How Does The Human Brain Work?

How Does The Human Brain Work?

The human brain is an extremely complex organ that operates through electrical and chemical signals. It essentially functions as a giant communication network composed of nerve cells called neurons.

The three main parts of the brain are:

• Cerebrum:

The cerebrum is the largest part of the brain and makes up approximately 80% of it.

The cerebrum consists of two hemispheres:

The right and left.

The right hemisphere controls the left side of the body, while the left hemisphere controls the right side.

These hemispheres are connected by a nerve network called the corpus callosum. The cerebral hemispheres are surrounded by white and gray matter. Gray matter consists of various cells, and white matter consists of axons.

• Cerebellum:

The cerebellum, also known as the cerebrum, is the brain region located behind the upper part of the brainstem that coordinates sensory input with muscle responses.

The cerebellum, one of the body’s balance organs and provides muscle control, is also considered a vital organ for healthy motor movements.

One of the three main parts of the brain, the cerebellum is located at the back of the head, between the cerebrum and the brainstem. It consists of a cortex covering the white matter and a fluid-filled ventricle. The cerebellum is also divided into two hemispheres.

The primary functions of the cerebellum are:

• Provides muscle control, including balance and movement.
• Ensures the functional maintenance of motor activity.
• Supports the harmonious functioning of muscles.
• Coordinates eye movements.
• Controls emotions.
• Plays an active role in decision-making.
• It is effective in cognitive processes.

Brainstem:

This structure is located at the base of the brain and directly connects to the spinal cord. As a region that controls the brain’s basic vital functions and is critical for survival, it regulates automatic and vital functions such as breathing, heart rate, and blood pressure. The brainstem acts as a bridge between the cerebral hemispheres and the spinal cord.

What are The Parts of The Brainstem?

The brainstem serves as a bridge between the cerebrum, cerebellum, and spinal cord.

And it consists of three parts:

• Midbrain
• Pons
• Medulla Oblongata

The brainstem contains the white and gray matter (also known as white matter and gray matter) where the brain’s axons are located.

Gray matter consists of nerve cell bodies and contains important brainstem nuclei.

The white matter tracts of the brainstem consist of neuron axons traveling between the cerebrum, cerebellum, and spinal cord. Afferent pathways carry information to the brain, and efferent pathways carry information from the brain.

The parts of the brainstem play a major and important role in regulating the body’s functions.

What are The Basic Parts of The Brain and Their Functions?

Parts and Functions of the Forebrain (Prosencephalon)

The forebrain is divided into two main parts:

1. Telencephalon:

This is the largest and outermost part of the forebrain. The cerebral hemispheres, cortex, and basal ganglia are located in this part.

Cerebral Hemispheres:

The brain is divided into two equal parts: right and left. These two hemispheres are called the “right hemisphere” and “left hemisphere.”

They communicate with each other through a network of nerve fibers called the corpus callosum.

What are The Functions of The Right and Left Brains?

• Right Brain:

The characteristics of the right brain are as follows:

• Musical creativity,
• Intuition,
• Creativity,
• Holistic thinking,
• Imagination,
• Recognizing faces,
• Understanding emotions,
• Using imagination.

Damage to the right side of the brain can lead to the following effects:

• Altered creativity and perception,
• Visual and spatial impairments,
• Decreased awareness of deficits,
• Inability to see the bigger picture,
• Impaired visual memory,
• Decreased motor control in the left side of the body.

• Left Brain:

Left brain characteristics can be listed as follows:

• Critical thinking ability,
• Logic and reasoning,
• Mathematics,
• Language skills,
• Sequencing,
• Linear thinking.

The effects of damage to the left side of the brain can be listed as follows:

• Sequencing disorders
• Logical errors
• Difficulties with speech and language
• Catastrophic reactions
• Decreased motor control in the right side of the body.

Cerebral Cortex:

• Conscious thought, memory, attention, learning, and control of voluntary movements occur here.
• Known as gray matter.

Basal Ganglia:

• Initiation and control of movements
• Ensures smooth execution of voluntary muscle movements.
• Associated with diseases such as Parkinson’s and Huntington’s.

Limbic System:

A complex of structures located deep within our brain that regulates many basic functions, such as emotional responses, memory, and motivation.

Functions of the Limbic System

• Hippocampus:

Memory formation and learning.

• Amygdala:

Processing of emotions (especially fear and anger).

Structures such as the cingulate gyrus, septum pellucidum, and fornix are also included.

It affects emotional states, instincts, and motivation.

What are The Lobes of The Brain and Their Functions?

1. Frontal Lobe:

Located in the forehead, at the front of the brain.

Functions:

• Controls voluntary muscle movements (the motor cortex is located here)
• Planning, decision-making, problem-solving
• Attention, concentration
• Regulation of personality and behavior
• Speech production (Broca’s area, in the left frontal lobe)

Damage:

• Behavioral changes,
• Attention deficit,
• Speech disorders (aphasia),
• Motor control problems

2. Parietal Lobe:

Located behind the frontal lobe, in the upper side.

Functions:

• Processes sensory information such as touch, pressure, temperature, and pain (somatosensory cortex)
• Spatial perception and orientation
• Hand-eye coordination
• Recognizing the size, shape, and orientation of objects

Some Important Structures in the Parietal Lobe

• Postcentral Gyrus:

This region is the primary sensory cortex of the brain. It is a region called the sensory homunculus, where sensory data from the body is processed, with each body part represented by a specific cortical area. It is also known as Brodmann’s area 3.

• Posterior Parietal Cortex:

Plays a vital role in coordinating movements and spatial reasoning. It enables attention triggered by new stimuli, such as an animal darting into the road while driving.

• Superior Parietal Lobule:

Allows the individual to orient themselves and other objects according to their environment. Because it also receives significant stimulation from the hands, it is thought to help coordinate fine motor skills.

• Inferior Parietal Lobule:

Also known as Gerschwind’s area, this area helps evaluate facial expressions and emotions. It may also play a role in other areas, such as language processing, simple mathematical operations, and body perception. The angular and supramarginal gyri are also located here.

Damage:

• Inability to perceive the opposite side of the body,
• Disorientation,
• Decreased body awareness

3. Temporal Lobe (Temple Lobe):

Located in the temporal region near the ear.

Functions:

• Hearing and sound recognition (the auditory cortex is located here)
• Language comprehension (Wernicke’s area, usually in the left temporal lobe)
• Memory and learning
• Facial recognition and emotional responses

Some Important Areas in the Temporal Lobe

• Limbic Lobe:

This region is actually located at the intersection of several lobes, but it is directly connected to the temporal lobe. It controls automatic emotional reactions such as the fight-or-flight response. The limbic lobe contains the hippocampus and amygdala, structures important for memory, learning, and attention. It controls unconscious emotional states such as appetite and sexual desire, as well as some automatic bodily functions.

• Wernicke’s Area:

This region is associated with speech comprehension.

• Broca’s Area:

It helps with speech production. Along with Wernicke’s area, it is an important part of communication.

Damage:

• Hearing Impairments,
• Difficulty Comprehension of Language,
• Memory Problems

4. Occipital Lobe (Posterior Lobe):

Located at the very back of the brain.

Functions:

• Processing visual information (the visual cortex is located here)
• Perception of color, light, movement, and shape

Damage:

• Visual disturbances,
• Inability to recognize objects (visual agnosia),
• Visual field defects

2. Diencephalon:

This part is located below the telencephalon and just above the brainstem.

Thalamus:

• Transmits sensory information (such as vision, hearing, and touch) to the cerebral cortex
• Sensory data processing center

Hypothalamus:

• Maintains internal body balance (homeostasis)
• Manages functions such as hunger, thirst, sleep, sexuality, body temperature, and hormone secretion
• Works with the pituitary gland to control the endocrine system

Epithalemus (Pineal Gland):

• Secretes the hormone melatonin
• Regulates the biological clock and sleep-wake rhythm.

Midbrain (Mesencephalon) Parts and Functions

The midbrain consists of four main parts:

1. Tegmentum:

Located in the inner part of the midbrain, at the anterior end of the brainstem.

Functions:

• Regulation of muscle tone and reflexes
• Control of eye movements
• Transmission of pain and sensory information

Contains:

• Red Nucleus (Rubber):

Involved in the control of muscle movements.

• Substantia Nigra (Black Matter):

Produces dopamine, ensuring smooth movement (this structure is damaged in Parkinson’s disease).

2. Tectum:

Located in the posterior (dorsal) part of the midbrain.

Functions:

Management of visual and auditory reflexes

Contains:

Consists of four ridged areas.

These are called the quadrigeminal corpora:

• Superior Colliculi:

Visual reflexes (e.g., response to sudden light)

• Inferior Colliculi:

Auditory reflexes (e.g., startle response to loud noise)

3. Cerebral Peduncles:

Located in the anterior portion of the midbrain.

Functions:

• Conduct motor commands between the cerebral cortex and the spinal cord, cerebellum, and brainstem.
• Plays a role in the transmission of voluntary movement.

4. Sylvian Aqueduct (Cereductus Cerebri):

A thin canal between the tegmentum and tectum.

Functions:

• Allows the flow of cerebrospinal fluid (CSF) between the ventricle and the 4th ventricle.

Hindbrain Parts and Functions

1. Midbrain (Mesencephalon):

It is the uppermost part of the brainstem.

Functions:

• Controls Visual and Auditory Reflexes:

The superior colliculus, located in the midbrain, regulates visual reflexes, while the inferior colliculus regulates auditory reflexes. This enables responses such as blinking and turning to sound.

• Regulates Muscle Movements:

The midbrain is involved in muscle tone and the coordination of voluntary muscle movements. Its dopamine-secreting regions, in particular, ensure the fluidity of motor movements.

• Provides Motor and Sensory Transmission:

It regulates sensory information from the spinal cord and motor commands from the brain, transmitting them to target areas.

• Affects the Autonomic Nervous System:

The midbrain also helps regulate autonomic (involuntary) functions such as heart rate and respiration.

• Plays a Role in Pain and the Sleep Cycle:

Some studies indicate that the midbrain also plays a role in pain perception and the wake-sleep cycle.

2. Pons (Varol’s Bridge):

Located between the midbrain and the medulla oblongata.

Functions:

• Motor and Sensory Communication:

The Varol’s Bridge serves as a bridge for transmitting motor and sensory signals between the cerebral hemispheres and the spinal cord. This facilitates communication between the upper brain and the body.

• Motor Control:

Motor commands from the upper brain pass through the Varol’s Bridge to be transmitted to the muscles.

• Sensory Information:

Sensory input generated in the body (e.g., touch, pain) passes through the Varol’s Bridge to reach the relevant regions of the brain.

• Respiratory Regulation:

The Varol’s Bridge (Pons) is a structure containing respiratory centers that control the rate and depth of breathing. These centers in the brainstem regulate respiratory reflexes and rhythm.

The respiratory system sends messages to the upper parts of the brain via the pons, and the body responds quickly as needed (for example, breathing faster during exercise).

• Sleep-Wake Cycle:

The pons plays an important role in the sleep-wake cycle. It becomes particularly active during REM sleep (rapid eye movement sleep) and controls brain waves.

When you wake up, the pons helps maintain alertness.

• Reflex and Muscle Coordination:

The pons regulates some basic reflexes and helps coordinate muscle movements. Accurate transmission of motor commands from the brain is crucial for smooth movements.

In particular, eye movements and facial muscle movements may be under the control of the pons.

• Brain-Spinal Cord Communication Related to Sensory and Motor Information:

The pons processes sensory information from other parts of the brain. Additionally, motor commands for the muscles are sent from the cerebral cortex to the medulla oblongata and from there to the appropriate muscles.

• Face and Eye Movements:

The pons contains some neural pathways that control the movement of the facial muscles and eye movements. Therefore, blinking, facial muscle movements, smiling, and facial expressions are related to the medulla oblongata.

3. Medulla Oblongata:

The lowest part of the brainstem, it is directly connected to the spinal cord.

Functions:

• Controls heart rate, blood pressure, and breathing:

The medulla oblongata is the region where the cardiovascular and respiratory systems connect into a unified system that controls heart rate, breathing, blood pressure, and more.

• Participates in the body’s automatic processes:

It participates in processes that the body performs automatically, such as coughing, sneezing, swallowing, vomiting, and balance. These processes generally involve actions that the person performs without having to think.

• Important for nerve connections:

The majority of the major nerves converge in the spine and carry signals to the brain. These signals pass through the spinal cord.

What Are the Most Common Brain Diseases?

Brain diseases can occur for a variety of reasons and can seriously affect an individual’s quality of life.

Here are some of the most common brain diseases:

1. Alzheimer’s Disease:

Alzheimer’s disease, a disease generally associated with aging, is characterized by memory loss, decreased thinking skills, and behavioral changes.

Symptoms:

• Forgetfulness,
• Disorientation,
• Difficulty with language skills,
• Personality changes.

2. Parkinson’s Disease:

It occurs as a result of decreased dopamine production in the areas of the brain that control movement. This disease leads to impaired motor skills.

Symptoms:

• Tremors,
• Muscle stiffness,
• Slowed movements,
• Balance problems.

3. Migraine:

This is a disease characterized by severe and recurring headaches, usually felt on one side of the head. Migraine attacks are sometimes accompanied by symptoms such as nausea, sensitivity to light, and vomiting.

Symptoms:

• Severe Headache,
• Light and Sound Sensitivity,
• Nausea,
• Vomiting.

4. Stroke:

This occurs when blood flow to the brain is suddenly interrupted. Brain cells are deprived of oxygen and become damaged.

Symptoms:

• Facial Asymmetry,
• Speech Disorder,
• Numbness or Weakness,
• Dizziness.

5. Epilepsy:

Seizures occur as a result of abnormal electrical activity in the brain. Epilepsy is a disorder in which seizures occur repeatedly.

Symptoms:

• Seizures,
• Loss of Consciousness,
• Convulsions,
• Crossing of the Eyes,
• Memory Loss.

6. Depression and Anxiety:

Mental health problems can develop due to chemical imbalances in the brain. Depression and anxiety are common disorders that affect brain function.

Symptoms:

• Persistent Sadness,
• Loss of Interest,
• Sleep Problems,
• Anxiety,
• Restlessness.

7. Multiple Sclerosis (MS):

This is an immune system disease that affects the brain and spinal cord. Nerve conduction is disrupted due to damage to the protective sheath (myelin) surrounding the nerves.

Symptoms:

• Vision Problems,
• Muscle Weakness,
• Loss of Balance,
• Numbness.

8. Brain Tumors:

This occurs when abnormal cells grow in the brain tissue. They can be benign or malignant.

Symptoms:

• Headaches,
• Nausea,
• Seizures,
• Vision Loss,
• Balance Problems.

9. Attention Deficit Hyperactivity Disorder (ADHD):

This is a neurodevelopmental disorder characterized by attention deficit and hyperactivity, usually beginning in childhood.

Symptoms:

• Attention Deficit,
• Restlessness,
• Hyperactivity,
• Impulsivity.

10. Schizophrenia:

This is a serious psychiatric illness characterized by disturbances in thinking, feeling, and behavior. It results from chemical imbalances in the brain.

Symptoms:

• Hallucinations,
• Delusions,
• Detachment from Reality,
• Disorganized Thoughts.

What Percentage of the Brain Does a Human Being Use?

If a person has a healthy brain, their entire brain can be used. This can change if there is damage to certain brain areas. These brain areas can shrink or disappear due to disease or damage.

How Many Hours of Sleep Does the Brain Need to Rest?

Adults and the elderly generally require 7 to 9 hours of sleep. For teenagers and school-aged children, this amount is approximately 9.5 hours. For infants, the recommended daily sleep time is 16 to 18 hours. This sleep time is crucial for growth and brain development in babies.