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All About the Brain

Fun fact: Did you know? The brain is about 60% fat. The remaining 40% is a combination of water, protein, carbs, and salts. The brain itself isn’t a muscle; it contains blood vessels and nerves, including neurons and glial cells

We all have a brain. We know it's that wrinkly thing in our heads that helps us think, remember stuff, and not bump into walls (usually). But let's be honest, sometimes our brains seem to go on vacation without us! Ever walked into the kitchen and completely forgotten why? Or spent ages searching for your keys, only to find them staring you right in the face? Yep, we've all been there. 

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But what's really going on in those moments? How does this incredible organ, the control center of our bodies, sometimes lead us on these wild goose chases?

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We may have learned about the brain back in school (ancient history, right?), but a little refresher never hurts! We'll explore how the brain communicates with the rest of the body, focusing on the areas where research has uncovered some fascinating differences in FND patients.

 

Ready to unlock the mysteries of the mind? Let's dive in! 

Jump to:

Overview of the Brain

Note: Although the brain is broken down into different sections/areas, it is important to remember that the brain is a constant interaction of these various sections. No one area works by itself- every thought or action is always a result of a 'group effort' or these areas. 

Fun fact: Your brain may be small, but it's mighty! This incredible organ accounts for just 2% of your body weight, yet it demands a significant portion of your energy – a full 15% .

The brain, despite its seemingly unified structure, is actually a collection of specialized parts working together seamlessly. These parts can be broadly categorized into three main regions:

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  • The Forebrain: This is the "thinking" brain, responsible for complex cognitive functions like language, memory, and reasoning. It also plays a crucial role in processing sensory information from the environment.
     

  • The Midbrain: This region acts as a vital link between the forebrain and hindbrain, relaying sensory and motor information. It's also involved in controlling eye movements and regulating sleep-wake cycles.
     

  • The Hindbrain: This is the "survival" brain, responsible for essential automatic functions like breathing, heart rate, and blood pressure. It also plays a role in coordinating movement and maintaining balance.

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Let's dive deeper into each of these regions and explore their unique roles.

brain

The Forebrain

This is the largest and most evolutionarily advanced part of your brain, responsible for a wide range of functions that make you, well, you. Think of the forebrain as the "CEO" of your brain, responsible for all the high-level thinking, planning, and decision-making. It's also the hub for processing sensory information, allowing you to experience the world around you.

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The forebrain, the most sophisticated part of your brain, is responsible for a wide array of functions that make you uniquely human. It's the seat of your consciousness, the command center for your thoughts and actions, and the processing hub for your senses.

At the heart of the forebrain lies the cerebrum, the largest and most prominent part of the brain. It's what you probably picture when you think of a brain – that iconic, wrinkled structure with two distinct hemispheres.

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Here's what makes the cerebrum so remarkable:

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  • The Seat of Consciousness: The cerebrum, which sits at the topmost part of the brain, is where our conscious thoughts and actions originate. It's where we store memories, plan for the future, engage in critical thinking, and unleash our imagination.
     

  • Two Hemispheres: A groove called "the great longitudinal fissure" divides the cerebrum into two halves, the left and right hemispheres. While the two hemispheres appear identical, they have different functions. For example, the ability to form words lies primarily in the left hemisphere, while the right hemisphere controls many abstract reasoning skills. 
     

  • Contralateral Control: Interestingly, each hemisphere controls the opposite side of the body. The right hemisphere primarily controls the left side of the body, and the left hemisphere primarily controls the right side. 
     

  • Corpus Callosum: The two hemispheres communicate with each other through a thick band of nerve fibers called the corpus callosum, which joins them at the bottom.

brain
corpus callosum
cerebral cortex

Cerebral Cortex: This is the outermost layer of the cerebrum, often referred to as the "gray matter." It's responsible for many of the things that make us human, including:

 

  • Consciousness: Your awareness of yourself and your surroundings.

  • Thought: Analyzing information, forming ideas, and making judgments.

  • Language: Understanding and producing spoken and written language.

  • Memory: Storing and retrieving information.

  • Sensory Perception: Processing information from your senses (sight, hearing, touch, taste, and smell)

Each cerebral hemisphere can be further divided into sections that specialize in different functions:

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  • Frontal Lobes: Located directly behind the forehead, the frontal lobes are involved in personality characteristics, decision-making, speech, voluntary movement, and behavior. They play a crucial role in planning, imagining the future, and using reasoned arguments. The frontal lobes also act as short-term storage sites, allowing you to hold one idea in mind while considering others. Within the frontal lobes, the motor cortices plan, control, and execute voluntary movements, while the premotor cortex guides eye and head movements and contributes to your sense of orientation.
     

  • Parietal Lobes: Positioned behind the frontal lobes, the parietal lobes are responsible for interpreting sensory information from the body, such as taste, smell, and touch. They integrate signals from various brain regions, allowing you to experience a delicious meal in its entirety. The parietal lobes also support reading, arithmetic, and object recognition. The somatosensory cortices within the parietal lobes receive information about temperature, taste, touch, and movement from the rest of the body.
     

  • Occipital Lobes: Located at the back of the brain, the occipital lobes process visual information from the eyes. They link this information with images stored in memory and influence how we perceive colors and shapes.
     

  • Temporal Lobes: Situated beneath the parietal and frontal lobes, around ear level, the temporal lobes are involved in auditory processing, memory formation, and object recognition. The upper part of each temporal lobe receives information from the ears, while the underside plays a crucial role in forming and retrieving memories. Other parts of the temporal lobe integrate memories and sensations of taste, sound, sight, and touch.

brain lobes

Beyond the cerebrum, the forebrain also includes other important structures, including the limbic system

Limbic System

As you can see, the forebrain is a busy place! It's a complex network of interconnected structures that work together to shape your thoughts, feelings, and behaviors. It's what allows you to experience the world, learn from your experiences, and interact with others.

Midbrain

Let's descend from the lofty heights of the forebrain and explore the fascinating world of the midbrain!

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The midbrain, or mesencephalon, is the uppermost part of the brainstem, that vital link between your brain and body. It's a small but mighty region packed with intricate structures and pathways. While smaller and less talked about than its upstairs neighbor, the midbrain plays a crucial role in connecting the forebrain to the hindbrain, acting as a vital relay station for information flowing between your brain and body. Think of it as the "middle management" of your brain, ensuring smooth communication and coordination.​​

Here's a glimpse into what makes the midbrain so important:

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  • A Complex Hub: The midbrain is far from simplistic. It's a very complex structure with a range of different neuron clusters (nuclei), neural pathways, and other structures. These features allow it to facilitate various functions, from basic actions like hearing and movement to more complex processes like calculating responses and adapting to environmental changes.

  • Reflex Central: The midbrain controls several reflex actions, particularly those related to vision and hearing. These reflexes help you quickly respond to sudden stimuli, like a loud noise or a bright light.

  • Movement Maestro: The midbrain is part of the circuit involved in controlling eye movements, allowing you to track moving objects, adjust your focus, and coordinate your eye movements with your head and body movements. It also plays a role in other voluntary movements.

  • Sensory Processing: The midbrain also helps process auditory and visual information. It helps you locate the source of sounds and integrate visual information with other senses.

  • Sleep-Wake Cycles: The midbrain is involved in regulating your sleep-wake cycles, helping you transition smoothly between alertness and sleep.

  • Alertness and Attention: It contributes to your overall level of alertness and helps you focus your attention on important stimuli.

So, while the midbrain may not be as glamorous as the forebrain, it's a vital part of your brain's intricate machinery. It helps you navigate the world, stay alert and attentive, and move with grace and precision.

The Hindbrain

Let's journey now to the base of the brain, where we find the ancient and powerful hindbrain. This is the oldest part of your brain, responsible for the essential functions that keep you alive and kicking. Think of it as the "operations center" of your brain, working tirelessly behind the scenes to ensure your survival.

Here's a breakdown of the hindbrain's key responsibilities:

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  • Life Support: The hindbrain controls many vital automatic functions that you don't even have to think about, such as:

    • Breathing: Regulating your breathing rate and depth to ensure you get enough oxygen.

    • Heart Rate: Keeping your heart pumping at the right pace to circulate blood throughout your body.

    • Blood Pressure: Maintaining a healthy blood pressure to deliver oxygen and nutrients to your cells.

    • Sleep-Wake Cycles: Regulating your sleep-wake patterns, ensuring you get the rest you need.

  • Coordination and Balance: The hindbrain plays a crucial role in coordinating your movements and maintaining your balance. It helps you walk, run, and perform complex actions with grace and precision.

  • Alertness and Arousal: It also contributes to your overall level of alertness and arousal, preparing you to respond to the world around you.

hindbrain

Key Structures of the Hindbrain:

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  • Cerebellum: This "little brain" is a wrinkled ball of tissue located at the back of the brain beneath the occipital lobes. It's separated from the cerebrum by the tentorium (a fold of tissue in the brain). The cerebellum fine-tunes motor activity and movements, helps maintain posture, and contributes to your sense of balance or equilibrium.

  • Brainstem: This is the lower extension of the brain, located in front of the cerebellum and connected to the spinal cord. It serves as a relay station, passing messages back and forth between various parts of the body and the cerebral cortex. The brainstem consists of the midbrain, pons, and medulla oblongata. Ten of the twelve cranial nerves originate in the brainstem.  

  • Medulla Oblongata: Located at the bottom of the brainstem, the medulla is where the brain meets the spinal cord. It's essential for survival, regulating many bodily activities, including heart rhythm, breathing, blood flow, and oxygen and carbon dioxide levels. The medulla also produces reflexive activities such as sneezing, vomiting, coughing, and swallowing. 

  • Pons: Acts as a bridge between the cerebrum and cerebellum, relaying signals and coordinating movements. Also involved in sleep and breathing.

So, while the hindbrain may not be involved in your deepest thoughts or most creative ideas, it's undeniably essential for your survival and well-being. It's the unsung hero of your brain, working tirelessly to keep you alive, alert, and moving through the world with ease.

Cranial Nerves

cranial nerves

The 12 pairs of cranial nerves are essential components of the peripheral nervous system, originating directly from the brain to serve the head, neck, and in some cases, organs in the chest and abdomen. These nerves are responsible for a wide array of functions, including sensory input like smell, vision, hearing, and taste, as well as motor control of eye movements, facial expressions, tongue movements, and swallowing. The first two nerves, olfactory and optic, arise from the cerebrum, while the remaining ten emerge from the brainstem. Each cranial nerve is identified by a specific name and number, reflecting its function and anatomical position. Damage to any of these nerves can result in a range of impairments, highlighting their critical role in our daily lives.

1: The first is the olfactory nerve, which allows for your sense of smell.

2: The optic nerve governs eyesight.

3: The oculomotor nerve controls pupil response and other motions of the eye, and branches out from the area in the brainstem where the midbrain meets the pons

4: The trochlear nerve controls muscles in the eye. It emerges from the back of the midbrain part of the brainstem

5: The trigeminal nerve has both sensory and motor function. It originates from the pons and conveys sensation from the scalp, teeth, jaw, sinuses, parts of the mouth and face to the brain, allows the function of chewing muscles, and more. 

6: The abducens nerve innervates some of the muscles in the eye. 

7: The facial nerve supports face movement, taste, glandular and other functions. 

8: The vestibulocochlear nerve facilitates balance and hearing. 

9: The glossopharyngeal nerve allows taste, ear and throat movement, and has many more functions. 

10: The vagus nerve allows sensation around the ear and the digestive system and controls motor activity in the heart, throat and digestive system

11: The accessory nerve innervates specific muscles in the head, neck and shoulder. 

12: The hypoglossal nerve supplies motor activity to the tongue.

The Vagus Nerve

Vagus nerve

The Vagus nerve is the longest and most complex of the 12 cranial nerves. “Vagus” is the Latin word for wandering. Your vagal nerves take a long, winding course through your body, exiting from your medulla oblongata in your lower brainstem, passing through your neck, chest, heart, lungs, abdomen, and digestive tract. The vagus nerves are the main nerves of your parasympathetic nervous system and contain 75% of your parasympathetic nerve fibers. 

The vagus nerve is a mixed nerve, meaning it has both sensory and motor functions:

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  • Sensory: It carries sensory information from the throat, larynx, ears, and organs in the chest and abdomen back to the brain. This includes sensations like fullness in the stomach, changes in heart rate, and irritation in the airways.

  • Motor: It controls muscles in the throat and larynx for speaking, swallowing, and coughing. It also regulates:

    • Heart rate: Slowing it down.

    • Breathing: Controlling the muscles involved in respiration.

    • Digestion: Stimulating the production of stomach acid and the movement of food through the digestive tract.

Temporoparietal Junction (TPJ)

The TPJ, or temporoparietal junction, is located at the intersection of the temporal lobe and parietal lobe. Remember those four lobes we discussed in the cerebral cortex? Well, the TPJ sits right where the temporal lobe (responsible for auditory processing, memory, and language) meets the parietal lobe (involved in processing sensory information and spatial awareness).  

TPJ

The TPJ is a sophisticated hub of information processing. More specifically, it's a heteromodal association cortex, meaning it receives input from multiple other areas of the brain. This allows it to integrate information from the limbic system (emotions and memory), visual, auditory, and somatosensory areas (your senses), and even the prefrontal cortex (decision-making and planning). It's like a central meeting point where different brain regions come together to share information and collaborate.

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This integration of information makes the TPJ crucial for a variety of complex cognitive functions, including:

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  • Attention: The TPJ helps you focus your attention on important stimuli and filter out distractions. Its anterior (front) part is particularly involved in monitoring for salient stimuli – things that grab your attention.

  • Social Cognition: The TPJ plays a crucial role in understanding and interacting with others. It helps you understand the mental states of others (their beliefs, intentions, and emotions), a concept known as "theory of mind." The posterior (back) part of the TPJ is particularly involved in reasoning about yourself and others.

  • Self-awareness: The TPJ also contributes to your understanding of your own thoughts and feelings.

  • Empathy: It helps you share the emotions of others and understand their perspectives.

  • Moral reasoning: The TPJ is involved in making judgments about right and wrong.

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