of metabolites (such as GABA and glutamate) in MRS and neurochemical challenge with GABAergic or glutamatergic substances. The imaging results provide the basis for the development of empirically realistic neural network models.
Neuropsychiatric approach: These mechanisms are also investigated in patients suffering from emotional disorders such as depression or anxiety, along with those who experience alterations in the self. Such investigations help to reveal the causes of these conditions, the knowledge of which is vital to the production of new treatments. In addition, an understanding of the alterations in brain function that underlie such changes in an individual's experience of self is an important component in the understanding of the link between the mind, brain and self.
Neurophilosophical approach: Our empirical studies require an epistemic, ontological and ethical reconsideration of the link between the self and the brain. They consequently also have implications for philosophical problems such as the mind-brain relationship and ”the self“. Most importantly, we aim to develop empirically plausible definitions of mental states (e.g. qualia), the self, and the mind-brain relationship. In addition, new developments in neuroscience and psychiatry that enable us to manipulate our mental states, the self, and our personal identity in novel ways call for clarification of the concepts involved and discussion of corresponding ethical issues.
Vision for the Future
Our vision is to reveal the key mechanisms that underlie the generation of mental states and the self. Insight into the physiology and psychology of CMS may elucidate specific functional principles underlying the link between mental and neural states, and thus between the self and the brain. Neuroscientific investigation into the subjective experience of the self may substantially improve our understanding of the underlying neuronal mechanisms in both healthy and psychiatric subjects. In addition, a translational approach – investigating the function and neurochemistry of cortical and subcortical midline structures in animals – will allow for a more in-depth understanding of these mechanisms. The combination of imaging, translational studies, network modelling and neuromonitoring may open the door for the development of reliable diagnostic markers and novel therapeutic interventions. Insight into the link between neural and mental states bears profound implications for understanding human nature, which in turn requires the development of neuroepistemology and neuroethics. As a result, this neurophilosophical approach may enrich and complement historic and current philosophical and ethical discourse.