A Brodmann area It is a region of the cerebral cortex in humans and primates, defined in 1909 by Dr. Brodmann according to the arrangement and organization of the brain cells it contains.
- 1 History
- 2 Function of Brodmann areas
- 3 Functional location according to the brain lobe
At the beginning of the 20th century, the German neurologist Dr. Korbinian Brodmann defined 52 differentiated regions present in the cerebral cortex of humans and primates that appeared to have a different cell morphology and organization. Over the past century, clinical findings and neurophysiological studies have shown that these microstructural differences correlate with the specialization of cortical function.
Thus, the studies carried out by Brodmann created a cortex map that includes the five lobes of each cerebral hemisphere and listed the areas he studied, recording the psychological and behavioral characteristics that accompanied each stimulation.
Role of Brodmann's areas
As Brodmann could determine, different parts of the cerebral cortex are involved in different cognitive and behavioral functions. At the same time, many of those brain areas defined by Brodmann have their own complex internal structures. In several cases, Brain areas are organized into topographic maps, where adjacent pieces of the cortex correspond to contiguous parts of the body, or some more abstract entity.
An example of this type of correspondence is the primary motor cortex, a band of tissue that extends along the leading edge of the central groove. The motor areas that innervate each part of the body leave a different zone of this zone of the cortex. The electrical stimulation of a point causes a muscular contraction in the part of the body represented. However, this somatotopic representation is not evenly distributed. The head, for example, is represented by a region approximately three times larger than the area for the entire back and trunk. The size of any zone correlates with the precision of the motor control and possible sensory discrimination.
In the visual areas, the maps are retinotopic; This means that they reflect the topography of the retina, the layer of light-activated neurons that lines the back of the eye. Also in this case, the representation is uneven: the fovea - the area in the center of the visual field - is very overrepresented compared to the periphery. The visual circuit in the human cerebral cortex contains several dozen different retinotopic maps, each dedicated to analyzing the visual input current in a particular way. The primary visual cortex (Brodmann area 17), which is the main direct input receptor of the visual part of the thalamus, contains many neurons that are activated more easily by the edges with a particular orientation that moves through a particular point in the visual field The visual areas later extract features such as color, movement and shape.
In auditory areas, the main map is tonotopic. The sounds are analyzed according to the frequency (i.e. high tone versus low tone) by subcortical auditory areas, and this analysis is reflected by the primary auditory zone of the cortex. As with the visual system, there are a series of tonotopic cortical maps, each dedicated to analyzing the sound in a particular way.
Functional location according to the brain lobe
The frontal lobe contains areas involved in the cognitive functioning, speech and language.
The area 4 corresponds to the precentral gyrus or primary motor area.
The area 6 It is the premotor or complementary motor area.
The area 8 It is prior to the premotor cortex. It facilitates eye movements and participates in visual reflexes, as well as in pupil dilation and constriction.
The areas 9, 10 and 11 They are responsible for cognitive processes such as reasoning and judgment that can collectively be called biological intelligence, including executive function.
The Areas 44 and 45 are the Broca area.
The areas in the parietal lobe play a role in the somatosensory processes.
Areas 3, 2 and 1 they are located in the primary sensory cortex, with area 3 above the other two. These are somasthetic areas, which means that they are the main sensory areas for touch and proprioception, including kinesthesia.
The areas 5, 7 and 40 they are located behind the primary sensory cortex and are considered areas of presensory association where somatosensory processing occurs.
The area 39 It is the angular gyrus.
The areas involved in the processing of the auditory and semantic information, as well as the appreciation of smell They are in the temporal lobe.
The area 41 It is the gyrus of Heschl, the primary auditory area.
The area 42 It is immediately inferior to area 41 and is also involved in speech detection and recognition. The processing performed in this area of the cortex provides a more detailed analysis than that performed in area 41.
The areas 21 and 22 They are the areas of auditory association. Both areas are divided into two parts; half of each area is on each side of area 42. Collectively they can be called the Wernicke area.
The area 37 It is located in the posterior-inferior part of the temporal lobe. Injuries here can cause anomia.
The occipital lobe contains areas that process visual stimuli.
The area 17 It is the main visual area.
The areas 18 and 19 they are the secondary (association) visual areas where visual processing occurs.