Part of a series on |
Alternative medicine |
---|
Body memory (BM) is a hypothesis that the body itself is capable of storing memories, as opposed to only the brain. While experiments have demonstrated the possibility of cellular memory [1] there are currently no known means by which tissues other than the brain would be capable of storing memories. [2] [3]
Modern usage of BM tends to frame it exclusively in the context of traumatic memory and ways in which the body responds to recall of a memory. In this regard, it has become relevant in treatment for PTSD. [4]
Peter Levine calls BM implicit memory or more specifically procedural memory, things that the body is capable of doing automatically and not in one's consciousness. He clarifies 3 types of BM and frames his work in terms of traumatic memory consequence and resolution: [5]
Nicola Diamond elaborates on the opinion of philosopher Merleau-Ponty and asserts that BM is formed by doing. Whether practicing a bodily activity or forming a reaction to a traumatic memory. [6]
Edward Casey speaks of BM as, "memory intrinsic to the body, how we remember by and through the body", rather than what is remembered about the body. [7]
Thomas Fuchs defines 6 different types of BM: procedural, situational, intercorporeal, incorporative, pain, and traumatic memory. He notes that they are not strictly separable from one another but "derived from different dimensions of bodily experience. [8] : 12 Michelle Summa further refines this definition as an implicit memory. A pre-thematic, operative consciousness of the past expressed through the body. [8] : 30
Antonio Damasio calls these reactions to memories somatic markers or emotions that are expressed primarily as physical feelings. [9]
These memories are often associated with phantom pain in a part or parts of the body – the body appearing to remember the past trauma. The idea of body memory is a belief frequently associated with the idea of repressed memories, in which memories of incest or sexual abuse can be retained and recovered through physical sensations. [2] It may also be associated with phantom limb sensation but this is less common. [10]
In 1993, Susan E. Smith, presented a paper relating the idea of "Survivor Psychology" at a false memory syndrome conference, stated about BM that, "body memories are thought to literally be emotional, kinesthetic, or chemical recordings stored at the cellular level and retrievable by returning to or recreating the chemical, emotional, or kinesthetic conditions under which the memory recordings are filed. [2] She went on in the abstract of the paper, "one of the most commonly used theories to support the ideology of repressed memories or incest and sexual abuse amnesia is body memories." and "The belief in these pseudoscientific concepts appears to be related to scientific illiteracy, gullibility, and a lack of critical thinking skills and reasoning abilities in both the mental health community and in society at large" [2]
A 2017 systematic review of cross-disciplinary research in body memory found that the available data neither largely support or refute the claim that memories are stored outside of the brain and more research is needed. [11]
In the Encyclopedia of Phenomenology Embree notes that, "To posit body memory is to open up a Pandora's Box", and links the idea to physical associations of memory rather than as a memory stored in a bodily manner. [12]
Cellular memory (CM) is a parallel hypothesis to BM positing that memories can be stored outside the brain in all cells. [13] The idea that non-brain tissues can have memories is believed by some who have received organ transplants, though this is considered impossible. The author said the stories are intriguing though and may lead to some serious scientific investigation in the future. [13] In his book TransplantNation Douglas Vincent suggests that atypical newfound memories, thoughts, emotions and preferences after an organ transplant are more suggestive of immunosuppressant drugs and the stress of surgery on perception than of legitimate memory transference. In other words, "as imaginary as a bad trip on LSD or other psychotropic drug." [14]
Cellular memory refers to the ability of cells to retain information about past states, exposures, or events and adapt their responses accordingly. This concept underpins various physiological and pathological processes, often mediated by hormonal pathways, feedback loops, and epigenetic mechanisms. The following are key examples illustrating the scientific basis of cellular memory.
The hypothalamic–pituitary–adrenal (HPA) axis, through the release of glucocorticoids like cortisol, plays a pivotal role in stress and emotional memory. Cortisol enhances the consolidation of emotionally charged memories by modulating hippocampal activity, yet it can impair memory retrieval. [15] This dual effect is supported by research showing that glucocorticoids improve consolidation of long-term memory, particularly for emotionally valenced information, while impairing retrieval processes. [16] Dysregulation of this pathway is implicated in stress-related disorders such as PTSD, where the over-consolidation of fear-based memories occurs. Studies have demonstrated that glucocorticoids facilitate memory encoding but may compromise the retrieval of information, creating a dynamic interplay between memory formation and stress responses.
Recent research has further elucidated how chronic stress shapes neural networks. Prolonged exposure to high cortisol levels can reduce hippocampal volume and inhibit neurogenesis, weakening the brain's capacity to form new memories while reinforcing maladaptive ones. [17] Those same studies have shown that chronic exposure to elevated cortisol levels, whether through stress or medical conditions, can lead to morphological changes in the hippocampus, suppress neuronal proliferation, and reduce hippocampal volume.
The dynamic interplay between memory formation and stress responses is evident in the research demonstrating that glucocorticoids facilitate memory encoding but may compromise the retrieval of information. [18] This relationship is thought to follow an inverted U-shaped curve, with optimal memory performance at moderate levels of cortisol and impairment at both low and high levels. [19] The differential activation of mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) at varying cortisol concentrations may explain this complex relationship between stress hormones and memory processes. [20]
Furthermore, the impact of glucocorticoids on memory is time-dependent and context-specific. While acute elevations in cortisol can enhance the consolidation of new memories, including extinction memories, chronic exposure to high cortisol levels may lead to detrimental effects on cognitive function. [21] This has important implications for the treatment of fear-related disorders, as glucocorticoid-based interventions may facilitate fear extinction by reducing the retrieval of aversive memories and enhancing the consolidation of extinction memories. [22]
Nutritional and metabolic states are encoded in cellular memory through hormonal and transcriptional mechanisms, including glucose-induced transcriptional hysteresis and thyroid hormone regulation. Prolonged hyperglycemia can induce lasting epigenetic changes in glucose-regulated pathways, contributing to long-term complications of diabetes, such as vascular damage and cognitive decline. [23] This phenomenon, known as "metabolic memory," involves persistent alterations in gene expression and cellular function even after normalization of glucose levels. [24]
Glucose-induced transcriptional hysteresis plays a significant role in this process. Studies have demonstrated that exposure to elevated glucose levels leads to a positive feedback loop, resulting in persistent expression of genes that promote glycolysis and inhibit alternative metabolic pathways. [25]
Similarly, during caloric deficits, the body adapts by lowering the basal metabolic rate and "remembering" prior energy-deprived states through alterations in leptin, ghrelin, and thyroid hormone signaling. These adaptive responses are examples of metabolic memory and highlight how previous nutritional environments shape cellular behavior. [26]
The concept of "memory" in hormonal states is indeed critical for maintaining metabolic homeostasis, but it can also lead to maladaptive outcomes in certain conditions. Chronic high glucose levels have been shown to alter epigenetic markers, leading to persistent vascular inflammation and oxidative stress. Transient hyperglycemia can induce long-lasting activating epigenetic changes in the promoter of the nuclear factor κB (NF-κB) subunit p65 in aortic endothelial cells. [27] These changes persist for at least 6 days of subsequent normal glycemia, resulting in increased expression of pro-inflammatory genes such as monocyte chemoattractant protein 1 (MCP-1) and vascular cell adhesion molecule 1 (VCAM-1). [28]
The establishment of these epigenetic changes may precede cardiovascular complications and help predict vascular lesions in diabetic patients. [29] Importantly, these epigenetic marks may be transmitted across several generations, increasing the individual risk of disease. [30]
The concept of metabolic memory extends beyond glucose regulation. Nutritional and metabolic states are encoded in cellular memory through various hormonal and transcriptional mechanisms. [31] These mechanisms form a complex network that governs metabolic memory and can emerge as novel targets for both detection and intervention of metabolic diseases. [32]
Hormonal fluctuations during critical developmental periods, such as puberty or pregnancy, create lasting imprints on cellular and systemic physiology. These hormonal effects influence cognitive functions, secondary sexual characteristics, and susceptibility to hormone-sensitive disorders.
Early-life estrogen exposure has been associated with long-term changes in brain plasticity and memory capacity, contributing to gender differences in neuropsychiatric conditions. Estrogen plays a crucial role in brain development, particularly in determining central gender dimorphism. [33] During puberty and other developmental stages, estrogen-induced synaptic plasticity is evident, affecting neurotransmitter synthesis, release, and metabolism. [34]
Estrogen's effects on the central nervous system are multifaceted, involving both genomic and non-genomic mechanisms. These actions protect against a wide range of neurotoxic insults and influence electrical excitability, synaptic function, and morphological features. [35] Clinical evidence shows that estrogen withdrawal during the climacteric period leads to modifications in mood, behavior, and cognition, while estrogen administration can improve cognitive efficiency in post-menopausal women. [36]
Emerging studies indeed reveal that testosterone levels during puberty influence neural development, affecting synaptic pruning and myelination in the prefrontal cortex. These changes have long-term implications for decision-making, risk assessment, and emotional regulation. During adolescence, high testosterone levels are associated with increased anterior prefrontal cortex (aPFC) involvement in emotion control. [37]
Elevated glucocorticoids during maternal stress have been shown to alter fetal epigenetic markers. Maternal adversity during pregnancy, including stress, anxiety, and depression, is associated with increased maternal and fetal glucocorticoid concentrations, which can lead to long-term physiological and pathophysiological outcomes in offspring. [38] Studies have found a significant correlation between psychosocial maternal stress and offspring methylation at a specific CpG site in the exon 1F of the human glucocorticoid receptor gene NR3C1, which may predispose offspring to mood disorders and metabolic dysregulation. [39]
Biologists at Tufts University have been able to train flatworms despite the loss of the brain and head. This may show memory stored in other parts of the body in some animals. [40] A worm reduced to 1/279th of the original can be regrown within a few weeks and be trained much quicker to head towards light and open space for food, an unnatural behavior for a flatworm. With each head removed training times appear reduced. This may just be a sign of epigenetics showing the appearance of memory. [41]
However, in the 1950s and 1960s James McConnell flatworm experiments measured how long it took to learn a maze. McConnell trained some to move around a maze and then chopped them up and fed them to untrained worms. The untrained group learned faster compared to a control that had not been fed trained worms. McConnell believed the experiment indicated cellular memory. [42] The training involved stressing the worms with electric shock. This kind of stress releases persistent hormones and shows no evidence for memory transfer. Similar experiments with mice being trained and being fed to untrained mice showed improved learning. It was not a memory that was transferred but hormone enriched tissue. [42]
In epigenetics there are various mechanisms for cells to pass on "memories" of stressors to their progeny. Strategies include Msn2 nucleo-cytoplasmic shuttling, changes in chromatin, partitioning of anti-stress factors, and damaged macromolecules between mother and daughter cells. [43]
In adaptive immunity there is a functional CM that enables the immune system to learn to react to pathogens through mechanisms such as cytoxic memory mediation in bone marrow, [44] innate immune memory in stromal cells, [45] fungal mediation of innate and inherited immunological response, [46] and T and B-cell immune training. [47] In this regard CM is essential for vaccine and immunity research.
Estrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy.
The hypothalamus is a small part of the vertebrate brain that contains a number of nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is part of the limbic system. It forms the basal part of the diencephalon. All vertebrate brains contain a hypothalamus. In humans, it is about the size of an almond.
The hypothalamic–pituitary–adrenal axis is a complex set of direct influences and feedback interactions among three components: the hypothalamus, the pituitary gland, and the adrenal glands. These organs and their interactions constitute the HPS axis.
The anterior pituitary is a major organ of the endocrine system. The anterior pituitary is the glandular, anterior lobe that together with the makes up the pituitary gland (hypophysis) which, in humans, is located at the base of the brain, protruding off the bottom of the hypothalamus.
Cortisol is a steroid hormone in the glucocorticoid class of hormones and a stress hormone. When used as medication, it is known as hydrocortisone.
A maternal effect is a situation where the phenotype of an organism is determined not only by the environment it experiences and its genotype, but also by the environment and genotype of its mother. In genetics, maternal effects occur when an organism shows the phenotype expected from the genotype of the mother, irrespective of its own genotype, often due to the mother supplying messenger RNA or proteins to the egg. Maternal effects can also be caused by the maternal environment independent of genotype, sometimes controlling the size, sex, or behaviour of the offspring. These adaptive maternal effects lead to phenotypes of offspring that increase their fitness. Further, it introduces the concept of phenotypic plasticity, an important evolutionary concept. It has been proposed that maternal effects are important for the evolution of adaptive responses to environmental heterogeneity.
Glucocorticoids are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebrate animal cell. The name "glucocorticoid" is a portmanteau and is composed from its role in regulation of glucose metabolism, synthesis in the adrenal cortex, and its steroidal structure.
A hormone receptor is a receptor molecule that binds to a specific hormone. Hormone receptors are a wide family of proteins made up of receptors for thyroid and steroid hormones, retinoids and Vitamin D, and a variety of other receptors for various ligands, such as fatty acids and prostaglandins. Hormone receptors are of mainly two classes. Receptors for peptide hormones tend to be cell surface receptors built into the plasma membrane of cells and are thus referred to as trans membrane receptors. An example of this is Actrapid. Receptors for steroid hormones are usually found within the protoplasm and are referred to as intracellular or nuclear receptors, such as testosterone. Upon hormone binding, the receptor can initiate multiple signaling pathways, which ultimately leads to changes in the behavior of the target cells.
Corticotropic cells, are basophilic cells in the anterior pituitary that produce pro-opiomelanocortin (POMC) which undergoes cleavage to adrenocorticotropin (ACTH), β-lipotropin (β-LPH), and melanocyte-stimulating hormone (MSH). These cells are stimulated by corticotropin releasing hormone (CRH) and make up 15–20% of the cells in the anterior pituitary. The release of ACTH from the corticotropic cells is controlled by CRH, which is formed in the cell bodies of parvocellular neurosecretory cells within the paraventricular nucleus of the hypothalamus and passes to the corticotropes in the anterior pituitary via the hypophyseal portal system. Adrenocorticotropin hormone stimulates the adrenal cortex to release glucocorticoids and plays an important role in the stress response.
Steroid hormone receptors are found in the nucleus, cytosol, and also on the plasma membrane of target cells. They are generally intracellular receptors and initiate signal transduction for steroid hormones which lead to changes in gene expression over a time period of hours to days. The best studied steroid hormone receptors are members of the nuclear receptor subfamily 3 (NR3) that include receptors for estrogen and 3-ketosteroids. In addition to nuclear receptors, several G protein-coupled receptors and ion channels act as cell surface receptors for certain steroid hormones.
In biochemistry, in the biological context of organisms' regulation of gene expression and production of gene products, downregulation is the process by which a cell decreases the production and quantities of its cellular components, such as RNA and proteins, in response to an external stimulus. The complementary process that involves increase in quantities of cellular components is called upregulation.
11β-Hydroxysteroid dehydrogenase enzymes catalyze the conversion of inert 11 keto-products (cortisone) to active cortisol, or vice versa, thus regulating the access of glucocorticoids to the steroid receptors.
The glucocorticoid receptor also known as NR3C1 is the receptor to which cortisol and other glucocorticoids bind.
Obesogens are certain chemical compounds that are hypothesised to disrupt normal development and balance of lipid metabolism, which in some cases, can lead to obesity. Obesogens may be functionally defined as chemicals that inappropriately alter lipid homeostasis and fat storage, change metabolic setpoints, disrupt energy balance or modify the regulation of appetite and satiety to promote fat accumulation and obesity.
Non-tropic hormones are hormones that directly stimulate target cells to induce effects. This differs from the tropic hormones, which act on another endocrine gland. Non-tropic hormones are those that act directly on targeted tissues or cells, and not on other endocrine gland to stimulate release of other hormones. Many hormones act in a chain reaction. Tropic hormones usually act in the beginning of the reaction stimulating other endocrine gland to eventually release non-tropic hormones. These are the ones that act in the end of the chain reaction on other cells that are not part of other endocrine gland. The Hypothalamic-pituitary-adrenal axis is a perfect example of this chain reaction. The reaction begins in the hypothalamus with a release of corticotropin-releasing hormone/factor. This stimulates the anterior pituitary and causes it to release Adrenocorticotropic hormone to the adrenal glands. Lastly, cortisol (non-tropic) is secreted from the adrenal glands and goes into the bloodstream where it can have more widespread effects on organs and tissues. Since cortisol is what finally reaches other tissues in the body, it is a non-tropic hormone. CRH and ACTH are tropic hormones because they act on the anterior pituitary gland and adrenal glands, respectively, both of which are endocrine glands. Non-tropic hormones are thus often the last piece of a larger process and chain of hormone secretion. Both tropic and non-tropic hormones are necessary for proper endocrine function. For example, if ACTH is inhibited, cortisol can no longer be released because the chain reaction has been interrupted. Some examples of non-tropic hormones are:
The effects of stress on memory include interference with a person's capacity to encode memory and the ability to retrieve information. Stimuli, like stress, improved memory when it was related to learning the subject. During times of stress, the body reacts by secreting stress hormones into the bloodstream. Stress can cause acute and chronic changes in certain brain areas which can cause long-term damage. Over-secretion of stress hormones most frequently impairs long-term delayed recall memory, but can enhance short-term, immediate recall memory. This enhancement is particularly relative in emotional memory. In particular, the hippocampus, prefrontal cortex and the amygdala are affected. One class of stress hormone responsible for negatively affecting long-term, delayed recall memory is the glucocorticoids (GCs), the most notable of which is cortisol. Glucocorticoids facilitate and impair the actions of stress in the brain memory process. Cortisol is a known biomarker for stress. Under normal circumstances, the hippocampus regulates the production of cortisol through negative feedback because it has many receptors that are sensitive to these stress hormones. However, an excess of cortisol can impair the ability of the hippocampus to both encode and recall memories. These stress hormones are also hindering the hippocampus from receiving enough energy by diverting glucose levels to surrounding muscles.
The sympathoadrenal system is a physiological connection between the sympathetic nervous system and the adrenal medulla and is crucial in an organism's physiological response to outside stimuli. When the body receives sensory information, the sympathetic nervous system sends a signal to preganglionic nerve fibers, which activate the adrenal medulla through acetylcholine. Once activated, norepinephrine and epinephrine are released directly into the blood by adrenomedullary cells where they act as the bodily mechanism for "fight-or-flight" responses. Because of this, the sympathoadrenal system plays a large role in maintaining glucose levels, sodium levels, blood pressure, and various other metabolic pathways that couple with bodily responses to the environment. During numerous diseased states, such as hypoglycemia or even stress, the body's metabolic processes are skewed. The sympathoadrenal system works to return the body to homeostasis through the activation or inactivation of the adrenal gland. However, more severe disorders of the sympathoadrenal system such as pheochromocytoma can affect the body's ability to maintain a homeostatic state. In these cases, curative agents such as adrenergic agonists and antagonists are used to modify epinephrine and norepinephrine levels released by the adrenal medulla.
Maternal fetal stress transfer is a physiological phenomenon in which psychosocial stress experienced by a mother during her pregnancy can be transferred to the fetus. Psychosocial stress describes the brain's physiological response to perceived social threat. Because of a link in blood supply between a mother and fetus, it has been found that stress can leave lasting effects on a developing fetus, even before a child is born. According to recent studies, these effects are mainly the result of two particular stress biomarkers circulating in the maternal blood supply: cortisol and catecholamines.
Epigenetics of anxiety and stress–related disorders is the field studying the relationship between epigenetic modifications of genes and anxiety and stress-related disorders, including mental health disorders such as generalized anxiety disorder (GAD), post-traumatic stress disorder, obsessive-compulsive disorder (OCD), and more. These changes can lead to transgenerational stress inheritance.
Sleep epigenetics is the field of how epigenetics affects sleep.