For over a century, theories have emerged that we are not singular selves but amalgamations of parts.

Different psychological models use different vocabulary to define a common phenomenon.

Modern techniques in neuroscientific research shed light on how and why this happens.

Over the last century, many seemingly different psychological theories have come to similar conclusions: that our identity and sense of self is not a singular thing but an amalgam of many, sometimes conflicting parts. Psychoanalyst Philip Bromberg called these self-states, coming from the perspective of dissociation. Carl Jung referred to these as archetypes, and maturation came through integrating their shadow versions. The Internal Family Systems model calls them, simply, parts.

Recent research into neuroscience shows us that what all these theories share in common may be true, down to a very biological level. Individual brain regions come together in patterned networks to perform specific, complex functions. These networks can sometimes activate together, but some networks may require inhibition of others that would cause too much conflict. This is called network neuroscience, and it can also be a guide to why we use certain defense mechanisms and how to more fluidly and optimally adapt to the dynamic world around us.

The brain is composed of distinct regions that support different emotional, cognitive, and somatic functions. Network neuroscience is the study of how these regions form large-scale networks to dynamically coordinate mental states. These networks allow us to shift between reflection, action, emotional regulation, and embodied experience.

Individual Brain Regions

Core Brain Networks

The reciprocal relationship between the DMN and AMN is of clinical relevance. These two networks compete for dominance: When one is active, the other is suppressed. This tells us that when our patients are working too hard, they may be avoiding critical feelings. It also lets us know why patients frozen by depressive ruminations benefit from a CBT technique called behavioral activation.

It is common to bring different parts of yourself to different situations. Your work self may act and dress one way to preserve a professional self, with family, you might find that you experience yourself as you were when you were much younger, with friends, yet another, more independently evolved part of your personality might show itself. All of these are your authentic self, and they wisely adapt and present in situations that are most appropriate for them to be in. Despite all these modes of being, you also experience continuity, that you are always you at your core.

Bromberg and other psychoanalysts believe that a healthy degree of dissociation is what allows this to happen. Neuroscience might say that your Action Mode Network is the more dominant system at work. The Salience Network and Default Mode Network come together to activate the parts of your personality that may be most relevant based on the social context.

The ability to shift self-states becomes dysregulated when the mind has been shaped by unresolved trauma, chronic stress, or early attachment wounds. Rather than fluid and adaptive, these internal shifts become rigid, volatile, or entirely dissociated.

In complex PTSD, for example, the Default Mode Network (DMN) and other emotional centers can become either overactivated, resulting in intrusive memories, or decoupled, resulting in dissociation. In borderline personality disorder, limitations in interoception and high degrees of emotional reactivity may leave switching between states all too easy and depriving one of a contiguous sense of self or coherent identity.

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Philip Bromberg viewed pathological dissociation as a defense, where entire self-states with their own emotional needs compete rather than communicate and ultimately operate in isolation because integration is too dangerous. For Jung, archetypal energies can possess the ego when not consciously integrated, leading to inner conflict and projection. In IFS, fragmentation reflects a breakdown in trust and collaboration between parts.

The most extreme form of self-state fragmentation is Dissociative Identity Disorder (DID), in which different self-states become so dominant that they present with completely different names and voices and often have amnesia for each other. DID is a legitimate and deeply complex condition that typically develops in the context of severe, repeated early life trauma. People with DID are not acting out or playing pretend; neuroimaging shows that the distinct self-states (commonly referred to as alters) activate different patterns of brain connectivity, sometimes even affecting sensory perception, pain thresholds, or motor responses.

Healing doesn’t mean becoming a single, unified self; it means learning to flexibly move through modes of being so that each part has space to be heard without overwhelming the whole. In therapy, this often looks like developing the capacity to observe your own states without becoming overtaken by them and to teach them how to communicate and negotiate with each other.

IFS calls this Self-leadership, a centered presence that relates to all parts with compassion. Psychoanalysis frames it as integration and internal cohesion, the ability to tolerate internal contradiction. Jung called it individuation, the process of integrating the shadows of our various archetypes into a mature and complete self.

We all live with different roles, moods, memories, and subpersonalities that help us navigate a complex and varying world. This does not need to be only an abstract concept. Our brains evolved to be this way, and now we are starting to know how it all comes together.

References

Bromberg, P. M. (1998). Standing in the spaces: Essays on clinical process, trauma, and dissociation. New Jersey: Analytic Press

Dosenbach, N. U. F., Raichle, M. E., & Gordon, E. M. (2025, January 2). The brain’s action‑mode network. Nature Reviews Neuroscience, 26(3).