336
V. Vuksanovi´ c
21.3 Morphology and Function
Corticocortical interactions form a communication system which underpins sensory
and higher cognitive and behavioural processes in the brain. It is important to identify specific network properties and how they facilitate this communication; are there
general rules that govern organisation of these interactions? In this context, the hierarchical, modular organization is widely documented across neural systems. A well
studied example at the micro-level is the modular columnar organisation of the neocortex (i.e., micro-scale of brain organisation related to functionally divided vertical
formations of the cortical surface or cortical columns representing the basic functional units of the cortex). Although spatially distant, columns in cytoarchitectural
areas usually share some common properties, which are repeated iteratively within
each area, and are most commonly grouped into entities by sets of dominating longrange, intracortical connection [50].
While cortical microstructure is mostly used to describe local properties of individual areas, studies investigating cortical connections focus on the relationship between
areas (i.e., their structural—morphological—features). Organization of long-range
cortical connections across different brain areas can inform our understanding of
how the cortical function emerges from structural constraints [40]. MRI studies take
a simplified view of cortical morphology by reducing it to a single measure: the mean
volume, cortical thickness, surface area, gyrification index or curvature. In contrast to
functional networks, computed on correlations of regional fMRI across time within
an individual brain, morphological networks are computed on correlations among
regional morphological properties across subjects. Only recently, morphometric similarity networks were extracted on an individual brain [62]. The connectivity architecture of these networks is shaped by genetic and environmental factors (that are
variable across individuals) [19, 40] and is related to human cognitive performances
(e.g, general intelligence) [62].
Mapping a cross-scale organisation at micro- (cytoarchitectonic) and macro(regional) levels, has shown evidence of a significant association between cytoarchitectonic features of human cortical organization and whole-brain corticocortical
connectivity [72, 80]. Findings suggest that aspects of microscale cytoarchitectonics and macroscale connectomics are related and may have the potential to reveal
more about the etiology of neuropathological processes in the diseased brain (see
Sect. 21.4). There is a number of studies regarding genetic influences upon the coordinated growth of spatially segregated areas during development (see for example
[67]) or longitudinal (although) focal changes in morphology following training and
learning new skills [9, 27]. With the exceptions of two recent studies [70, 74], comparative studies of whole-brain functional and morphological networks are lacking.
Recent findings from fMRI studies, suggest that interindividual variability in functional connectivity is not uniformly distributed across the cortex: the association
regions, including language, executive control, and attention networks, are likely
more variable than the unimodal regions, such as the visual and sensorimotor cortices [51]. It is known that these cortices share similar morphology and projecting
V. Vuksanovi´ c
21.3 Morphology and Function
Corticocortical interactions form a communication system which underpins sensory
and higher cognitive and behavioural processes in the brain. It is important to identify specific network properties and how they facilitate this communication; are there
general rules that govern organisation of these interactions? In this context, the hierarchical, modular organization is widely documented across neural systems. A well
studied example at the micro-level is the modular columnar organisation of the neocortex (i.e., micro-scale of brain organisation related to functionally divided vertical
formations of the cortical surface or cortical columns representing the basic functional units of the cortex). Although spatially distant, columns in cytoarchitectural
areas usually share some common properties, which are repeated iteratively within
each area, and are most commonly grouped into entities by sets of dominating longrange, intracortical connection [50].
While cortical microstructure is mostly used to describe local properties of individual areas, studies investigating cortical connections focus on the relationship between
areas (i.e., their structural—morphological—features). Organization of long-range
cortical connections across different brain areas can inform our understanding of
how the cortical function emerges from structural constraints [40]. MRI studies take
a simplified view of cortical morphology by reducing it to a single measure: the mean
volume, cortical thickness, surface area, gyrification index or curvature. In contrast to
functional networks, computed on correlations of regional fMRI across time within
an individual brain, morphological networks are computed on correlations among
regional morphological properties across subjects. Only recently, morphometric similarity networks were extracted on an individual brain [62]. The connectivity architecture of these networks is shaped by genetic and environmental factors (that are
variable across individuals) [19, 40] and is related to human cognitive performances
(e.g, general intelligence) [62].
Mapping a cross-scale organisation at micro- (cytoarchitectonic) and macro(regional) levels, has shown evidence of a significant association between cytoarchitectonic features of human cortical organization and whole-brain corticocortical
connectivity [72, 80]. Findings suggest that aspects of microscale cytoarchitectonics and macroscale connectomics are related and may have the potential to reveal
more about the etiology of neuropathological processes in the diseased brain (see
Sect. 21.4). There is a number of studies regarding genetic influences upon the coordinated growth of spatially segregated areas during development (see for example
[67]) or longitudinal (although) focal changes in morphology following training and
learning new skills [9, 27]. With the exceptions of two recent studies [70, 74], comparative studies of whole-brain functional and morphological networks are lacking.
Recent findings from fMRI studies, suggest that interindividual variability in functional connectivity is not uniformly distributed across the cortex: the association
regions, including language, executive control, and attention networks, are likely
more variable than the unimodal regions, such as the visual and sensorimotor cortices [51]. It is known that these cortices share similar morphology and projecting