[vc_row el_class=”mr-b-26″][vc_column][vc_column_text single_style=””]<\/p>\n
Table of Contents<\/b><\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_single_image image=”6209″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Figure 1. My microbes made me to do it! ~ The gut-brain axis.<\/b> The role of the gut microbiome in early childhood development is a rapidly growing area of research. Here are some key points based on recent studies: (a) Critical windows in early life<\/b>: the first few years of life are crucial for both microbiome and brain development. During this period, the gut microbiome can significantly influence neurodevelopmental processes.\u00a0Studies have shown that disruptions in the gut microbiome during these critical windows can lead to long-term effects on brain function and behavior. (b) Neurodevelopmental disorders:<\/b> there is growing evidence linking gut microbial dysfunction to various neurodevelopmental disorders, such as autism spectrum disorder (ASD<\/b>) and attention-deficit\/hyperactivity disorder (ADHD<\/b>).\u00a0For instance, children with ASD often exhibit altered gut microbiota composition compared to neurotypical children. (c) Mechanisms of influence:<\/b> the gut microbiome can affect brain development through several mechanisms, including modulation of the immune system, production of neuroactive metabolites, and direct neural communication via the vagus nerve.\u00a0These interactions can influence processes such as neurogenesis, myelination, and synaptic pruning. (d) Potential interventions<\/b>: understanding the role of the gut microbiome in early neurodevelopment opens up possibilities for interventions.\u00a0Probiotics, prebiotics, and dietary modifications are being explored as potential strategies to support healthy brain development and mitigate the risk of neurodevelopmental disorders. These insights highlight the importance of maintaining a healthy gut microbiome during early childhood to support optimal brain development.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”introduction”][vc_column][vc_custom_heading text=”Introduction”][vc_single_image image=”6211″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Box-1. All disease begins in the gut ~ Hippocrates of Kos.<\/b> (<\/i>Mood by microbe: towards clinical translation. Dinan and Cryan 2016 Genome Medicine 8:36: 1\u20133<\/i><\/u><\/span>)<\/i> [1].<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n \u2018My microbes made me do it!\u2019<\/b> Until now, this assertion would have sounded like a pretext of last resort, and any indications that the gut microbiome may influence our behavior would have been discounted as fanciful speculation. Recent research has certainly shown that the gut microbiome can significantly influence our behavior, mood, and cognitive functions<\/span> (learning, memory, and emotional state<\/span><\/i>). This is primarily due to the \u2018gut-brain axis,\u2019 <\/i><\/b>a complex communication network that links the gut and the brain through biochemical and physical pathways (see Figure 1; Box-1; Box-2<\/b>).<\/p>\n [\/vc_column_text][vc_single_image image=”6214″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Box-2. Earliest insights into the gut-brain axis ~ The story of Alexis St. Martin and Dr. William Beaumont.<\/b> Dr. William Beaumont\u2019s meticulous observations of the digestive process in real time. (<\/i>Cryan et al., 2019 Physiol Rev 99: 1877\u20132013<\/u><\/span><\/i>)<\/i> [2].<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Gut microbes produce neurotransmitters, hormones, and metabolites<\/span> that can affect our emotions, thought processes, and behaviors.<\/span>\u00a0For example, the gut produces a large portion of the body\u2019s serotonin, a neurotransmitter that plays a key role in mood regulation.\u00a0Studies have shown that changes in the gut microbiome can lead to alterations in brain function and behavior, as seen in experiments with laboratory mice and fruit flies<\/i><\/b>.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Nonetheless, given the evolutionary history of interactions between animals and their resident microorganisms, it is reasonable to expect that these findings are relevant to humans as well. This area of research is still evolving, but it holds promising potential for understanding and possibly treating various mental health conditions through modulation of the gut microbiome.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-1″][vc_column][vc_custom_heading text=”Microbiomes, the Brain, and Behavior”][vc_column_text single_style=””]What is Behavior <\/strong><\/p>\n Behavior can be defined as the coordinated response of an animal to external or internal stimuli. The following examples of the cat and mouse<\/i><\/b> illustrate how behavior can be driven by both external and internal stimuli<\/i><\/b>, and how these can interact.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Many biologist and most psychologists would add a proviso to this definition ; that [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Moreover, behavior does not necessarily involve movement. Cognitive processes, such as planning your activities for the day, are indeed behavior with significant consequences, even though they may not involve physical action (no movement), for example, blinking.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-2″][vc_column][vc_custom_heading text=”Nervous System and its Role in Behavior”][vc_column_text single_style=””]<\/p>\n The biological substrate for animal behavior is the nervous system, including the brain.<\/span> The essential functional unit of the nervous system is the neuron<\/i><\/b> (also known as nerve cell; a nerve is made up of many neurons). The nervous system transmits information very rapidly, by electrical signals<\/i><\/b> along the length of each neuron (axons) and by chemical signal<\/i><\/b>s (neurotransmitters) related at specialized sites, called synapses<\/i><\/b>, between neurons.<\/p>\n [\/vc_column_text][vc_single_image image=”6213″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Figure 2. The nervous system as the substrate for behavior.<\/b> The three-step process comprises: (1) <\/b>sensory input<\/i><\/b>, (2) <\/b>integration<\/i><\/b> of the sensory inputs and the internal state of the animal, lead to (3)<\/b> a behavioral response, which usually involves movement of the animal, i.e., motor output<\/i><\/b>. Note that integration ranges in complexity from a single relay neuron (as shown) to complex patterns of signaling that involve multiple regions of the brain and sophisticated evaluation of information, generating a coordinated behavioral response; and some behavioral outputs do not involve movement.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n To recapitulate, the three-step process of sensory input, central integration, and behavioral response is fundamental to understanding how organisms interact with their environment. The sheer number of neurons and synapses in the human brain highlights the incredible capacity for processing and integrating information.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-3″][vc_column][vc_custom_heading text=”Gut-Brain Axis”][vc_column_text single_style=””]<\/p>\n There is now accumulating evidence that the gut microbiome can influence nervous system function, and particularly the central integration that dictates the behavioral response to internal and external stimuli. At a glance, this appears biologically far-fetched because the gut microbiome is remote from the brain.<\/u><\/span> However, interactions between the gut microbiome and brain function are a mere extension to the long-recognized physiological relationship between the brain and gut,\u00a0 this connection is primarily mediated by several pathways, including the nervous, endocrine, and immune system:<\/u><\/span> the so called gut-brain axis<\/i><\/b> (see Figure 1<\/b>).<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Gut microbes produce neurotransmitters and other chemicals that can affect brain function.\u00a0For instance, they help produce serotonin, a key neurotransmitter involved in mood regulation.\u00a0Additionally, the vagus nerve, which runs from the gut to the brain, plays a crucial role in this bidirectional communication. Research has shown that changes in the gut microbiome can influence stress responses, anxiety, and even cognitive functions like memory. This is why maintaining a healthy gut microbiome is increasingly seen as important for overall mental health and well-being.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n One does not have to be a physiologists to appreciate how emotional state, including stress, influences appetite and gut function, as well as how eating a nourishing meal can promote our sense of wellbeing.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-4″][vc_column][vc_custom_heading text=”Microbial Products and Brain Function”][vc_column_text single_style=””]<\/p>\n How do microorganism in the gut affect brain function?<\/span> The simple answer is that (see Figure 4):<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text single_style=””]<\/p>\n There is more complicated answer to the question about how gut microorganisms influence brain function (see Figure 4<\/strong>).<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n In the next section, we present some of the patterns of interactions by addressing some widely held claims about how gut microbe-brain interactions affect the so-called happiness hormone.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-5″][vc_column][vc_custom_heading text=”The \u201cHappiness Hormone\u201d Serotonin”][vc_column_text single_style=””]<\/p>\n Serotonin is a small molecule that packs a big punch. It is an evolutionarily ancient molecule found across all domains of life. While typically regarded as neurotransmitter, serotonin serves a diverse range of roles across disparate biological systems [3]. [\/vc_column_text][vc_single_image image=”6207″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Figure 3. The \u201chappiness hormone\u201d ~ Serotonin. <\/b>Serotonin, <\/i><\/b>also known as 5-hydroxytryptamine<\/i><\/b> (5-HT<\/b>), is a neurotransmitter and hormone that helps transmit signals between nerve cells. It is primarily produced in the gastrointestinal tract<\/i><\/b> (about 90%)<\/i><\/b> and in the brain<\/i><\/b> (about 10%)<\/i><\/b> from the amino acid tryptophan<\/i><\/b>. Serotonin plays a crucial role in regulating mood, sleep, digestion, appetite, blood clotting, and bone health. It is often referred to as the \u201cfeel-good\u201d<\/span> chemical because it contributes to feelings of well-being and happiness.\u00a0Low levels of serotonin are associated with depression and anxiety<\/i><\/b>. In the gut, serotonin helps control bowel movements and function.\u00a0It also plays a role in reducing appetite while eating. Serotonin is involved in regulating the sleep-wake cycle and is a precursor to melatonin, a hormone that regulates sleep. Serotonin reuptake inhibitors<\/i><\/b> (SSRIs<\/b>) work by blocking the reabsorption (reuptake<\/span><\/i>) of serotonin into neurons, making more serotonin available to improve transmission of messages between neurons. They are called selective because they primarily affect serotonin and no other neurotransmitters. SSRIs are commonly prescribed to treat depression, anxiety disorders, panic disorder, obsessive-compulsive disorder (OCD<\/b>), post-traumatic stress disorder (PTSD<\/b>), and other mood disorders. Some widely used SSRIs include fluoxetine (Prozac), sertraline (Zoloft), citalopram (Celexa), escitalopram (Lexapro), and paroxetine (Paxil). Common side effects of SSRIs can include nausea, insomnia, dizziness, dry mouth, and sexual dysfunction.\u00a0They are generally considered to have fewer side effects compared to other types of antidepressants. SSRIs are considered relatively safe and effective for long-term use in treating various mental health conditions.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Let us break down these misunderstandings further:<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Focusing on the scientific facts, we know with confidence that:<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Therefore, in essence, although the gut microbiome does not contribute directly to the serotonin levels in the brain, various behavioral and neurophysiological studies suggest strongly that the gut microbiome can contribute to emotional health. Some of the underlying mechanisms for this and other behavioral traits are addressed subsequently below.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-6″][vc_column][vc_custom_heading text=”The Gut Microbiome and the Brain”][vc_column_text single_style=””]<\/p>\n The gut microbiome indeed plays a crucial role in influencing behavior through its interactions with various physiological systems, including the nervous system, immunity, and metabolism<\/u><\/span> (see Figure 4). Here are some key points based on recent research:<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-7″][vc_column][vc_custom_heading text=”The Role of Vagus Nerve in the Microbiome-Gut-Brain Axis”][vc_column_text single_style=””]<\/p>\n The first and most obvious route for gut microbiome communication with the brain is one that requires a neural connection between the gut and the brain, i.e., the vagus nerve<\/u><\/span>.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n These interactions emphasize the complexity and importance of the gut microbiome in regulating not just physical health but also mental and emotional well-being.<\/p>\n [\/vc_column_text][vc_single_image image=”6210″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Figure 4. Mind altering microorganisms ~ Gut-brain neurotransmitter signaling.<\/b> Illustration depicts some established facts about gut-brain neurotransmitter signaling<\/i><\/b>: (i)<\/b> Bidirectional communication<\/u> – the gut-brain axis involves two-way communication between the gastrointestinal tract and the central nervous system. This communication occurs through neural, hormonal, and immune pathways; (ii)<\/b> Neurotransmitters in the gut<\/u> – the gut produces several neurotransmitters, including serotonin, dopamine, and gamma-aminobutyric acid (GABA<\/b>). About 90% of the body\u2019s serotonin is produced in the gut. (iii)<\/b> Vagus nerve<\/u>: the vagus nerve is a critical component of the gut-brain axis, facilitating direct neural communication between the gut and the brain. It plays a key role in transmitting signals related to gut health and function. (iv)<\/b> Microbial metabolites<\/u> – gut bacteria produce metabolites such as short-chain fatty acids <\/i><\/b>(SCFAs<\/b>), which can influence brain function. These metabolites can cross the blood-brain barrier and affect neurotransmitter systems. (v)<\/b> Impact on mood and behavior<\/u> – changes in gut microbiota composition can influence mood and behavior. For example, certain gut bacteria can produce metabolites that affect the production and regulation of neurotransmitters involved in mood regulation; (vi)<\/b> Neuroendocrine signaling<\/u> – the gut-brain axis includes neuroendocrine signaling, where hormones released by the gut can influence brain function. This includes hormones like ghrelin<\/i><\/b> and leptin<\/i><\/b>, which regulate appetite and energy balance<\/i><\/b>. (vii) <\/b>Immune system Involvement<\/u> – the immune system is also a key player in gut-brain communication. Cytokines<\/i><\/b> and other immune signaling molecules<\/i><\/b> produced in the gut can affect brain function and behavior. These points highlight the complex and dynamic nature of gut-brain neurotransmitter signaling, emphasizing its importance in maintaining overall health and well-being.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-8″][vc_column][vc_custom_heading text=”The Role of Immune System in the Microbiome-Gut-Brain Axis”][vc_column_text single_style=””]<\/p>\n The second important route by which microbes can influence the brain is via immune system<\/u><\/span>. The immune system is a critical pathway through which the gut microbiome can influence brain function and behavior. Here are some key points that illustrate this complex interaction:<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n These interactions underscore the importance of the gut-immune-brain axis<\/em><\/strong> in maintaining overall health and influencing behavior.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-9″][vc_column][vc_custom_heading text=”The Intricate Role of Macrophages in the Microbiome-Gut-Brain Axis”][vc_column_text single_style=””]<\/p>\n Research on one type of immune cells, the macrophage, illustrates how the immune system can act as a go-between from the gut microbiome to brain function.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Macrophages are mobile cells associated with many organs of the body, including the gut wall and they provide protection against invasive microorganisms. Macrophages are indeed pivotal in the immune response, acting as both defenders against pathogens and regulators of inflammation.<\/span> They respond to cytokines (small proteins produced by various cells types of the human body), which are signaling molecules that orchestrate the immune response. Pro-inflammatory cytokines can be induced by certain gut bacteria, leading to an inflammatory state.<\/p>\n [\/vc_column_text][vc_single_image image=”6215″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Figure 5. Modulation of gut immune cells by the gut microbiome can influence cognition in the brain.<\/b> The gut microbiome plays a crucial role in modulating immune responses, which in turn can affect brain function and cognition. The interaction between gut microbiota and immune cells like macrophages is a key part of this process. When the gut microbiome is in a pro-inflammatory state, it can lead to increased production of kynurenine<\/i> <\/b>by macrophages. Kynurenine is a metabolite that can cross the blood-brain barrier and influence brain chemistry, potentially leading to cognitive impairments.<\/i><\/b><\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n When macrophages are activated by pro-inflammatory cytokines, they produce kynurenine<\/i><\/b>.\u00a0The kynurenine pathway is a major route of tryptophan metabolism<\/span> [4]. This molecule can cross the blood-brain barrier and is subsequently converted into neuroactive metabolites like kynurenic acid<\/i>.\u00a0These metabolites play a role in modulating neurotransmission and can impact cognitive functions such as learning and memory.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n While moderate levels of kynurenine and its metabolites are essential for normal brain function, excessive levels can be detrimental.<\/span>\u00a0High concentrations of kynurenine, often resulting from chronic inflammation, can suppress key neurotransmission processes, potentially leading to cognitive impairments (see Figure 5<\/b>).<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Thus, the composition of the gut microbiome significantly influences the production of cytokines and, consequently, the activity of macrophages. A balanced microbiome promotes a healthy immune response, whereas dysbiosis (an imbalance in the microbiome) can lead to excessive inflammation and altered kynurenine metabolism.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n These facts indicates the complex interplay between the gut microbiome, immune system, and brain function.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-10″][vc_column][vc_custom_heading text=”Role of Nutrition and Metabolism in Microbiome-Gut-Brain Axis”][vc_column_text single_style=””]<\/p>\n The gut microbiome can also affect behavior through its influence on nutrition and metabolism. One route that is mechanistically trivial but behaviorally important concerns microorganism which provide essential nutrients. Certain gut microorganisms synthesize essential nutrients that the host cannot produce on its own<\/span>. When there\u2019s a deficiency in these nutrients, either due to diet or microbial imbalance, it can trigger specific hunger and foraging behaviors. This adaptive response ensures that the host seeks out and consumes foods rich in the missing nutrients or a shift in food choice (see Figure 6<\/strong>).<\/p>\n [\/vc_column_text][vc_single_image image=”6208″ img_size=”full”][vc_column_text single_style=””]<\/p>\n Figure 6. Microbial drivers of behavior ~<\/sup> Gut-brain axis regulators. <\/b>Illustration identifies common factors influencing the gut-brain axis<\/i><\/b> and the behaviors affected by its perturbation. Factors influencing microbiota-gut-brain activity:<\/i><\/b> (i)<\/b> diet \u2013 nutrient intake, fiber, probiotics, and overall dietary patterns; (ii) <\/b>congenital heredity and epigenetics<\/u> \u2013 genetic predisposition and epigenetic modifications; (iii)<\/b> environment<\/u> \u2013 exposure to pollutants, toxins, and overall living conditions; (iv)<\/b> medications \u2013 antibiotics, SSRIs, and other pharmaceuticals; (v)<\/b> exercise<\/u> \u2013 physical activity levels and types of exercise; (vi) <\/b>mode of delivery at birth \u2013 vaginal birth versus cesarean section. Behaviors affected by microbiota-gut-brain axis perturbation:<\/i><\/b> (i)<\/b> cognitive behaviors<\/u> \u2013 learning, memory, and decision-making; (ii)<\/b> social behaviors<\/u> \u2013 sociability, communication, and interaction; (iii)<\/b> stress<\/u> \u2013 response to stressors and overall stress levels; (iv)<\/b> fear \u2013 anxiety, fear responses, and phobias; (v)<\/b> food intake<\/u> \u2013 appetite, eating habits, and food preferences.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n The gut microbiome can affect host metabolism, including blood sugar regulation. In\u00a0Drosophila\u00a0flies<\/i><\/b>, for instance, the presence and composition of gut bacteria have been shown to influence locomotion by modulating blood sugar levels<\/i><\/b>.\u00a0These changes in blood sugar can affect the activity of specific neurons in the brain that control movement [5].<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Gut bacteria produce various metabolites, such as short-chain fatty acids<\/i><\/b> (SCFAs<\/b>), which can influence brain function and behavior.\u00a0These metabolites can cross the blood-brain barrier and affect neurotransmitter systems, thereby impacting mood, cognition, and overall behavior. The diet significantly shapes the composition and function of the gut microbiome (see Figure 6<\/b>).\u00a0For example<\/b>, diets high in fiber promote the growth of beneficial bacteria that produce SCFAs, which have anti-inflammatory and neuroprotective effects.<\/u><\/span><\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n These facts underscore the complex and dynamic relationship between the gut microbiome, nutrition, metabolism, and behavior.<\/i><\/u><\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_id=”blog-scroll-point-12″][vc_column][vc_custom_heading text=”The Role of Maternal Microbiota in Fetal and Offspring Neurodevelopment”][vc_column_text single_style=””]<\/p>\n Finally, There is a very special route by which the gut microbiome can influence the brain development of the fetus, particularly through the placenta during pregnancy<\/span>, ultimately, the behavior of the offspring after birth (see Figure 6<\/b>) [6].<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Studies on germ-free mice have shown that the absence of gut microbiota can lead to altered neural circuits, especially in the thalamus<\/i><\/b>, which is crucial for relaying sensory information to the brain cortex, where many behavior decisions are made. These abnormal connections are laid down to the developing fetus of germ-free mothers; after the offspring are born, they display lifelong problems in sensing touch, even if they are provided with gut microbes.<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n The introduction of specific bacteria, such as clostridia<\/i><\/b>, to the mother can mitigate these effects. Clostridia release small molecules that cross the placenta and influence fetal brain development<\/u><\/span>. This interaction highlights the profound impact that material microbiota can have on the offspring\u2019s neural development and subsequent behavior. (Cf. previous blogs entitled as: \u201cDevelopmental Origins of Health and Disease: Neonatal Gut Microbiome ~<\/sup> Day 0 to 30\u201d<\/a><\/u> & \u201cDevelopmental Origins of Health and Disease: Infant Gut Microbiome ~<\/sup> Day 31 to 364\u201d<\/a><\/u> & \u201cDevelopmental Origins of Health and Disease: Transition from Infant to Child Microbiome ~<\/sup> Day 365 to 1,000 Beyond\u201d<\/a><\/u>).<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n Researchers are actively investigating how these microbial molecules affect neuronal growth and connectivity in the fetal brain. This line of inquiry could lead to new insights into neurodevelopmental disorders and potential therapeutic interventions [7].<\/p>\n [\/vc_column_text][vc_column_text single_style=””]<\/p>\n In the upcoming blog, we will address how the combined study of humans and laboratory animals has in fact provided compelling evidence that disruptions in the gut microbiome, know as dysbiosis<\/i><\/b>, can contribute to various neurodevelopmental disorders, particularly <\/i>autism spectrum disorder<\/i><\/b> (<\/i>ASD<\/i><\/b>) and neurodegenerative diseases, including <\/i>Alzheimer\u2019s and Parkinson\u2019s diseases<\/i><\/b>, as well as mental health conditions, such as <\/i>depression and anxiety disorders<\/i><\/b> [8-9]. The potential for microbial therapy, such as probiotics or fecal microbiota transplantation<\/span>, offers a promising avenue for treating these conditions by restoring a healthy gut microbiome balance.<\/p>\n [\/vc_column_text][\/vc_column][\/vc_row][vc_row el_class=”blog-text-35795″ el_id=”blog-scroll-point-13″][vc_column][vc_custom_heading text=”Take Home Messages” el_class=”blog-text-35795″][vc_column_text single_style=””]Bidirectional communication<\/em><\/strong><\/p>\n [\/vc_column_text][vc_column_text single_style=””]Influence on behavior<\/em><\/strong><\/p>\n [\/vc_column_text][vc_column_text single_style=””]Critical developmental windows<\/em><\/strong><\/p>\n [\/vc_column_text][vc_column_text single_style=””]Neurodevelopmental and neurodegenerative disorders<\/em><\/strong><\/p>\n\n
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\nbehavior has evolved to have consequences<\/i><\/b><\/span>, to effect either a change in the relationship of the organism with its environment (the cat catches the mouse<\/i>) or to maintain the status quo (the mouse escapes<\/i>). This interaction is a key aspect of understanding animal behavior, including humans. Thus, the idea that behavior has evolved to have consequences is crucial, as it underscores the role of behavior in survival and adaptation<\/i><\/b>.<\/p>\n
\nThe basis of behavior is a three-step process:<\/b> sensory input, central integration, and the behavior response, which usually involves motor output<\/span> (see Figure 2<\/b>). The integration step can be highly sophisticated, especially in organisms with flexible or complex behaviors, and it can involve large numbers of neurons in multi-way communication via synaptic connections that stimulate or depress<\/b> the electrical activity of other neurons. In most animals, the central site of integration is the brain. The human brain contains approximately 100 billion (10<\/i><\/b>11<\/sup><\/i><\/b>) neurons<\/i><\/b>, each of which estimated to have, on average, 1,000 synapses<\/i><\/b> with other neurons.<\/p>\n\n
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\nIt is best known for its role in supporting the feelings of well-being. Depression is associated with low serotonin levels in the brain and various anti-depressant medications function to boost serotonin levels<\/span> (see Figure 3<\/b>). The popular press and internet are flooded with narratives that the gut microbiome promotes happiness via its effect on brain serotonin levels. These accounts are based on two fundamental misconceptions.<\/p>\n\n
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