Inside a synesthete's head: A functional connectivity analysis with grapheme-color synesthetes

Sinke, Christopher; Neufeld, Janina; Emrich, Hinderk M.; Dillo, Wolfgang; Bleich, Stefan; Zedler, Markus; Szycik, Gregor R.

doi:10.1016/j.neuropsychologia.2012.09.015

Cited by 28 publications

(44 citation statements)

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“…However, it has yet to be determined whether synesthesia-like experiences in drug-induced altered states of consciousness are qualitatively and mechanistically related to synesthesia experienced outside of this context and it is also worth noting that increased visual to heteromodal cortical functional connectivity has been found in color-grapheme synesthesia (Dovern et al, 2012; Sinke et al, 2012) as well as in the present study.…”

Section: Discussionmentioning

confidence: 61%

The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers

Roseman

Leech

Feilding

et al. 2014

Front. Hum. Neurosci.

198

159

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Perturbing a system and observing the consequences is a classic scientific strategy for understanding a phenomenon. Psychedelic drugs perturb consciousness in a marked and novel way and thus are powerful tools for studying its mechanisms. In the present analysis, we measured changes in resting-state functional connectivity (RSFC) between a standard template of different independent components analysis (ICA)-derived resting state networks (RSNs) under the influence of two different psychoactive drugs, the stimulant/psychedelic hybrid, MDMA, and the classic psychedelic, psilocybin. Both were given in placebo-controlled designs and produced marked subjective effects, although reports of more profound changes in consciousness were given after psilocybin. Between-network RSFC was generally increased under psilocybin, implying that networks become less differentiated from each other in the psychedelic state. Decreased RSFC between visual and sensorimotor RSNs was also observed. MDMA had a notably less marked effect on between-network RSFC, implying that the extensive changes observed under psilocybin may be exclusive to classic psychedelic drugs and related to their especially profound effects on consciousness. The novel analytical approach applied here may be applied to other altered states of consciousness to improve our characterization of different conscious states and ultimately advance our understanding of the brain mechanisms underlying them.

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Section: Discussionmentioning

confidence: 61%

The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers

Roseman

Leech

Feilding

et al. 2014

Front. Hum. Neurosci.

198

159

View full text Add to dashboard Cite

show abstract

“…An alternative theory to dual coding and/or color expertise posits that the superior performance of synesthetes in declarative memory tasks stems from differences in their brain function or structure, e.g., increased white matter connectivity (Rouw and Scholte, 2007; Whitaker et al, 2014), or functional connectivity (Dovern et al, 2012). Functional brain differences between synesthetes and controls during perceptual processing of non-synesthesia-inducing shapes have been examined with EEG (Barnett et al, 2008) and fMRI (Sinke et al, 2012). Both studies found these processing differences to occur as early as in cortical area V1.…”

Section: Introductionmentioning

confidence: 99%

Associative memory advantage in grapheme-color synesthetes compared to older, but not young adults

et al. 2014

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People with grapheme-color synesthesia perceive enriched experiences of colors in response to graphemes (letters, digits). In this study, we examined whether these synesthetes show a generic associative memory advantage for stimuli that do not elicit a synesthetic color. We used a novel between group design (14 young synesthetes, 14 young, and 14 older adults) with a self-paced visual associative learning paradigm and subsequent retrieval (immediate and delayed). Non-synesthesia inducing, achromatic fractal pair-associates were manipulated in visual similarity (high and low) and corresponded to high and low memory load conditions. The main finding was a learning and retrieval advantage of synesthetes relative to older, but not to younger, adults. Furthermore, the significance testing was supported with effect size measures and power calculations. Differences between synesthetes and older adults were found during dissimilar pair (high memory load) learning and retrieval at immediate and delayed stages. Moreover, we found a medium size difference between synesthetes and young adults for similar pair (low memory load) learning. Differences between young and older adults were also observed during associative learning and retrieval, but were of medium effect size coupled with low power. The results show a subtle associative memory advantage in synesthetes for non-synesthesia inducing stimuli, which can be detected against older adults. They also indicate that perceptual mechanisms (enhanced in synesthesia, declining as part of the aging process) can translate into a generic associative memory advantage, and may contribute to associative deficits accompanying healthy aging.

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“…This region receives mainly multimodal input (Bremmer et al, 2001) and shows structural differences in synesthetes ). It also shows activation differences in grapheme-color Sinke et al, 2012a) and in auditory-visual synesthetes . Furthermore inhibitory transcranial magnetic stimulation (TMS) of the IPC disrupts the synesthetic Stroop effect , which is usually observed in grapheme-color synesthetes .…”

Section: Introductionmentioning

confidence: 91%

“…Following the idea that attention already has particular impact on early stages of sensory processing in synesthesia, involvement of attention-related parietal cortex in perception could be expected. In fact, evidence for the parietal cortices key role in synesthetic perception comes from several neuroimaging studies with groups of grapheme-color synesthetes Van Leeuwen et al, 2010;Sinke et al, 2012a), spatial sequence synesthetes and auditory-visual synesthetes . Importantly, connectivity analyses identified an area in the parietal cortex which showed stronger connections with primary sensory areas in synesthetes Sinke et al, 2012a).…”

Section: Reaction Time M(sd) Msmentioning

confidence: 99%

“…In fact, evidence for the parietal cortices key role in synesthetic perception comes from several neuroimaging studies with groups of grapheme-color synesthetes Van Leeuwen et al, 2010;Sinke et al, 2012a), spatial sequence synesthetes and auditory-visual synesthetes . Importantly, connectivity analyses identified an area in the parietal cortex which showed stronger connections with primary sensory areas in synesthetes Sinke et al, 2012a). This is consistent with a model of parietal modulation of sensory processing which has been found to explain neuroimaging data of associator synesthetes .…”

Section: Reaction Time M(sd) Msmentioning

confidence: 99%

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Developing Synaesthesia

2015

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Inside a synesthete's head: A functional connectivity analysis with grapheme-color synesthetes

Cited by 28 publications

References 50 publications

The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers

The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers

Associative memory advantage in grapheme-color synesthetes compared to older, but not young adults

Developing Synaesthesia

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