In his essay on The Normal and the Pathological (Canguilhem, 1991), Canguilhem undertook to make a fervent critique of Broussais’ principle according to which, a pathological state would be a modification in the normal state that could be understood in purely quantitative terms. Canguilhem’s theorisation of a qualitative approach to the individual who is in a state of morbidity, although not referring specifically to psychoanalysis, is nevertheless rich in possible links to Freudian psychopathology.In this article we will begin by questioning the meta-psychology of the normal and the pathological, from the stand point of the problematic of a possible continuum, reduced to a purely quantitative understanding, of the pathological processes. We will then go on to study what changes recent discoveries in neurosciences have introduced to the problematic of the qualitative and the quantitative in psychopathology. Although advances in genetics and neurobiology have linked a dysregulation of the dopamine system to schizophrenia, thus reintroducing a quantitative measure where for Canguilhem there was no measurable and objective criteria for psychopathology, we propose investigating how research on neuronal plasticity – in the wake of by the Nobel prize for medicine given to Eric Kandel – makes it possible to reintroduce the problematic of the qualitative into these considerations.