Seeing Inside The Brain
Photo: A PET brain scan. Photo courtesyof Lawrence Berkeley National Laboratory and US Department of Energy.
Knowing what’s going on inside someone’s head has always been one oflife’s mysteries. The 19th-century phrenologists thought bumps on theskull could solve that problem. Today, neuroscientists use a variety ofdifferent methods for “seeing” inside the brain:
Lesion studiesremain one ofthe most important methods of probing the brain’s secrets. If humans oranimals have suffered brain lesions and losevery specific mental functions as a result, neuroscientists can usethat knowledge to build up a picture of which bits of the brain areresponsible for which functions.
Electroencephalography hasbeen used to measure brain activity in many experiments for the lastfew decades. Electrodes are fastened to the scalp to measure thevoltage changes that are produced when the person is asked to carry outdifferent tasks.
CAT scans are essentially X rays ofthe brain. CAT scannersbuild up pictures of the brain using a narrow beam of X rays that makesan imaginary “cut” through the brain along a particular axis and drawsa cross-section on a computer screen.
PET scans trail the progress ofradioactive glucose as itcourses through the brain. In more detail: the glucose releases positrons , which are rapidly annihilated when they meet electrons,giving off a burst of gamma radiation that is picked up by the scanner.
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.
Searching For Happiness In The Brain
Neuroscience, biology, and psychology all have important roles in deciphering and elucidating the mechanisms and purpose of positive emotions. Great scientists, from Charles Darwin to William James to Sigmund Freud, have studied in detail our most basic negative emotional processes, such as fear, stress, anxiety, anger, and aggression, and how they relate to the brain, nervous system, hormones, and internal organs. Their findings provided most of the knowledge we have today about the neural correlates of emotion in general, particularly the role of subcortical structures such as the limbic system, hypothalamus, thalamus, basal ganglia, and midbrain.
Positive emotions, however, used to be considered too subjective and difficult to study, so for a long time neuroscientists neglected them. Unhappiness was considered to arrive on its own, since fear, anger, and defense are responses to danger from the external world and are vital for our survival . But our feelings of pleasure and happiness were thought to be largely cultural and were regarded only as guiding our behavior toward desirable situations.
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Research Focus: Identifying The Unique Functions Of The Left And Right Hemispheres Using Split
We have seen that the left hemisphere of the brain primarily senses and controls the motor movements on the right side of the body, and vice versa. This fact provides an interesting way to study brain lateralization the idea that the left and the right hemispheres of the brain are specialized to perform different functions. Gazzaniga, Bogen, and Sperry studied a patient, known as W. J., who had undergone an operation to relieve severe seizures. In this surgery, the region that normally connects the two halves of the brain and supports communication between the hemispheres, known as the corpus callosum, is severed. As a result, the patient essentially becomes a person with two separate brains. Because the left and right hemispheres are separated, each hemisphere develops a mind of its own, with its own sensations, concepts, and motivations .
Although Gazzanigas research demonstrated that the brain is in fact lateralized, such that the two hemispheres specialize in different activities, this does not mean that when people behave in a certain way or perform a certain activity they are only using one hemisphere of their brains at a time. That would be drastically oversimplifying the concept of brain differences. We normally use both hemispheres at the same time, and the difference between the abilities of the two hemispheres is not absolute .
Neuroscience Research Points Toward The Role Our Brains Play In Our Happiness Even If We Dont Understand All The Brains Mysteries Yet
Ever wonder why we get a warm feeling when we come home? Or why laughter makes us feel so good? Or why, even though exercise is good for us, so many of us tend to avoid it?
If so, you may want to pick up Dean Burnetts book Happy Brain: Where Happiness Comes From, and Why. Burnett, a neuroscientist and standup comic, explores some of the inner workings of our brains to reveal how our neural networks support us in experiencing happiness so we can move forward in life and love.
Neuroscience is a fascinating field, but, as Burnett warns, its also a relatively new science, and many of its findings are exploratory in nature rather than conclusive. He points to the expense of running fMRI studies, which limits the number of study participants and the certainty about results. And, as so much of our brain activity can be influenced by individual personalities or environmental circumstances, its hard to make any grand proclamations about what happiness looks like in the brain.
Add to that some pretty weird anomalieslike the neurotransmitter serotonin, which modulates mood, being produced primarily by our gut bacteriaand it becomes clear that we dont understand everything about our brains and happiness. Much of it may be out of our conscious control.
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What Does The Brain Look Like While Processing And Regulating Emotions
Now, in the first section, you learned about feelings, which scientists call emotions. You heard that emotions can lead to a reaction in your body. You also know that sometimes we experience several emotions at once and that sometimes it is necessary to control a feeling and not to act on it. This process is called emotion regulation. In the second section, you learned how an MRI camera works and how it can be used to take images of the structure and function of the brain. In the next section, we want to combine these two things and talk about the parts of the brain that are responsible for processing and regulating emotion.
- Figure 3 – The emotion processing network includes several areas of the brain.
- Some of these areas are shown here shaded in blue and you can see their different jobs: the amygdala recognizes and sorts the emotions before transporting them to other areas. In the picture, this transportation is visualized by a train driving along the dotted track line to the most frontal part of the brain. Once the information arrives there, the prefrontal cortex and the cingulate cortex act as a control center , deciding what has to be done next with the incoming emotions. Many areas work together to process an emotion! .
The Hippocampus And The Anterior Cingulate Cortex
Best known for its role in helping to store long-term memories, thehippocampusthe seahorse-shaped structure adjoining the amygdalaalsoseems to play a key role in our emotional reactions. Davidson and hiscolleagues have suggested the hippocampus is a kind of emotional”chaperone” that helps to ensure our behavior is appropriateto its social context. This may explain why people with hippocampaldamage often show emotions that are quite inappropriate at a particulartime and place. Patients who suffer from post-traumatic stress disorder, such as victims of war and violent attacks, can experiencesudden extreme emotional reactions to quite innocuous stimuli: warveterans who burst into tears or dive behind the sofa when carsbackfire are just one example. The anterior cingulate cortex alsoseems to be involved in emotional processing, monitoring conflicts andtriggering other brain circuits to carry out more detailed processingwhen they occur.
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How The Brain Processes Emotions
When it comes to emotions, it turns out that there are regions in the brain, specifically in the limbic system, that are associated with each of the 6 main emotions.
As we all know, emotions are complex. Psychologists say that we have only 6 basic emotions, which are happiness, anger, sadness, fear, surprise, and disgust. All of our other emotions are built from the 6 basic emotions. For example, jealousy stems from a combined feeling of anger or sadness, while satisfaction can be a type of happiness.
When it comes to emotions, it turns out that there are regions in the brain, specifically in the limbic system, that are associated with each of the 6 main emotions. Emotions are actually experiences that are associated with activation of certain regions in the brain.
Emotion structures in brain
Positron Emission Tomography scanning and functional MRI studies have shown that some emotions are more likely to be associated with different regions of limbic system activity than other emotions.
1. Happiness activates several areas of the brain, including the right frontal cortex, the precuneus, the left amygdala, and the left insula. This activity involves connections between awareness and the feeling center of the brain.
2. Fear activates the bilateral amygdala, the hypothalamus and areas of the left frontal cortex. This involves some thinking , a gut feeling , and a sense of urgency typically associated with survival
Integration With Our Depression Model
It can be concluded that neuroplastic changes seem to connect all five theories on the pathogenesis of depressive disorder. Chronic treatment with antidepressants of several different classes is known to influence the expression of neurotrophic factors, for example, antidepressants increase BDNF expression in both animals and patients cortisol and several cytokines have profound neuroplastic effects and the disturbed circadian cortisol rhythm may cause the biological clock mechanism to induce neuroplastic changes. All these changes might occur during chronic activation of the stress response, due to continuous stressful circumstances. In fact, it would make sense for the system to evolve in ways that improved the chance of survival under difficult living conditions. This evolution may be accomplished by memorizing a successful behavioral reaction and the circumstances that activated the reaction. This behavior can be memorized through an adaptation in the hardware that initiates and mediates the stress response.
Certain components of our anatomical model require verification. For example, our model indicates the existence of re-entry circuits that regulate misery-fleeing and reward-seeking behaviors. To our knowledge, no study has shown that the fibers running from the thalamus to the subgenual cingulate cortex contribute to a cortical-subcortical re-entry circuit .
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What Brain Imaging Shows
The fantastic progress in techniques for obtaining functional images of the braincolor images that reveal precisely what brain structures are activated and deactivated when certain emotions or behaviors occur in human beingshas had a major impact on neuropsychology in the last decade. These images allow us to study the brain basis of emotions in a non-invasive way, without having to intervene in the brain as scientists do with experimental animals, for example by implanting electrodes or creating lesions.
Damasio proposed a distinction between emotions and feelings. According to his somatic marker hypothesis, the sensory system detects peripheral changes in the heart, circulatory system, skin, and muscles that are commanded by emotions in the brain and interprets these changes as feelings.5 This could explain why Aristotle considered that the heart was the seat of the soul and emotions, something we still see in our everyday language and symbolsfor example, the universal sign of love is a heart. As various biochemicals act on the neural circuits of our hearts, we discern different patterns and strengths of heartbeats, which lead us to feel, variously, contentment, happiness, love, joy, despair, depression, fear, or anger. The heaviness of heart we feel in an amorous deception is quite different from the flutter of passion.
Hacking Into Your Happy Chemicals
Since your brain already has these neurotransmitters and hormones, it makes sense to maximize them, right? But doing so doesnt require a secret code. All it takes is a few simple tasks and basic planning to boost these chemical messengers.
For starters, eat well and incorporate exercise into your diet. A 20-minute workout or a light jog can help stimulate dopamine due to the pleasure you receive from accomplishing a feat. Exercising can also stimulate serotonin and endorphins by causing you to feel satisfied and enjoy the positive results of a workout.
Exercising primarily influences boosting endorphins, but remember to laugh, too.
A simple meditation can help boost serotonin. There are ways to achieve this even without physical activity. Self confidence can go a long way in stimulating serotonin. The feeling of believing in yourself will translate to others respecting you, which ultimately promotes serotonin production.
To boost dopamine, complete simple tasks that make you feel good or set a goal you can easily achieve. The simple fact of even approaching a reward will stimulate these neurotransmitters. This explains why seeing the finish line at the end of a race activates dopamine.
For oxytocin, give someone a compliment. You may not see this as building trust, but communicating with others even strangers in social settings can reward you with positive feelings. Being kind also can boost serotonin and dopamine.
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The Role Of The Pleasure Pathway In Addiction
Certain activities that are performed and which are vital to our survival stimulate the pleasure pathway, but these activities are not the only ones capable of giving us that sensation. There are also habits, like drug use, that set the reward mechanism in motion.
The great majority of substances attack the brains reward system, releasing dopamine. Said neurotransmitter can be found in different regions of the brain that regulate movement, motivation, emotions, and the sensation of pleasure. The release of dopamine through drug use can overstimulate the system, leading to a sensation of euphoria that strongly reinforces consumption.
When drugs like cocaine are taken, 2 to 10 times more dopamine can be released than with a normal reward in addition, the effect is immediate and the effects can last longer. Drug tolerance, produced through repeated consumption, can lead to profound changes in the brain pathways, because in some way, they have the power to make them unnecessary.
Is There A Zone Of Happiness In The Brain
A team of neuroscientists seems to have found, almost by chance, what could be the zone of happiness in the human brain. A specific area of the cingulate beam could act as an access point to various networks that regulate mood.
Today we are talking about a study that has been presented in relation to the fascinating functioning of our brain, about which we know something more every day. It seems that the zone of happiness that can be electrically stimulated could have been found. This opens a new range of possibilities for the treatment of certain pathologies.
Actually, the research began as a brain mapping by electrical stimulation of patients suffering from epilepsy.
What they found by chance is that electrical stimulation of the cingulum produced an incredible number of laughs. It also seemed to induce incredible well-being and a pleasant sense of calm.
We already knew that stimulating certain parts of the brain can cause an uncontrollable urge to laugh.
But the novelty of this discovery is that this is the first time that one of them has been identified the same that also seems to significantly reduce anxiety when stimulated.
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Can I Change My Brain
Neuroplasticity refers to your brain’s ability to restructure or rewire itself when it recognizes the need for adaption. In other words, it can continue developing and changing throughout life. … Rewiring your brain might sound pretty complicated, but it’s absolutely something you can do at home.
Monoamines And Antidepressant Activity
Based on the foregoing observations, it can be concluded that norepinephrine, serotonin, and dopamine may play important roles in the genesis of depressive disorders. The role of dopamine is restricted to a specific subset of depressive reactions, including TCA/SSRI refractory depression, depression in schizophrenia , depression in Parkinson’s and Alzheimer’s Diseases, and antipsychotic drug-induced depression. We propose that norepinephrine primarily exerts effects in the hypothalamus, PFC, and striatum , and that serotonin primarily exerts effects in the hippocampal complex/amygdala. In both cases, the effects increase the likelihood that an inappropriate response is suppressed and an appropriate response takes over. This explains the time needed for an actual change to occur. Thus, it is the basis for the lag in treatment effects.
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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.