The current fMRI study investigates this issue further by directly comparing intrinsic intra-item binding (object/colour), extrinsic intra-item binding (object/location), and inter-item binding (object/object).
With respect to intra-item binding, a further distinction can be made.
In the present study, we used a delayed-match-to-sample (DMS) task, comparing an intrinsic intra-item binding condition (object/colour), an extrinsic intra-item binding condition (object/location), and a between-domain inter-item binding condition (object/object), with a non-binding condition as baseline.
The contrast extrinsic intra-item binding specifically activated the superior parietal lobe extending into the precuneus, and the frontal eye fields bilaterally.
In compliance with the results of our previous study, no specific neural correlates involved in the maintenance of the intrinsic intra-item binding condition were observed.
The contrast intrinsic intra-item binding did not reveal any significant activation, even at a very lenient threshold of p<0.1.
In the inter-item binding condition we observed activation in the MTL, including the parahippocampal gyrus and the amygdala, suggesting that the process of binding of two unrelated objects, a face and a house, depends on the MTL.
Areas implicated in spatial processing, including the superior parietal lobe extending into the precuneus, and the frontal eye fields (FEF) were activated in the extrinstic intra-item binding condition (object/location).
For instance, the binding of objects and their locations can be seen as a form of intra-item binding in which and item (the object) is bound with an extrinsic feature (its location).
However, when the MTL is important for the binding of non-overlapping neural representations, one would expect the MTL to be activated during the maintenance of both the extrinsic intra-item and the inter-item binding condition.
If on the other hand the integration of representations does not overlap as a result of feature characteristics that crucially recruit the MTL, one would expect that both the extrinsic intra-item binding and the between-domain inter-item conditions activate the MTL.
