Prenatal stress heightened adult chronic pain

This 2019 McGill rodent study found:

Prenatal stress exacerbates pain after injury. Analysis of mRNA expression of genes related to epigenetic regulation and stress responses in the frontal cortex and hippocampus, brain structures implicated in chronic pain, showed distinct sex and region-specific patterns of dysregulation.

In general, mRNA expression was most frequently altered in the male hippocampus and effects of prenatal stress were more prevalent than effects of nerve injury. Recent studies investigating chronic pain-related pathology in the hippocampus in humans and in rodent models demonstrate functional abnormalities in the hippocampus, changes in associated behavior, and decreases in adult hippocampal neurogenesis.

The change in expression of epigenetic- and stress-related genes is not a consequence of nerve injury but rather precedes nerve injury, consistent with the hypothesis that it might play a causal role in modulating the phenotypic response to nerve injury. These findings demonstrate the impact of prenatal stress on behavioral sensitivity to a painful injury.

Decreased frontal mRNA expression of BDNF and BDNF IV in male offspring following neuropathic pain or prenatal stress respectively. Relative mRNA expression of other stress-related genes (GR17, FKBP5) and epigenetic-related genes (DNMTs, TETs, HDACs, MBDs, MeCP2) in male offspring.

A drastic decrease in expression of HDAC1 was observed in all groups compared to sham-control animals. CCI: chronic constriction injury.”


The study’s design was similar to the PRS (prenatal restraint stress) model, except that the PRS procedure covered gestational days 11 to 21 (birth):

“Prenatal stress was induced on Embryonic days 13 to 17 by restraining the pregnant dams in transparent cylinder with 5 mm water, under bright light exposure, 3 times per day for 45 min.”

None of the French, Italian, and Swiss PRS studies were cited.

The limitation section included:

  1. “Although our study shows significant changes in expression of epigenetic enzymes, it didn’t examine the impact of these changes on genes that are epigenetically regulated by this machinery or their involvement in intensifying pain responses.
  2. The current study is limited by the focus on changes in gene expression which do not necessarily correlate with changes in protein expression.
  3. Another limitation of this study is the inability to distinguish the direct effects of stress in utero vs. changes in the dam’s maternal behavior due to stress during pregnancy; cross-fostering studies are needed to address this issue.
  4. Functional experiments that involve up and down regulation of epigenetic enzymes in specific brain regions are required to establish a causal role for these processes in chronic pain.”

What do you think about possible human applicability of this study’s “effects of prenatal stress were more prevalent than effects of nerve injury” finding?

What professional would recognize that if a person’s mother was stressed while pregnant, their prenatal experiences could cause more prevalent biological and behavioral effects than a painful injury?

https://www.sciencedirect.com/science/article/pii/S0166432819315219 “Prenatal maternal stress is associated with increased sensitivity to neuropathic pain and sex-specific changes in supraspinal mRNA expression of epigenetic- and stress-related genes in adulthood” (not freely available)

OCD and neural plasticity

This 2019 New York rodent study investigated multiple avenues to uncover mechanisms of obsessive-compulsive disorder:

“Psychophysical models of OCD propose that anxiety (amygdala) and habits (dorsolateral striatum) may be causally linked. Numerous genetic and environmental factors may reduce striatum sensitivity and lead to maladaptive overcompensation, potentially accounting for a significant proportion of cases of pathological OCD-like behaviors.

Our results indicate that both the development and reversal of OCD-like behaviors involve neuroplasticity resulting in circuitry changes in BLA-DLS and possibly elsewhere.”


The researchers explored two genetic models of OCD, showed why these insufficiently explained observed phenomena, then followed up with epigenetic investigations. They demonstrated how and the degree to which histone modifications and DNA methylation regulated both the development and reversal of OCD symptoms.

However, the researchers also carelessly cited thirteen papers outside the specific areas of the study to support one statement in the lead paragraph:

“Novel studies propose that modulations in gene expression influenced by environmental factors, are connected to mental health disorders.”

Only one of the thirteen citations was more recent than 2011, and none of them were high-quality studies.

https://www.nature.com/articles/s41598-019-45325-6.pdf “Amelioration of obsessive-compulsive disorder in three mouse models treated with one epigenetic drug: unraveling the underlying mechanism”

How do memories transfer?

This 2018 Chinese study electronically modeled the brain’s circuits to evaluate memory transfer mechanisms:

“During non-rapid-eye-movement (NREM) sleep, thalamo-cortical spindles and hippocampal sharp wave-ripples have been implicated in declarative memory consolidation. Evidence suggests that long-term memory consolidation is coordinated by the generation of:

  • Hierarchically nested hippocampal ripples (100-250 Hz),
  • Thalamo-cortical spindles (7-15 Hz), and
  • Cortical slow oscillations (<1 Hz)

enabling memory transfer from the hippocampus to the cortex.

Consolidation has also been demonstrated in other brain tasks, such as:

  • In the acquisition of motor skills, where there is a shift from activity in prefrontal cortex to premotor, posterior parietal, and cerebellar structures; and
  • In the transfer of conscious to unconscious tasks, where activity in initial unskilled tasks and activity in skilled performance are located in different regions, the so-called ‘scaffolding-storage’ framework.

By separating a neural circuit into a feedforward chain of gating populations and a second chain coupled to the gating chain (graded chain), graded information (i.e. information encoded in firing rate amplitudes) may be faithfully propagated and processed as it flows through the circuit. The neural populations in the gating chain generate pulses, which push populations in the graded chain above threshold, thus allowing information to flow in the graded chain.

In this paper, we will describe how a set of previously learned synapses may in turn be copied to another module with a pulse-gated transmission paradigm that operates internally to the circuit and is independent of the learning process.”


The study had neither been peer-reviewed, nor were the mechanisms tested in living beings.

https://www.biorxiv.org/content/early/2018/07/27/351114 “A Mechanism for Synaptic Copy between Neural Circuits”

Ideaesthesia!

This 2018 UK review subject was colored-hearing experiences from music:

“Music-colour synaesthesia has a broad scope encompassing not only tone-colour synaesthesia elicited on hearing individual tones, but a complex and idiosyncratic mixture of phenomenological experiences often mediated by timbre, tempo, emotion and differing musical style.

The possession of synaesthesia or absolute pitch was shown to have very little effect on the actual colours chosen for each of the musical excerpts, but it might be reasonable to expect that music that elicits a strong emotional response may be more likely to induce synaesthesia than music that does not.

The examination of eight neuroimaging studies were found to be largely inconclusive in respect of confirming the perceptual nature of music-colour synaesthesia. Neither the hyperconnectivity nor the disinhibited feedback theory currently holds as a single categorical explanation for synaesthesia.

Theories promoting the notion of ‘ideaesthesia’ have highlighted the importance of the role of concept and meaning in the understanding of synaesthesia..and a replacement definition: Synaesthesia is a phenomenon in which a mental activation of a certain concept or idea is associated consistently with a certain perception-like experience.”

Much of the review was philosophizing and casting around for clues. The review cited interesting studies and reviews, including The Merit of Synesthesia for Consciousness Research.


One relevant element missed by the underlying research and the review was critical periods of human development. A cited reference in How brains mature during critical periods was Sensitive periods in human development: Evidence from musical training (not freely available) which illuminated some aspects of the research:

“In contrast to a critical period, where a function cannot be acquired outside the specific developmental window, a sensitive period denotes a time where sensory experience has a relatively greater influence on behavioral and cortical development. Sensitive periods may also be times when exposure to specific stimuli stimulates plasticity, enhancing changes at the neuronal and behavioral levels.

The developmental window for absolute pitch may be more similar to a critical than a sensitive period.

The auditory cortex appears to have an unusually long period of developmental plasticity compared with other sensory systems; changes in its cellular organization and connectivity continue into late childhood.

The effects of musical training have been shown to impact auditory processing in the brainstem as well.”

Let’s say that a researcher wanted – as one cited study did – to examine absolute pitch, a rare trait, present in a subset of synesthetes – music-color, another rare trait. The study as designed would probably be underpowered due to an insufficient number of subjects, and it would subsequently find “very little effect.”

Let’s say another researcher focused on brain areas in the cerebrum, and like the eight cited studies, ignored the nuclei in the pons part of the brainstem which are the first brain recipients of sound and equilibrium information from the inner ear via the eighth cranial nerve. Like those studies, the researcher was also biased against including limbic brain areas that would indicate “a strong emotional response.” A study design that combined leaving out important brain-area participants in the synesthesia process with a few number of synesthetes would be unlikely to find conclusive evidence.

The reviewer viewed the lack of evidence from “eight neuroimaging studies” as indicating something about the “perceptual nature of music-colour synaesthesia.” An alternative view is that the “inconclusive” evidence had more to do with study designs that:

  • Had a small number of subjects;
  • Omitted brain areas relevant to the music-color synesthesia process;
  • Didn’t investigate likely music-color synesthesia development periods; and
  • Didn’t investigate associations of music-color synesthesia with epigenetic states.

Consider the magnitude of omitting the thalamus from synesthesia studies as one “perceptual nature” example. Just the background information of Thalamus gating and control of the limbic system and cerebrum is a form of memory indicated its relevance to synesthesia:

Despite the fundamental differences between visual, auditory and somatosensory signals, the basic layouts of the thalamocortical systems for each modality are quite similar.

For a given stimulus, the output neural response will not be static, but will depend on recent stimulus and response history.

Sensory signals en route to the cortex undergo profound signal transformations in the thalamus. A key thalamic transformation is sensory adaptation in which neural output adjusts to the statistics and dynamics of past stimuli.”

One of this study’s researchers described ways that an individual’s “stimulus and response history” became unconscious memories with the thalamus. Including the thalamus in synesthesia studies may also have findings that involve reliving or re-experiencing a memory, possibly an emotional memory.

In such future research, it could be a design element to ask synesthetes before and after the experiment to identify feelings and memories accompanying synesthesia experiences.

It shouldn’t be a requirement, however, to insist that memories and emotions be consciously identified in order to be included in the findings. Human studies, for example, Unconscious stimuli have a pervasive effect on our brain function and behavior have found:

“Pain responses can be shaped by learning that takes place outside conscious awareness.

Our results support the notion that nonconscious stimuli have a pervasive effect on human brain function and behavior and may affect learning of complex cognitive processes such as psychologically mediated analgesic and hyperalgesic responses.”


Does an orangy twilight of aging sunflowers help you feel?

https://www.sciencedirect.com/science/article/pii/S1053810017305883 “Music-colour synaesthesia: Concept, context and qualia” (not freely available)

Resiliency in stress responses

This 2018 US Veterans Administration review subject was resiliency and stress responses:

Neurobiological and behavioral responses to stress are highly variable. Exposure to a similar stressor can lead to heterogeneous outcomes — manifesting psychopathology in one individual, but having minimal effect, or even enhancing resilience, in another.

We highlight aspects of stress response modulation related to early life development and epigenetics, selected neurobiological and neurochemical systems, and a number of emotional, cognitive, psychosocial, and behavioral factors important in resilience.”

The review cited studies I’ve previously curated:


There were two things I didn’t understand about this review. The first was why the paper isn’t freely available. It’s completely paid for by the US taxpayer, and no copyright is claimed. I recommend contacting the authors for a copy.

The second was why the VA hasn’t participated in either animal or human follow-on studies to the 2015 Northwestern University GABAergic mechanisms regulated by miR-33 encode state-dependent fear. That study’s relevance to PTSD, this review’s subject, and the VA’s mission is too important to ignore. For example:

“Fear-inducing memories can be state dependent, meaning that they can best be retrieved if the brain states at encoding and retrieval are similar.

“It’s difficult for therapists to help these patients,” Radulovic said, “because the patients themselves can’t remember their traumatic experiences that are the root cause of their symptoms.”

The findings imply that in response to traumatic stress, some individuals, instead of activating the glutamate system to store memories, activate the extra-synaptic GABA system and form inaccessible traumatic memories.”

I curated the research in A study that provided evidence for basic principles of Primal Therapy. These researchers have published several papers since then. Here are the abstracts from three of them:

Experimental Methods for Functional Studies of microRNAs in Animal Models of Psychiatric Disorders

“Pharmacological treatments for psychiatric illnesses are often unsuccessful. This is largely due to the poor understanding of the molecular mechanisms underlying these disorders. We are particularly interested in elucidating the mechanism of affective disorders rooted in traumatic experiences.

To date, the research of mental disorders in general has focused on the causal role of individual genes and proteins, an approach that is inconsistent with the proposed polygenetic nature of these disorders. We recently took an alternative direction, by establishing the role of miRNAs in the coding of stress-related, fear-provoking memories.

Here we describe in detail our work on the role of miR-33 in state-dependent learning, a process implicated in dissociative amnesia, wherein memories formed in a certain brain state can best be retrieved if the brain is in the same state. We present the specific experimental approaches we apply to study the role of miRNAs in this model and demonstrate that miR-33 regulates the susceptibility to state-dependent learning induced by inhibitory neurotransmission.”

Neurobiological mechanisms of state-dependent learning

“State-dependent learning (SDL) is a phenomenon relating to information storage and retrieval restricted to discrete states. While extensively studied using psychopharmacological approaches, SDL has not been subjected to rigorous neuroscientific study.

Here we present an overview of approaches historically used to induce SDL, and highlight some of the known neurobiological mechanisms, in particular those related to inhibitory neurotransmission and its regulation by microRNAs (miR).

We also propose novel cellular and circuit mechanisms as contributing factors. Lastly, we discuss the implications of advancing our knowledge on SDL, both for most fundamental processes of learning and memory as well as for development and maintenance of psychopathology.”

Neurobiological correlates of state-dependent context fear

“Retrieval of fear memories can be state-dependent, meaning that they are best retrieved if the brain states at encoding and retrieval are similar. Such states can be induced by activating extrasynaptic γ-aminobutyric acid type A receptors (GABAAR) with the broad α-subunit activator gaboxadol. However, the circuit mechanisms and specific subunits underlying gaboxadol’s effects are not well understood.

Here we show that gaboxadol induces profound changes of local and network oscillatory activity, indicative of discoordinated hippocampal-cortical activity, that were accompanied by robust and long-lasting state-dependent conditioned fear. Episodic memories typically are hippocampus-dependent for a limited period after learning, but become cortex-dependent with the passage of time.

In contrast, state-dependent memories continued to rely on hippocampal GABAergic mechanisms for memory retrieval. Pharmacological approaches with α- subunit-specific agonists targeting the hippocampus implicated the prototypic extrasynaptic subunits (α4) as the mediator of state-dependent conditioned fear.

Together, our findings suggest that continued dependence on hippocampal rather than cortical mechanisms could be an important feature of state-dependent memories that contributes to their conditional retrieval.”


Here’s an independent 2017 Netherlands/UC San Diego review that should bring these researchers’ efforts to the VA’s attention:

MicroRNAs in Post-traumatic Stress Disorder

“Post-traumatic stress disorder (PTSD) is a psychiatric disorder that can develop following exposure to or witnessing of a (potentially) threatening event. A critical issue is to pinpoint the (neuro)biological mechanisms underlying the susceptibility to stress-related disorder such as PTSD, which develops in the minority of ~15% of individuals exposed to trauma.

Over the last few years, a first wave of epigenetic studies has been performed in an attempt to identify the molecular underpinnings of the long-lasting behavioral and mental effects of trauma exposure. The potential roles of non-coding RNAs (ncRNAs) such as microRNAs (miRNAs) in moderating or mediating the impact of severe stress and trauma are increasingly gaining attention. To date, most studies focusing on the roles of miRNAs in PTSD have, however, been completed in animals, using cross-sectional study designs and focusing almost exclusively on subjects with susceptible phenotypes.

Therefore, there is a strong need for new research comprising translational and cross-species approaches that use longitudinal designs for studying trajectories of change contrasting susceptible and resilient subjects. The present review offers a comprehensive overview of available studies of miRNAs in PTSD and discusses the current challenges, pitfalls, and future perspectives of this field.”

Here’s a 2017 Netherlands human study that similarly merits the US Veterans Administration’s attention:

Circulating miRNA associated with posttraumatic stress disorder in a cohort of military combat veterans

“Posttraumatic stress disorder (PTSD) affects many returning combat veterans, but underlying biological mechanisms remain unclear. In order to compare circulating micro RNA (miRNA) of combat veterans with and without PTSD, peripheral blood from 24 subjects was collected following deployment, and isolated miRNA was sequenced.

PTSD was associated with 8 differentially expressed miRNA. Pathway analysis shows that PTSD is related to the axon guidance and Wnt signaling pathways, which work together to support neuronal development through regulation of growth cones. PTSD is associated with miRNAs that regulate biological functions including neuronal activities, suggesting that they play a role in PTSD symptomatology.”


See the below comments for reasons why I downgraded this review’s rating.

https://link.springer.com/article/10.1007/s11920-018-0887-x “Stress Response Modulation Underlying the Psychobiology of Resilience” (not freely available)

Differing approaches to a life wasted on beliefs

Let’s start by observing that people structure their lives around beliefs. As time goes on, what actions would a person have taken to ward off non-confirming evidence?

One response may be that they would engage in ever-increasing efforts to develop new beliefs that justified how they spent their precious life’s time so far.

Such was my take on the embedded beliefs in https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5684598/pdf/PSYCHIATRY2017-5491812.pdf “Epigenetic and Neural Circuitry Landscape of Psychotherapeutic Interventions”:

“Animal models have shown the benefits of continued environmental enrichment (EE) on psychopathological phenotypes, which carries exciting translational value.

This paper posits that psychotherapy serves as a positive environmental input (something akin to EE).”

The author conveyed his belief that wonderful interventions were going to happen in the future. However, when scrutinized, most human studies have demonstrated null effects of psychotherapeutic interventions on causes. Without sound evidence that treatments affect causes, his belief seemed driven by something else.

The author cited the findings of research like A problematic study of oxytocin receptor gene methylation, childhood abuse, and psychiatric symptoms as supporting external interventions to tamp down symptoms of patients’ presenting problems. Did any of the paper’s 300+ cited references concern treatments where patients instead therapeutically addressed their problems’ root causes?


For an analogous religious example, a person’s belief caused him to spend years of his life trying to convince men to act so that they could get their own planet after death, and trying to convince women to latch onto men who had this belief. A new and apparently newsworthy belief developed from his underlying causes:

“The founder and CEO of neuroscience company Kernel wants “to expand the bounds of human intelligence.” He is planning to do this with neuroprosthetics; brain augmentations that can improve mental function and treat disorders. Put simply, Kernel hopes to place a chip in your brain.

He was raised as a Mormon in Utah and it was while carrying out two years of missionary work in Ecuador that he was struck by what he describes as an “overwhelming desire to improve the lives of others.”

He suffered from chronic depression from the ages of 24 to 34, and has seen his father and stepfather face huge mental health struggles.”

https://www.theguardian.com/small-business-network/2017/dec/14/humans-20-meet-the-entrepreneur-who-wants-to-put-a-chip-in-your-brain “Humans 2.0: meet the entrepreneur who wants to put a chip in your brain”

The article stated that the subject had given up Mormonism. There was nothing to suggest, though, that he had therapeutically addressed any underlying causes for his misdirected thoughts, feelings, and behavior. So he developed other beliefs instead.


What can people do to keep their lives from being wasted on beliefs? As mentioned in What was not, is not, and will never be:

“The problem is that spending our time and efforts on these ideas, beliefs, and behaviors won’t ameliorate their motivating causes. Our efforts only push us further away from our truths, with real consequences: a wasted life.

The goal of the therapeutic approach advocated by Dr. Arthur Janov’s Primal Therapy is to remove the force of the presenting problems’ motivating causes. Success in reaching this goal is realized when patients become better able to live their own lives.


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An update on brain zapping

This 2017 general-audience article entitled Ultrasound for the brain provided a hyped update on brain zapping:

“Ultrasound could potentially treat other movement disorders, as well as depression, anxiety and a host of intract­able neuropsychiatric disorders..

This could be a breakthrough..

Researchers hope one day to help people with neuropsychiatric conditions by repairing or resetting the relevant neural pathways..

The potential advantages, especially for deep brain areas, are huge..”

Though not the main thrust of the article, another potential use of ultrasound would be to activate drugs delivered to a specific area, as this image portrays:


Vanderbilt University was again at the forefront of brain zapping, as noted in What’s an appropriate control group for a schizophrenia study? for example. I hope the disclosures for subjects participating in Vanderbilt’s brain-zapping studies made it clear that:

“At high intensities, such as those used to relieve essential tremor, ultrasound’s effects are largely thermal: the tissue heats up and cells die.”


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