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What Part Of The Brain Controls Vision

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The Cerebrum And Cerebral Cortex

Vision and the Brain: Unseen Complexities Part 2

The cerebrum is the largest portion of the brain. It is covered in a thick layer of gray tissue called the cerebral cortex. Interior to the gray matter of the cerebral cortex is the white matter portion of the cerebrum. The white color comes from the layer of insulation called myelin that is on the neurons in this part of the brain.

The cerebrum is divided into two hemispheres that are joined by a band of nerves which allow communication between the two halves. The left hemisphere controls the right side of the body and the right hemisphere controls the left side of the body.

S Of The Brain Involved In Speech

In recent decades, there has been an explosion of research into language processing in the brain. Its now generally accepted that the control of speech is part of a complex network in the brain.

The formation of speech requires many different processes, from putting thoughts into words, forming a comprehensible sentence, and then actually making the mouth move to make the correct sounds.

There are several areas of the brain known to play a role in speech:

Impact Of The Parental/familial/home Environment On Eatingbehavior

In the same cohort of 616 children aged 6 to 12 years discussed above,Dubé and colleagues also measured attachment .Attachment is an extensively studied construct in both animals andhumans, Dubé explained, with a measure of attachment providinginformation about the role of the primary caregiver in defining how ananimal or person decides to explore beyond what has been programmed atbirth. More secure attachment allows child and adult alike to engagewith confidence in novel activities, including exploring alternatives tobiological programming such as an innate liking for sugar and dislike of bitter foods . Using 24-hourrecall not just for food but also for other healthy and unhealthyeating-related habits, Dubé and colleagues found that childrenwith insecure attachment experienced high eating schematicity for allthree DEBQ eating behaviors greater consumption of salty snacks lowerconsumption of water and fruit and greater likelihood of skippingbreakfast, eating out, and eating in front of the television duringweekdays. In Dubés opinion, these findings suggest thatmore attention should be paid, in both research and practice, toexploring how the early home environment influences a life course ofeating behavior.

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What Treatments Are Available

Treatment options vary depending on the type, grade, size and location of the tumor whether it has spread and your age and general health. The goal of treatment may be curative or focus on relieving symptoms . Treatments are often used in combination with one another. The goal is to remove all or as much of the tumor as possible through surgery to minimize the chance of recurrence. Radiation therapy and chemotherapy are used to treat tumors that cannot be removed by surgery alone. For example, surgery may remove the bulk of the tumor and a small amount of residual tumor near a critical structure can later be treated with radiation.

Observation

Sometimes the best treatment is observation. For example, benign, slow growing tumors that are small and have few symptoms may be observed with routine MRI scans every year until their growth or symptoms necessitate surgery. Observation may be the best option for people who are older or with other health conditions.

Medication

Medications are used to control some of the common side effects of brain tumors.

Surgery

Image-guided surgery technologies, tumor fluorescence, intraoperative MRI/CT, and functional brain mapping have improved the surgeonâs ability to precisely locate the tumor, define the tumorâs borders, avoid injury to vital brain areas, and confirm the amount of tumor removal while in the operating room.

Laser Interstitial Thermal Therapy

Radiation

Figure 6.

Chemotherapy

Adjunct therapies

The Brain Stem Relays Signals Between The Brain And Spinal Cord And Manages Basic Involuntary Functions

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The brain stem connects the spinal cord to the higher-thinking centers of the brain. It consists of three structures: the medulla oblongata, the pons, and the midbrain. The medulla oblongata is continuous with the spinal cord and connects to the pons above. Both the medulla and the pons are considered part of the hindbrain. The midbrain, or mesencephalon, connects the pons to the diencephalon and forebrain. Besides relaying sensory and motor signals, the structures of the brain stem direct involuntary functions. The pons helps control breathing rhythms. The medulla handles respiration, digestion, and circulation, and reflexes such as swallowing, coughing, and sneezing. The midbrain contributes to motor control, vision, and hearing, as well as vision- and hearing-related reflexes.

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A Sorting Station: The Thalamus Mediates Sensory Data And Relays Signals To The Conscious Brain

The diencephalon is a region of the forebrain, connected to both the midbrain and the cerebrum. The thalamus forms most of the diencephalon. It consists of two symmetrical egg-shaped masses, with neurons that radiate out through the cerebral cortex. Sensory data floods into the thalamus from the brain stem, along with emotional, visceral, and other information from different areas of the brain. The thalamus relays these messages to the appropriate areas of the cerebral cortex. It determines which signals require conscious awareness, and which should be available for learning and memory.

Examples Of Parasympathetic Responses

An easy acronym to remember how and where the PSNS works is SLUDD. This stands for:

  • Salivation: As part of its rest-and-digest function, the PSNS stimulates production of saliva, which contains enzymes to help your food digest.
  • Lacrimation: Lacrimation is a fancy word for making tears. Tears keep your eyes lubricated, preserving their delicate tissues.
  • Urination: The PSNS contracts the bladder, which squeezes it so urine can come out.
  • Digestion: The PSNS stimulates the release of saliva to promote digestion. It also enacts peristalsis, or the movement of the stomach and intestines, to digest food as well as release bile for the body to digest fats.
  • Defecation: The PSNS constricts the sphincters in the intestine and moves digested food material down the digestive tract so a person can have a bowel movement.

Keeping these things in mind, you can see why doctors may also call the parasympathetic system the feed and breed system.

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What Part Of The Brain Controls Vision

The brain consists of four main segments called lobes. The frontal lobe up front, the parietal lobe on top, the temporal lobe on bottom and the occipital lobe pulling up the rear. All of our senses, thoughts and actions start in one of these lobes.

Most visual functions are controlled in the occipital lobe, a small section of the brain near the back of the skull. But processing eyesight is no simple task, so other parts of the brain have to pitch in too.

From The Eye To The Brain

Parts of the Brain-Human Brain Structure and Function

The axons of ganglion cells exit the retina to form the optic nerve, which travels to two places: the thalamus and the superior colliculus. The LGN is the main relay for visual information from the retina to reach the cortex. Despite this, the retina only makes up about 20% of all inputs to the LGN, with the rest coming from the brainstem and the cortex. So more than simply acting as a basic relay for visual input from retina to cortex, the LGN is actually the first part of our visual pathway that can be modified by mental states.

The superior colliculus helps us to control where our head and eyes move, and so determines where we direct our gaze. Saccades, the jumpy eye movements that you are using as you read this text, are also controlled by the superior colliculus. As with the LGN, the superior colliculus receives strong input from the cortex, which provides the dominant command as to where our gaze moves.

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Components Of The Brainstem

The three components of the brainstem are the medulla oblongata, midbrain, and pons.

Brainstem Anatomy: Structures of the brainstem are depicted on these diagrams, including the midbrain, pons, medulla, basilar artery, and vertebral arteries.

The medulla oblongata is the lower half of the brainstem continuous with the spinal cord. Its upper part is continuous with the pons. The medulla contains the cardiac, respiratory, vomiting, and vasomotor centers regulating heart rate, breathing, and blood pressure.

The midbrain is associated with vision, hearing, motor control, sleep and wake cycles, alertness, and temperature regulation.

The pons lies between the medulla oblongata and the midbrain. It contains tracts that carry signals from the cerebrum to the medulla and to the cerebellum. It also has tracts that carry sensory signals to the thalamus.

Vision Changes Caused By Stroke

A stroke can cause significant changes in vision. Most of the time, a stroke survivor experiences only one or, possibly, a few of these vision changes, but not all of them. This is because different regions of the brain work together to control vision. So, depending on the size and location of a stroke, it may or may not affect various aspects of vision.

Learn more about the types of vision problems a stroke survivor may experience.

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Impact Of The Fetal Environment On Eating Behavior

Dubé characterized the fetal environment as a key context inbiology and behavior. She pointed to the Barker hypothesis as anexample. hypothesized that low birth weight is associated with increased risk ofmetabolic syndrome, diabetes, and obesity later in life. Dubépointed workshop participants to a forthcoming review in theAnnals of the New York Academy of Sciences onintrauterine growth restriction and its impact later in life.

In fact, researchers are finding correlations between IUGR and eatingbehavior not just later in life but early on as well. A study of24-year-old women who had been observed over their lifetime showed thatlow-birth-weight women were consuming more carbohydrates and had higherBMIs . Meanwhile, a study of 27-week-old preterm newbornbabies showed that low-birth-weight babies reacted less to sensitivitytests, postulated as being due to increased need, compared withnon-low-birth-weight babies of the same gestational age .Numerous other studies have found similar correlations across a widerange of ages .

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Building Our Visual World Step By Step

In our brain, which part controls vision?

Our visual cortex is not uniform, and can be divided into a number of distinct subregions. These subregions are arranged hierarchically, with simple visual features represented in ‘lower’ areas and more complex features represented in ‘higher’ areas.

At the bottom of the hierarchy is the primary visual cortex, or V1. This is the part of visual cortex that receives input the thalamus. Neurons in V1 are sensitive to very basic visual signals, like the orientation of a bar or the direction in which a stimulus is moving. In humans and cats , neurons sensitive to the same orientation are located in columns that span the entire thickness of the cortex.

That is, all neurons within a column would respond to a horizontal bar. In a neighbouring column, all neurons would respond to oblique but not horizontal or vertical bars . As well as this selectivity for orientation, neurons throughout most of V1 respond only to input from one of our two eyes. These neurons are also arranged in columns, although they are distinct from the orientation columns. This orderly arrangement of visual properties in the primary visual cortex was discovered by David Hubel and Torsten Wiesel in the 1960s, for which they were later awarded the Nobel Prize.

Orientation columns in primary visual cortex, as viewed from above. All neurons within a column respond preferentially to bars of a specific orientation, denoted here by colour.Crair et als/Wikimedia

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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.

Types Of Brain Tumors

Pinealoma Medulloblastoma

The World Health Organization developed a classification and grading system to standardize communication, treatment planning, and predict outcomes for brain tumors. Tumors are classified by their cell type and grade by viewing the cells, usually taken during a biopsy, under a microscope.

Cell type. Refers to the cell of origin of the tumor. For example, nerve cells and support cells give rise to tumors. About half of all primary brain tumors grow from glial cells . There are many types of gliomas because there are different kinds of glial cells.

Grade. Refers to the way tumor cells look under the microscope and is an indication of aggressiveness . Tumors often have a mix of cell grades and can change as they grow. Differentiated and anaplastic are terms used to describe how similar or abnormal the tumor cells appear compared to normal cells.

Table 1. Glioma Grading Scale

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The Hypothalamus Manages Sensory Impulses Controls Emotions And Regulates Internal Functions

The hypothalamus is part of the diencephalon, a region of the forebrain that connects to the midbrain and the cerebrum. The hypothalamus helps to process sensory impulses of smell, taste, and vision. It manages emotions such as pain and pleasure, aggression and amusement. The hypothalamus is also our visceral control center, regulating the endocrine system and internal functions that sustain the body day to day. It translates nervous system signals into activating or inhibiting hormones that it sends to the pituitary gland. These hormones can activate or inhibit the release of pituitary hormones that target specific glands and tissues in the body. Meanwhile, the hypothalamus manages the autonomic nervous system, devoted to involuntary internal functions. It signals sleep cycles and other circadian rhythms, regulates food consumption, and monitors and adjusts body chemistry and temperature.

Which Controls Involuntary Actions In The Body

Mind Control – Reptilian Brain. The Eyes Are Directly Connected To The Reptilian Brain.

The autonomic nervous system regulates involuntary and unconscious actions, such as internal-organ function, breathing, digestion, and heartbeat. This system consists of two complementary parts: the sympathetic and parasympathetic systems. It reduces bodily arousal, slowing the heartbeat and breathing rate.

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The Basics Of The Vestibular System

Think of the vestibular system as a messenger service. Located in the inner ear, the vestibular system provides your brain with information on things like motion, the position of your head, and sudden movements. This helps you maintain your balance by ensuring that your brain processes your bodys position every time it changes. Overall, the vestibular system helps you maintain a sense of equilibrium, preventing falls and dizziness.

Where Do Emotions Come From

The limbic system is a group of interconnected structures located deep within the brain. Its the part of the brain thats responsible for behavioral and emotional responses.

Scientists havent reached an agreement about the full list of structures that make up the limbic system, but the following structures are generally accepted as part of the group:

  • Hypothalamus. In addition to controlling emotional responses, the hypothalamus is also involved in sexual responses, hormone release, and regulating body temperature.
  • Hippocampus. The hippocampus helps preserve and retrieve memories. It also plays a role in how you understand the spatial dimensions of your environment.
  • Amygdala. The amygdala helps coordinate responses to things in your environment, especially those that trigger an emotional response. This structure plays an important role in fear and anger.
  • Limbic cortex. This part contains two structures, the cingulate gyrus and the parahippocampal gyrus. Together, they impact mood, motivation, and judgement.

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What Happens When The Cerebellum Is Damaged

When the cerebellum is injured, some of its functions can be compromised and cause motor problems. There may be a loss of the ability to precisely control the direction, force, speed and amplitude of movements, as well as the ability to adapt output patterns to changing conditions.

The deficits can be produced suddenly by injury, or gradually by degeneration of the cerebellum. The cerebellar syndrome can be caused by injury to the cerebellum or the cerebellar pathways.

Organ damage can lead to two different symptomatic syndromes: vermian syndrome with alterations in static and gait, and cerebellar hemispheric syndrome with alterations in movement coordination.

The lesion of the afferent pathways produces an archicerebellar syndrome, and that of the efferent pathways is manifested by a neocerebellar syndrome.

A person with a cerebellar injury may find it difficult to maintain a seasonal posture , and trying to do so leads to tremors.

It is also common to detect abnormalities in balance, gait, speech and even in the control of eye movements. So movements of all kinds can be affected. It is difficult for those who suffer from it to learn new motor sequences.

What Is A Brain Tumor

The Brain

Normal cells grow in a controlled manner as new cells replace old or damaged ones. For reasons not fully understood, tumor cells reproduce uncontrollably.

A primary brain tumor is an abnormal growth that starts in the brain and usually does not spread to other parts of the body. Primary brain tumors may be benign or malignant.

A benign brain tumor grows slowly, has distinct boundaries, and rarely spreads. Although its cells are not malignant, benign tumors can be life threatening if located in a vital area. A malignant brain tumor grows quickly, has irregular boundaries, and spreads to nearby brain areas. Although they are often called brain cancer, malignant brain tumors do not fit the definition of cancer because they do not spread to organs outside the brain and spine.

Metastatic brain tumors begin as cancer elsewhere in the body and spread to the brain. They form when cancer cells are carried in the blood stream. The most common cancers that spread to the brain are lung and breast.

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