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Show Auditory-Olfactory Synesthesia Coexisting With Auditory-Visual Synesthesia Thomas E. Jackson, MRCOphth, Soupramanien Sandramouli, FRCOphth Abstract: Synesthesia is an unusual condition in which stimulation of one sensory modality causes an experience in another sensory modality or when a sensation in one sensory modality causes another sensation within the same modality. We describe a previously unreported association of auditory-olfactory synesthesia coexisting with auditory-visual synesthesia. Given that many types of synesthesias involve vision, it is important that the clinician provide these patients with the necessary information and support that is available. Journal of Neuro-Ophthalmology 2012;32:221-223 doi: 10.1097/WNO.0b013e31825d3c44 © 2012 by North American Neuro-Ophthalmology Society Synesthesia is a condition in which stimulation of one sensory modality causes an experience in another sen-sory modality or when a sensation in one sensory modality causes another sensation within the same modality. For example, in audiotory-visual synesthesia, sounds are heard, but they also elicit a visual response. A guitar may sound like dark green circles or a piano like brown corduroy. Synesthesia may be auditory-visual, visual-tactile, visual-gustatory, or almost any combination of 2 senses. Our case is unique in describing the coexistence of auditory-olfactory synesthesia with auditory-visual synesthesia. CASE REPORT A 30-year-old man was referred to the ophthalmology clinic with a history of "seeing sounds." From approximately 5 years, he experienced shapes and colors whenever he heard sounds. All sounds created images, some more distracting than others. These were rarely static and tended to move across his visual field before slowly fading. He had originally thought that this was a normal sensation but later realized that it was unique to him. Certain sounds were experienced as shapes in his vision. Voices created a collection of circles that rippled across the lower part of his vision and became stacked on top of each other when more than one voice was heard. Shouting caused the circles to be scattered across his whole field of vision and were more difficult to ignore. Clicking sounds such as a light switch or hard shoes on a floor were seen as a square, while treading on grass was a small triangle and treading on gravel or ripping paper was a larger triangle. Other sounds were seen as numbers: an untuned television, for example, was 1, 9, and 20; deep bass sounds were the number 400; and a washing machine was 1, 9, and 5. The patient was usually able to ignore the images, but there were times that he described "sensory overload" when they became overpowering. If he was in a room with a num-ber of children playing and shouting, he experienced so many images that his vision became cluttered and over-whelmed to the point that he needed to leave. Similarly, he found it too difficult to visit the local shopping center and described himself as a solitary individual who had al-ways been prone to spending long periods of time alone in his bedroom. He worked as a computer programmer but found it hard to concentrate because of the constant images created by background office noise; he coped by listening on headphones a repeating list of music tracks. Although the music continued to create images, these were predictable and interfered less with his work. He also drank large volumes of caffeinated drinks, which helped him remain focused on a particular task while blocking out other sensa-tions, but the caffeine frequently interrupted his regular sleep pattern. On further questioning, the patient reported that certain sounds elicited smells. He described the sound of a drill smelling like bleach, a vacuum cleaner like vomit, and Birmingham and Midland Eye Centre (T.E.J.), Birmingham, United Kingdom; and Wolverhampton Eye Infirmary (S.S.), Wolverhampton, United Kingdom. No funding was received for this work. The authors report no conflict of interest. Address correspondence to: Thomas E. Jackson, Birmingham and Midland Eye Centre, City Hospital, Dudley Road, Birmingham B17 8QH, United Kingdom; E-mail: drtomjackson@yahoo.co.uk Jackson and Sandramouli: J Neuro-Ophthalmol 2012; 32: 221-223 221 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. music like food. These smells could also be overpowering, and the strong smell of bleach had caused him to vomit on a number of occasions. The auditory-visual and auditory-olfactory sensations were unidirectional such that sights or smells did not stimulate other sensory modalities. He had mild asthma, was a nonsmoker, and denied any alcohol or drug use. On examination, the visual acuity was normal, and the ophthalmic examination was unremarkable. DISCUSSION The first known reference to synesthesia was in 1690 (1), and it was described in detail by Francis Galton in 1880 (2). Synesthesia was repeatedly dismissed as a fictitious condi-tion, and it is only recently that brain imaging techniques, including the use of functional magnetic resonance imaging (fMRI) (3,4) and positron emission tomography (PET) (5) have confirmed that it is a genuine condition. Synesthesia may occur between any 2 sensory modalities or within the same sensory modality, and at least 61 different combinations have been reported, many of which involve the visual system (Table 1) (6). This is the first reported case of auditory-visual synesthesia coexisting with auditory-olfactory synesthesia. The incidence of synesthesia has been reported as between 1% and 4% (7); however, it remains controversial with esti-mates of anywhere from 1 in 20 to 1 in 250,000 (8). Some forms of synesthesia are more prevalent than others; the most common is grapheme-color synesthesia, where graphemes (numbers, letters, or symbols) generate the sensation of a color, so the number 3 may cause the sensation of green or the letter "t" may cause the sensation of blue. The pairing of color to grapheme may vary between synesthetes but remains constant for each individual. Auditory-visual synesthesia is another common form of synesthesia. In some patients, such as in our case, any auditory stimulus triggers a visual perception, but there are also forms of auditory-visual synesthesia where the auditory stimulus is limited to voices or music (chords, keys, or individual notes). The composer Nikolai Rimsky-Korsakov, for example, experienced the key of C major as white and the key of B major as gloomy dark blue with a steel shine, while jazz-rock guitarist Tony DeCaprio experienced in-dividual notes as different colors (1). Synesthesia is usually unidirectional; however, there are cases in which it is bidirectional, for example, numbers give an experience of colors and colors also give an experience of numbers. The pairing is automatic and present since childhood. Brain imaging techniques in patients with both auditory-color and grapheme-color synesthesia involved small numbers of patients but showed changes in the visual association pathways and not in the primary visual cortex. fMRI found visual association areas V4 and V8 to be activated by a word or grapheme stimulus (3,4) while PET scans found the posterior inferior temporal gyrus and parieto-occipital junction to be activated (5). Beeli et al (9) used electrodiagnostic testing patients with auditory-color synesthesia and demonstrated ac-tivation of the color area V4 and the posterior inferior tem-poral during color perception elicited by auditory stimuli. While imaging techniques have illustrated abnormal brain activity, the neural basis remains unclear. It may be a problem of anatomy in which failure to prune early abundant connec-tions in the normal infant brain may result in extra connection between brain regions. Alternatively, it may be attributable to disinhibition of existing pathways that are normally masked in the adult brain (10). A further possibility is that there are multisensory brain regions that bind together different sensory stimuli to build a complete picture and that problems in this area may lead to synesthesia (11). It is interesting that most synesthetes prefer not to be cured of their condition and, in fact, synesthesia can be a help rather than a hindrance. Grapheme-color synesthetes are often better at remembering numbers, whereas other types of synesthesia are linked to musical and artistic ability with a number of famous people thought to have been synesthetes, including composer Franz Liszt, pianist Duke Ellington, and artist David Hockney (6). Synesthesia is a complex condition with no current treat-ment options. Our patient has spent a lifetime developing various coping strategies to manage his condition. He was not looking for a treatment, but what he really sought was a formal diagnosis to help him understand his condition and to allow him to explain it to others. Information and sup-port can help patients understand this condition, and there TABLE 1. Types of synesthesia involving vision Triggering Stimulus Resultant Experience Prevalence Among Synesthetes (%) Graphemes Color 64.4 Music Visual 27.7 General sounds Visual 15.3 Voice Visual 7.5 Personalities Visual 6.4 Flavors Visual 6.3 Smells Visual 6.3 Pain Visual 5.6 Touch Visual 3.8 Emotions Visual 2.9 Visual Flavors 2.9 Visual Auditory 2.6 Temperature Visual 2.2 Orgasm Visual 2.0 Visual Touch 1.8 Visual Smells 1.3 Visual Temperatures 0.2 Kinetics Visual 0.1 Visual Kinetics 0.1 Modified from Day (6). 222 Jackson and Sandramouli: J Neuro-Ophthalmol 2012; 32: 221-223 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. are a number of useful websites, including the American Synesthesia Association (http://www.synesthesia.info) and Synesthesia (http://www.daysyn.com). Many countries also have their own synesthesia associations that offer local sup-port and annual conferences. For clinicians, further infor-mation regarding this complex subject is available in a number of good review articles (1,12). Synesthesia is a condition that is rarely diagnosed by ophthalmologists because of its rare presentation. It is important that ophthalmologists recognize synesthesia to provide patients with necessary information and support that is available. REFERENCES 1. Pearce JMS. Synaesthesia. Eur Neurol. 2007;57:120-124. 2. Galton F. Visualised numerals. Nature. 1880;21:252-256. 3. Sperling JM, Prvulovic D, Linden DE, Singer W, Stirn A. Neuronal correlate of colour-graphemic synaesthesia: a fMRI study. Cortex. 2006;42:295-303. 4. Rich AN, Williams MA, Puce A, Syngeniotis A, Howard MA, McGlone F, Mattingley JB. Neural correlates of imagined and synaesthetic colours. Neuropsychologia. 2006;44: 2918-2925. 5. Paulesu E, Harrison J, Baron-Cohen S, Watson JD, Goldstein L, Heather J, Frackowiak RS, Frith CD. The physiology of coloured hearing. A PET activation study of colour-word synaesthesia. Brain. 1995;118:661-676. 6. Day S. Types of synesthesia. 2011. Available at: http://www. daysyn.com/Types-of-Syn.html. Accessed March 19, 2012. 7. Simner J, Mulvenna C, Sagiv N, Tsakanikos E, Witherby SA, Fraser C, Scott K, Ward J. Synaesthesia: The prevalence of atypical cross-modal experiences. Perception. 2006;35: 1024-1033. 8. Mulvenna C, Walsh V. Synaesthesia. Curr Biol 2005;15: 399-400. 9. Beeli G, Esslen M, Jancke L. time course of neural activity correlated with colored-hearing synesthesia. Cereb Cortex. 2008;18:379-385. 10. Simner J. Defining synaesthesia. Br J Psychol. 2012;103: 1-15. 11. Goller AI, Otten LJ, Ward J. Seeing sounds and hearing colors: an event-related potential study of auditory-visual synesthesia. J Cogn Neurosci. 2009;21:1869-1881. 12. Hubbard EM. Neurophysiology of synesthesia. Cur Psychiatry Rep. 2007;9:193-199. Jackson and Sandramouli: J Neuro-Ophthalmol 2012; 32: 221-223 223 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. |
