Dr. Sofie Valk, research group leader at the Max Planck Institute for Human Cognitive and Brain Sciences and Forschungszentrum Jülich: Just like the rest of the body, the brain has two halves. For example, the visual field is divided into a left and right half, with information from the left half of the visual field being sent to the right half of the brain and information from the right half of the visual field being sent to the left half of the brain. In addition, information from the left hand is sent to the right half of the brain and information from the right hand is sent to the left half of the brain.

Sensory Perception is therefore lateralized. This means that it is processed preferentially or completely in one of the two halves of the brain. The control of motor functions is also clearly lateralized: the right half of the brain controls the left half of the body and the left half of the brain controls the right half.

A classic example of lateralization in cognition is the control and processing of language, although the extent of this varies from person to person. Important centers for this are Wernicke's area and Broca's area, which are located more in the left Hemisphere of the brain. However, new research shows that the right hemisphere also plays an important role in language processing and that the extent of the differences is not the same in every person.

Another form of lateralization can be seen in certain aspects of attention, for which the right hemisphere tends to be more decisive. However, the degree of lateralization varies from person to person and changes over the years. With increasing age, the lateralization of attention tasks decreases, so that the brain areas responsible for attention become increasingly symmetrical in both hemispheres.

So there are differences between the two hemispheres, but they also perform many similar functions. Both hemispheres are essential and work closely together. For reasons of efficiency, one hemisphere may take on a particular task more strongly, while its counterpart is more dominant for another function.

Looking at the anatomy of the brain, it is apparent that certain areas of the left and right hemispheres are of different thicknesses. Analyses of the microstructure also reveal differences in the structure of the cortical layers between the two hemispheres. These findings suggest that structural differences could lead to functional variations, keeping the brain's organization dynamic. On the other hand, there are individual differences, some of which can be attributed to genetic components. A key challenge of these anatomical analyses is therefore to distinguish genetic influences from developmental and environmental factors.

Recorded by Stefanie Flunkert