My high school once brought a band to play at an assembly
that had a particularly unique approach to how they played their music. They described that they did not have
particular songs they had learned, but instead would pick shapes and colors and
play whatever came to their mind. They
went on to then play for us a blue circle.
Needless to say, everyone thought they were crazy!
The more I learn about synesthesia however, the more I
wonder if these musicians might have had this condition. Synesthesia is a phenomenon in which an
individual has cross-sensory activation by particular stimuli. For example, the most common manifestation is
that letters and numbers are linked with colors (grapheme – color), such that a sentence might look like this, when
it is really black text on a white background.
Another common manifestation is music inducing colors. How terrible would it be to have mirror-pain
synesthesia, where watching another person get hurt will actually illicit pain
in the observer? Mirror-touch on the
other hand might not be so bad…
The traditional interpretation of this condition is that it
is due to structural connectivity, for example, neurons that recognize letters
are connected to and innervating neurons that interpret colors. Recent research however challenges this
view. Wasowicz
and Werning have been able to show
that individuals with color-motor synesthesia can evoke color activation just
by thinking about swimming motions (2012).
These findings further complicate synesthesia since imagining motor
activation is sufficient enough to stimulate color perception.
In a recent case study, an individual has been found who has
had synesthesia induced following head trauma (Brogard
et al. 2012). This individual sees
moving or rounded objects as having additional complex geometrical structures.
For example, he drew what he saw when presented with a wheel
and a balloon (left). Remarkably, when
presented with the same stimuli 3 months later, he saw nearly the same
thing. Additionally, after taking a high
level math class, mathematical formula’s evoke complex shapes as well.
This is what he sees when presented with 29
(left) and hf = mc2 (right).
fMRI analysis revealed increases in both regions activated
and intensity of activations with image-inducing formulas (left) compared to
non image-inducing formulas (right). The
authors of this paper support a previous studies conclusion, that synesthesia
might exist in everyone, but it takes a disruption in brain function to be
consciously aware of it!
References
Brogaard, B., Vannie, S., Silvanto, J. Seeing mathematics: Perceptual experience and brain activity in acquired synesthesia. Neurocase: The Neural Basis of Cognition, 1-10, 2012.
Mroczko-Wasowicz, A., Werning, M. Synesthesia, sensory-motor contingency, and semantic emulation: how swimming style-color synesthesia challenges the traditional view of synesthesia. Frontiers in Psychology, 3, 279, 1-12, 2012.
References
Brogaard, B., Vannie, S., Silvanto, J. Seeing mathematics: Perceptual experience and brain activity in acquired synesthesia. Neurocase: The Neural Basis of Cognition, 1-10, 2012.
Mroczko-Wasowicz, A., Werning, M. Synesthesia, sensory-motor contingency, and semantic emulation: how swimming style-color synesthesia challenges the traditional view of synesthesia. Frontiers in Psychology, 3, 279, 1-12, 2012.
So the suggestion is that damage or disruption produces this gain of function? If we assume this to be true I see how this contributes to other synesthesia instances like drug induced synesthesia. I just can't think of instances of a disruption creating new functional tracts. Does not disruption typically result in a loss of function (blindness), or changed function (personality alteration)?
ReplyDeleteThe only explanation I can think of is that if these synesthetic pathways already exist, then damage must be removing the inhibitory neurons that prevent this interaction. Thus allowing it to proceed. I read an article recently that referred to a statistical/mathematical model that can predict visual pathways and mapping in individuals. I wonder if this model could also predict the unseen synesthetic pathways that they are suggesting exist. www.sciencedaily.com/releases/2012/10/121004121556.htm/
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ReplyDeleteAfter looking into synesthesia a bit more, I saw that it is commonly known that more women demonstrate synesthesia than men, though why is not known (http://webpub.allegheny.edu/employee/a/adale/p108/Synesthesia%20Phenomenology%20And%20Neuropsychology.htm).
ReplyDeleteI did see an abstract (no article readily available) that linked a man with Aspergers who sees colored halos around faces which allows him to see emotion in others through these colored halos (http://www.ncbi.nlm.nih.gov/pubmed/22115465).
Extrapolating widely from my Psychology & Gender undergrad course, perhaps because females tend to exhibit more emotion than men (more connected to emotion - related to oxytocin that Kaylee posted about), females may be more apt to also exhibit synesthesia - so the possibility that it takes brain disruption to be consciously aware of it may be true - and maybe it might take a bit more conscious activation for emotion.
The first thing that comes to mind when I read this was intense pain inducing someone to see different shapes and colors and hear sounds. Watching the movie 27 hours, when Aron hits a nerve as he is cutting off his arm, the sound artist played a sound that was strikingly familiar to me. I don't know when I experienced it, but I remember having a sever acute pain and hearing almost the same sound. I wonder if this is an acute induction of synesthesia. Also, synesthesia can be inherited, so it was of interest to me as to if there was a selective pressure keeping the gene around. This led me to an article (Survival of the Synesthesia Gene: Why Do People Hear Colors and Taste Words?) that looked into this. They concluded more genetic knowledge was needed. But they also did ask an interesting question about synesthesia and if it is a phylogenetically old trait, if it is conserved in animals. The cited a study that induced a synesthesia like response in mice by mutating the α2δ3 gene showing "reduced pain sensitivity due to the failure of transmission from the thalamus to the cortex, yet pain instead causes activation of visual and auditory regions similar to the cross-activation seen in synesthesia. It remains to be seen whether this gene is related to synesthesia in humans, but it provides an interesting candidate for research."
ReplyDeleteBrang D, Ramachandran VS. 2011.Survival of the Synesthesia Gene: Why Do People Hear Colors and Taste Words?. PLOS Biology. November 2011