Current Research into Synaesthesia - Essay Example

? Current Research into Syn?sthesia of the of the Current Research into Syn?sthesia Introduction In the year 1812, Georg Tobias Ludwig Sachs described the condition of syn?sthesia. This area of knowledge has undergone a revival of interest in the recent decades. Such resurgence has provided a broad range of scientists with an engrossing area of study. However, syn?sthesia has been defined with conflicting presumptions. The scientists tend to depict this condition in a manner that admits of different approaches. These individuals have also adopted imperceptibly diverse methodologies towards the description of this condition and the necessary or sufficient characteristics for identifying it (Simner, 2012, p. 1). In the year 1690, John Locke recorded the account of a blind person, who described the colour scarlet as the sound made by a trumpet. This has generally been regarded as the first known reference to syn?sthesia. Such isolated case studies were recorded over the years for quite some time (Mulvenna & Walsh, 2005, p. R399). In the year 1883, Francis Galton provided a detailed description of syn?sthesia (Harrison, 2001, p. 28). Thereafter, syn?sthesia was regarded as a phantom condition and ignored. However, in the recent past, syn?sthesia obtained credibility among the scientific community. This was principally due to the application of brain imaging techniques. As a result, syn?sthesia has been deemed to be an authentic neurological condition (Mulvenna & Walsh, 2005, p. R399). However, it was in the 1890s that the word syn?sthesia emerged. However, this condition was known to the medical community, even in the distant past. This condition had not been codified until the end of the 19th century. The reason for this reluctance and delay was that syn?sthesia was contrary to the classification of the five senses, by Aristotle, in De anima (Greenberg , 2009, p. 363)Any description of syn?sthesia depends upon a class of central facts; namely that a small proportion of the population reports extraordinary sensations with regard to sensory sensations, like taste, shape and smell. These sensations arise from run-of-the-mill activities, such as eating, listening to music and reading. Syn?sthetes could envision colours upon hearing sounds, which has been termed as music colour syn?sthesia; or experience tastes in the mouth, while reading or speaking, which has been designated as lexical gustatory syn?sthesia (Rich, 2006, p. 444). In addition, the sensations experienced by syn?sthetes tend to be explicit, in as much as these individuals experience them consciously in their day to day life. Moreover, syn?sthetic sensations occur in addition to the usual modality specific perceptions. As such, there is no supplanting of the latter sensations by the syn?sthetic sensations. Thus, when a syn?sthete perceives colours upon being exposed to musical sounds, such perception is in addition to the normal auditory sensations that arise in the average individual (Simner, 2012, p. 2). Description of Synaesthesia Some scholars have provided a working definition of syn?sthesia as being a neurological hyper association that has as its objective greater inclusivity of its variants. This definition has been criticised, by some scholars, as being excessively inclusive. An instance of such over inclusiveness has been cited with regard to the assertion that syn?sthesia tends to be characterised by the conjoining of a specific triggering stimulus with a particular resultant experience. Such definition includes a wide range of processes that cannot be classified as syn?sthesia (Kadosh & Terhune, 2012, p. 22). In addition, some researchers have criticised the commonly held assumptions regarding syn?sthesia. For instance, the following presumption has been subjected to criticism. It states that syn?sthesia is a rare condition, wherein a stimulus producers an extra perceptual quality that is not usually correlated to that stimulus. This condition comes to the fore during the early stages of development and remains in force throughout the lifetime of the affected individual (Jewanski, Day, & Ward, 2009, p. 293). Such assumptions suggest the presence of a genetic component. Moreover, there are several different types of syn?sthesia, and different variants of this condition can be seen to occur within the same person and family. Studies based upon functional imaging have disclosed that syn?sthetes exhibit a different physiological response to stimuli that induces syn?sthesia. In fact, structural cerebral imaging reveals disparities in the organisation of white matter (Jewanski, Day, & Ward, 2009, p. 294). Prevalence of Syn?sthesia One of the contemporary studies related to the prevalence of this condition, has shown that around 4% of the adult population were affected by syn?sthesia that entailed one of the five classical senses. This condition tends to be concealed to a major extent. The conjectured genetic contribution to this disease and its high degree of prevalence indicates its antiquity (Jewanski, Day, & Ward, 2009, p. 294). Furthermore, syn?sthetes are described as depicting functional and structural differences in the cortical regions, when they experience colours at the time of perceiving numbers. These cortical regions pertain to the areas that undertake colour and number processing. Some researchers employed transcranial direct current stimulation or transcranial magnetic stimulation to demonstrate that grapheme colour syn?sthesia was characterised in humans by the presence of increased excitability of the cortex in the primary visual cortex. They also established that such cortical excitability could be attenuated or augmented by anodal or cathodal stimulation, respectively (Flight, 2012, p. 2). Consequently, syn?sthesia assumes weak and strong forms. Such strong and weak forms differ in prevalence and phenomenology. Furthermore, it has been conjectured by some researchers that these strong and weak forms of syn?sthesia could even differ in the mechanisms that were at the basis of their expression. Strong syn?sthesia has been observed to express itself in perceptual experience. On the other hand, weak syn?sthesia has been seen to be clearly present in cross modal metaphorical language and in cross model matching and selective attention (Martino & Marks, 2001, p. 65). The employment of positron – emission tomography (PET) and functional magnetic resonance imaging (fMRI) has confirmed the presence of sensory cross activation in the brain of syn?sthetes. Upon subjecting syn?sthetes, who had been blindfolded, to words that induced visual experiences; it was perceived that there was an activation of the regions of the brain that were associated with visual perception (Kay & Mulvenna, 2006, p. 209). Moreover, it was established that these cerebral activations were totally unlike the activations observed among non – syn?sthetes or the very same syn?sthetes who had been exposed to sounds that did not arouse visual experiences (Mulvenna & Walsh, 2005, p. R399). Furthermore, it was discerned that there was an activation of the cerebral areas that were intimately related to the perception of colours, among a group of word – colour syn?sthetes. Such activation was absent among the non – syn?sthetes, despite their being imparted with training to correlate pairings of words with colours. Several studies were subsequently undertaken to evaluate the presence of this neurological trend in the subsidiary varieties involving other senses (Mulvenna & Walsh, 2005, p. R399). It has been proposed that syn?sthesia results from reduced apoptosis, which promotes differentiation of the brain’s sensory regions during the first months after birth. This conjecture discounts the contention that syn?sthesia results from the growth of additional connections between the sensory areas. Such increased sensory connectivity or a few of the experiences between some of the senses in infancy could persist in the brain. If this conjecture were to be true, then every individual would have been a syn?sthete at some stage of development (Mulvenna & Walsh, 2005, p. R399). Different Forms of Synaesthesia As such, the various forms of syn?sthesia differ between the configuration of joint senses, types of sensations and people. However, certain general traits have been noticed with this condition. These general characteristics have been identified on the basis of the literature on syn?sthesia and the reports regarding individuals with this condition (Rogowska , 2011, p. 213). The first of these is that syn?sthetic sensations arise in response to a stimulus and these are voluntary. The syn?sthetic individual does not exercise any influence upon the experienced sensations. However, concentration of attention on the stimulus can substantially alter the consciousness and strength of associations (Rogowska , 2011, p. 213). Another trait is that a solitary stimulus produces the simultaneous perception of several sensory modalities. For instance, music played on a Hammond organ could evoke simultaneous sensations of an auditory, olfactory and ocular nature. There is a considerable body of research that affirms the spontaneous manifestation of syn?sthesia and its perceptual lineament (Rogowska , 2011, p. 213). A high degree of constancy is displayed by syn?sthesia, when perceived from the level of the individual. There is a persistent correlation with the perception of the individual that does not undergo change. Moreover, specific stimuli induce identical sensations. Thus a person who visualises the colour yellow, upon hearing the key of E – major, will continue to do so, on a permanent basis (Rogowska , 2011, p. 213). As such, syn?sthesia varies on an individual basis, with each syn?sthete depicting a distinctive arrangement of senses. As a consequence, no two persons portray the same sensual associations with regard to the same group of stimuli. Such disparity has been seen to extend to even identical twins (Rogowska , 2011, p. 213). The sensory life of people tends to vary, with some individuals having a more complicated sensory life than the others. For instance, some people associate the colour red with the letter “S” or make some other inappropriate association between stimulus and response. This condition is termed syn?sthesia, and it continues to tantalise brain scientists (The Economist, 2007, p. 103). Progress in Research of Syn?sthesia Some progress was achieved, with the development of the diffusion – tensor imaging. This test was applied to 18 women with the most common form of syn?sthesia. It has been termed as grapheme – colour syn?sthesia and it produces the tendency to perceive numbers and letters in colour. This test succeeds the PET and fMRI techniques (Cavallaro, 2013, p. 20). Syn?sthesia constitutes a perplexing commingling of the cerebral circuits. Individuals with such unusual brain circuitry tend to experience this condition. In one study, an individual was examined, who perceived a different colour upon seeing different numbers. Another female was observed to experience a different colour for each musical note (Cookson, 2011). Yet another lady experienced a vivid emotion upon touching a specific texture. In the past, this condition had been regarded as being comparatively rare. However, several distinguished neuroscientists, notably Ramchandran, have shown that the prevalence of syn?sthesia is not all that uncommon (Cookson, 2011). The initial research works on the memorisation of natural sounds had shown that sounds were committed to memory as an amalgamated structure that embraced several prominent acoustical elements and meaningful labels. Such thought had been derived from the theory of dual coding for images, which stated that images were coded as images and verbal labels (Polotti & Lemaitre, 2013, p. 72). Contemporary research in the area of cognitive neuroscience has illustrated that sound identification depends on more features than just linguistic mediation. From the related research it can be surmised that auditory stimuli evoke sensory traces, and amodal and semantic representation in memory that incorporates a vast array of associated concepts (Polotti & Lemaitre, 2013, p. 72). In the realm of musical melodies, it has been shown that melodies with a clear structure are better memorised by listeners. Other researchers have discerned that there was a better memorisation of the association between labels and sounds, whenever there was a direct semantic relationship between the sounds and the labels (Polotti & Lemaitre, 2013, p. 72). Conclusion Syn?sthesia constitutes a comparatively infrequent neurological condition. It is characterised by the production of an unrelated perceptual experience or conceptual association, by a stimulus. Such supplementary experiences tend to be of a sensory nature and can transpire across sensory modalities. It is essentially a phenomenon, wherein the stimulation of a sense can bring about the activation of other senses. Persons with this condition tend to view their surroundings somewhat differently than the other individuals. It is now well established that this condition is the outcome of heightened neural connections and not the consequence of hallucination or imagination. References Cavallaro, D. (2013). Synesthesia and the Arts. Jefferson, North Carolina, USA: McFarland . Cookson, C. (2011, January 14). Mind games. Retrieved November 15, 2013, from The Financial Times Ltd: http://www.ft.com/cms/s/2/2275273a-1f56-11e0-8c1c-00144feab49a.html Flight, M. H. (2012). 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