Brain hemispheres

Brain hemispheres . The term cerebral hemisphere designates each of the two structures that make up the largest part of the brain . They are inverses of each other, but not inversely symmetrical, they are asymmetric, like the two sides of the individual’s face. A deep midline sagittal fissure (the cerebral interhemispheric or longitudinal fissure) divides them into the right hemisphere and the left hemisphere. This fissure contains a fold of the dura and the anterior cerebral arteries. In the deepest part of the fissure, the corpus callosum (a commissure formed by a conglomerate of white nerve fibers), connects both hemispheres crossing the midline and transferring information from one side to the other …


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  • 1 routes
  • 2 Right hemisphere
  • 3 Left hemisphere
  • 4 Source


The white matter of the cerebral hemispheres is found below the cortex and is made up of myelinated axons. The nerve fibers that make up the white matter of the cerebral hemisphere are classified as:

  • Commissural fibers: connect and transmit nerve impulses from one hemisphere to the other; they cross the midline, forming a thick and compact structure ( corpus callosum).
  • Association fibers operate in the convolutions of the same hemisphere: they communicate neuronsfrom one part of the cortex of one hemisphere with those from another part of the same hemisphere.
  • Projection fibers: transmit impulses from the brainto the spinal cord (and vice versa); they depart from the cortex to lower centers; they start from almost all areas of the cortex and converge towards the inner capsule. This sheet of white matter separates the basal nuclei from the thalamus .


Right hemisphere

It governs as many specialized functions as the left. Its way of preparing and processing information is different from the left hemisphere. It does not use the conventional mechanisms for the analysis of the thoughts that the left hemisphere uses. It is an integrating hemisphere, center of the non-verbal visuo-spatial faculties, specialized in sensations , feelings , prosody and special abilities; as visual and sound not of language as artistic and musical.

Conceives the situations and strategies of thought in a total way. Integrates various types of information ( sounds , images, smells, sensations) and transmits them as a whole. The elaboration method used by the right hemisphere adjusts to the type of immediate response that is required in visual and spatial orientation processes. The right frontal lobe and the right temporal lobe appear to be responsible for carrying out specialized nonverbal activities in the right hemisphere. This corresponds, in many respects, to the speech control functions of the frontal lobe and the temporal lobe of the left hemisphere. The other two lobes of the right hemisphere, the parietal and the occipital lobe, appear to have fewer functions.

However, as a result of studying patients with a divided (sectioned) brain, or patients with lesions in the left hemisphere, a small degree of verbal comprehension has been detected in the right parietal lobe, which has the ability to understand a selection of nouns and simple verbs. And conversely, the left parietal lobe appears to have certain limited spatial functions. Therefore, although the right hemisphere is undoubtedly specialized in nonverbal functions, specifically visuospatial functions, it is not easy to discern the differences between the two hemispheres. The right hemisphere is considered in any way, as the receiver and identifier of spatial orientation, responsible for our perception of the world in terms of color, shape and place.John Huglings Jackson reported that a patient with a tumor on the right side of the brain did not recognize objects, places, or people. Using their faculties we are able to situate ourselves and orient ourselves; we can know which street we are walking by simply looking at the architecture of the buildings on either side of it, this is the shape and appearance of the facades, roofs and entrance doors. If we walk down the street and recognize a face, the identification of that face is also carried out by the visual memory of the right hemisphere.

On the other hand, the name that corresponds to the person who has this known face is provided by the left hemisphere.

Many of the activities attributed to the unconscious are its own. It mainly processes the information using the synthesis method, composing or forming the information from its elements, to a set. It also controls the left side of the human body. In this case, an embolism can cause functional loss or affect motor skills on the left side of the body. It can also cause disturbance of normal attention to the left body and its surroundings even with the other.

Left hemisphere

It is the motor part capable of recognizing groups of letters forming words, and groups of words forming sentences, both in terms of speech, writing, numbering, mathematics and logic, as well as the faculties necessary to transform a set. of information in words, gestures and thoughts. John Hughlings Jackson, a British neurologist, as early as 1878 described the left hemisphere as the center of the faculty of expression. Depending on its severity, an embolism that affects this structure can produce functional losses, functional loss of speech and affect motor skills on the right side of the body.

According to psycholinguistic theory, the phrase construction process is governed by a number of related ideas, but the mechanism that allows the mind to group words to form grammatical phrases is not fully deciphered. The hemisphere stores concepts that it then translates into words (amor, amour, amore, love, liebe) rather than a textual memory. That is, the brain understands ideas , concepts, and stores them in nonverbal language , which it then translates into a language or language learned by the individual through culture.

Intelligence tests that investigate vocabulary, verbal comprehension, memory and mental arithmetic calculation, detect the origin of activity in the left hemisphere. The left hemisphere specializes in articulated language, motor control of the articulating phone apparatus, logical information management, proportional thinking, information processing in series one by one, mathematical information management , verbal memory, grammatical logical aspects of language, organization of syntax, phonetic discrimination, focused attention, time control, planning, execution and decision making and long-term memory. Intelligence tests mainly measure the activity of this hemisphere.

Many of the activities attributed to the conscious are its own. It mainly governs the right part of the body. It processes the information using analysis, which is the method of solving a problem by breaking it down into pieces and examining them one by one.


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