Tractography, a specialised form of magnetic resonance imaging, confirms and extends traditional views about the extensive interconnections between different regions of cerebral cortex. Three examples are briefly described below.

 

Catani, M., Jones, D. K., Donato, R., & ffytche, D. H. (2003). Occipito-temporal connections in the human brain. Brain, 126, 2093-2107.

Classical anatomical studies described direct fibre connections between occipital and anterior temporal cortex in a bundle labelled the inferior longitudinal fasciculus (ILF).

Virtual in vivo dissection of occipito-temporal connections was performed in the group-averaged data. Further detailed virtual dissection was performed on the single brain data sets.

Their results support a major associative connection between the occipital and anterior temporal lobe, provided by a fibre bundle whose origin, course and termination are consistent with classical descriptions of the ILF in man and with monkey visual anatomy

One of the figures for the ILF, which they surmise mediates interactions between visual information and the amygdala, was shown in the lectures.



Catani, M., Jones, D. K., & Ffytche, D. H. (2005). Perisylvian language networks of the human brain. Annals of Neurology, 57(1), 8-16.

The arcuate fasciculus of the left hemisphere was reconstructed from tractography data (11 normal subjects)

Beyond the classical arcuate pathway connecting Broca's and Wernicke's areas directly, they showed a previously undescribed, indirect pathway passing through inferior parietal cortex. The indirect pathway runs parallel and lateral to the classical arcuate fasciculus (aka superior longitudinal fasciculus) and is composed of an anterior segment connecting Broca's territory with the inferior parietal lobe and a posterior segment connecting the inferior parietal lobe to Wernicke's territory.

Their fig. 3 shows the classical arcuate fasciculus in red and the the indirect pathway in green and yellow.



Kier, E. L., Staib, L. H., Davis, L. M., & Bronen, R. A. (2004). MR imaging of the temporal stem: Anatomic dissection tractography of the uncinate fasciculus, inferior occipitofrontal fasciculus, and Meyer's loop of the optic radiation. American Journal of Neuroradiology, 25(5), 677-691.

This study clarified the MR anatomy of the uncinate fasciculus, and two other adjacent fibre bundles by comparing magnetic resonance tractography data of formalin treated brain specimens with progressive anatomical dissections of the specimens. Two of many figures were shown in the lecture, of the uncinate facsculus in the dissected specimen, and the MR version.