Disorders of perception are those that affect how senses such as smell, vision, taste, hearing, touch can be devastating to a person because humans rely significantly on our senses to function in the daily world. Imagery and perceptual disorders can vary from being able to determine what a form of an object is to being unable to recognize the use of an object (Andrewes, 2002). This perceptual analysis occurs using two systems which are the ventral and dorsal pathways. A PET scan can identify the brain activity in these areas and demonstrates that the mango layers and parvo layers are pathways that are separate and manage the interpretation of the motion and color (mango layers) as well as shape (parvo layers). The occipital lobes send outputs these two layers through fiber bundles and although their purposes are different (‘what is it’ versus ‘where is it’) they operate in conjunction to facilitate perceptive processes (Stirling, 2002).
One specific perception disorder is that of achromatopsia. Achromatopsia is a disorder that is associated with the parvo and mango pathways and those diagnosed with this perceptual disorder report seeing colors as being grey or lacking color dimension. The American Association for Pediatric Ophthalmology (2008) states that on in every 40,000 children globally are born with this disorder and the color blindness is a result of an unbalanced distribution of the function red, green, and blue cones in the retina. However, many people are not born with this perception disability; rather it occurs from brain lesions or a stroke. Although this can be very disruptive in daily activities such as reading, discriminating between colors for decision making processes, or eating, there is some evidence that partial recovery from achromatopsia for those whose onset resulted from a stroke is possible, although full recovery has not yet been noted (Spillman, Laskowski, & Lange, 2000).
Apraxia is the loss of ability to perform certain complex movement tasks and it can come in one of four forms which are ideomotor apraxia, verbal apraxia, buccofacial apraxia, or ideation apraxia (Andrewes, 2002). Ideomotor apraxia, which is the inability to make gestures, can affect daily activities such as being able to hammer a nail, making symbolic hand gestures (waving goodbye), using a toothbrush, pretending to drive a car, or combing hair (Andrewes, 2002; Kaya, Unsal-Delialioglu, Kurt, Altinok, & Ozel, 2006). Although some of these behaviors may demonstrate similarities to muscle paralysis, it is actually the loss of the ability to control basic coordinated muscle movements. This is a result of lesions in the dominant parietal lobe, damage in the supplementary motor areas, or lesions of the corpus callosum and, although patients mentally are aware of the movement that they wish to replicate, they are unable to physically demonstrate the movement (Kaya et al., 2006). Common sense recommendations that would benefit those with ideomotor apraxia include removal of any harmful (sharp) objects that could be inadvertently used from the person’s living space, write down detailed instructions how to perform a specific task, and work on repeated muscular movements in a rehabilitative setting.
American Association for Pediatric Ophthalmology. (2008, April 8). What is achromatopsia? Retrieved from: http://www.aapos.org/displaycommon.cfm?an=1&subarticlenbr=60.
Andrewes, D. (2002) Neuropsychology: From theory to practice. New York: Psychology Press.
Kaya, K., Unsal-Delialioglu, S., Kurt, M., Altinok, N., & Ozel, S. (2006). Evalutation of ideomotor apraxia in patients with stroke: A study of reliability and validity. Journal of Rehabilitative Medicine, 38(2), 108-12.
Spillman, L., Laskowski, W., & Lange, K. W. (2000). Stroke-blind for colors, faces, and locations: Partial recovery after three years. Restorative Neurology and Neuroscience, 17(2-3), 89-103.
Stirling, J. (2002). Introducing neuropsychology. New York: Psychology Press.