Familial patterns and the origins of individual differences in synaesthesia

Barnett, Kylie J.; Finucane, Ciara; Asher, Julian E.; Bargary, Gary; Corvin, Aiden; Newell, Fiona N.; Mitchell, Kevin J.

doi:10.1016/j.cognition.2007.05.003

Cited by 142 publications

(187 citation statements)

References 50 publications

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“…The innate predisposition to develop synesthesia (Asher et al, 2009) is general rather than to a particular kind of synesthesia (Barnett et al, 2008). Indeed, specific synesthetic associations must develop as an interaction between innate ( Baron-Cohen et al, 1996;Rich et al, 2005;Ward and Simner, 2005) and environmental Witthoft and Winawer, 2006;Beeli et al, 2007) factors.…”

Section: What Underlies the Development Of Synesthesia?mentioning

confidence: 99%

Neural Basis of Individual Differences in Synesthetic Experiences

Rouw¹,

Scholte²

2010

J. Neurosci.

129

146

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Little is known about how the properties of our private mental world relate to the physical and functional properties of our brain. Studying synesthesia, where a particular experience evokes a separate additional sensory experience, offers the unique opportunity to study phenomenological experiences as a stable trait in healthy subjects. A common form of synesthesia is grapheme-color synesthesia, where a particular letter or number evokes a particular color experience. We studied the neural basis of qualitative different properties of the synesthetic experience by using individual differences in grapheme-color synesthesia. Specifically, the synesthetic color can be experienced "in the mind" (associator synesthetes) or "in the outside world" (projector synesthetes). Gray matter structure and functioning (imaged using voxel-based morphometry and functional magnetic resonance imaging, respectively) were examined in grapheme-color synesthetes (N ϭ 42, 16 projectors and 26 associators) and nonsynesthetes. Results indicated partly shared mechanisms for all grapheme-color synesthetes, particularly in posterior superior parietal lobe, which is involved in the integration of sensory information. In addition, the nature of synesthetic experience was found to be mediated by distinct neural mechanisms. The outside-world experience is related to brain areas involved in perceiving and acting in the outside world (visual cortex, auditory cortex, motor cortex) as well as frontal brain areas. In contrast, the in-the-mind experience is related to the hippocampus and parahippocampal gyrus, known for their role in memory. Thus, the different subjective experiences are related to distinct neural mechanisms. Moreover, the properties of subjective experiences are in accordance with functional properties of the mediating brain mechanisms.

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Section: What Underlies the Development Of Synesthesia?mentioning

confidence: 99%

Neural Basis of Individual Differences in Synesthetic Experiences

Rouw¹,

Scholte²

2010

J. Neurosci.

129

146

View full text Add to dashboard Cite

show abstract

“…In congenital synaesthetes, for example, a particular number or auditory tone may automatically elicit a specific colour experience. Accumulating evidence from familial studies suggests that synaesthesia is hereditary (Barnett et al, 2008;Baron-Cohen, Burt, Smith-Laittan, Harrison, & Bolton, 1996) and there is preliminary research pointing to possible genetic polymorphisms underlying this condition (Asher et al, 2009;Tomson et al, 2011). In contrast, the available evidence suggests that the particular inducerconcurrent pairings that one experiences may be driven by environmental constraints (Witthoft & Winawer, 2013).…”

Section: Introductionmentioning

confidence: 99%

A placebo-controlled investigation of synaesthesia-like experiences under LSD

et al. 2016

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The induction of synaesthesia in non-synaesthetes has the potential to illuminate the mechanisms that contribute to the development of this condition and the shaping of its phenomenology. Previous research suggests that lysergic acid diethylamide (LSD) reliably induces synaesthesia-like experiences in nonsynaesthetes. However, these studies suffer from a number of methodological limitations including lack of a placebo control and the absence of rigorous measures used to test established criteria for genuine synaesthesia. Here we report a pilot study that aimed to circumvent these limitations. We conducted a within-groups placebo-controlled investigation of the impact of LSD on colour experiences in response to standardized graphemes and sounds and the consistency and specificity of grapheme-and sound-colour associations. Participants reported more spontaneous synaesthesia-like experiences under LSD, relative to placebo, but did not differ across conditions in colour experiences in response to inducers, consistency of stimulus-colour associations, or in inducer specificity. Further analyses suggest that individual differences in a number of these effects were associated with the propensity to experience states of absorption in one's daily life. Although preliminary, the present study suggests that LSD-induced synaesthesia-like experiences do not exhibit consistency or inducer-specificity and thus do not meet two widely established criteria for genuine synaesthesia.

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“…There are many synesthetic associations, ranging from taste-touch (Cytowic, 2002) to sound-color (Baron-Cohen, 1996) to grapheme-color (Weiss et al, 2005;Dixon et al, 2006). The prevalence of synesthesia is estimated between 1 and 4% of the population (Simner et al, 2006;Barnett et al, 2008), depending on which form is examined, and some forms co-occur more commonly than others. To determine how likely forms of synesthesia are to co-occur, we previously performed a factor analysis on 12,234 verified synesthetes phenotyped through the Synesthesia Battery and found that synesthesia forms cluster into five main groups (Novich et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Neural Networks of Colored Sequence Synesthesia

Tomson¹,

Narayan

Allen

et al. 2013

Journal of Neuroscience

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Synesthesia is a condition in which normal stimuli can trigger anomalous associations. In this study, we exploit synesthesia to understand how the synesthetic experience can be explained by subtle changes in network properties. Of the many forms of synesthesia, we focus on colored sequence synesthesia, a form in which colors are associated with overlearned sequences, such as numbers and letters (graphemes). Previous studies have characterized synesthesia using resting-state connectivity or stimulus-driven analyses, but it remains unclear how network properties change as synesthetes move from one condition to another. To address this gap, we used functional MRI in humans to identify grapheme-specific brain regions, thereby constructing a functional "synesthetic" network. We then explored functional connectivity of color and grapheme regions during a synesthesia-inducing fMRI paradigm involving rest, auditory grapheme stimulation, and audiovisual grapheme stimulation. Using Markov networks to represent direct relationships between regions, we found that synesthetes had more connections during rest and auditory conditions. We then expanded the network space to include 90 anatomical regions, revealing that synesthetes tightly cluster in visual regions, whereas controls cluster in parietal and frontal regions. Together, these results suggest that synesthetes have increased connectivity between grapheme and color regions, and that synesthetes use visual regions to a greater extent than controls when presented with dynamic grapheme stimulation. These data suggest that synesthesia is better characterized by studying global network dynamics than by individual properties of a single brain region.

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Familial patterns and the origins of individual differences in synaesthesia

Cited by 142 publications

References 50 publications

Neural Basis of Individual Differences in Synesthetic Experiences

Neural Basis of Individual Differences in Synesthetic Experiences

A placebo-controlled investigation of synaesthesia-like experiences under LSD

Neural Networks of Colored Sequence Synesthesia

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