Thursday, April 28, 2022

Which Brain Structure Is Associated With The Limbic System

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Drugs And The Limbic System

The Limbic SystemParts of the Limbic System

Drugs and the Limbic SystemAll drugs that people abuse allchange the way the limbic system works.  Drugs disrupt the carefulmodulation of feelings and motivations that underlie normal behavior. When these feelings lose touch with reality, the person receives artificialrelief, pleasure, contentment, and relaxation take over.

The Brain Reward SystemThe Brain Reward System is a specificlimbic circuit that generates the feelings of pleasure.  This systemoriginates in a group of neurons that are located in the mid brain .  These neurons then connect toa variety of places within the limbic system, but the important connectionis to the nucleus accumbens in the basal ganglia.  The basal gangliaare a large, complex set of structures within the limbic system that functionin generating movements, some cognitive functions, emotional and motivationalactivities. When a drug activates the VTA neurons, these neurons releasedopamineinto the nucleus accumbens and the person feels pleasure.

Key Components of the Brain RewardSystem 

Anatomical And Neuroimaging Findings In Panic Disorder

Neuroimaging in patients who have panic disorder under resting conditions and under anxiety- or panic-provoking conditions has identified neuroanatomical alterations associated with symptom severity or treatment response.

Single-photon emission computed tomography identified lower metabolism in the left inferior parietal lobe and overall decreased bilateral cerebral blood flow in patients who had PD as compared with control subjects, and this decrease corresponded with symptom severity. Other studies, however, have demonstrated elevated glucose uptake in the amygdala, hippocampus, thalamus, midbrain, caudal pons, medulla, and cerebellum as measured by positron emission tomography . These elevations normalize after successful pharmacological or behavioral therapy, suggesting that the increased glucose uptake in these regions is state dependent. Patients who had PD had decreased frontal activity bilaterally but increased activity in the right medial and superior frontal lobe in SPECT studies. Interestingly, the CBF asymmetry and shift to the right hemisphere correlated with disorder severity in individual patients .

What Part Of Brain Is Limbic System

The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.

You may ask, Is the cerebellum part of the limbic system?

Glossary of Terms Amygdala: Limbic structure involved in many brain functions, including emotion, learning and memory. It is part of a system that processes reflexive emotions like fear and anxiety. Cerebellum: Governs movement. Cingulate Gyrus: Plays a role in processing conscious emotional experience.

What Part Of The Brain Controls Fear

From a biological standpoint, fear is a very important emotion. It helps you respond appropriately to threatening situations that could harm you.

This response is generated by stimulation of the amygdala, followed by the hypothalamus. This is why some people with brain damage affecting their amygdala dont always respond appropriately to dangerous scenarios.

When the amygdala stimulates the hypothalamus, it initiates the fight-or-flight response. The hypothalamus sends signals to the adrenal glands to produce hormones, such as adrenaline and cortisol.

As these hormones enter the bloodstream, you might notice some physical changes, such as an increase in:

  • heart rate
  • blood sugar
  • perspiration

In addition to initiating the fight-or-flight response, the amygdala also plays a role in fear learning. This refers to the process by which you develop an association between certain situations and feelings of fear.

The Structure Of The Brain

Pin by Victor Vitoria on Neuroscience & Sensory ...

The developing brain goes through many stages. In the embryos of vertebrates, the predecessor to the brain and spinal cord is the neural tube. As the fetus develops, the grooves and folds in the neural tube deepen, giving rise to different layers of the brain. The human brain is split up into three major layers: the hindbrain, the midbrain, and the forebrain.

The embryonic brain: The layers of the embryonic brain. The telencephalon and diencephalon give rise to the forebrain, while the metencephalon and myelencephalon give rise to the hindbrain.

Psychology In Everyday Life: Why Are Some People Left

Across cultures and ethnic groups, about 90% of people are mainly right-handed, whereas only 10% are primarily left-handed . This fact is puzzling, in part because the number of left-handers is so low, and in part because other animals, including our closest primate relatives, do not show any type of handedness. The existence of right-handers and left-handers provides an interesting example of the relationship among evolution, biology, and social factors and how the same phenomenon can be understood at different levels of analysis .

At least some handedness is determined by genetics. Ultrasound scans show that nine out of 10 fetuses suck the thumb of their right hand, suggesting that the preference is determined before birth , and the mechanism of transmission has been linked to a gene on the X chromosome . It has also been observed that left-handed people are likely to have fewer children, and this may be in part because the mothers of left-handers are more prone to miscarriages and other prenatal problems .

But culture also plays a role. In the past, left-handed children were forced to write with their right hands in many countries, and this practice continues, particularly in collectivistic cultures, such as India and Japan, where left-handedness is viewed negatively as compared with individualistic societies, such as Canada and the United States. For example, India has about half as many left-handers as the United States .

Substructures Of The Limbic System

Hippocampus

There are two hippocampi, located in each hemisphere of the brain. They are seahorse-shaped and are structures mainly associated as being the memory centres of our brains.

Episodic memories are formed in the hippocampus and then filed away into long-term storage throughout other parts of the cerebral cortex.

The hippocampus always plays a role in spatial navigation and has also been associated with learning and emotions .

The hippocampus is also known as a site where neurogenesis occurs â this means that new nerve cells are made here from adult stem cells.

Due to the hippocampusâs involvement in memory, damage to this area can lead to severe memory impairments.

Damage can also be detrimental to spatial memory, for instance, remembering directions to locations that should be familiar to the individual.

Amygdala

The amygdala is an almond-shaped structure, located right next to the hippocampus. The main function of the amygdala is in emotional responses, including feelings of happiness, fear, anger, and anxiety.

This area is also key for the formation of new memories. The amygdala interacts with the hippocampus by attaching emotional content to memories.

It has a role in how memorable memories can be â memories that have strong emotional components tend to stick, rather than those with little emotional content.âFear learningâ is also an element of the amygdala.

Cingulate Gyrus
Hypothalamus

The hypothalamusâ most basic function is in homeostasis .

Seizures Arising From The Limbic System

The limbic system is a collection of brain structures that are functionally and anatomically related through interconnecting pathways. These structures include the association areas of the temporal lobe, the cingulate gyrus, the mesial and orbital frontal areas, and the septal nuclei. Seizures confined to the limbic system are complex partial seizures and always involve some alteration of consciousness. Although seizure foci are known to occur in a number of different limbic structures, most often they reside in the temporal lobe; hence, the designation, temporal lobe epilepsy. The types of lesions giving rise to partial complex seizures have been well studied. The most common pathologic finding, which occurs in 50 to 60 percent of cases, is gliosis in either the hippocampus, amygdala, or uncus. This lesion has been called mesial temporal sclerosis and is generally thought to be an acquired lesion, possibly caused by perinatal or childhood hypoxia. Hamartomas are the next most common lesion and are found in approximately 20 percent of patients. Other lesions have included glial neoplasms, arteriovenous malformations and posttraumatic scars. In about 14 to 20 percent of surgically removed temporal lobes, no lesion has been found. In all cases, patients have had intractable complex partial seizures, and preoperative clinical and electrographic study indicates abnormal function of the removed tissue.

Table 2.5. Clinical symptoms of complex partial seizures

What Does The Limbic Lobe Do

The limbic lobe plays a role in a range of complex emotional reactions. When most people think of emotions, they might think of simple reactions such as anger or sadness, but the complex and varied roles of the limbic system goes much deeper than just aiding people to understand or feel their emotions.

One of the most critical roles the limbic system plays is in the regulation of endocrine system responses to emotions, such as the adrenaline-based fight-or-flight response. Without any voluntary input, the limbic system triggers a reaction to perceived danger. It also regulates both conscious and unconscious functions such as sexual desire, some homeostatic mechanisms, and appetite. Other roles of the limbic system include:

The limbic lobe and the systems associated with it are vital areas of interest to brain researchers, with hundreds of studies done on the region’s functions each year.

Interesting Facts And History Of The Limbic System

The functions that different regions of the brain are responsible for have been debated since the time of Aristotle thousands of years ago. Neuroscience has come a long way since then, especially recently thanks to imaging studies like MRIs, and its now widely accepted that the prefrontal cortex, amygdala, anterior cingulate cortex, hippocampus and insula participate to control the majority of human emotional processes.

Today, teaching people who struggle with anxiety or depression to intentionally learn to calm their autonomic nervous systems is a major focus in psychology, therapy and neuroscience research.

In recent decades, scientists have come to understand that our brains are always adapting to our environments throughout our entire life spans. The brains capacity to learn and change itself depending on its environment is called neuroplasticity, which when used to our advantage helps us become happier in addition to more knowledgeable.

The limbic system is responsible for governing avoidance versus approach behaviors in most animals in other words feelings of pleasure versus anxiety/pain. Approach and avoidance are exactly what help keep us alive and ensure survival. Thats why the limbic system is said to be so primitive and is found in all types of species.

Final Thoughts on the Limbic System

Read Next: The Lymphatic System: How to Make It Strong & Effective

Morphology Of The Limbic System

The cerebrum includes the âlimbicâ system that forms a âlimbusâ in the cerebrum .

Fig. 1.32. Hippocampus, similar things.

The center of limbic system is the hippocampus, which is a primitive cerebral cortex. The hippocampus and fornix in the superior view resemble a seahorse. A seahorse lives in water; but the HIPPOcampus lives near water which is the cerebrospinal fluid in the temporal horn of lateral ventricle . The hippocampus in the coronal plane is shaped like Ammon horn.

Fig. 1.33. Hippocampus, adjacent structures .

Histologically, the hippocampus is subdivided into CA1, CA2, CA3, CA4 . The parahippocampal gyrus is connected to the subiculum, CA1, CA2, CA3, CA4 in sequence.

The hippocampus is in contact with the fornix . The dentate gyrus, which is another primitive cerebral cortex, is facing the hippocampus.

Fig. 1.34.

Two hands held with the fingers wrapping each other resemble the hippocampus and dentate gyrus.

Fig. 1.35. Hippocampus, fornix.

The above figure shows that the dentate gyrus and fornix are located on the medial side of the hippocampus. The fornix is an arch extending from the hippocampus to the mammillary body, which is a part of hypothalamus .

Fig. 1.36.

The bilateral fornices meet each other , being observable in the median plane .

Julia Vogt, … Umkalthoom Alzubaidi, in, 2020

Explain The Limbic System And Its Function Of Each Part

A complex system of nerves and networks in the brain, involving several areas near the edge of the cortex concerned with instinct and mood. It controls the basic emotions and drives .Function. The structures and interacting areas of the limbic system are involved in motivation, emotion, learning, and memory. The limbic system is where the subcortical structures meet the cerebral cortex.

Answer:

The inner parts of the cerebral hemispheres and a group of associated deep structures like amygdala, hippocampus etc., form a complex structure called the limbic lobe or limbic system.

Along with the hypothalamus, the limbic system is involved in the

Regulation of sexual behaviour.

Expression of various emotional reactions like excitement, fear.

Regulation of motivation in an organism.

The Reticular Activating System

Anatomy Of Limbic System

The reticular activating system is a network of neurons that runs through the core of the hindbrain and into the midbrain and forebrain. The RAS is made up of the midbrain reticular formation, the mesencephalic nucleus , the thalamic intralaminar nucleus , the dorsal hypothalamus, and the tegmentum.

The reticular activating system: The reticular activating system is involved in arousal and attention, sleep and wakefulness, and the control of reflexes.

The RAS is involved with arousal and attention, sleep and wakefulness, and the control of reflexes. The RAS is believed to first arouse the cortex and then maintain its wakefulness so that sensory information and emotion can be interpreted more effectively. It helps us fulfill goals by directing our concentration toward them and plays a role in individuals responses to situations and events.

What Part Of The Brain Controls Happiness

Happiness refers to an overall state of well-being or satisfaction. When you feel happy, you generally have positive thoughts and feelings.

Imaging studies suggest that the happiness response originates partly in the limbic cortex. Another area called the precuneus also plays a role. The precuneus is involved in retrieving memories, maintaining your sense of self, and focusing your attention as you move about your environment.

A 2015 study found that people with larger gray matter volume in their right precuneus reported being happier. Experts think the precuneus processes certain information and converts it into feelings of happiness. For example, imagine youve spent a wonderful night out with someone you care about. Going forward, when you recall this experience and others like it, you may experience a feeling of happiness.

It may sound strange, but the beginnings of romantic love are associated with the stress response triggered by your hypothalamus. It makes more sense when you think about the nervous excitement or anxiety you feel while falling for someone.

As these feelings grow, the hypothalamus triggers release of other hormones, such as dopamine, oxytocin, and vasopressin.

Dopamine is associated with your bodys reward system. This helps make love a desirable feeling.

Vasopressin is similarly produced in your hypothalamus and released by your pituitary gland. Its also involved in social bonding with a partner.

Where Is The Limbic Lobe

The limbic system was once thought to be a discrete set of brain structures, but now we know that the limbic system involves a complex range of brain structures, as well as the hormones that affect these structures. Because hormone production and interaction can be affected by a range of environmental and genetic factors, the limbic system is inextricably linked to virtually every area of the body. Pain in a finger can trigger a limbic reaction. So too can a scent, a sound, or a visual image that calls to mind a memory.

The limbic lobe, by contrast, is a discrete set of brain structuresthe same structures once thought to constitute the entirety of the limbic system. For this reason, a number of references may use the two terms interchangeably.

The limbic lobe is a C-shaped region that crosses brain hemispheres within the cortex, including portions of the temporal, parietal, and frontal lobes. All mammals have a limbic lobe. Which parts of the brain make up the limbic lobe is a subject for some debate, with some authors excluding structures that others include. Key components of the limbic lobe include the amygdala, hippocampus, mamillary body, and cingulate gyrus.

Other structures that are often attributed to the limbic lobe include:

  • paraterminal gyrus
  • collateral sulcus 

Genetic Contribution To Panic Disorder

PD is thought to be the most heritable of the anxiety disorders. First-degree relatives of proband patients who have PD have a sevenfold increased likelihood for PD and also have an increased risk for phobic disorders.â Twin studies suggest that 30% to 40% of the variance in vulnerability for PD is derived from genetic factors and the remainder from individual-specific, but not shared, environment/life experiences.

Linkage studies in families that have PD have been hampered by non-replication and small numbers., A large analysis including 120 pedigrees with more than 1500 individuals revealed two loci with genome-wide significance on chromosomes 2q and 15q, but these results await further replication. A large number of genetic association studies for PD have been published, implicating many genes. A recent review compiled the genes that have been associated with PD in more than one study thus far, although in some cases different polymorphisms within these genes have been associated with PD in different studies, complicating any attempt to draw causal conclusions from these data . The genes associated with PD in multiple studies are:

  • COMT

  • 5HT2A receptor

  • Monoamine oxidase-A

  • Cingulate Gyrus: The Limbic Big Boy

    I love the cingulate gyrithey look like something Professor X would wear to help him look for new mutants. While it isn’t known whether they can enhance one’s telepathic ability to locate others with superhuman abilities, the cingulate gyri are known for other things that are just as cool .

    Ever been so excited about something that your arms flail around, or so angry that your hands clench into fists? The cingulate gyrus, a large arch-shaped structure, plays a role in expressing emotions through gestures.

    Image from Human Anatomy Atlas.

    A gyrus is a convolution, or fold, in the brain that acts to increase surface area, which in turn increases the number of neurons, as well as gray matter. There are many gyri that interact with the limbic system and the brain as a whole. The precentral gyrus contains the primary motor cortex and controls the precise movements of skeletal muscles. The postcentral gyrus contains the primary somatosensory cortex and is responsible for spatial discrimination .

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    Circuit Control And Regulation

    Through classical neuroanatomical approaches, we have now reached a stage at which the basic circuitry regulating reproductive, defensive and maternal care behaviors are generally established. More recent studies utilizing a combination of techniques at the vanguard of science are revealing the molecular underpinnings of circuit formation and function. For example, novel optogenetic techniques allow for the subtype-specific and temporal control of neuronal activity in order to elucidate the circuitry driving innate behaviors. In addition, we are also gaining a significantly greater understanding of not only the genes that are required for normal circuit formation and function, but also how non-cell autonomous stimuli such as hormones shape neuronal populations comprising innate circuits.

    Which Brain Structure Is Associated With The Limbic System

    It contains the thalamus, One of these structures, 13 studies were selected.The limbic system, is involved in the formation of long-term memory, Which defined a group of structures surrounding the brain stem aslimbus brain , the term was born in 1664 with Thomas Willis, though the two primary structures of the system are consistently noted to be the amygdala and hippocampus.Limbic SystemLimbic system includes cortical and subcortical structures which are located mainly in medial and ventral regions of the cerebral hemispheres Simplification of Limbic Functions and Corresponding Key Structures mnemonic: HOME , but rather a group of brain structures that work together, and motivation, Thalamus

    Right Brain Left Brain

    The cerebrum is divided into two halves: the right and left hemispheres They are joined by a bundle of fibers called the corpus callosum that transmits messages from one side to the other. Each hemisphere controls the opposite side of the body. If a stroke occurs on the right side of the brain, your left arm or leg may be weak or paralyzed.

    Not all functions of the hemispheres are shared. In general, the left hemisphere controls speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic, and musical skills. The left hemisphere is dominant in hand use and language in about 92% of people.

    The Role Of Ventral Tegmentum In The Emotional Brain

    Limbic Encephalitis

    Located within the midbrain, the ventral tegmentum is important in cognition, motivation, intense emotional responses related to love, and our sense of natural reward. The VTA is responsible for processing emotional output from the amygdale, and is, therefore, thought to play an integral role in our avoidance and fear response. Much of the activity that occurs in the VTA takes place unconsciously, and it is this region of the brain that determines much of our impulsive behavior. The VTA contains dopaminergic neurons, which release dopamine when stimulated by sensory information. This biological response reinforces the impulsive actions, such as buying food that is bad for us, that excite the dopaminergic neurons, which creates what we refer to as the reward system .

    A Functional Classification: The Limbic System Is Well A System

    When one speaks aloud about the limbic system, it sounds as though they consider it to be a single structure. That’s simply not true. While theres some debate in the scientific community about which structures are part of the limbic system, there’s a unanimous agreement about three of them: the amygdala, hippocampus, and cingulate gyrus. In addition, theres also the dentate gyrus, parahippocampal gyrus, fornix, and other nuclei and septa.

    Image from Human Anatomy Atlas.

    The limbic system functions to facilitate memory storage and retrieval, establish emotional states, and link the conscious, intellectual functions of the cerebral cortex with the unconscious, autonomic functions of the brain stem.

    While the sensory cortex, motor cortex, and association areas of the cerebral cortex allow you to perform certain tasks, the limbic system makes you want to do those tasks. It’s your very own internal motivational speaker!

    The Autonomic Nervous System

    The autonomic nervous system is part of the peripheral nervous system in humans. It is regulated by the hypothalamus and controls our internal organs and glands, including such processes as pulse, blood pressure, breathing, and arousal in response to emotional circumstances. The ANS is generally thought to be outside of voluntary control.

    The ANS can be further subdivided into the sympathetic and parasympathetic nervous systems. When activated, the sympathetic nervous system controls the endocrine glands to prepare the body for emergency action. SNS activation causes the adrenal glands to produce epinephrine , which results in the fight-or-flight response. The fight-or-flight response involves increased blood flow to the muscles, increased heart rate, and other physiological responses that enable the body to move more quickly and feel less pain in situations perceived to be dangerous.

    Conversely, the parasympathetic nervous system  functions when the body is relaxed or at rest; it helps the body store energy for future use. Effects of PN activation include increased stomach activity and decreased blood flow to the muscles.

    The parasympathetic and sympathetic divisions of the ANS have complementary functions, and they operate in tandem to maintain the bodys equilibrium. Equilibrium of the body, in which biological conditions are maintained at optimal levels, is known as homeostasis.

    Puberty And The Limbic System

    Puberty is the beginning of major changes in the limbic system

    • Part of the limbic system, the amygdala is thought to connect sensory information to emotional responses. Its development, along with hormonal changes, may give rise to newly intense experiences of rage, fear, aggression , excitement and sexual attraction.
    • Over the course of adolescence, the limbic system gradually comes under greater control of the prefrontal cortex .
    • As additional areas of the brain start to help process emotion, older teens gain some equilibrium and have an easier time interpreting others. But until then, they often misread others eg teachers and parents.

    The Limbic System: What Is It And How Does It Work

    Our brain is one of the most wonderful structures in our body. And although its one of the most studied parts of the body, there is still much yet to discover about how it functions. Despite this, we know that within our brain lie different systems that have specialized roles in making our body work. One of the most important systems we currently know of is the limbic system.

    The first time the limbic system was discussed, though in a less conceptualized and more primitive way than we do now, it was because Paul Broca named an area near the pineal gland.

    Out of limb or border, he called it the area of the great limbic lobe. Hence the logic of its name, because it is situated in the limbo or edge of other structures that we already knew about.

    However, the limbic system as we know it today was conceptualized by physiologist MacLean in 1949. He extended the initial conceptualization of this system that Papez started in 1939, giving it its current name.

    MacLean expanded the number of structures that make up the limbic system. He considered that the development of the cerebral cortex was just as important in our evolution as the development of our emotional brain.

    Happiness is a mental state activated by the limbic system.

    -Antonio Damasio-

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