Neuroscience confirms Freud’s theory of the human psyche.
Posted Mar 18, 2020
As is well known, Freud divided the human psyche into three functional parts: the id, ego, and superego. The id is a “dark,” "inaccessible” (unconscious), non-rational component of the psyche that seeks pleasure. The superego, on the other hand, is the moral conscience arising from internalized parental authority. Its demands are absolutistic and inflexible, and, therefore, in conflict with the capricious id. Accordingly, the ego’s function is to resolve this internal conflict such that the id can satisfy its drives in a socially/morally acceptable manner. To accomplish the latter function, the ego maintains a grasp on reality (the external world), navigating the headwaters of reality in order to fulfill its function.
It is noteworthy that Freud began his career as a neurologist with keen interest in grounding his psychodynamic approach in the workings of the human brain. Unfortunately, Freud never accomplished this goal, having invested the lion’s share of his time in clinical research toward the development of his psychoanalytic theory. However, with the rapidly developing area of neuropsychology aided by technologies such as functional magnetic resonance imagery (fMRI), the functional analysis of the human psyche in terms of the human brain has become increasingly more feasible.
The purpose of this blog is accordingly to suggest possible brain substrates for Freud’s tripartite division of the human psyche by aligning the specific functions of certain brain regions with that of id, ego, and superego, based on pertinent fMRI, lesion, and transcranial magnetic stimulation (TMS) studies.
The Amygdala as Id
In his essay, “Beyond the Pleasure Principle,” Freud states:
In the psycho-analytical theory of the mind we take it for granted that the course of mental processes is automatically regulated by the pleasure-principle‘: that is to say, we believe that any given process originates in an unpleasant state of tension and thereupon determines for itself such a path that its ultimate issue coincides with a relaxation of this tension, i.e. with avoidance of pain‘ or with production of pleasure.
Freud’s above description of “the pleasure principle,” coincides succinctly with the function of a subcortical (and therefore non-rational) region of the human brain called the amygdala. This brain region has traditionally been associated with fear in response to environmental danger. This response involves messaging to the hypothalamus-pituitary-adrenal axis increasing cardio-respiratory activity and peripheral (“sympathetic”) nervous system activity preparing the body for “fight or flight.” Here, such automatic, non-conscious responsiveness to danger tracks the function of Freud's id in avoidance of pain.
Further, more recent research suggests that the function of the amygdala "... goes beyond encoding aversive stimuli to also encode the appetitive, requiring an appreciation of the amygdala's mediation of both appetitive and fearful behavior through diverse psychological processes.”
According to Freud, “all instincts have as their aim the reinstatement of an earlier condition.” In the case of pleasure, the drive is towards repetition of the experiences that produce the pleasure. Suitably, the amygdala appears to satisfy this Freudian notion. It has been hypothesized that “the amygdala functions as a memory storage device, associating neutral stimuli with 'motivationally relevant' stimuli such as food, sex, or danger," thereby building up stimulus-response bonds based on reward as well as punishment. This is not only consistent with Freud’s treatment of the pleasure principle inherent in the function of the id; it epitomizes its very nature.
The Ventromedial Prefrontal Cortex as Superego
Several studies have consistently linked moral judgment with the cortical region of the brain known as the ventromedial prefrontal cortex (VMPFC). This area of the brain has reciprocal neural connections with the amygdala and is intimately bound up with emotional control. Hence, it is poised to serve as a source of “conflict” with the amygdala “id.” Clinical studies also point to major involvement of the VMPFC in “guilt-related affective processing,” thereby further marking this brain region out as a likely substrate for the superego.
According to one study, other areas of the brain associated with abstract reasoning and cognitive reappraisal are involved in moral decision-making in the case of difficult moral dilemmas involving personal sacrifice. One such brain region is the dorsolateral prefrontial cortex (DLPFC).
In the study, subjects were presented with a war scenario in which a crying baby was endangering the lives of many townspeople who were hiding from the enemy. While being monitored with fMRI scans, the subjects were asked to determine whether or not it would be morally acceptable to smother one’s own baby in this situation.
Subjects who considered such a response to be appropriate had greater activity in their DLPFC than subjects who considered such a response inappropriate regardless of the costs. The latter reflects absolutistic ideas of morality akin to that identified in the Freudian superego. Indeed, the fact that there was increased DLPFC activity in the subjects who judged the measure to be appropriate suggests an adjustment or reappraisal of the unconditional disapprobation of such an action made by the superego activity occurring in the VMPFC. This supports the native tendency of the latter region to support an absolutistic view of morality similar to that of the Freudian superego unless tempered by the DLPFC ego.
Further confirmation of this hypothesis comes from another study that used the same “crying baby” scenario while disrupting the right DLPFC of subjects. In this case, the disruption via repetitive TMS tended to evoke a self-defeating “nonutilitarian” response in the subjects; that is, the decision to let everyone die, including the baby.
Still further confirmation comes from other studies that demonstrate the role played by the DLPFC in making more flexible moral decisions. In one study subjects evaluated 40 moral and 20 non-moral (control) scenarios to determine whether the action in question was morally right or wrong, and whether, given the costs and benefits of each, they would still do the action in real life even if they thought it to be wrong. Subjects were given MRI scans during the activity. The results showed increased activity in the DLPFC and in another cortical region, the temporoparietal junction, in subjects who were more flexible in their responses. This study, along with the others cited here, suggests the native tendency of the VMPFC, when not modulated by the DLPFC in concert with other associated regions, to be toward rigidity, and thus akin to the Freudian superego.
The DLPFC as Ego
The aforementioned reappraisal activity of the DLPFC is akin to the function of the Freudian ego. The DLPFC is also associated with inductive reasoning, which involves making logical inferences about the external world. It has a role in forming rules based on experience (“All lemons are sour”) and in applying these rules (avoiding sucking the lemon). Consequently, its profile renders it a viable candidate for ego function.
It has the capacity for meta-cognition (thinking about its own thinking and perceptual activities) which is requisite to recognizing one’s own existence as a “self.”
It has also been shown to be active when subjects attempt to exercise “self-control” over eating unhealthy foods. In the case of individuals with good self-control, when activity in the DLPFC increases, activity in the VMPFC decreases, confirming the role of the former in self-control.
This is not to discount the role of other regions of the brain in constraining the VMPFC in moral decision-making. For example, some studies have suggested that the anterior cingulate cortex (ACC) may also play a role in moral conflict detection or control. So, it would be an oversimplification to claim that the DLPFC comprises the ego or self, independent of a multi-functional, integrated set of neural networks throughout various other cortical regions of the brain. Nevertheless, it appears that the DLPFC plays a major role in modulating the DLPFC in moral decision-making toward greater flexibility. In the Freudian context, this may be interpreted as modulating the superego in its relation to the id in concert with external reality.
As more data becomes available, the analysis presented here may be further confirmed, or not. However, based on the studies introduced here, the case for the Freudian brain is compelling. While the implications of this tentative analysis have yet to be explored, the psychodynamic role played by Freud’s theory of the human psyche in psychoanalysis and other psychotherapeutic modalities is substantial and therefore the implications for treatment should not be underestimated. For example, problems of ego strength may track problems in the functioning of the DLPFC, or related structures. This may, in turn, suggest modalities of treatment that target this area of the brain. With advancing knowledge of how these neural circuits operate, such information may prove valuable in advancing the treatment of mental disorders.