Igor Branchi

Nature is a continuum of living and nonliving systems from the microscale to the macroscale that are interdependent and dynamically interact with each other. Approaching such complexity by identifying its levels of organization and the associated regularities would significantly impact both the scientific and philosophical inquiry. Here, the interface of complex systems, that is the structures and activities that allow the functional interaction between the system and its context, is discussed as a pivotal concept for understanding the levels of organization in life sciences. Interfaces are ontological identifiable entities that have unique properties as they (1) are a privileged level of control over complex systems, (2) provide a level of analysis with high regularity and predictability, and (3) represent a boundary between types of causal relationships occurring within and outside a system. This theoretical framework entails not only theorical but also applied implications that, on the one hand, may promote the comprehension of the brain-mind interplay and, on the other, may pave the way for novel therapeutic strategies for mental disorders. While the discussion on the interface is here primarily focused on the neuroscience and psychiatric fields, this conceptual tool is expected to be applicable to complex systems across disciplines, from biology to economics.

Notwithstanding the huge progress in molecular and cellular neuroscience, our ability to understand the brain and develop effective treatments promoting mental health is still limited. This can be partially ascribed to the reductionist, deterministic and mechanistic approaches in neuroscience that struggle with the complexity of the central nervous system. Here, I introduce the Context theory of constrained systems proposing a novel role of contextual factors and genetic, molecular and neural substrates in determining brain functioning and behavior. This theory entails key conceptual implications. First, context is the main driver of behavior and mental states. Second, substrates, from genes to brain areas, have no direct causal link to complex behavioral responses as they can be combined in multiple ways to produce the same response and different responses can impinge on the same substrates. Third, context and biological substrates play distinct roles in determining behavior: context drives behavior, substrates constrain the behavioral repertoire that can be implemented. Fourth, since behavior is the interface between the central nervous system and the environment, it is a privileged level of control and orchestration of brain functioning. Such implications are illustrated through the Kitchen metaphor of the brain. This theoretical framework calls for the revision of key concepts in neuroscience and psychiatry, including causality, specificity and individuality. Moreover, at the clinical level, it proposes treatments inducing behavioral changes through contextual interventions as having the highest impact to reorganize the complexity of the human mind and to achieve a long-lasting improvement in mental health.

Despite the huge and constant progress in the molecular and cellular neuroscience fields, our capability to understand brain alterations and treat mental illness is still limited. Therefore, a paradigm shift able to overcome such limitation is warranted. Behavior and the associated mental states are the interface between the central nervous system and the living environment. Since, in any system, the interface is a key regulator of system organization, behavior is proposed here as a unique and privileged level of control and orchestration of brain structure and activity. This view has relevant scientific and clinical implications. First, the study of behavior represents a singular starting point for the investigation of neural activity in an integrated and comprehensive fashion. Second, behavioral changes, accomplished through psychotherapy or environmental interventions, are expected to have the highest impact to specifically reorganize the complexity of the human mind and thus achieve a solid and long-lasting improvement in mental health.