Friday, May 6, 2022

Where Is The Limbic System Located In The Brain

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Why Am I Constantly Aware Of My Heartbeat

The Limbic System

Awareness of one’s heartbeat is known to be correlated with a number of psychological problems, including anxiety disorders. Patients typically perceive their heart rate more clearly than most people. “But someone who does not suffer from this type of disorder can also be aware of their heartbeat,” said Roy.

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Functions Of The Cortex

When the German physicists Gustav Fritsch and Eduard Hitzig ;applied mild electric stimulation to different parts of a dogs cortex, they discovered that they could make different parts of the dogs body move. Furthermore, they discovered an important and unexpected principle of brain activity. They found that stimulating the right side of the brain produced movement in the left side of the dogs body, and vice versa. This finding follows from a general principle about how the brain is structured, called contralateral control, meaning the brain is wired such that in most cases the left hemisphere receives sensations from and controls the right side of the body, and vice versa.

Just as the motor cortex sends out messages to the specific parts of the body, the somatosensory cortex, an area just behind and parallel to the motor cortex at the back of the frontal lobe, receives information from the skins sensory receptors and the movements of different body parts. Again, the more sensitive the body region, the more area is dedicated to it in the sensory cortex. Our sensitive lips, for example, occupy a large area in the sensory cortex, as do our fingers and genitals.

The Old Brain: Wired For Survival

The brain stem;is the oldest and innermost region of the brain. Its designed to control the most basic functions of life, including breathing, attention, and motor responses . The brain stem begins where the spinal cord enters the skull and forms the medulla, the area of the brain stem that controls heart rate and breathing. In many cases the medulla alone is sufficient to maintain life animals that have the remainder of their brains above the medulla severed are still able to eat, breathe, and even move. The spherical shape above the medulla is the pons, a structure in the brain stem that helps control the movements of the body, playing a particularly important role in balance and walking.

Running through the medulla and the pons is a long, narrow network of neurons known as the reticular formation. The job of the reticular formation is to filter out some of the stimuli that are coming into the brain from the spinal cord and to relay the remainder of the signals to other areas of the brain. The reticular formation also plays important roles in walking, eating, sexual activity, and sleeping. When electrical stimulation is applied to the reticular formation of an animal, it immediately becomes fully awake, and when the reticular formation is severed from the higher brain regions, the animal falls into a deep coma.

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The Cerebral Cortex Creates Consciousness And Thinking

All animals have adapted to their environments by developing abilities that help them survive. Some animals have hard shells, others run extremely fast, and some have acute hearing. Human beings do not have any of these particular characteristics, but we do have one big advantage over other animals we are very, very smart.

You might think that we should be able to determine the intelligence of an animal by looking at the ratio of the animals brain weight to the weight of its entire body. But this does not really work. The elephants brain is one-thousandth of its weight, but the whales brain is only one ten-thousandth of its body weight. On the other hand, although the human brain is one-sixtieth of its body weight, the mouses brain represents one-fortieth of its body weight. Despite these comparisons, elephants do not seem 10 times smarter than whales, and humans definitely seem smarter than mice.

What Part Of The Brain Controls Happiness

Flashcards

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.

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Limbic System And Hippocampus Function And Structure

The limbic system sits atop the brain stem, which is believed to be one of the first parts of the brain to develop, react to stimuli and the most basic in terms of sustaining life. Its located on both sides of the thalamus and underneath the cerebrum.

Theres not total consensus among neuroscientists about which structures of the brain are technically part of;the limbic system, considering its very hard to to neatly classify cortical areas given how much neural overlap there is. That being said, most consider the limbic system to be made up of cortical regions , including:

  • Hippocampus: generally associated with memory and focus, but also helps with motor control
  • Amygdala: tied to fear and anxious emotions
  • Hypothalamus: primarily responsible for regulating hormones and maintaining homeostasis
  • tied to pleasure and learning through reward and/or reinforcement
  • Cingulate Cortex: involved in many aspects of memory and emotion
  • Parahippocampal Gyrus: also helps with memory
  • Mammillary Bodies: connected to the amygdala and hippocampus
  • Fornix: connects other parts of the brain, including hippocampus and mammillary bodies

The limbic system is one hard-working region of the brain, as you can tell. Some specific limbic system functions include:

  • Controlling emotions like anger and fear
  • Controlling aggressive or violent behavior
  • Responding to sensory information, especially sense of smell

Blood Supply To The Brain

Two sets of blood vessels supply blood and oxygen to the brain: the vertebral arteries and the carotid arteries.

The external carotid arteries extend up the sides of your neck, and are where you can feel your pulse when you touch the area with your fingertips. The internal carotid arteries branch into the skull and circulate blood to the front part of the brain.

The vertebral arteries follow the spinal column into the skull, where they join together at the brainstem and form the basilar artery, which supplies blood to the rear portions of the brain.

The circle of Willis, a loop of blood vessels near the bottom of the brain that connects major arteries, circulates blood from the front of the brain to the back and helps the arterial systems communicate with one another.

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Damage To The Limbic System

Damage to the limbic system is dependant on which region is affected. Amygdala damage could affect a personâs fear processing , which could result in more risk-taking behaviors and putting themselves in dangerous situations.

Damage to the hippocampus could lead to deficits in being able to learn anything new, as well as affecting memory.

Hypothalamus damage can affect the production of certain hormones, including those which can affect mood and emotion.

Below is a non-exhaustive list of symptoms associated with limbic system damage:

  • Uncontrolled emotions â more aggression, anxiety, and agitation.
  • Olfactory impairments
  • Alzheimerâs disease
  • Movement disorders â Huntingtonâs and Parkinsonâs disease

A potential treatment for limbic impairments is deep brain stimulation . Successful treatment of some cognitive disorders such as anxiety and posttraumatic stress disorder has come from DBS of the amygdala.

DBS has also shown to be useful in targeting the nucleus accumbens in relation to drug addiction .

Similarly, the use of antidepressant medications has shown links with restoring the underlying physiological differences in the limbic system in major depressive disorder .

What Does The Limbic System Do

THE LIMBIC SYSTEM & HYPOTHALAMUS by Professor Fink

The limbic system serves a variety of fundamental cognitive and emotional functions.;The hippocampi, which lay on the inside edge of the temporal lobes, is essential to memory formation.;The amygdalae sit on top of the front portion of each hippocampus.;Each amygdala is thought to be important in processing emotion. The amygdala communicates closely with the hippocampus, which helps explain why we remember things that are more emotionally important.;The amygdala also communicates closely with the hypothalamus, the area of the brain that is responsible for regulating temperature, appetite, and several other basic processes required for life.;The hypothalamus itself is sometimes, but not always, included as part of the limbic system.;Through the hypothalamus, as well as some key areas in the brainstem, the limbic system communicates with our autonomic nervous system , endocrine system, and the viscera .;

Nerve cells in the brain are organized in different fashions depending on location.;The cerebral cortex is predominantly neocortical, meaning that cells exist in 6 layers.;This is different from the limbic system, where cells are either arranged in fewer layers , or more jumbled . This less complex organization of the limbic system, as well as the limbic systems control of fundamental processes of life,;has led doctors to believe that the limbic structure is evolutionarily older than the cerebral cortex.;

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Parts Of The Limbic System

The limbic system is the portion of the brain that deals with three key functions: emotions, memories and arousal . This system is composed of several parts, which are found above the brainstem and within the cerebrum. The limbic system connects parts of the brain that deal with high and low functions.

Schematic of the Limbic System

Let’s talk about the major parts of the limbic system. First, we have the thalamus, which is a portion of the brain that is responsible for detecting and relaying information from our senses, such as smell and vision. The thalamus is located within the brainstem and is part of the pathway of information into the cerebrum, which is the section of the brain that is responsible for thinking and movement.

Next, we have the hypothalamus, which is a vital portion of the limbic system that is responsible for producing multiple chemical messengers, called hormones. These hormones control water levels in the body, sleep cycles, body temperature and food intake. The hypothalamus is located beneath the thalamus.

The cingulate gyrus, meanwhile, serves as a pathway that transmits messages between the inner and outer portions of the limbic system.

The hippocampus is another section of the temporal lobe that is responsible for converting short-term memories into long-termed memories. The hippocampus is thought to work with the amygdala for memory storage, and damage to the hippocampus may lead to amnesia .

Areas Of The Forebrain

forebrainthalamus

Figure 1. The thalamus serves as the relay center of the brain where most senses are routed for processing.

The limbic system is involved in processing both emotion and memory. Interestingly, the sense of smell projects directly to the limbic system; therefore, not surprisingly, smell can evoke emotional responses in ways that other sensory modalities cannot. The limbic system is made up of a number of different structures, but three of the most important are the hippocampus, the amygdala, and the hypothalamus . The hippocampus is an essential structure for learning and memory. The amygdala is involved in our experience of emotion and in tying emotional meaning to our memories. The hypothalamus regulates a number of homeostatic processes, including the regulation of body temperature, appetite, and blood pressure. The hypothalamus also serves as an interface between the nervous system and the endocrine system and in the regulation of sexual motivation and behavior.

Figure 2. The limbic system is involved in mediating emotional response and memory.

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The Limbic System And Other Brain Areas Quizlet

limbic association area.Posterior Association Area. … runs through the central core of the brain system, arousal of the brain reticular activating system: maintains consciousness and alertness, functions in sleep and arousal from sleep …Other Quizlet sets. American History Unit 2. 30 terms. emily_lowry_28. Cell Structure and Function II …

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  • Midbrain And Hindbrain Structures

    Robb Wolf

    The midbrain is comprised of structures located deep within the brain, between the forebrain and the hindbrain. The reticular formation is centered in the midbrain, but it actually extends up into the forebrain and down into the hindbrain. The reticular formation is important in regulating the sleep/wake cycle, arousal, alertness, and motor activity.

    The substantia nigra and the ventral tegmental area are also located in the midbrain . Both regions contain cell bodies that produce the neurotransmitter dopamine, and both are critical for movement. Degeneration of the substantia nigra and VTA is involved in Parkinsons disease. In addition, these structures are involved in mood, reward, and addiction .

    Figure 3. The substantia nigra and ventral tegmental area are located in the midbrain.

    The hindbrain is located at the back of the head and looks like an extension of the spinal cord. It contains the medulla, pons, and cerebellum . The medulla controls the automatic processes of the autonomic nervous system, such as breathing, blood pressure, and heart rate. The word pons literally means bridge, and as the name suggests, the pons serves to connect the brain and spinal cord. It also is involved in regulating brain activity during sleep. The medulla, pons, and midbrain together are known as the brainstem.

    Figure 4. The pons, medulla, and cerebellum make up the hindbrain.

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    Damage Of The Limbic Lobe

    Damage to the structures of the limbic lobe and the limbic-reticular complex, in general, can be accompanied by different clinical symptoms. Those include pronounced changes in the emotional sphere of permanent and paroxysmal nature, anorexia or bulimia, sexual disorders, memory impairment, and especially signs of the Korsak syndrome, in which the patient loses the ability to remember current events .

    Moreover, the symptoms of the limbic system damage include vegetative-endocrine disorders, sleep disorders, psychosensory disorders in the form of illusions and hallucinations, changes in consciousness, clinical manifestations of akinetic mutism, and seizures.

    Pathological processes in the limbic area cause marked disturbances of the vegetative-visceral functions.

    How Does The Brain Work

    The brain sends and receives chemical and electrical signals throughout the body. Different signals control different processes, and your brain interprets each. Some make you feel tired, for example, while others make you feel pain.

    Some messages are kept within the brain, while others are relayed through the spine and across the bodys vast network of nerves to distant extremities. To do this, the central nervous system relies on billions of neurons .

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    List Of Regions In The Human Brain

    Hence, there is overlap of structures in the limbic system and in other classifications of brain structures. The following areas have been considered part of the limbic system. Cortical areas: Limbic lobe; Orbitofrontal cortex: a region in the frontal lobe involved in the process of decision-making; Piriform cortex: part of the olfactory system

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    Anatomy And Physiology: The Limbic System’s Major Three

    The Limbic System

    Posted on 3/27/15 by Courtney Smith

    What is your earliest memory?

    Mine is the sound of my older brother Steve muttering, “I don’t know why you’re laughing, we’re going to get in trouble,” and the rush of sand as he helped me pour a bucketful over my head. We were at my Yiayia’s house in her sun-soaked backyard, sitting in the little turtle sandbox that was missing an eye . The bed of wildflowers nearby kept catching on Steve’s shirt and smelled earthy-sweet. While the adults lounged about on the back deck, toasting my mother for keeping her too-curious child alive long enough to see a second birthday, Steve helplessly held the now empty yellow bucket in his hand while I cackled triumphantly to myself.

    Sometimes when I’m lounging in my Yiayia’s backyard , I’ll smell the wildflowers and bam. Suddenly I’m two years old again with sand in my hair and so very proud of the fact.

    Long-term memory is still a mystery in a lot of ways, but we do know that the limbic system has a hand in processing and consolidating it. That’s not all the limbic system does, however, and we’re going to take a look at the role three of its major components play in the brain.

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    The Case Of Henry Molaison

    In 1953, Henry Gustav Molaison was a 27-year-old man who experienced severe seizures. In an attempt to control his seizures, H. M. underwent brain surgery to remove his hippocampus and amygdala. Following the surgery, H.Ms seizures became much less severe, but he also suffered some unexpectedand devastatingconsequences of the surgery: he lost his ability to form many types of new memories. For example, he was unable to learn new facts, such as who was president of the United States. He was able to learn new skills, but afterward he had no recollection of learning them. For example, while he might learn to use a computer, he would have no conscious memory of ever having used one. He could not remember new faces, and he was unable to remember events, even immediately after they occurred. Researchers were fascinated by his experience, and he is considered one of the most studied cases in medical and psychological history . Indeed, his case has provided tremendous insight into the role that the hippocampus plays in the consolidation of new learning into explicit memory.

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