espanolEl Proyecto de Psicologia para Neurologos constituye el mas energico intento de Freud de formular un modelo de funcionamiento psiquico en el marco de las Ciencias Naturales. Asi, estudia la composicion del sistema mental llegando a diferenciar la existencia de tres subsistemas neuronales y analiza los avatares de la cantidad Q, esencia de la dinamica psiquica y fundamento de la organizacion Yoica. El proposito de este trabajo es explicitar el uso de los conceptos provenientes de la Fisica de su epoca y la forma que tomaron en el Proyecto. Se presentan cuatro ejes: (1) La nocion de sistema, estado y cambio de estado, para analizar las proposiciones metateoricas. (2) La sustentacion de la dinamica psiquica en el primer y segundo principio de la Termodinamica. (3) El simil de las nociones electrodinamicas en el funcionamiento del aparato psiquico. (4) El estudio de las caracteristicas ondulatorias como sustento del tercer subsistema neuronal del modelo. EnglishThe Project for a Scientific Psychology is Freud's most forceful attempt to formulate a model of psychic functioning within the framework of the natural sciences. In order to do this he defines the psychism as a system constituted by specifiable material particles, the neurons, particles subject to changes ofstate according to an operator of change of state conceived as an amount (Q) and on which the laws of Newton validly operate. In this way, he studies the composition of the mental system, differentiating the existence of three neuronal subsystems (Fi, Psi and Omega) and analyzing the avatars of the quantity Q as a state change operator, which is essentially the motor of the Psychic dynamics and foundation of the Ego organization organization, taking this organization as a particular state of the distribution of Q in the system. The purpose of this work is to make explicit the use of the concepts coming from the physics of that time and the form they took in the Project. This paper presents four axes: 1) The notion of system, state and change of state. Freud advocates for a Psychology defined as natural science as capable of representing phenomena as quantitatively determined states of specifiable material particles. The system issubject to state changes according to a physical and measurable change ofstate operator, which corresponds to the notion of quantity (Q). 2) The support of psychic dynamicsin the first and second principles of thermodynamics. The tendency described in the Project as an impulse to the discharge of the neuronal tension to zero, is heiress of a model constructed according to the first two principles of the thermodynamics. The notion of the general irreversibility of the psychic process, despite the mechanisms that retard, and even partially reverse the direction of the process, is an implicit idea on which all repetitive phenomena are based. The concept of facilitation itself involvesthe irreversibility of the process since it does not contemplate the possibility that mechanisms exist that may allow the reverse operation, except in the exceptional situation in which, for different reasons, the expected spontaneous sense is reversed, generating the process of regression. 3) The analogy of electrodynamics notions in the functioning of the psychic apparatus. Neurons, as conductors charged by a current flowing in a given direction, are also capable of storing a quantity of excitation, cathexis, neologism derived from the word cathode, used in physics. The idea of gradual local differences in potential is the only possible justification within the model for explaining psychic work as a product of the interrelationship between energy and work. Thus, it is difficult to say that when Freud developed his project he was not thinking of an electrodynamics model, it is difficult to imagine that he did not think of current (electron flow) when he spoke of current, or that he did not think of physical resistances when he spoke of resistances, or that he did not think about tension when he described the storage of potential excitation, or else that he did not seek, finally, to formulate an Ohm law of neural function, when he spoke of their relations. 4) The study of the wave characteristics as the basis of the third neuronal subsystem of the model. The Project solves the problem of the quality by assigning to the currents in flow another property, the periodicity, independent of the quantity. This periodicity refers to frequency and frequency changes, which only in the Omega system become significant, because in the Psisystem they do not exist, neither in Fi. These are, in Freud's words, monotonous, that isto say of uniform and constant frequency so as to give a unique tone.