Deja Vu:
A Neurobiological Phenomenon of Consciousness Automatic translate

Déjà vu is one of the most mysterious phenomena of human consciousness, which continues to intrigue researchers around the world. This short-term experience of false recognition affects fundamental processes of memory, perception, and temporal consciousness.

Origin of the term and historical context

The term "déjà vu" (French déjà vu - "already seen") was introduced into scientific circulation by the French psychologist Emile Boirac in 1876 in his work "The Future of Psychical Sciences". Until then, such phenomena were described by various terms - "paramnesia", "false recognition" or "promnesia".

The first mentions of the phenomenon of false recognition can be found in antiquity. Aristotle considered such states as short-term mental disorders, while the followers of Plato and Pythagoras explained them as memories from past lives. St. Augustine made the first attempts to study “false memory” more than 1,600 years ago.

Neurobiological Basis of Deja Vu

Modern neurobiological research has significantly advanced our understanding of the mechanisms of déjà vu. The main brain structures involved include the temporal lobes, hippocampus, and frontal cortex.

The role of the medial temporal lobe

The medial temporal lobe (MTL) plays a central role in the formation of déjà vu. This region is responsible for storing and classifying declarative memory, which includes factual knowledge and personal memories. The MTL functions as a critical processing point for information before it is transferred to long-term memory.

The temporal lobe contains several key structures. The hippocampus is involved in forming new memories and linking incoming information to existing memories. The parahippocampal region processes spatial and contextual information. The entorhinal cortex serves as the primary interface between the hippocampus and the neocortex.

Theory of Disjointed Familiarity

Current neurobiological theory suggests that déjà vu is caused by dysfunction of the parahippocampal region. According to the dissociated familiarity hypothesis, déjà vu is produced by a faulty sense of familiarity that does not match current cognitive processing.

Normal memory functioning involves two parallel processes: recognition (a sense of familiarity) and recall (retrieval of specific details). In déjà vu, the recognition system is activated without the corresponding recall, creating a paradoxical feeling of familiarity without the ability to recall specific details.

The role of the frontal lobes

A groundbreaking 2016 study by Akira O’Connor’s team at the University of St Andrews demonstrated the key role of the frontal lobes in déjà vu. Using functional magnetic resonance imaging (fMRI), the researchers found that it was the frontal decision-making areas of the brain that were activated during déjà vu, rather than the hippocampus as previously thought.

The frontal lobes act as “memory checkers” — they analyze incoming information and send signals when they detect discrepancies between what a person actually experiences and what they think they experience. Thus, déjà vu may serve as an indicator of the normal functioning of the memory control system.

Neurochemical aspects

Arc protein and interneuronal communication

An important role in memory processes is played by the protein Arc (activity-regulated cytoskeleton-associated protein), which has been identified as a key regulator of synaptic plasticity. Studies have shown that Arc behaves like viral proteins, forming capsid-like structures that transfer RNA between neurons.

Arc accumulates in synapses during learning and is sent to the neuron nucleus when certain neurons are stimulated. This protein acts as a master regulator of the memory process, controlling which genes are turned on and off at specific times to form long-term memories.

Arc dysfunction may lead to disturbances in the formation and consolidation of memories, potentially contributing to false recognition phenomena, including déjà vu.

The Effects of Stress and Cortisol

Chronic stress and elevated cortisol levels have a significant impact on the functioning of the hippocampus. Cortisol, produced by the adrenal glands in response to stressful situations, can damage the hippocampus in excess amounts, leading to a decrease in its volume and mass.

This damage can cause disruptions in the synchronization of information, causing a person to perceive the present as something they have seen before. Thus, stress can increase the likelihood of experiencing déjà vu through the mechanism of disruption of the normal functioning of the hippocampus.

Experimental approaches to the study of deja vu

Creating Deja Vu in the Lab

One of the main obstacles to studying déjà vu has been its unpredictability and short duration. Researchers at the University of St Andrews have developed an innovative method for creating déjà vu in the laboratory.

The method is based on the technique of false memory recall. Participants are given a list of semantically related words (e.g., "bed," "pillow," "night"), but the key word ("sleep") is omitted. The subjects are then asked whether they have heard words that begin with a certain letter. After a negative answer, they are presented with the key word, which causes a feeling of déjà vu — the word seems familiar, but the participants realize that they could not have heard it.

This method was able to create déjà vu in two-thirds of the volunteers, making it possible to study the neural correlates of this phenomenon using neuroimaging.

Studies of patients with epilepsy

Patients with temporal lobe epilepsy provide a unique opportunity to study déjà vu, as the phenomenon often precedes epileptic seizures. Electrical stimulation of the temporal regions in such patients can induce déjà vu sensations, allowing researchers to study neural mechanisms in a controlled setting.

French researchers have successfully produced déjà vu in epileptic patients using electrical stimulation of the cerebral cortex. The area responsible for these sensations is located in the rhinal cortex, under the hippocampus. During an attack, the electrical activity of neurons changes, and impulses spread to the adjacent temporal lobe, causing the sensation of déjà vu.

Classification of deja vu phenomena

Main types of deja vu

Modern classification identifies several types of deja vu, each of which has its own characteristics and mechanisms of occurrence.

Déjà vécu (already experienced) is the most common form of déjà vu. In this type, the person not only sees the situation as familiar, but also recognizes smells, sounds, and sensations in detail. There is often a strong feeling that the person knows what will happen next.

Déjà visité (already visited) is characterized by an inexplicable knowledge of a new place. A person may know the route in an unfamiliar city, despite having never been there. This type concerns spatial and geographical information.

Déjà senti (already felt) is a mental phenomenon that rarely remains in memory. It occurs when hearing another person’s voice, thoughts being spoken, or reading. Unlike other types of déjà vu, it is not accompanied by a feeling of something paranormal.

Antonymous phenomena

Jamais vu (never seen) is the opposite of déjà vu. It is a state in which familiar places, people, or words suddenly seem completely unfamiliar. Research has shown that 68% of participants experienced jamais vu after repeatedly writing a common word, indicating that the phenomenon is linked to brain fatigue.

Presque vu (almost seen) describes a "tip of the tongue" state where a person feels they are about to recall a needed word or piece of information but is unable to do so. This sensation can be intrusive and distracting, often accompanied by partial memories of the characteristics of the forgotten word.

Theories of the origin of deja vu

Split Perception Theory

According to the split perception theory, déjà vu occurs when a person perceives the same object or situation twice within a short period of time. Initially, the information is perceived in the peripheral attention or “corner of the eye,” then when full attention switches to the object, a sensation of re-perception occurs.

For example, a person may notice a cafe with their peripheral vision without focusing on it. The brain receives and processes this information on a subconscious level. When a person consciously pays attention to the cafe, there is a feeling that they have already seen this place.

Processing Delay Theory

This theory suggests that déjà vu may be caused by a slight delay in the transmission of information between different parts of the brain. If one part of the brain receives information before another, then when the other part processes the same information, a sense of repetition occurs.

Modern research shows that such time mismatches can occur at the millisecond level. If a signal from the senses first reaches the thalamus, then the hippocampus, and only then the corresponding areas of the cortex, a feeling of “already seen” may arise.

Dual Processing Theory

Dual processing theory suggests that déjà vu occurs when two parallel cognitive systems are out of sync. One system is responsible for recognizing new information, the other for retrieving memories. When their work is temporarily out of sync, new information can be perceived as already known.

Phenomenological theory of memory

Some researchers view déjà vu as the result of the activation of fragmentary memories that are not fully conscious. The current situation may contain elements similar to a past experience - smells, sounds, visual details. The brain detects these similarities at a subconscious level, which creates a feeling of familiarity without the ability to accurately recall the source.

The connection between deja vu and pathological conditions

Temporal lobe epilepsy

Déjà vu is most clearly associated with temporal lobe epilepsy, where it often serves as an aura — a precursor to an epileptic seizure. In patients with temporal lobe epilepsy, déjà vu may occur several times a month and be accompanied by other symptoms, such as strange scene-like experiences, abnormal heart rhythms, or loss of consciousness.

Pathological déjà vu in epilepsy has several distinctive features. It occurs more often than in healthy people, can last longer, and is often accompanied by other neurological symptoms. Such episodes require medical attention and may indicate the need for antiepileptic therapy.

Dementia and neurodegenerative diseases

Patients with dementia, especially frontotemporal dementia, may experience pathological forms of déjà vu. A case of an 80-year-old man was described who constantly experienced a state of "déjà vécu" - the conviction that every day was a repeat of the previous one. The patient believed that his electronic devices were broken, because they showed the same programs and met the same people on the street.

Neuroimaging of this patient revealed generalized atrophy of the left temporal region and hypometabolism in the left temporal and bilateral frontal lobes. Déjà vécu syndrome with confabulation of memories has been associated with Alzheimer’s disease and other neurodegenerative disorders.

Mental disorders

Frequent déjà vu may be a symptom of various mental disorders. Patients with schizophrenia, anxiety disorders, and depersonalization-derealization syndrome have an increased frequency of déjà vu episodes. This may be due to disturbances in the temporal lobes, which regulate not only memory but also cardiovascular function.

Age-related features of deja vu

Prevalence in different age groups

Déjà vu is most common in people between the ages of 15 and 25, after which its frequency gradually decreases. This may be due to the peculiarities of brain development during adolescence and young adulthood, when neural networks are still forming and may be more susceptible to temporary failures.

In adolescence, déjà vu may be associated with a lack of life experience, which the memory tries to compensate for by creating false memories. The heightened emotionality characteristic of this period can also contribute to the emergence of déjà vu.

Deja vu in old age

Deja vu is less common in older people, which may be due to age-related changes in the functioning of memory systems. However, when deja vu occurs in older people, it may be a sign of the onset of cognitive impairment or neurodegenerative diseases.

Age-related changes in the prefrontal cortex, which is responsible for monitoring and verifying memories, may lead to a reduced ability to distinguish between real and false memories. This may explain both the decrease in the frequency of normal déjà vu and the emergence of pathological forms of false recognition in older people.

Cultural and individual differences

The influence of education and travel

Research shows that déjà vu is more common among people with a high level of education, those who travel a lot, and those who are open to new experiences. This may be due to the greater volume and variety of accumulated experiences, which creates more opportunities for false connections to arise between current events and past memories.

People with a more developed capacity for reflection and introspection may also be more likely to notice and remember episodes of déjà vu. Cultural differences in attitudes toward such phenomena may also influence the frequency of their reporting and interpretation.

Individual characteristics of the nervous system

Individual differences in brain structure and function may influence susceptibility to déjà vu. Hemispheric asymmetry, differences in temporal neural connectivity, and genetic factors may determine the frequency and intensity of déjà vu experiences.

Modern research methods

Neuroimaging

Functional magnetic resonance imaging (fMRI) has become the main method for studying the neural correlates of déjà vu. Current research uses both analysis of resting brain activity and tasks aimed at artificially creating déjà vu.

Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are also used to study metabolic changes in the brain during déjà vu. These methods are especially useful in studying patients with pathological forms of déjà vu.

Electrophysiological methods

Electroencephalography (EEG) and intracranial electrocorticography in patients with epilepsy provide unique opportunities to study the temporal dynamics of neural activity during déjà vu. These methods allow us to study the processes of synchronization and desynchronization of different brain regions with high temporal resolution.

Therapeutic approaches

Treatment of pathological deja vu

In pathological forms of déjà vu associated with epilepsy, the main treatment method is antiepileptic therapy. Control of epileptic seizures usually leads to a decrease in the frequency and intensity of déjà vu episodes.

In cases where déjà vu is associated with mental disorders, treatment is aimed at the underlying disorder. Antidepressants, anxiolytics, or neuroleptics may be used depending on the specific diagnosis.

Prospects for neuromodulation

The development of non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) opens up new possibilities for studying and potentially treating memory disorders. Targeted stimulation of the temporal lobes can influence the processes of memory formation and retrieval.

Philosophical and ethical aspects

Deja Vu and the Nature of Consciousness

The phenomenon of déjà vu raises fundamental questions about the nature of consciousness, time, and reality. It demonstrates how our perception of the present moment is influenced by past experiences and can be distorted by memory processes.

The study of déjà vu contributes to our understanding of how the brain constructs the subjective experience of time and how different memory systems interact to create a coherent experience of consciousness. This has important implications for the philosophy of mind and cognitive science.

Ethical issues in research

Research into déjà vu, particularly involving invasive techniques in patients with epilepsy, raises important ethical issues. A balance must be struck between the scientific value of the research and the welfare of patients, ensuring informed consent and minimising risks.

Practical applications

Diagnostic capabilities

Understanding the mechanisms of déjà vu may contribute to the development of new diagnostic methods for detecting early stages of neurodegenerative diseases. Pathological forms of déjà vu may serve as early markers of cognitive impairment.

Analysis of the frequency and characteristics of déjà vu may complement existing neuropsychological tests and aid in the differential diagnosis of various forms of dementia.

Educational aspects

The study of déjà vu and related phenomena may provide insights into how memory and learning work. This knowledge may be used to develop more effective educational methods and memory strategies.

Future research directions

Genetic research

Future research may focus on identifying genetic factors that influence susceptibility to déjà vu. Studying familial clustering of cases of pathological déjà vu may help identify relevant genes and biological pathways.

Artificial Intelligence and Modeling

The development of computational models of memory and artificial intelligence can help in understanding the mechanisms of déjà vu. The creation of artificial systems capable of experiencing analogs of déjà vu can shed light on the fundamental principles of memory and consciousness.

Pharmacological research

The development of specific pharmacological agents that affect memory processes may open new possibilities for the study and treatment of disorders associated with déjà vu. Such studies may also contribute to the understanding of the neurochemical basis of various forms of false recognition.

Deja vu is one of the most intriguing phenomena of human consciousness. It combines issues of neurobiology, psychology, philosophy and clinical medicine. Scientific research is gradually revealing the complex mechanisms of this phenomenon, opening new horizons for understanding the work of the human brain and the nature of consciousness. The study of deja vu has practical significance for the diagnosis and treatment of various neurological and mental disorders.