A lack of parental stimulation and affection during early development leads to high levels of cortisol with the absence of balancing hormones such as oxytocin which disrupts and overloads the childs stress response systems, which is thought to lead to underdevelopment of the childs brain that deals with emotion, empathy and ability to connect to other humans on an emotional level. According to Dr. Bruce Perry in his book The Boy Who Was Raised as a Dog, "the [infants developing] brain needs patterned, repetitive stimuli to develop properly. Spastic, unpredictable relief from fear, loneliness, discomfort, and hunger keeps a babys stress system on high alert. An environment of intermittent care punctuated by total abandonment may be the worst of all worlds for a child." Cultural influences
The sociocultural perspective of clinical psychology views disorders as influenced by cultural aspects; since cultural norms differ significantly, mental disorders such as ASPD are viewed differently. Robert D. Hare has suggested that the rise in ASPD that has been reported in the United States may be linked to changes in cultural mores, the latter serving to validate the behavioral tendencies of many individuals with ASPD.
Supernumerary phantom limb is a condition where the affected individual believes and receives sensory information from limbs of the body that do not actually exist, and never have existed, in contradistinction to phantom limbs, which appear after an individual has had a limb removed from the body and still receives input from it. An fMRI study of a subject with a supernumerary phantom left arm was done by Khateb et al. at the Laboratory of Experimental Neuropsychology at the University of Geneva. When the subject was told to touch her right cheek with the phantom limb, there was increased activity in the motor cortex of her brain in the area roughly corresponding to the left arm. When she announced that she had touched the phantom limb to her cheek, activity was monitored in the area of the somatosensory cortex that corresponded to the right cheek. At times during the experiment, the subject was asked to move the phantom limb to a location that was obstructed or otherwise unfeasible. In these instances, there was similar activation of the motor cortex but no such activity in the somatosensory cortex. Affected areas of the brain
Motor cortex
Somatosensory cortex
Tactile (touch) controlling areas

See also
Body integrity identity disorder (BIID)
Supernumerary body part – having an extra limb

References

McGeoch, P.D. et al. (2009). Apotemnophilia – the neurological basis of a ‘psychological’ disorder. Nature Precedings DOI: 10101/npre.2009.2954.1.