Human Brain: Characteristics, Structures And Associated Pathologies
For many years, psychobiology has attempted to establish the biological bases of human behavior.
Today we know that the nervous system of any person is a control and integration mechanism that regulates and supervises all the activities carried out by the body. This is divided into two: the central nervous system (CNS) and the peripheral nervous system.
In turn, the CNS is divided into two more substructures: the brain and the spinal cord. Within the brain we find three substructures: cerebrum, cerebellum and brainstem. Today we will talk about one of them, a very important structure that differentiates us from other species: the human brain
The human brain is a complex organ formed by the cortex (lobes) and different subcortical structures (white matter and gray nuclei). The cortex would be the surface of the brain, which is divided into two: left hemisphere and right hemisphere.
An adult brain weighs approximately 1,500 grams. Although its weight represents only 2% of body weight, it consumes the same amount of energy as skeletal muscles at rest.
Regarding the two hemispheres that divide it, it is known that the right one is more related to visual perception and a more global perception; the left would be more related to language, and would be more analytical. However, this distinction is relative, and generally, with some exceptions, both hemispheres of the human brain do everything.
The cerebral cortex is responsible for learning, thinking and decision making, and sends signals to other parts of the brain to allow us to move and communicate. Furthermore, it uses information from the senses and allows us to interact with the world and adapt to it.
The cortex is made up of six cellular layers that allow it to organize the afferents (receive information) and efferents (send information) of its neurons (approximately 60,000 million).
Its organization in cerebral lobes
The human brain is made up of 5 lobes (parts of the cerebral cortex with specific functions):
Injuries and associated pathologies
Damage to the different brain lobes causes diverse pathological consequences, studied by neurology and neuropsychology Let’s see the most important ones.
Injury to the occipital lobe
Visual agnosias (not recognizing objects or people by sight), Anton Syndrome and Bálint Syndrome.
Injury to the parietal lobe
Constructive apraxias, Gerstmann syndrome, asterognosia (inability to recognize objects by touch).
Temporal lobe injury
Impairment of hearing and understanding, Klüver-Bucy Syndrome.
Frontal lobe injury
Impairment of executive functions (dysexecutive syndrome), movement disorders, pseudodepression and pseudopsychopathy.
Ontogenetic development: divisions and structures
The human brain is divided into various structures that arise from three main divisions during gestation and development of the nervous system.
Prosencephalon (forebrain, towards the face)
Made up of the telencephalon and the diencephalon In turn, the telencephalon is formed by the cerebral cortex, the basal ganglia and the limbic system (“the center of emotions”); and the diencephalon is formed by the thalamus, hypothalamus, subthalamus, epithalamus, retina and optic nerves.
Formed by a subdivision with the same name, mesencephalon. This in turn is formed by the tectum, the tegmentum and the substantia nigra.
Hindbrain (back brain, all the way back)
Formed by the metencephalon and the myelencephalon. The metencephalon is formed by the cerebellum and pons, and the myelencephalon by the medulla oblongata
Differences and similarities between humans and animals
The first difference we find between the human brain and the brain of primates, for example, is their size (larger in humans). It is known that the greater the evolutionary proximity of the species (with respect to humans), the larger they are. Besides, the cerebral cortex of the human brain is larger and rougher than that of other animals of the same size.
On the other hand, the human brain has many more cells than those in the brains of other primates, and they also show more interconnections, that is, they have greater processing capacity.
Regarding similarities, both in animals and humans, it is known that within the already mentioned limbic system there is a subcortical structure, the amygdala, which has been consistently related to emotions and aggressive behaviors.
Furthermore, recent studies reveal that in both animals and humans, aggressive behavior is frequently associated with a decrease in the activity of serotonergic neurons.
