Neural Basis of Individual Differences in Synesthetic Experiences

@article{Rouw2010NeuralBO,
  title={Neural Basis of Individual Differences in Synesthetic Experiences},
  author={Romke Rouw and H. Steven Scholte},
  journal={The Journal of Neuroscience},
  year={2010},
  volume={30},
  pages={6205 - 6213}
}
  • R. Rouw, H. Scholte
  • Published 5 May 2010
  • Psychology, Medicine
  • The Journal of Neuroscience
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… 
Grapheme-color synesthesia subtypes: Stable individual differences reflected in posterior alpha-band oscillations
Grapheme-color synesthesia is a condition in which seeing letters and numbers produces sensations of colors (e.g., the letter R may elicit a sky-blue percept). Recent evidence implicates posterior
The neural bases of grapheme-color synesthesia are not localized in real color-sensitive areas.
TLDR
It is found that color areas and retinotopic areas were not activated by synesthetic colors, whatever the strength of synesthetic associations measured objectively for each subject, and that the key to synesthetic color experience might not lie in the color system.
Behavioral and brain mechanisms of grapheme-color synesthesia and their relationships with perceptual binding and visual imagery
Synesthesia is an unusual blending of the senses that occurs in about four percent or more of the human population. Much effort has been devoted to establishing criteria to define what synesthesia is
Neuroanatomical basis of number synaesthesias: A voxel-based morphometry study
TLDR
Results reveal neuroanatomical differences between synaesthetes and controls, and show the impact of the type of inducer in the synaesthetic brain, in line with current neurobiological models of synaesthesia.
Intrinsic Network Connectivity Reflects Consistency of Synesthetic Experiences
TLDR
These findings constitute the first direct evidence of increased functional network connectivity in synesthesia, and strongly suggest that altered differences in intrinsic network connectivity are directly related to the phenomenology of human experiences.
Neural Networks of Colored Sequence Synesthesia
TLDR
It is suggested 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 graphe me stimulation, which suggests that synesthesia is better characterized by studying global network dynamics than by individual properties of a single brain region.
Effective Connectivity Determines the Nature of Subjective Experience in Grapheme-Color Synesthesia
Synesthesia provides an elegant model to investigate neural mechanisms underlying individual differences in subjective experience in humans. In grapheme–color synesthesia, written letters induce
Brain areas involved in synaesthesia: a review.
TLDR
This contribution sheds light on the role of particular brain regions in synaesthetic experiences and proposes that these regions are related to three different cognitive processes inherently part of synaesthesia; the sensory processes, the (attentional) 'binding' processes, and cognitive control processes.
Assessing Lateral Interaction in the Synesthetic Visual Brain
TLDR
It is concluded that the occipital activity related to lateral interactions in synesthetes does not substantially differ from that observed in controls, and a significant correlation was found between long-range lateral interactions and the type of synesthesia experience (projector versus associator).
'Special cases': neural mechanisms and individual differences in synaesthesia.
  • R. Rouw
  • Psychology, Medicine
    Journal of neuropsychology
  • 2011
TLDR
The unusual experiences of synaesthetes provide an extraordinary opportunity to address some of the most hotly debated questions in the field of neuroscience, including what are the mechanisms behind cross-modal sensory integration, how can a conscious sensory experiences arise in the absence of the appropriate external stimulus, and what is the neural basis of perceptual awareness.
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 81 REFERENCES
The multiple synaesthete E.S. — Neuroanatomical basis of interval-taste and tone-colour synaesthesia
TLDR
Increased FA and volumetric white and grey matter peculiarities in E.S.'s auditory and gustatory areas are reported, hence explaining the interval-taste synaesthesia and might have implications for the understanding of multimodal integration.
Neurophysiology of synesthesia
  • E. Hubbard
  • Psychology, Medicine
    Current psychiatry reports
  • 2007
TLDR
Recent research examining the neural basis of the two most intensively studied forms of synesthesia suggest that these forms ofsynesthesia are elicited through anomalous activation of color-selective areas, perhaps in concert with hyper-binding mediated by the parietal cortex.
A systematic, large-scale study of synaesthesia: implications for the role of early experience in lexical-colour associations
TLDR
It is suggested that the development of lexical-colour synaesthesia in many cases incorporates early learning experiences common to all individuals, and that the learning of such sequences during an early critical period determines the particular pattern of lexicals-colour links and that this pattern then generalises to other words.
Neurophysiological aspects of synesthetic experience.
TLDR
The authors studied possible electrophysiological correlates of synesthetic experience in 17 subjects claiming to continuously experience chromatic-graphemical synesthesia and a matched control group and found Synesthetic subjects had significantly and clearly more positive waveform over frontal and prefrontal scalp regions than control subjects for target and nontarget stimuli.
The physiology of coloured hearing. A PET activation study of colour-word synaesthesia.
TLDR
The results suggest that colour-word synaesthesia may result from the activity of brain areas concerned with language and visual feature integration, as conscious visual experience appears to occur without activation of the primary visual cortex.
Time course of neural activity correlated with colored-hearing synesthesia.
TLDR
The findings replicate and extend earlier reports with functional magnetic resonance imaging and positron emission tomography in colored-hearing synesthesia and contribute new information on the time course in synesthesia demonstrating the fast and possibly automatic processing of this unusual and remarkable phenomenon.
Evidence Against Functionalism from Neuroimaging of the Alien Colour Effect in Synaesthesia
TLDR
It is reported that, in functional magnetic resonance imaging of the Stroop task, hippocampal activation differentiates synaesthetes with the ACE from those without it and from non-synaesthete controls, confirming the reality of coloured hearing synaesthesia and the ACE.
Synaesthesia and cortical connectivity
TLDR
It is argued for structural differences in the brains of synaesthetes, which might be more widespread than expected, and how synaesthesia could be an informative model to investigate how patterns of connectivity between cortical areas are established.
Functional magnetic resonance imaging of synesthesia: activation of V4/V8 by spoken words
TLDR
Using functional magnetic resonance imaging (fMRI), this work locates the region activated by speech in synesthetes to area V4/V8 in the left hemisphere, and demonstrates overlap with V3/V4 activation in normal controls in response to color.
Synaesthesia: The Prevalence of Atypical Cross-Modal Experiences
TLDR
The first test of synaesthesia prevalence with sampling that does not rely on self-referral, and which uses objective tests to establish genuineness is presented, and it is suggested that female biases reported earlier likely arose from (or were exaggerated by) sex differences in self-disclosure.
...
1
2
3
4
5
...