The Heart-Brain Connection

For all you with inquiring minds here's the entire article from our PeggyJudyTimeKnewsletter

Emotional Rescue: The Heart-Brain Connection Michael Miller, M.D "The silent, often subconscious conversation that is taking place inside us is one of the most vital communications we will ever find ourselves engaged in. It’s the dialogue of emotion-based signals between our hearts and our brains, also known as the heart-brain connection. Our author tells us what research has uncovered and some of the keys to a longer, healthier life."

"We’ve known for decades that smoking, hypertension, high cholesterol, and diabetes account for most cardiovascular problems. But it wasn’t until publication of the Interheart study (25,000 volunteers spanning 52 countries) that emotional stress was identified as another key risk factor, accounting for about one-third of heart attacks and strokes. Previously, in the 1970s, when volunteers were asked to begin to count to 100 and then to serially subtract seven’s in quick succession (in a test of “mental stress”), blood vessels constricted as if they had taken and failed a cardiac stress test. Except in these cases, testing occurred at rest. In other words, external stressors that are not effectively managed have direct internal implications by placing undue stress on the heart. Fast forward from the 1970s to the present era, and a recent study of more than 135,000 men and women in Sweden that found a history of stress-related disorders, such as post-traumatic stress syndrome, increased the risk of cardiovascular disease by more than 60 percent within just the first year of diagnosis. Mechanistically, the underlying cause of a heart attack is a sudden rupture of an unstable plaque within a coronary artery. During stressful situations, the “fight-or-flight” response jumps into full gear, releasing biochemical compounds such as adrenaline, which raises heart rate and blood pressure, and signals platelets to release a chemical, neuropeptide Y, that can cause spasm and transient occlusion of the coronary artery."

"Another cardiac condition that can result from acute emotional stress is Takotsubo cardiomyopathy, named for the Japanese octopus-trapping pot that the heart comes to resemble. Most commonly occurring after a sudden catastrophic event such as losing a spouse, an outpouring of adrenaline creates a transiently “shocked” state characterized by markedly abnormal contractions in a section of left ventricle and by heart failure. Resolution of the emotional crisis coupled with supportive care generally, but not always, leads to recovery of heart function."

"Beyond single, severely stressful events, living day-to-day with stress is clearly associated with increased risk of heart attack and stroke. We have only recently begun to understand the neurochemical pathways that generate atherosclerosis and cardiovascular disease. They include close communication between the central nervous system, heart, adrenal gland, and kidneys involved in the activation and release of stress hormones such as cortisol and heart damaging neuropeptides. On another level, we have come to appreciate that chronic psychosocial or mental stress accelerates cardiovascular disease by promoting inflammation, oxidative stress, and abnormal function of the endothelium, the protective inner lining of our blood vessels."

Connecting to the Brain’s Emotional Coding Center "If we are to understand how to improve emotional health, it would be useful to probe the brain’s emotional coding center, the amygdala. As an undergraduate at Rutgers University, I had the opportunity to work with Drs. Arthur Kling and Robert Deutsch, a psychiatrist and a neuroscientist doing seminal research into the role of the amygdala in socialization and emotion. After Kling’s team induced frontal lobe lesions in rhesus monkeys and severed connections to the amygdala, their social interactions came to a near halt. Similar behavioral patterns have been reported following amygdalotomy for other emotional behaviors in humans, including pathologic aggression. Loss of socialization skills also occurred after prefrontal lobotomy, as I directly encountered when recording social interactions in patients who had undergone the procedure."

"The association between high levels of social connectivity and favorable cardiovascular effects, including better outcomes after stroke, raises the possibility that a larger amygdala may afford cardioprotection. The Leiden Longevity Study supports this concept: large left amygdala volumes were not only associated with a high level of emotional health, but also correlated with familial longevity. By contrast, reduced social interactions caused by panic disorders have been associated with reduced amygdala volumes in the lateral and basal regions believed to process fear and anxiety. These disorders correlate with reduced parasympathetic tone, a known contributor to cardiovascular disease risk. Amygdala activity has also been suggested to play a role in cardiovascular disease risk prediction. For example, residing in high-paced, crowded, noisy, and polluted cities leads to activation of the perigenual anterior cingulate cortex, a brain region that regulates amygdala activity and response to psychosocial stress. Chronic exposure to stress results in allostatic load that adversely impacts brain plasticity and cardiovascular risk factors, including an exaggerated blood pressure response owing to activation of the perigenual cingulate cortex."

"In a study conducted in Boston, increased amygdala activity at rest, assessed by PET/CT imaging, was also associated with blood vessel inflammation and risk of cardiovascular events over the next four years. The authors proposed that emotional stress signals a region of the amygdala to activate the sympathetic nervous system, promoting the production of pro-inflammatory white blood cells that may trigger heart attack, stroke, or sudden death. This study, among the first to demonstrate a direct relationship between emotional stressors and risk of cardiovascular events builds upon prior work identifying a direct association between amygdala reactivity (in response to threatening facial expressions) and increased carotid intima-media thickness, an anatomic biomarker of atherosclerosis and cardiovascular risk predictor."

"Does counteracting negative stressors reduce cardiovascular risk? While no clinical outcome trials have been conducted to date, adoption of lifestyle strategies aimed at improving positive emotions seems to improve biomarkers of cardiovascular health, such as inflammation, arterial stiffness, and endothelial function. In my cardiology practice and as elaborated upon below, I recommend that my patients employ these five strategies to reduce day-to-day stressors:"

1. Meditation (serotonin activated relaxation practices)

2. Yoga (GABA induced mood stabilization)

3. Laughter (endorphin mediated visual effects)

4. Music (dopamine regulated auditory effects

5. Massages, hugging (oxytocin activated tactile responses)

Relaxation Practices "There are several mechanisms by which relaxation strategies such as these improve biomarkers of cardiovascular risk. The first is improvement in parasympathetic tone, the heart’s ability to maintain blood pressure and/or heart rate in the face of daily stressors. (This contrasts with the “fight-or-flight” response described earlier, an adaptive physiological mechanism characterized by increased sympathetic tone with associated rise in blood pressure and heart rate). Examples include the inordinate or “hysterical” strength that arose in a daughter attempting to save her father who was pinned under a car and a mother fighting off a lion that attacked her son."

"Such isolated “spring into action” situations have no lasting cardiovascular consequences in otherwise healthy individuals. But regularly occurring stressful situations can result in persistently heightened sympathetic tone. Under these conditions, the heart is chronically stressed by exaggerated blood pressure and heart rate responses that endure after the stressful situation is resolved. A persistent increase in sympathetic tone, moreover, raises the likelihood of inflammation, abnormal heart rhythms, and increased risk of sudden cardiac death. On the other hand, reduced sympathetic or increased parasympathetic or vagal tone enables the heart to manage stressors, keeping blood pressure and heart rate under better control during stress, and shortening recovery time after activities that raise heart rate (such as aerobic activity). Relaxation strategies like those described above are among the most effective ways to improve parasympathetic tone. Their benefits are also indicated by tests using heat mapping to evaluate the expression of genes that promote oxidative stress and inflammation, important biomarkers for cardiovascular disease."

"One recent study, for example, found that in a group that had practiced meditation on a regular basis, the expression of pro-inflammatory genes was reduced compared to those who had never mediated. In the second stage of the study, one half of the non-meditating group was randomly assigned to relaxation training sessions incorporating meditation, prayer, and yoga. After two months, genetic expression of pro-inflammatory genes resembled that of long-time meditators. Practicing relaxation also reduced the expression of genes promoting insulin resistance, the forerunner of Type 2 diabetes. The results of this study not only affirmed the importance of brain-heart connections on a molecular level but found that relaxation can have a robust effect in a very short time, supporting the adage “never too late to start.”

"Mindfulness meditation, which has become one of the most popular relaxation practices over the past decade, combines heightened, non-judgmental awareness of one’s surroundings and feelings with slow deep breathing exercises. A stress-reduction program based on mindfulness has been associated with improvement in hypertension and depression, while strengthening the immune system and raising activity of telomerase, an enzyme that slows biological aging. Researchers have also studied the cardiovascular impact of practices that incorporate relaxation and movement. Yoga and Tai Chi, for example, improve balance and coordination to help the elderly prevent falls and fractures, and bolster strength and stabilization. In cardiovascular terms, yoga is associated with reduced systolic blood pressure and cholesterol: a recent meta-analysis of 49 trials found that three sessions of yoga weekly reduced systolic blood pressure as much as low-dose antihypertensive medication. Tai Chi has been shown to help suppress inflammation and depression, both cardiovascular disease risk factors. Finally, yoga may also raise brain levels of γ-aminobutyric acid (GABA), a neurotransmitter involved in mood stabilization and stress reduction and both yoga and meditation practices lead to the release of serotonin, another important neurotransmitter involved in mood regulation."

Comic Relief "While it has long been thought that laughter can induce a sense of well-being through the release of endorphins, its connection to cardiovascular health has only become apparent in recent years. Specifically, the β-endorphins released by a hearty belly laugh bind to receptors on the surface of the vascular endothelium to release nitric oxide, a molecule with multiple cardioprotective properties. Recent studies have, in fact, found the risk of heart attack and stroke is reduced in individuals who laugh on a regular basis, compared to those who never or rarely laugh. Laughter also reduces stiffness and aging of blood vessels, including those in the brain."

"A popular way to combine laughter with deep breathing techniques is through laughter yoga. The origins of this practice date back to 1995 when Dr. Madan Kataria, a family physician, assembled a small group in a public park in Mumbai, who met each morning to laugh together through a series of funny expressions and movements that Dr. Kataria devised. Nearly 25 years later, more than 15,000 laughter yoga clubs exist in more than 70 countries worldwide."

"A typical session lasts from 30 to 60 minutes, during which a leader engages participants in exercises designed to elicit forced laughter that converts to emotional laughter as the session wears on. One popular exercise is “milkshake or cocktail laughter,” where participants pretend to pour a glass of milk (or cocktail) into one hand saying “here” then into the other hand repeating “here” and then pretending to drink it or discard it behind their shoulder with repeated laughter. The benefits of laughter yoga include decreased cortisol levels and systolic blood pressure, as well as improvement in indices of depression and overall life satisfaction. While research in this field remains sparse, the encouraging results from these small-scaled studies support the development of a clinical trial in which laughter therapy is one component of an integrated therapeutic lifestyle designed to reduce cardiovascular events."

Music to Your Ears "A number of studies have demonstrated that listening to joyful music offers cardioprotective and neurobiological effects, including reduced inflammation, blood pressure and heart rate, improved parasympathetic tone, and shortened recovery following surgery. The “frisson effect” or the feeling of chills down the spine is a physiological consequence related to the release of dopamine in response to listening to or anticipating pleasurable music. A pilot study suggested that focusing on this sensation (i.e., mindful music) may be a useful intervention to speed recovery following stroke."

The Moral Molecule "The hormone and neurotransmitter oxytocin, released from the posterior pituitary during physical encounters such as touching and hugging, can lower blood pressure and heart rate. More surprisingly, research in recent years has demonstrated that the compound has a direct cardioprotective effect. In animal models, administration of oxytocin not only prevents the death of heart tissue that results in heart failure but may also regenerate new cells. In human studies, intranasal oxytocin has been shown to improve parasympathetic tone during a mental stress test and may offer relief in chronic pain; the latter has intriguing cardiovascular implications, because chronic pain is associated with increased risk of death from heart disease and stroke. More work needs to be done to pinpoint the impact of many of the practices mentioned above. But there is already enough research to conclude that effective management of day-to-day psychosocial stressors is vital to good overall heart and brain health. Beyond good nutrition and regular physical activity, then, consider practicing meditation or yoga on a routine basis. Laugh, listen to music, and hug your favorite people and pets. Such are the keys to a longer, happier life."

Michael Miller, M.D., is Professor of Cardiovascular Medicine at the University of Maryland School of Medicine and serves on the American Heart Association Leadership Council for Lifestyle and Cardiometabolic Health. He is past president of the American Society of Preventive Cardiology, serves as consultant for the National Library of Medicine and assisted the US Postal Service in developing the “Heart Health Stamp.” Miller earned his medical degree at Rutgers Medical School and completed residency at the University of Cincinnati Hospital and fellowships in metabolism and cardiovascular diseases at the Johns Hopkins Hospital. He has published more than 250 original scientific publications, book chapters and three books. His most recent book is Heal Your Heart, The Positive Emotions Prescription to Prevent and Reverse Heart Disease (Random House, 2014). Miller’s twitter feed is @mmillermd1

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075501/

Do Trees Really Support Each Other through a Network of Fungi?

Here's the complete article we excerpted in the March 2023

PeggyJudyTime Newsletter. Trees communicate and cooperate through a fungal web, according to a widespread idea. But not everyone is convinced

By Stephanie Pappas

"The tips of tree roots are intertwined with filaments of fungus, forming a hidden underground network that seems to benefit both organisms: the filaments, known as hyphae, break down minerals from the soil that trees can then take into their roots, while the fungus gets a steady source of sugar from the trees. More poetically, research has hinted that these connections—known as mycorrhizal networks—can extend between trees, enabling one tree to transfer resources belowground to another. Some researchers even argue that trees are cooperating, with older trees passing resources to seedlings and nurturing them as a parent might." "This idea of forests as cooperative, caring places has caught on both in the scientific literature and popular culture, notably in the 2022 book Finding the Mother Tree: Discovering the Wisdom of the Forest, by forest ecologist Suzanne Simard of the University of British Columbia. There is even a punny popular name for the phenomenon: the “wood-wide web.”'

"A new analysis published in Nature Ecology & Evolution, however, argues that the evidence for mycorrhizal networks facilitating tree cooperation is not as strong as the popular story would suggest. It’s not that relationships between trees and fungi don’t exist, says co-author Justine Karst, an ecologist who studies mycorrhizal networks at the University of Alberta. Rather, in many cases, suggestive evidence or studies with many caveats have been taken as more definitive than they really are. “We don’t want to kill anyone’s joy or curiosity or wonder about the forest, but we just want to tamp down on some of the misinformation,” Karst says."

"The problem with researching mycorrhizal networks is that they’re very delicate: dig up a root, and you’ve destroyed the very web of fungi and wood you wanted to study. That makes it hard to tell if a particular fungus is really connecting any two trees. The best way to get around the problem is to sample fungi from different locations, sequence their genetic information, and make a map of where genetically identical fungi are growing. This is a tremendous amount of work, Karst says, and she and her co-authors could find only five such studies across just two forest types, comprising only two tree species and three types of fungi."

"Making these studies even more challenging is the ephemeral nature of fungal networks. Fungi can grow as individuals after being split, says Melanie Jones, a plant biologist at the University of British Columbia and a co-author of the new analysis. Even genetic samples provide only a snapshot and can’t reveal whether the bits of fungi collected at two different trees are still actually connected. They may have been severed by part of the fungus dying or by something taking a bite out of it. “It’s a very thorny issue,” Jones says."'

"These limitations raise questions about how widespread mycorrhizal networks are, and how long they last. It is clear that substances from one tree can end up being taken up by a neighboring tree in the forest. Researchers can test this by providing one tree with a chemical compound tagged with a certain marker. In a 2016 study in a Swiss forest, researchers sprayed some trees’ leaves with a particular isotope of carbon and found that isotope showed up in unsprayed neighbors. However, it’s not clear that fungi are necessarily responsible for this transfer, Jones says. Resources can also move directly root-to-root and through the soil, and it’s very difficult to separate out those pathways in a real forest. Researchers try to set up barriers between trees so that fungal hyphae and roots can’t connect them, leaving only the soil pathway as a possible means of transmission. But these barriers themselves (usually made of fine mesh) can affect tree growth, complicating the picture."

"To test the effect of mycorrhizal networks, researchers also often set up wide-mesh barriers, allowing fungi but not tree roots through. But Karst and Jones contend that in such cases, some researchers have rarely checked to make sure a connected mycorrhizal network has actually formed. The strongest evidence for trees sending resources via fungal pathways versus roots or soil came from one 2008 study in which mesh was used to allow only fungus, but not roots, to connect Ponderosa pine seedlings to older pines in a real forest, Karst and Jones say. The researchers then cut several older pines and treated the cut trunks with dyed water. The dye showed up in the seedlings, despite the lack of connections between roots, indicating that fungal hyphae had done the transfer."

"That is suggestive of trees transferring water, Jones says, but still leaves open the question: Does any of this matter for the seedlings? If mycorrhizal networks have evolved to allow older trees to help their younger kin survive, the resource transfer must improve seedling survival. There, too, Karst and Jones claim some of the evidence is shaky. “In the really well-controlled experiments, less than 20 percent show that the seedlings performed better,” Jones says. In the remaining 80 percent, she adds, the hyphae-connected seedlings performed either equivalently or worse than the ones cut off from the fungal network."

"Meanwhile, the idea that trees send underground warnings to one another about herbivorous insects or other dangers is predicated on a single greenhouse study in which a Douglas fir and a Ponderosa pine were connected only by fungal networks. When researchers stressed the Douglas fir by exposing it to insects, the Ponderosa pine also started pumping out defense chemicals. However, the effect disappeared when the firs and pines were connected by both roots and fungi, which is what happens in the wild. “The main message is that this hasn’t been tested in a forest,” Karst says. “When you see those pictures of ancient forests, big trees and they’re passing signals to each other, it just hasn’t been tested.” "The idea of forests as cooperative, rather than competitive, also conflicts with the fundamentals of natural selection, says Kathryn Flinn, a plant community ecologist at Baldwin Wallace University in Ohio, who was not involved in the new analysis. The argument for cooperation is that trees in a healthy forest survive better than trees in a sickly one, but such instances of group natural selection are rare in the wild, Flinn says. And in forests, individual selection favors competition, with particular trees vying for resources in a way that would prevent any group benefits. “I find this whole controversy really interesting because it’s an example of people wanting to project their own values onto nature and or wanting to see in nature a model for human behavior,” Flinn says."

Simard, whose research on forests has provided much of the basis for the arguments that trees cooperate, declined to answer specific questions about the new analysis but said in a statement that she stands by her research. “Forests provide crucial support to life on our planet. Reducing ecosystems to their individual parts hinders us from understanding and appreciating the emergent relationships and behaviors that make these complex ecological systems thrive,” she says. “For decades, a compartmentalized approach has hindered us from better understanding why forests help regulate global climate and harbor such rich biodiversity. Applying reductionist science to complex systems accelerates the exploitation and degradation of forests worldwide.” "Karst, Jones and their study co-author Jason Hoeksema of the University of Mississippi agreed that a reductionist view of the forest—in which individual parts of the network are tested individually rather than in context—is not the only way to study ecology. However, these reductionist studies have been used to make big claims about mycorrhizal networks, they said, adding that they wanted to focus their analysis on what the results really showed. They limited their analysis to studies conducted in real forests, they said, because these are most relevant to the real world."

"Karst says that she and her colleagues are not intending to put a chill on research in this area, but to push it into new types of forests and encourage investigation of the most promising areas, such as water transfer between trees. For her part, Karst believes there may still be truth to the idea that mycorrhizal networks are involved in at least some tree-to-tree networking, and better-designed experiments could get at that truth. “I want to have another go at it,” Karst says." Stephanie Pappas is a freelance science journalist.

March - When eyes meet, neurons start to fire

by Bill Hathaway, Yale University "Although not as romantic as the first dance floor encounter, a new Yale study was able to chart this surprisingly widespread neuronal response in multiple brain areas when the eyes of two individuals meet and social gaze interaction happens, researchers report May 10 in the journal Neuron."

"There are strong robust signals in the brain that are signatures of an interactive social gaze," said Yale's Steve Chang, associate professor of psychology and neuroscience, a member of the Wu-Tsai Institute and the Kavli Institute for Neuroscience, and the senior author of the study.

The phenomenon of extracting meaning in the gaze between two people has been documented in art and literature for millennia but scientists have had a difficult time uncovering how the brain accomplishes such a subtle feat. They have extensively studied the neurobiology of social perception, usually by giving brain scans to individuals as they are presented with specific static images, such as angry or happy faces or direct or averted gazes. However, the interactions of two individual minds as they dynamically and reciprocally extract information from each other's eyes are difficult to tackle.

Chang's lab overcame this obstacle by monitoring the brain activity of monkeys while simultaneously tracking the eye positions of two animals. This enabled them to record a large array of neurons as the animals spontaneously gazed at each other.

"They were spontaneously engaging in social interactions while we examined neural firing," Chang said. "Importantly, we were not imposing any tasks, so it was up to them to decide how and when they would interact." They found that specific sets of socially tuned neurons fired across multiple brain regions at different times during mutual eye contact. For instance, one set of neurons fired when one individual initiated mutual eye contact, but not when that individual followed the other's gaze. Another set of neurons were active when the monkeys were in the process of deciding whether to complete mutual eye contact initiated by the other. And interestingly, when fixing a gaze onto another individual some neurons marked the distance relative to another's eyes, but when receiving a gaze yet another set of neurons signaled how close the other individual was. The brain regions in which neuronal activation took place provided hints into how the brain assesses the meaning of the gaze. Surprisingly, part of the network activated during social gaze interaction included the prefrontal cortex, the seat of higher-order learning and decision-making, as well as the amygdala, the center for emotion and valuation.

"Multiple regions within the prefrontal cortex, in addition to the amygdala, are recruited to compute selective aspects of interactive social gaze, suggesting the importance of a more contemplative role during social gaze interaction," Chang said. These areas in the prefrontal-amygdala networks activated during the processing of social gaze interaction are also known to be disrupted in cases of atypical social conditions, such as autism. This attests to their importance in achieving feelings of social connectedness, he said. Social gaze interaction likely serves a critical role in shaping social connectedness, he added, and the prefrontal-amygdala networks might make that happen. "The fact that interactive social gaze neurons are found widely in the brain also speaks to the ethological importance of social gaze interaction," Chang said. Yale's Siqi Fan and Olga Dal Monte are co-lead authors of the study.

More information: Olga Dal Monte et al, Widespread implementations of interactive social gaze neurons in the primate prefrontal-amygdala networks, Neuron (2022). DOI: 10.1016/j.neuron.2022.04.013 Journal information: Neuron Provided by Yale University

https://medicalxpress.com/news/2022-05-eyes-neurons.html