The fields of psychoanalysis and neuroscience use different methods of description, analysis and comprehension of reality, and because each is based on a different methodology, each approach constructs a different representation of reality. Thus, psychoanalysis could contribute to a general psychology involving neuroscience to the extent that a "psychoanalytical psychology" (the theory of mental functioning that is extrapolated from psychoanalytical practice) defines natural objects of study (mind functions) for a multidisciplinary approach. However, the so called "naturalisation" of psychoanalytical concepts (metapsychology) does not imply the reduction of these concepts to biology; rather, it suggests a search for compatibility between psychoanalytical concepts and neuroscientific description. Such compatibility would mean the search for common objects that could be described from either a psychoanalytic or a neuroscientific point of view. We suggest that inter-subjectivity, empathy or "co-thinking" processes, from early development to the psychoanalytic relationship or the interaction between the patient and the analyst, could be such a common object for cognitive social neuroscience and psychoanalysis. Together, neuroscience and psychoanalysis could then contribute to a multidisciplinary approach of psychic inter- or co-activity.