LONI: Laboratory of Neuro Imaging

Structure - Micro

In previous research we created and validated computational methods that allowed us to segment the cortical mantle according to its histological layer-specific architecture. We then applied these methods to the classification of visual functional areas and demonstrated the localization of the visual - so called - 'motion area' MT in the human brain. The localization of MT was based on the observer independent analysis of cortical myeloarchitecture and on the application of multiple complementary staining techniques, including histochemical and immunocytological protocols.

Architecture of the Cerebral Cortex and Subcortical Nuclei

MRI post mortem scans of 12 specimens were acquired before processing the tissue histologically. This enabled us to register the architectonic maps of the hemispheres to functional data via the ICBM stereotaxic average template. The topographical classification of human MT by architectonic structure (via 3-D reconstruction) matched the localization of human MT derived from functional imaging.

In addition, human MT was localized by the histotopographic method in relation to definite macroscopic landmarks (the sulcal geometry of the occipito-tempral region). This approach elegantly exemplifies the ICBM scientific objectives which aim at investigating the relationship between macroscopic landmarks of the cortical mantle and the underlying functional architecture.

Cytoarchitectonic Mapping of the Human Superior Parietal Lobule and Anterior Medial Intraparietal Sulcus

Monkey and human superior parietal lobule (SPL) and intraparietal sulcus (IPS) are crucially involved in visuomotor

transformations, spatial attention, perception, and memory. Functional studies suggest a similar organization for human SPL (Brodmann areas (BA) 5 and 7). We have analyzed cytoarchitectonic sections of ten adult human brains.

Our cytoarchitectonic parcellation of human SPL and IPS is comparable to that of the macaque (areas PE, PEc, PEci, PEip). It is also more complex than the classical Brodmann map. The cytoarchitectonic differences between the subareas may reflect different aspects of visuomotor function with a shift of the dominating sensory modality from somatosensory (rostral) to visual (caudal).

Parcellation of the Human Ventral Extrastriate Cortex

Retinotopic mapping in the human brain revealed a detailed parcellation of the extrastriate visual cortex, similar to those of non human primates. We analyzed the cytoarchitecture of the ventral extrastriate visual cortex, to test the hypothesis of whether the ventral occipital cortex can further be subdivided based on cytoarchitectonic criteria, and to compute probabilistic stereotaxic maps of the areas.

Two distinct areas were identified within the ventral occipital cortex lateral to V2. The first, rather small area (hOc3v) was mainly located in the collateral sulcus, next to V2. More laterally, a second, larger area was identified (hOc4v). It was also located in the collateral sulcus, but reached the fusiform gyrus in the more caudal sections. Both areas were mainly located on the ventral aspect of the occipital lobe, but occupied parts of its lateral surface at the occipital pole. Thus, in contrast to Brodmann's tripartition of the visual cortex, we found a more detailed parcellation of the ventral extrastriate cortex, which corresponds to more recent receptorarchitectonic and connectivity data.

Receptorarchitecture of the Human Temporal Cortex

To study the differences in the distribution patterns of neurotransmitter receptors between human primary and non-primary auditory areas, we performed receptorarchitectonic analysis in five deep frozen human hemispheres. We found that the functional hierarchy of human auditory processing is reflected by differences in receptorarchitecture between primary and non-primary auditory areas. More