HUMAN BRAIN: FUNCTIONS AND PARTS (WITH PICTURES) - NEUROPSYCHOLOGY - 2024

The human brain is the central organ of the nervous system, located in the head of the human being and protected by the skull. It has the same general structure and anatomy as the brain of other mammals, but with a more developed cerebral cortex.

Larger animals such as whales or elephants have larger brains in absolute terms, but when measured using the coefficient of encephalization, which compensates for body size, the coefficient of the human brain is almost twice as large as that of the dolphin. common and three times larger than that of the chimpanzee.

Most of the expansion is due to the cerebral cortex, especially the frontal lobes, which are associated with executive functions such as reasoning, planning, self-control, and abstract thinking.

The visual cortex, the part of the brain cortex dedicated to vision, is also broader in humans.

Parts of the brain and their characteristics

Much of the physiological functions of the brain involve receiving information from the rest of the body, interpreting it, and guiding the body's response. It is ultimately responsible for the thought and movement that the body produces.

The types of stimuli that the brain interprets include sounds, light, smells, and pain.

The brain is also involved in vital operations such as breathing, releasing hormones or maintaining the level of blood pressure.

It allows humans to successfully interact with the environment by communicating with others and interacting with inanimate objects.

The brain is made up of nerve cells that interact with the rest of the body through the spinal cord and the nervous system.

In addition, various chemical compounds are found in the brain that help the brain maintain its homeostasis.

Keeping nerve cells functioning properly and chemicals balanced is essential for brain health.

The main parts of the brain will be discussed below.

Cerebral cortex

It is the integrating part of the afferent and efferent information.

The cortex is almost symmetrical and is divided into the right and left hemispheres.

Scientists have conventionally divided it into 4 lobes: frontal, parietal, occipital, and temporal.

However, this division is not because of the actual structure of the cerebral cortex, but because of the bones of the skull that protect it.

The only exception is that the frontal and parietal lobes are separated by the central sulcus, a fold where the primary somatosensory and motor cortex meet.

The different areas of the cerebral cortex are involved in different behavioral and cognitive functions.

Frontal lobe

The frontal lobe is one of the 4 lobes of the cerebral hemisphere.

This lobe controls various functions such as problem solving, creative thinking, judgment, intellect, attention, behavior, physical reactions, abstract thinking, coordinated movements, coordinated muscles, and personality.

Parietal lobe

This lobe focuses on movement, calculation, orientation, and certain types of recognition.

If an injury occurs in this area, you may be unable to do simple daily tasks.

In the parietal lobe can be found:

• The motor cortex: allows the brain to control the movement of the body. It is located in the upper middle part of the brain.
• The sensory cortex: It is located in the front part of the parietal lobe and receives information from the spinal cord about the position of various parts of the body and how they move. This region can also be used to transmit information from the sense of touch, including pain or pressure, which affects different parts of the body.

Temporal lobe

The temporal lobe controls visual, auditory memory, and speech understanding.

It includes areas that help control speech and listening skills, behavior and language.

Wernicke's area is a portion of the temporal lobe that surrounds the auditory cortex and formulates and understands speech.

Occipital lobe

The occipital lobe is located at the back of the head and controls vision.

An injury in this area can cause reading difficulties.

Striated body

It is located in the walls of the cerebral hemispheres and in it are the correlation and coordination centers that regulate the rhythm of movements, facial expressions during communication.

Limbic system

Limbic system

Much of the hormonal responses that the body generates start in this area.

It is related to memory, attention, sexual instincts, emotions (eg pleasure, fear, aggressiveness), personality and behavior.

The limbic system includes:

• Hypothalamus: includes centers that regulate the internal balance and homeostasis of the body. Control your mood, temperature, hunger and thirst.
• Amygdala: allows you to respond to emotions, fear or memories. It is a large portion of the telencephalon.
• Hippocampus: Its main functions are learning and memory, specifically to convert short-term memory into long-term memory.

Thalamus

The thalamus is a relay center that controls attention through which afferent stimuli pass that reach consciousness.

Brain stem

All vital life functions originate in the brain stem including blood pressure, respiration, and heartbeat.

In humans, this area contains the medulla, midbrain, and pons.

• Midbrain: conducts motor impulses from the cerebral cortex to the brainstem bridge and conducts sensory impulses from the spinal cord to the thalamus.
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• Medulla oblongata: Its functions include the transmission of impulses from the spinal cord to the brain. They also regulate cardiac, respiratory, gastrointestinal, and vasoconstrictor functions.

Cerebellum

The cerebellum is also known as the "little brain" and is considered the oldest part of the brain on the evolutionary scale.

The cerebellum controls essential body functions such as posture, coordination, or balance, allowing humans to move properly.

Principal functions

The main function of the brain is to keep the body alive to interact with the environment.

Everything that the human being thinks, feels and does has to do with specific functions of the brain.

These functions can be:

Sensitive (data reception)

Information is received from the stimuli and processed.

Stimuli of external or internal origin are captured through different receptors.

These receptors transform the received stimuli through energetic signals.

Motorboats

The brain controls voluntary and involuntary movements.

The motor cortex is located in the frontal lobe, in front of the Roland fissure.

Integrative

They refer to mental activities such as attention, memory, learning or language.

Most patients who suffer some type of brain damage lose some behavior or cognitive ability.

Cognition

Nervous system and brain

Understanding the mind-body relationship is both a philosophical and scientific challenge.

It is difficult to understand how mental activities such as emotions and thoughts can be implemented by real physical structures such as neurons or synapses.

This is what led René Descartes and the later majority of humanity to believe in dualism: the beliefs that the mind exists independently of the body.

However, there is substantial evidence against that argument.

Injuries to the brain can affect the mind in different ways, thus the brain and mind are interrelated.

For example, the cortical stimulation that occurs in epilepsy also causes the appearance of complex sensations such as flashbacks, hallucinations and other cognitive phenomena.

Therefore, most neuroscientists tend to be materialists; they believe that the mind is reducible to a physical phenomenon.

Language

The main areas of the brain for speech are Broca's area and Wernicke's area.

Metabolism

MRI of the brain

The brain consumes 10 times more energy than it should considering its size.

According to scientist Marcus Raichie from the University of Washington, 60-80% of the energy consumed by the brain is dedicated to maintaining the connection between the different neurons, while the rest of the energy is dedicated to responding to the demands of the environment.

Weight and capacity

Weight

According to a study by the University of Basel that performed more than 8000 autopsies on women and men without mental illness, the normal weight of the human brain for men is 1,336 grams, while for women it is 1,198 grams.

With increasing age, weight decreases 2.7 grams in men and 2.2 grams in women, each year.

With every inch of height, the weight of the brain increases 3.7 grams on average.

On the other hand, brain weight is not related to body mass index.

Capacity and memory How many neurons does the brain have?

The human brain is made up of approximately 100 trillion neurons and each of them has 1000 or more connections - synapses - with other neurons.

The strength of those synapses depends on experience. When two neurons on either side of a synapse fire, that connection becomes stronger. Also, in order to adapt to the strength of the new connection, the dendrite of one of the neurons becomes larger.

These changes in the strength of connections and in the size of the dendrites influence human memory and learning.

If each neuron could only help to maintain a limited memory capacity, with the accumulation of experiences and things to remember, the available neurons would end.

It can be said that in that case there would only be a few gigabytes of space, similar to what a smartphone or USB memory has.

However, neurons combine to help recreate many memories at the same time, exponentially increasing the brain's ability to retain memory and therefore its ability. For this capacity, the brain's capacity is calculated to be 2.5 petabytes.

If the brain worked as a movie recorder, it would be enough to retain 3 million hours of series, movies and other content. You would have to run a television for 300 years to use all that capacity (scientificamerican.com).

Myth of 10% brain use

There is a popular myth that only 10% of the brain is used by most people. It is said that if people used the rest of their ability, they could be much smarter and achieve greater achievements.

However, this statement is an urban legend, it is not based on science. Although there is still much to research and learn about the human brain - such as consciousness or memory - his studies so far suggest that each part has a function.

Neuroscientist Barry Beyerstein establishes 7 pieces of evidence that reject that only 10% is used:

Brain damage studies: if only 10% of the brain is used, damage to other areas should not influence performance. However, almost all areas of the brain that are damaged produce some type of loss of abilities.

Brain scans show that whatever healthy people do, all areas of the brain are always active.

The brain consumes a large amount of energy compared to the rest of the human body. It can require up to 30% energy, despite weighing only 2% of the body. If only 10% were used there would have been an adaptive advantage for humans with smaller and more efficient brains, who consume less energy.

The brain does not act as a uniform mass, but consists of different regions that process different types of information.

Microstructural analyzes have been performed that insert a small electrode into the brain to measure the activity of a cell. If 90% of neurons were deactivated, it would have been known.

Brain neurons that are not active have a tendency to degenerate. Therefore, if 90% were deactivated, an autopsy would reveal great degeneration.

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Brain tissue can be divided into two large classes: gray matter and white matter.

The white matter is made up mainly of axons and its function is to correctly process brain information.

White and gray matter

The gray matter is made up of neuronal bodies and their bodies, and is involved in motor control, sensory perception (sight, hearing), memory, emotions, language, decision-making and self-control.

Evolution

The primate brain is generally nearly twice that expected for mammals of the same size. Through nearly 7 million years, the human brain has nearly tripled in size, with most of the growth in the past two years.

In the first two-thirds of human evolution, the brain of human ancestors was about the size of other primates today.

Australopithecus afarensis had skulls with internal volumes of between 400 and 550 millimeters, that of the chimpanzee around 400 ml and that of gorillas between 500 and 700 ml. Australopithecines - a sub-tribe of hominoid primates - began to show small changes in shape and structure. For example, the neocortex began to expand.

In the last third of human evolution, almost all of the increase in brain size occurred. Homo habilis, the first genus Homo to appear 1.9 million years ago, had a small increase in brain size, including the expansion of Broca's area.

The first Homo erectus fossil we have, dating back 1.8 million years, is somewhat larger, 600 ml.

Later the 1000 ml capacity was reached, about 500,000 years ago. Early Homo sapiens had brains similar to today's humans, averaging 1,200 ml or more.

The changes in Homo sapiens occurred in regions related to planning, communication, problem solving and other adaptive cognitive functions.

In the last 10,000 years, with nutritional problems in agricultural societies, there has been a decrease in brain volume, although in the last 100, with industrial societies, improved nutrition and the decrease in diseases, there has been a new increase.

The future of the human brain could lie in integration with artificial intelligence or in improvements from genetic engineering.

How does it work

See articles:

How the human brain works.

Biological bases of behavior.

Formation and development

See articles:

Development of the nervous system in humans (prenatal stage, postnatal stage, cellular mechanisms)

Neurodevelopment.

Synaptogenesis (the process of synapse formation).

Related Posts

Curiosities about the human brain.

How much the brain of an adult weighs.

How many neurons does the human brain have.

References

1. Human brain. Taken from en.wikipedia.org.
2. Brain. Taken from innerbody.com.
3. Picture of the brain. Mattew Hoffman. Taken from webmd.com.
4. Brain Structures and their Functions. Serendip studio. Taken from serendip.brynmawr.edu.
5. Brain. Taken from en.wikipedia.org.
6. What Is the Memory Capacity of the Human Brain? Paul Reber (2010). Taken from scientificamerican.com.
7. How Has the Human Brain Evolved? Taken from scientificamerican.com.