Somatosensory agnosias are characterized by the partial or complete inability to recognize sensory stimuli when there are no impairment in sensation or alertness. Asomatognosia refers to the loss of sense of self through body and may include the unawareness of, indifference to, or denial of an illness, an inability to identify body parts, and an absence of normal reactions to pain. .
With the knowledge that the most devastating impairments of spatial cognition are found in patients with lesions to the posterior parietal cortex researchers have been able to conclude that this region is essentially responsible for spatial awareness and visomotor guidance of egocentric movements in space. Damage received to the parietal lobe is not always symmetrical, in fact damage to the right and left lobes typically results in very different symptoms. Right parietal lobe lesions can result in contralateral neglect (hemispatial neglect), or the neglecting of the opposite side of the body and or space. While hemispatial neglect is a syndrome that can occur with lesions on either side of the brain, it is typically lesions in the right side of the brain that results in the most severe expression of symptoms. Individuals ignore bodily information completely on the side which is contralateral to the lesion. The most visible result of this symptom is the impairment in many personal care skills such as dressing and washing. In dramatic cases individuals even deny that the limbs on this side of their body belong to them. Neglect is the general term for attention deficit in which a person ignores sensory information that is normally considered important. We know from this symptom that the parietal region is important in contributing to spatial aspects of attentional functioning in humans and providing a spatial map of the world. In addition from studying these patients it has been revealed that there are multiple spatial frameworks that we use to function including a map of external and personal space based on the midline of the trunk and one in regard to the position of the head.