Synesthesia

Lower and upper

According to Ramachandran, there's 2 types of synesthesia

Arbitrary, semantic associations, heightened common cross-modal associations

According to lecture, synesthetes' pairings may be influenced by what factors?

"Hyperactivity gene" is expressed throughout the brain, not just in the fusiform and angular gyrus areas, potentially resulting in heightened metaphorical ability to make connections between unseemingly unrelated concepts

Characteristics of global hyperactivity

-"Hyperactivity gene" is expressed higher up in processing -Activation occurs in angular gyrus, resulting in experience driven by numerical concept -Ordinality and sequence are represented higher up in TPO junction (may explain why certain synesthetes associate colors with days, months, years

Characteristics of higher synesthesia

-"Hyperactivity gene" is expressed earlier in processing -Activation occurs in fusiform gyrus, resulting in experience driven by visual appearance -In color-number synesthetes, perception of color not driven by numerical concept (which is represented higher up), but by visual appearance of number

Characteristics of lower synesthesia

Associators

Concurrent idea; percept occurs concurrently with another; may make associations with "mind's eye"

Francis Galton

Credited with being the first scientist to report cases of synesthesia, though this is hotly debated

50-60

Currently, how many described types of synesthesia are there?

Strobe lights at concerts

Example of a modern day attempt at eliciting synesthetic experiences

Kiki-bouba

Experiment/effect provides evidence that there's strong shape-sound correspondence in the brain

Richard Cytowic

First academic to bring the study of synesthesia to modern day science

Brain stem and thalamus

If indirect activation is to explain for the mixed sensations experienced by synesthetes, what brain structure(s) would likely be involved?

Weak border formation, lack of specific targeting, lack of stereotypic pruning

If synesthesia is in fact due to direct cross-activation of supplementary connections, what 3 things may cause these extra connections?

Concurrency

If you are a synesthete and normally see the number 7 as blue and I write a number 7 in yellow, you will overlay the yellow 7 with a blue 7. This is an example of?

Alexander Luria

Leading researcher of synesthetes

Direct cross-activation

Most evidence of cortical activation of synesthetes points to what kind of activation?

Lexical - gustatory

Of the few inducer/current forms of synesthesia discussed in lecture, which of them in very rare cases can be bi-directional?

Projectors

Percept projects out in front of you; physically see a percept projected onto another every single time

Women

Synesthesia is more common among men or women?

-Pre-existing cross-activation of hand and mouth regions of the brain, which are next to each other in Penfield's motor map of the brain -Pre-existing non-arbitrary translation of visual representation in the fusiform gyrus and auditory representation in auditory cortex -Non-arbitrary cross-activation of visual representation in fusiform gyrus and Broca's area

Synesthetic bootstrapping theory of origin

Test-retest, perceptual grouping, stimulus detection, say word & ignore color (vice versa), Stroop task timing

Ways of objectively testing if synesthesia exists

Synesthesia (definition)

When one sensory stimulus evokes two specific, consistent, and concurrent perceptual experiences

Hesitation to self-report, don't know they have it

Why is there such variation in the percentage of reported cases of synesthesia?