|Title||A cross-modal perspective on the relationships between imagery and working memory|
|Publication Type||Journal Article|
|Year of Publication||2013|
|Journal||Frontier in Psyhology|
|Date Published||Jan 2013|
|Keywords||drawing, fMRI, primary visual cortex V1, visual imagery, visuo-spatial sketchpad, working memory|
Mapping the distinctions and interrelationships between imagery and working memory
(WM) remains challenging. Although each of these major cognitive constructs is defined
and treated in variousways across studies, most accept that both imagery andWMinvolve a
form of internal representation available to our awareness. InWM, there is a further emphasis
on goal-oriented, active maintenance, and use of this conscious representation to guide
voluntary action. MulticomponentWM models incorporate representational buffers, such
as the visuo-spatial sketchpad, plus central executive functions. If there is a visuo-spatial
“sketchpad” forWM, does imagery involve the same representational buffer? Alternatively,
doesWM employ an imagery-specific representational mechanism to occupy our awareness?
Or do both constructs utilize a more generic “projection screen” of an amodal nature?
To address these issues, in a cross-modal fMRI study, I introduce a novel Drawing-Based
Memory Paradigm, and conceptualize drawing as a complex behavior that is readily adaptable
from the visual to non-visual modalities (such as the tactile modality), which opens
intriguing possibilities for investigating cross-modal learning and plasticity. Blindfolded participants
were trained through our Cognitive-Kinesthetic Method (Likova, 2010a, 2012) to
draw complex objects guided purely by the memory of felt tactile images. If thisWM task
had been mediated by transfer of the felt spatial configuration to the visual imagery mechanism,
the response-profile in visual cortex would be predicted to have the “top-down”
signature of propagation of the imagery signal downward through the visual hierarchy.
Remarkably, the pattern of cross-modal occipital activation generated by the non-visual
memory drawing was essentially the inverse of this typical imagery signature. The sole
visual hierarchy activation was isolated to the primary visual area (V1), and accompanied
by deactivation of the entire extrastriate cortex, thus ’cutting-off’ any signal propagation
from/to V1 through the visual hierarchy. The implications of these findings for the debate
on the interrelationships between the core cognitive constructs ofWM and imagery and
the nature of internal representations are evaluated.