Face to Face with Prosopagnosia

Face to Face with Prosopagnosia An article on the mechanisms, theories, and deficits of face recognition: “eei g is de ei i g, drea i g is elie i g, it's ok ot to e oka ... - Jessie J Abstract Our visual world is created in the Ventral Visual Processing Stream, in an elegant compositional process where specialized groups of neurons fire in harmonious responses to electrochemical signals received from our eyes. Trauma to this area causes Visual Agnosia. There exists in this processing stream a highly specialized area called the Fusiform Face Area, named for its high sensitivity to faces. Trauma to this area appears to result in the inability to recognize faces; a condition called Acquired Prosopagnosia. A number of associated syndromes exist, for example Capgras Syndrome, where an individual believes that a close friend or loved one is an imposter and Congenital- or Developmental Prosopagnosia; the inability or difficulty to recognize faces since birth or from a very early age. Initially thought to be very rare, new research seem to indicate that as much as 2.5% of the human population suffer from Congenital Prosopagnosia, many of these individuals are on the autistic spectrum. Although no formal treatment for Prosopagnosia exists apart from training in the use of other modalities as aid to facial recognition, there are promising methods currently under research. Introduction: How do we see what we see? It is both scary and amazing to think that the world we see around us is pretty much created by our brains: Our eyes register an object by accepting light that falls within the visible spectrum of wavelengths reflecting from the objects in our environment into our eyes. Our optic nerves then convert that light into electrochemical signals which can be understood by the operating system of our brain. These electric signals pass along a neural network to the back of the brain to the occipital region. The first area to receive visual information in the occipital region is known by many different names, but we will call it the visual cortex. This area is specifically responsible for the processing of visual information. (Banich & Compton, 2011, p.153) There is a visual cortex in each half (hemisphere) of the brain. The left hemisphere visual cortex receives electrical signals from the right eye or visual field, and the right hemisphere visual cortex receives signals from the left visual field. In this way each half of our brains contains a retinotopic map of the visual space surrounding us. Because this is the first area of the brain to receive visual information, the information is not very complex and therefore the retinotopic map can be compared to a two dimensional image or representation of our field of vision. (Banich & Compton, 2011, p154) From the visual cortex the visual information is divided into two processing streams, one heading upwards or dorsally towards the parietal lobe and the other downwards or ventrally towards the temporal lobe. two referred These streams are to the hat a d the as he e st ea s i depe de tl . The he e st ea is the o e headi g upwards to the parietal lobe where the locations of objects in space is determined using the visual information in conjunction with additional information such as sound. In order to better understand how our ai s eate the o ld e see, e a e follo i g the hat stream heading down in what is called the ventral visual processing stream. (Banich & Compton, 2011, p. 163) As we move forward or anteriorly in the ventral visual processing stream we notice that the cells we pass along the way apparently become more advanced as we progress. The cells closer to the visual cortex respond (or fire) in reaction to relatively simple stimuli such as 2 colour, texture and size for example, while cells further away respond to more complex stimuli such as specific forms e.g. hands and faces. (Banich & Compton, 2011, p. 180) When seeing is no longer believing: Most of what we know about how our brains recognize objects comes from studying people who have problems identifying objects. Olivier Sacks, a neurologist, wrote a number of well-known books. One called The Ma ho Mistook his Wife fo a Hat is a olle tio of case histories of patients treated by Dr Sacks, who all had injuries or damage to the right hemisphere of their brains. In this book Dr Sacks relates the following incident involving himself and the patient who is the inspiration behind the title of his book; Dr P: I had stopped at a florist o a to his apartment and bought myself an extravagant red rose for my buttonhole. Now I removed this and handed it to him. He took it like a botanist or morphologist given a specimen, not like a person given a flower. A out si i hes i le gth, he o e ted. A o voluted red form with a li ear gree atta h e t. Yes, I said e ouragi gl , a d hat do ou thi k it is, Dr P.? Not eas to sa . He see ed perple ed. It la ks the si ple s etr of the Platonic solids, although it may have a higher symmetry of its own. . . . I think this ould e a i flores e e or flo er. -From The Man who Mistook his Wife for a Hat by Olivier Sacks (Sacks, 1985, p.14) What Dr Sacks is describing here is a condition called visual agnosia. Freud came up with the term agnosia derived from the Greek word gnosis meaning knowledge and the prefix aindicating without. Freud felt that agnosia is not so much a disability to recognize objects as the inability to access the information stored in memory necessary to identify the object. (Banich & Compton, 2011, p. 182) Visual agnosia is the inability to recognize objects that is seen. In his book Dr Sacks go on to relate how, after he encouraged Dr P to smell the rose he could identify it quite effortlessly: “ ell it, I suggested, and he again looked somewhat puzzled, as if I had asked him to smell a higher symmetry. But he complied courteously, and took it to his nose. Now, suddenly, he came to life. Beautiful! he e lai ed. A earl rose. What a hea e l s ell! -F o The Man who Mistook his Wife for a Hat Oli ie “a ks “a ks, 5, p. 5 3 Association and Perception: Research confirm what Dr Sacks has observed: people who suffer from visual agnosia can recognize objects once they use their other senses to give them additional information pertaining to the identity of the mysterious object, which means that visual agnosia is modality specific, meaning it manifests in only one of the senses namely sight. (Banich & Compton, 2011, p. 182) Visual agnosia has traditionally been classified as either associative agnosia or apperceptive agnosia where the latter allows the individual only access to very basic visual information such as colours and outlines but leave the individual unable to describe or identify the object as a whole. The individual has no mental concept of what he or she observes. With associative agnosia individuals can perceive detailed information about a given object. When they mistakenly identify an object as another it is usually because the misidentified o je t has a si ila shape to the o e the a e a tuall o se i g. Although D “a ks does t make this distinction in his narrative we can infer that Dr P more than likely fell into the category of associative visual agnosia: Your shoe, I repeated. Perhaps ou d put it o . He continued to look downwards, though not at the shoe, with an intense but ispla ed o e tratio . Fi all his gaze settled o his foot: That is shoe, es? Did I mis-hear? Did he mis-see? M e es, he e plai ed, a d put a ha d to his foot. This is shoe, o? No, it is ot. That is our foot. There is our shoe. Ah! I thought that as foot. … He also appeared to have decided that the examination was over and started to look around for his hat. He reached out his ha d a d took hold of his ife s head, tried to lift it off, to put it on. He had apparently mistaken his wife for a hat! His wife looked as if she was used to such things. Fo The Man who Mistook his Wife for a Hat Oli ie “a ks “a ks, 1985, p.12&13) Apperceptive and associative visual agnosia are very different and as expected caused by trauma or injury to two different areas of the brain; apperceptive agnosia is cause by trauma spread over the occipital lobe while associative agnosia usually occurs as the result of trauma or injury to the occipitotemporal regions of both hemispheres of the brain. (Banich & Compton, 2011, p. 184) Unfortunately Dr Sacks never go into great detail ega di g the spe ifi a eas of D P. s appea that he e e dete ai that as da aged. From his narrative it would i ed the ause of D P. s condition, he only said that what he called the o ga i p e e uisite of all pi to ial i age was damaged and finally ended his 4 a ati e as i i g D P. s death fou years later to a p o ess i the isual pa ts of his ai . assi e tu ou o dege e ati e (Sacks, 1985, p.17 & p.19) Agnosia for faces: There is at least one variety of visual agnosia that is specific to a certain type of object, namely faces; this is called prosopagnosia. Being unable to identify faces is easy to identify but difficult to explain. Researchers are in two minds as to what is behind this deficit; it is clear that there is a malfunction somewhere, but is it that there exist within the brain a specialized system with the express purpose to identify faces, or is the malfunction in a system or systems essential in facial recognition, but not necessarily specialized only for that purpose? (Duchaine, 2000) We know that the ventral visual processing stream is responsible for object recognition and that cells get more specialized as the signals progress in the stream, but how specialized are we talking here? Could it be as specialized as having a specific cell to recognize your uncle Bob and another for your girlfriend or boyfriend? This is a hugely simplified version but this idea illustrates the concept theorists call sparse coding. This hugely simplified version is referred to as the grandmother cell theory, (Banich & Compton, 2011, p. 188) having one unique cell to identify Granny or Larry-the-Latest-Boyfriend. I su e ou can see the problem with this theory: we all know our brain cells die periodically: Does this imply that you may wake up one morning after a night of revelry only to discover darling Larry has become a stranger? Brain imaging technology available to us today is not yet refined enough to answer questions relating to individual cells. Most research available to us to date has used monkeys as subjects but on rare occasions single cell recording have been conducted with human epileptic patients who had electrodes implanted to track neural activity associated with seizures. In one such recording a single cell responded only to Jennifer Arniston in various poses but not to any other actors, not even when she was in photos with Brad Pitt. Could this be the discovery of the Jennifer Arniston cell? (Quiroga, Reddy, Kreiman, Koch & Fried, 2005 cited in Banich & Compton, 2011, p. 189) An alternative theory is population coding. This theory suggests that there may be a number of cells who together are responsible for facial recognition, and that they fire in a 5 specific pattern in response to each unique face. Much like keys on a piano; when a specific combination of keys are played together it produces a specific cord; when a unique individual is recognize a number of cells fire together. The weakness in this theory is the necessity to be able to link additional information to Larry the boyfriend; his specific adorable laugh, his specific aftershave and the fact the he walks like a cowboy. Are all these identifier variables - located in other areas of the brain - connected to the Larry-cord? According to Banich & Compton (2011, p. 189) this makes for an unwieldy system. However, theoretical support for the population coding notion can be found in a number of studies: An area on the right side of the brain, called the fusiform gyrus has been named the fusiform face area (FFA) because it shows higher electrochemical responsiveness on functional imaging scans to faces than to other objects. O Co o, (Barton, Press, Keenan, & ; Kanwisher, McDermott, & Chun, 1997 as cited in Banich & Compton, 2011, p. 195) Lost and forgotten, or just misplaced? As mentioned previously Freud postulated that agnosia is not due to a fault in how information is processed but rather an inability to access the correct data stored somewhere in the brain. Research seem to support this: When individuals with prosopagnosia were given a number of photos of faces and asked to say who they think they recognize their verbal answers were based on chance but in some cases their skins became sweatier; this was measured by means of electro dermal skin responses. (Tranel & Damasio, 1988 as cited in Banich & Compton, 2011, p185) We find more evidence deeper in the brain: The P300 is a specific brain wave that is associated not with the identification of a o se ed o je t ut ith a pe so s espo se to it. Ba i h & Co pto , the sa e ki d of e pe i e t o e p osopag osia patie t s P espo se , p.358) In as fou d to e larger to familiar faces than to unfamiliar faces. (Bobes et al., 2004 as cited in Banich & Compton, 2011, p.185) Both cases seem to indicate that at least on a subconscious level patients with prosopagnosia still recognize previously known faces. Your true love: Your wife or your car? The role of the FFA in facial recognition is widely accepted in theoretical circles, but some researchers wondered if other stimuli can activate this region and found through neuroimaging that this is true, but only for objects the observer is very familiar with. For 6 example in one such study individuals who were experts in two fields, namely cars and birds respectively, showed increased activity in the FFA region when shown images of their own area of expertise, be it cars or birds. Further research showed that activity in the FFA region increases as a person becomes more familiar with an object. In a study to investigate this theory research participants were trained to become experts at curious face-like objects alled g ee les. As expected, activity in the FFA increased gradually over time as the research participants became greeble experts. (Gauthier, Skudlarski, Gore, & Anderson, 2000 as cited in Banich & Compton, 2011, p.199) Does this mean that faces are not unique in inciting responses in the FFA? As social animals we humans are not only reliant on other humans, who we mostly identify by their faces, for physical survival but also for emotional one-ness. Why then is it that other non-human objects incite similar responses in this area thought to exclusively respond to faces? Theorists believe that it could be because of the face-like qualities of these objects. One just ha e to thi k of the a i ated fil Ca s to see ho effo tlessl the a i ato s managed to create individual personalities for the cars using the headlights, fenders and unique shapes to see that this can indeed be true. nose-like p ot usio s e pe ts all Both birds and greebles have eyes and o figu al st u tu e aki to fa es. As Duchaine (2000) implied it would appear that the FFA is essential for facial recognition but not necessarily only specialized for that. You stole my love’s face: The most devastating result of acquired prosopagnosia is when individuals are unable to recognize those who they love or even themselves. I a fi tio al o el alled The Echo Make ‘i ha d Po e s tells the sto of a a alled Ma k, ho afte a oad a cident, cannot recognize his friends or even his own face and who believes his only sister, who leaves her life to take care of him, is an imposter: "What are you doing here, anyway? Who sent you?" Her skin went metal. "Stop it, Mark," she said, harsher than intended. Sweet again, she teased, "You think you sister wouldn't look after you?" "My sister? You think you're my sister?" His eyes drilled her. "If you think you're my sister, there's something wrong with your head." From The Echo Maker ‘i ha d Powers (Powers, 2006, p. 59) 7 The sister called Karin, contacts a doctor who could have been inspired by our Dr Oliver Sacks to help. This doctor diagnosed Mark with prosopagnosia and an additional syndrome called Capgras Syndrome. Capgras syndrome is defined as the delusional belief that the sig ifi a t people i the i di idual s life a e i posto s o dou les. This moving fictional tale is the fearsome reality for a large number of individuals. Whereas individuals with prosopagnosia are unable to identify faces of people known to them, individuals with Capgras syndrome correctly identifies the face but believes that the person is a double or an imposter, and not the friend of family member who they know. People with prosopagnosia exhibit trauma to the fusiform area of the brain located in the occipitotemporal lobes of the brain. MRI scans show that individuals suffering from Capgras Syndrome also display trauma to the occipitotemporal regions of the brain on both sides. (Lewis, 1987) Mommy I can’t see your face: Traditionally, it was thought most cases of prosopagnosia are the results of trauma or degeneration, called acquired prosopagnosia. Cases where individuals were unable or had great difficulty to recognize faces all their lives, is known as developmental or congenital prosopagnosia. This condition can be the result of trauma in utero, in early childhood or genetics. Initially medical research thought developmental prosopagnosia to be rare but new research seems to indicate as many as 2.5% of the o ld s populatio a e affe ted, many of these individuals are on the autistic spectrum. (Prosopagnosia Research, n.d) Although people who suffer from prosopagnosia find social interaction very difficult, most learn to make use of alternative methods to help them identify individuals. (Duchaine & Nakayama, 2004) Facing the future To date no official treatment for prosopagnosia exists other than training affected individuals in the use of alternative modalities. However, an optician, Ian Jordan, claimed to have accidentally discovered a method that can help people affected by prosopagnosia: The method involves lenses made specifically for the affected individual which should be worn on a daily basis. This would apparently build up the injured or undeveloped area to eventually enable the person to see like everyone else. According to Jordan, looking at the 8 world with certain colours filtered out and other colours enhanced enables the brain to receive all the information it needs to correctly identify a face. (Cameron, 2011) Although the e a e i di iduals ho lai ed to ha e ee helped Jo da s le ses it is more than likely individuals with congenital prosopagnosia, seeing as research seem to indicate that acquired prosopagnosia may be related to difficulty in retrieving previously known information necessary for the identification of faces rather that the inability to e ei e the information. I hope that research into this and other methods will continue with great success, because I cannot imagine what it must be like to live in a world where loved ones wear the faces of strangers. Good- e, till e eet agai ! she said as heerfull as she ould. I should t k o ou agai if e did eet, Hu pt Du pt replied i a discontented tone, gi i g her o e of his fi gers to shake: ou re so e a tl like other people. The fa e is hat o e goes , ge erall , Ali e re arked i a thoughtful tone. That s just hat I o plai of, said Hu pt Du pt . Fo Through the Looking-glass and what Alice found there by Lewis Carroll (Carroll, 1897) References: Banich, M.T., & Compton, R.J. (2011). Cognitive Neuroscience (3rd, ed.). London: Wadsworth/Cengage learning. Ba to , J. J., P ess, D. )., Kee a , J. P., & O Co o , M. . Lesions of the fusiform face area impair perception of facial configuration in prosopagnosia. Neurology, 58(1), 71-78. Retrieved May 26, 2014 from http://www.neurology.org/content/58/1/71.full Cameron, K. (2011, June 17). Re: First ever treatment for face-blindness set to transform lives of thousands on autistic spectrum and beyond [Web log post]. Retrieved from http://kmcameron.wordpress.com/2011/06/17/first-ever-treatment-for-face-blindness-setto-transform-lives-of-thousands-on-autistic-spectrum-and-beyond/ Carroll, L. (1897) Through the Looking Glass (And What Alice Found There). Philadelphia: Henry Altemus. Duchaine, B. C. (2000). Developmental prosopagnosia with normal configural processing. Neuroreport, 11(1), 79-83. Retrieved May 31, 2014, from http://www.faceblind.org/social_perception/papers/duchaine00neuroreport.pdf 9 Duchaine, B. C., & Nakayama, K. (2004). Developmental prosopagnosia and the Benton Facial Recognition test. Neurology, 62(7), 1219-1220. Retrieved May 24, 2014 from https://www.neurology.org/content/62/7/1219.full Lewis, S. W. (1987). Brain imaging in a case of Capgras' syndrome. The British Journal of Psychiatry, 150(1), 117-121. Retrieved May 31, 2014 from http://bjp.rcpsych.org/content/150/1/117.full Powers, R. (2006). The Echo Maker. New York: Farrar, Straus & Giroux. P osopag osia ‘esea h Ce t es at Ha a d U i e sit a d U i e sit College Lo do – ‘esea h. .d.) Retrieved May 26, 2014, from https://www.faceblind.org/research/index.html 10