Split-brain theory

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Split-brain theory and self-transcendence

The split-brain theory, also known as lateralization of brain function, is a fascinating topic in neuroscience that explores the consequences of cutting the corpus callosum, the bundle of nerve fibres that connects the two hemispheres of the brain. The theory suggests that such a surgical procedure can lead to a breakdown of functional integration between the left and right sides of the brain, resulting in different cognitive and perceptual abilities in each hemisphere.

However, the theory also raises some intriguing questions about the nature of consciousness and self-awareness. Is there a single unified self that transcends the division of the brain, or are there two independent selves that coexist in a split-brain patient? How does this relate to the concept of self-transcendence, which is the ability to go beyond one’s ego and personal identity and connect with something greater than oneself? In this article, we will review some of the key findings and debates in split-brain research, and discuss how they can inform our understanding of self-transcendence and its implications for human wellbeing.

Summary of the hypothesis

The hypothesis suggests that the two hemispheres of the brain have different and complementary functions, such as logic, language, creativity and intuition.

The hypothesis is based on the observation that some cognitive processes are more dominant in one hemisphere than the other, and that the hemispheres communicate through the corpus callosum.

The hypothesis has been challenged by recent research that shows more overlap and integration between the hemispheres, and more variability among individuals.  The hypothesis has also been criticized for being oversimplified, exaggerated and influenced by cultural stereotypes.

However, many psychologists and therapists have found this model useful, and it serves as a basis for successful left brain/right brain reintegration therapies such as eye movement desensitization and reprocessing (EMDR).

Origins of the hypothesis

The idea of split-brain theory has the following origins

• The work of Roger W. Sperry, who won the Nobel Prize in 1981 for studying brain functioning in patients who had their corpus callosum (the structure that connects the two hemispheres of the brain) surgically severed to treat refractory epilepsy.
• The observation of lateralization of brain function, which is the tendency for some neural functions or cognitive processes to be specialized to one side of the brain or the other. This phenomenon has been traced back to the evolution of vertebrates 500 million years ago.
• The hypothesis that the left hemisphere is more involved in controlling well-established patterns of behaviour, such as language, grammar, and right-handedness, while the right hemisphere is more involved in detecting and responding to unexpected stimuli, such as spatial relations, face recognition, and emotion.

Split-brain theory and current psychological thinking

The split brain theory is the idea that cutting the corpus callosum, the main route of communication between the cerebral hemispheres, leads to a breakdown of conscious unity. This means that each hemisphere can function independently and have different experiences, perceptions, and intentions.

The split brain phenomenon has been studied extensively by neuroscientists and psychologists, who have devised various tests to reveal the differences and similarities between the hemispheres.

For example, when a split brain patient is shown an image in their left visual field, which is processed by the right hemisphere, they cannot verbally name it because language is typically controlled by the left hemisphere. However, they can point to it or draw it with their left hand, which is also controlled by the right hemisphere.

Conversely, when a split brain patient is shown an image in their right visual field, which is processed by the left hemisphere, they can verbally name it but not point to it or draw it with their right hand.

These findings suggest that the hemispheres have different cognitive abilities and specializations, such as language, spatial reasoning, emotion, and creativity.

Not an absolute split

However, the split brain phenomenon is not absolute, as some processes seem to remain unified across the hemispheres, such as action control, attention, and awareness.

Moreover, some researchers have argued that split brain patients do not have a split consciousness, but rather a single conscious agent with partial information access.

They propose that consciousness is not dependent on inter-hemispheric communication, but on intra-hemispheric integration. They also suggest that split brain patients can use alternative pathways of communication between the hemispheres, such as subcortical structures or eye movements.

The split brain theory has implications for understanding consciousness and its relation to the brain, as well as for clinical applications and ethical issues.

Impact on thinking regarding trauma

The split brain theory also relates to current psychological approaches related to trauma, especially complex trauma and post-traumatic stress disorder (PTSD), which involve prolonged or repeated exposure to abuse or violence.

complex trauma can cause dissociation, which is a psychological defence mechanism that involves separating parts of one’s personality or memory from conscious awareness.

dissociation can manifest in different ways, such as dissociative amnesia (forgetting traumatic events), dissociative identity disorder (having multiple personalities), or depersonalization/derealization disorder (feeling detached from oneself or reality).

dissociation can be seen as a form of split brain phenomenon at a psychological level, where different aspects of one’s self are isolated and disconnected from each other. It can also be linked to neurobiological mechanisms that involve the hemispheres of the brain.

For example, some researchers have proposed that complex trauma can cause structural dissociation of the personality into two parts: an apparently normal part (ANP) that attends to daily functioning and is associated with the logical left hemisphere, and an emotional part (EP) that stores the unconscious memories of the trauma and is associated with the emotional right hemisphere.

According to this model, the ANP and the EP are separated by a barrier of amnesia and function independently of each other. However, this separation is incomplete, as the EP can intrude into the ANP’s awareness through flashbacks, nightmares, or somatic symptoms.

The goal of trauma therapy is to overcome this internal self-alienation and integrate the ANP and the EP into a coherent and unified self.

Relationship with self-transcendence

The split brain theory has some implications for the concept of self-transcendence, which is defined as the ability to go beyond one’s ego and personal identity and connect with something greater than oneself. Some researchers have suggested that self-transcendence is associated with increased activity in the right hemisphere of the brain, which is more involved in holistic, intuitive, and creative thinking. They have also proposed that self-transcendence can be enhanced by stimulating the right hemisphere or inhibiting the left hemisphere, which is more involved in analytical, logical, and rational thinking.

However, other researchers have challenged this view and argued that self-transcendence is not a function of one hemisphere over another, but rather a result of a balanced and harmonious interaction between both hemispheres. They have pointed out that self-transcendence requires both cognitive and emotional aspects, which are distributed across both hemispheres. They have also suggested that self-transcendence can be achieved by integrating different modes of thinking and experiencing, rather than suppressing or favouring one over another.

Therefore, the split brain theory relates to self-transcendence by showing that having a divided brain can impair one’s ability to transcend one’s ego and personal identity and connect with something greater than oneself. It also shows that having a unified brain can facilitate one’s ability to transcend one’s ego and personal identity and connect with something greater than oneself. The split brain theory highlights the importance of coherence and integration between different aspects of one’s self for achieving self-transcendence.

Further reading

If you are interested in learning more about split-brain theory, here are some weblinks that you can explore:

Split-Brain: What We Know Now and Why This is Important for Understanding Consciousness : This is a collective review paper that summarizes the empirical common ground, the different interpretations, and the remaining questions about the consequences of cutting the corpus callosum, the main bond between the brain’s left and right hemispheres.

Is Split Brain Theory Really a Myth? What New Research Says: This is an article that challenges the split-brain theory, claiming there is no evidence of a divided consciousness in patients or that one side of the brain is universally dominant than the other.

The split brain: A tale of two halves: A journalistic article that narrates the personal stories and experiences of some of the split-brain patients who underwent corpus callosotomy. It describes how they coped with the challenges and benefits of having a disconnected brain, and how they contributed to the advancement of neuroscience by participating in numerous experiments and tests.

The Split-Brain Phenomenon Revisited: A Single Conscious Agent with Split Perception: A scientific paper that proposes a new model of consciousness for split-brain patients, based on the integrated information theory. This model asserts that a split brain produces one conscious agent who experiences two parallel, unintegrated streams of information. It also suggests that self-transcendence can be achieved by increasing the integration of information across different levels of organization in the brain.

Dual consciousness: A Wikipedia entry that introduces the concept of dual consciousness, which is the possibility that a person may develop two separate conscious entities within their one brain after undergoing a corpus callosotomy. It also provides some historical background, some examples from literature and popular culture, and some criticisms and alternatives to this idea.