|
| Hyperconnectivity Theory |
Ramachandran and Hubbard |
Caused by increased connectivity between cortical regions. |
Connectivity is likely caused by failure of cortical pruning of
neurons. |
| Disinhibition-unmasking hypothesis |
Grossenbacher and Lovelace |
Caused by a decreased level of feedback from inhibitory cortical
areas. |
This theory suggests constitutive inhibitory cortical feedback is
present in everyone. |
| Learned association theory |
Calkin |
Suggests that synesthetic links are caused by learned associations early
in life. |
Discredited due to genetic component and increased incidence in
women. |
| Awareness theory |
Cytowic |
Suggests that synesthesia is part of a normal perceptual process, and
the phenomenon is caused by a failure of our brain to suppress the
concurrent which he hypothesizes occurs in everyone. |
Implicates the limbic system as important especially the
hippocampus. |
| Neonatal synaesthesia |
Maurer |
This theory suggests that humans are all born with synesthesia-like
tendencies, which in “normal” people are lost through age. |
Widely refuted. Discussed at length later. |
