Synonyms
Neocortex, Isocortex
Definition
The neocortex represents the youngest part of the brain in terms of evolutionary history. It can be subdivided into four lobes, which take over different brain functions.
Frontal lobe
Anatomy & Function: The frontal lobe plays the central role in the initiation of motor function. In the motocortex (gyrus precentralis) the movements are “designed”. It is somatotopically structured.
This means that each area of the motocortex is assigned to a specific body part. The hand, face and tongue are clearly disproportionately represented. The motocortex directs its information via the pyramidal tract to the periphery.
However, the information is first transferred to the cerebellum and basal ganglia for fine-tuning and coordination. The motor speech center (Broca’s area) is also located in the frontal lobe. However, only in the dominant, usually the left, hemisphere of the brain.
It is indispensable for speech production and understanding and is closely linked to the Wernicke area (see below) in the temporal lobe. Clinical presentation: A lesion in the motocortex causes paralysis (paresis) in the opposite hemisphere of the body, since a large part of the pyramidal tract crosses the opposite side on its way from central to peripheral. A lesion in the Broca’s area leads to Broca’s aphasia.
The affected persons can understand what is said and written, but their own speaking and writing is significantly more difficult. Often, only a few choppy words can be formulated. Frontal lobe = red (frontal lobe, frontal lobe) Parietal lobe = blue (parietal lobe, parietal lobe) Occipital lobe = green (occiptital lobe, occipital lobe) Temporal lobe = yellow (temporal lobe, temporal lobe)
Parietal lobe
Anatomy & Function: In the parietal lobe it is mainly sensitive stimuli that are integrated and processed. Thus, after passing through the thalamus, the information about protopathy (pain, temperature, coarse tactile sensation) and epicritics (fine touch and proprioception) reaches the postcentral gyrus, where the primary somatosensory cortex is located. This is located in the precentreal gyrus of the frontal lobe, where the motor function is generated.
Information about touches or other sensitive stimuli that have reached the primary somatosensory cortex is perceived as such, but is not yet interpreted. This happens only in the secondary somatosensory cortex. The parietal lobe also contains – among other regions – the gyrus angularis.
It is the switch point between the secondary visual cortex and the sensory speech center, i.e. the Wernicke area. It is essential for clinical purposes: Like the motor pathways, the sensitive pathways also cross over to the opposite side at some point on their way from periphery to center. Accordingly, a lesion in the area of the primary somatosensory cortex leads to a loss of function in the opposite (contralateral) half of the body.
The affected person no longer feels anything in the corresponding part of the body. In contrast, a lesion in the secondary somatosensory cortex leads to tactile agnosia. Tactile objects are no longer recognized. This is due to the fact that the secondary sensitive cortex is not responsible for the perception of the sensation itself but for its interpretation. A lesion of the cinguli gyrus leads to disorders of the