Synesthesia Outline Introduction (What is Synesthesia?) ∙ Definition of Synesthesia ∙ Synesthetic Perception ∙ Synesthetic Conception Theories of Synesthesia ∙ Original Discovery / Theory ∙ History of Synesthesia research Forms of Synesthesia ∙ Sound & Color ∙ Grapheme & Color ∙ Word & Gustatory ∙ Number Form Experiments & Research Data as a heightened ASC ∙ Neuroimaging (FMRI, PET) ∙ “Pop Out” effects ∙ Neurobasis of Synesthesia Further Discussion ∙ Temporary vs. Permanent? ∙ Innate vs. Learned?

- Neurologically-based phenomenon * leads to involuntary experiences * real information of one sense is accompanied by a perception in another sense

 Synesthetic perception: -induced by perceiving a stimulus  Synesthetic conception: - induced by conceiving

Sound Color Grapheme Color Word Gustatory Time period Color and shape *Perceptual vs conceptual *Combinations of these?!

Carol Carol is an artist. She has experienced synesthesia for as long as she can remember, perceiving colors in numbers, letters and when hearing certain sounds. Selected forms of touch like acupressure and acupuncture also lead to the perception of both colors and shapes. "With acupuncture, I experience color in layers" "Orange is my default color for pain" Karen Karen is a language researcher and project manager. Her synesthesia dates back to childhood and involves the perception of colors when viewing text or hearing spoken words. "Linguistics is a grayish-purple-blue word"

The “Pop Out” Effect Normal Control Perception

The “Pop Out” Effect Grapheme- Color Synesthetes Perception

Synesthetes tend to be: Women: in the U.S., studies show that three times as many women as men have synesthesia; in the U.K., eight times as many women have been reported to have it. Left-handed: synesthetes are more likely to be left-handed than the general population. Neurologically normal: synesthetes are of normal (or possibly above average) intelligence, and standard neurological exams are normal. In the same family: synesthesia appears to be inherited in some fashion; It seems to be a dominant trait and it may be on the X-chromosome.

 Involuntary  Projected  Durable and Generic  Memorable  Emotional

Biological Basis of Synesthesia  synesthesia results from "crossed-wiring" in the brain  some researchers believe that these crossed connections are present in everyone at birth, and only later are the connections refined  Cross activation at V4 seen

Biological Basis of Synesthesia Where in the Brain?? limbic system includes several brain structures primarily responsible for regulating our emotional responses. cerebral cortex studies have shown a particularly interesting effect in the cortex: colored-hearing synesthetes - display activity in several areas of the visual cortex when they hear certain words. In particular, areas of the visual cortex associated with processing color are activated when the synesthetes hear words. Non-synesthetes do not show activity in these areas, even when asked to imagine colors or to associate certain colors with certain words.

Biological Basis of Synesthesia

Experiments & Research Data as Heightened ASC Experiments & Research Data as Heightened ASC Diffusion Tensioner Imaging show the amount of connectivity is correlated to the intensity of Synesthesia. Rouw & Scholte show increased connectivity of the Fusiform Gyrus, Frontal Cortex, and Intraparietal Sulcus FMRI & PET show significant differences in V4 actiavtion between Synesthetes and Normal Control

Is Synesthesia Altered Consciousness? Different Levels of Synesthesia through Disinhibited Feedback to Higher Order Cortical Regions Synesthetes are very sensitive to external stimuli. Often creating creative art forms. Synesthetes have problems with math, writing, and left and right confusion. Important in understanding Synesthesia because it provides a window to consciousness.

Further Discussion: Temporary Synesthesia? LSD & Mescaline Can Induce Synesthesia Like Effects Psychedelic drugs can cause inhibition of feedback pathways causing an increase in excitation of V4

Innate vs Learned? Theories that Synesthesia is a product of colored alphabets and refrigerator magnets But substantial evidence it is innate not learned. However the environment can play an role in the type of Synesthesia SNP (single nucleotide polymorphisms) variations in genome can be a possible cause for family members with Synesthesia

The Potential For Synesthesia About 1 in 23 have Synesthesia. Slight tendency for women, but this could be a cultural difference due to women biased towards self reporting. Most likely a sex ratio of 1:1.1 (Male : Female)

Bobo and Kiki

We all might have Synesthesia Most would name the blob, Bobo, and the spiky object Kiki We all have the ability to understand and create metaphors. Suggests we all might the potential for Synesthesia

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Cytowic, R., Synesthesia: Phenomenology and Neuropsychology, A Review of Current Knowledge. Psyche: An interdisciplinary journal of research on consciousness. Synesthesia: Phenomenology And Neuropsychology Grossenbacher, P.G. & C.T. Lovelace (2001), "Mechanisms of synesthesia: cognitive and physiological constraints", Trends in Cognitive Sciences 5 (1): 36-41Synesthesia: Phenomenology And Neuropsychology Nunn, J.A., Gregory, L.J., Brammer, M., Williams, S.C.R., Parslow, D.M., Morgan, M.J., Morris, R.G., Bullmore, E.T., Baron-Cohen, S., and Gray, J.A. Functional magnetic resonance imaging of synesthesia: activation of V4/V8 by spoken words, Nature Neuroscience, 5: , Ramachandran, V.S. & E. M. Hubbard (2001), "Synaesthesia: A window into perception, thought and language", Journal of Consciousness Studies 8 (12): 3-34Synaesthesia: A window into perception, thought and language Simner, J.; C. Mulvenna & N. Sagiv et al. (2006), "Synaesthesia: The prevalence of atypical cross-modal experiences", Perception 8 (35): "Synesthesia." Wikipedia. 7 Mar "Neural Basis of Synesthesia." Wikipedia. 7 Mar