The relationship between callosal axons and cortical neurons in the planum temporale: Alterations in schizophrenia

Simper, R C; Walker, Mary A.; Black, Georgia; Rosa, Enrica Di; Crow, Timothy J.; Chance, Steven A.

doi:10.1016/j.neures.2011.08.007

Cited by 15 publications

(10 citation statements)

References 27 publications

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“…In general, more symmetrical brains appear to have a larger corpus callosum and thus showed increased interhemispheric connectivity (Geschwind and Galaburda, 1985a,b,c; Galaburda et al, 1990; Aboitiz et al, 1992c; Dorion et al, 2000). For example, fewer callosal projections between the plana temporales were found when their minicolumn spacing was more asymmetrical (Chance et al, 2006) and there is a correlation between the magnopyramidal neuron density in the planum temporale and axon number in the isthmus of the corpus callosum and this correlation seems to be absent in schizophrenia (Simper et al, 2011). Therefore, the hypothesis of neuronal interconnectivity as a function of brain size can be related to the symmetry / asymmetry of cortical brain regions and might also account for the repeatedly observed stronger lateralization of brain functions in men.…”

Section: Discussionmentioning

confidence: 99%

The hypothesis of neuronal interconnectivity as a function of brain sizeâ€”a general organization principle of the human connectome

Hänggi

Fövenyi

Liem

et al. 2014

Front. Hum. Neurosci.

119

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Twenty years ago, Ringo and colleagues proposed that maintaining absolute connectivity in larger compared with smaller brains is computationally inefficient due to increased conduction delays in transcallosal information transfer and expensive with respect to the brain mass needed to establish these additional connections. Therefore, they postulated that larger brains are relatively stronger connected intrahemispherically and smaller brains interhemispherically, resulting in stronger functional lateralization in larger brains. We investigated neuronal interconnections in 138 large and small human brains using diffusion tensor imaging-based fiber tractography. We found a significant interaction between brain size and the type of connectivity. Structural intrahemispheric connectivity is stronger in larger brains, whereas interhemispheric connectivity is only marginally increased in larger compared with smaller brains. Although brain size and gender are confounded, this effect is gender-independent. Additionally, the ratio of interhemispheric to intrahemispheric connectivity correlates inversely with brain size. The hypothesis of neuronal interconnectivity as a function of brain size might account for shorter and more symmetrical interhemispheric transfer times in women and for empirical evidence that visual and auditory processing are stronger lateralized in men. The hypothesis additionally shows that differences in interhemispheric and intrahemispheric connectivity are driven by brain size and not by gender, a finding contradicting a recently published study. Our findings are also compatible with the idea that the more asymmetric a region is, the smaller the density of interhemispheric connections, but the larger the density of intrahemispheric connections. The hypothesis represents an organization principle of the human connectome that might be applied also to non-human animals as suggested by our cross-species comparison.

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Section: Discussionmentioning

confidence: 99%

The hypothesis of neuronal interconnectivity as a function of brain sizeâ€”a general organization principle of the human connectome

Hänggi

Fövenyi

Liem

et al. 2014

Front. Hum. Neurosci.

119

View full text Add to dashboard Cite

show abstract

“…Finally, it is important to mention that Simper and colleagues (Simper et al 2011) provided first evidence for a positive relationship between the number of corpus callosum axons in the isthmus of the cc and the total density of magnopyramidal neurons in the bilateral PT. Even though in the present work we did not reveal between-group differences in terms of transcallosal fibre volume, we found evidence for reduced RD in musicians that is known to reflect increased myelin integrity.…”

Section: Relationship Between Pt Characteristics and Transcallosal Fimentioning

confidence: 98%

Interhemispheric transcallosal connectivity between the left and right planum temporale predicts musicianship, performance in temporal speech processing, and functional specialization

2014

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Currently, there is strong evidence showing that musicianship favours functional and structural changes of the left planum temporale (PT), and that these cortical reorganizations facilitate the discrimination of temporal speech cues. Based on the proposition of a division of labour between the left and right PT, here we postulated that the musicians' advantage in processing temporal speech cues and PT specialization origin, at least in part, from increased white matter connectivity between the two auditory-related cortices. In particular, we assume that increased transcallosal PT connectivity might promote functional specialization and asymmetry of homotopic brain regions. With this purpose in mind, we applied diffusion tensor imaging and compared axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) of the interhemispheric connection between the left and right PT in thirteen musicians and 13 nonmusicians. Furthermore, in the form of an addendum, we integrated cortical surface area values and blood oxygenation level dependent (BOLD) responses of the left PT that were collected in the context of two previous studies conducted with the same sample of subjects. Our results indicate increased connectivity between the left and right PT in musicians compared to nonmusicians, as indexed by reduced mean RD. We did not find significant between-group differences in FA and AD. Most notably, RD was related to the performance in the phonetic categorization task, musical aptitudes, as well as to BOLD responses in the left PT. Hence, we provide first evidence for a relationship between PT connectivity, musicianship, and phonetic categorization.

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“…Cellular changes in these 1132 regions were related to white matter connections 1133 (Chance et al, 2008;Simper et al, 2011), which also 1134 showed sex-dependent effects (Highley et al, 1998). It 1135 has been suggested that age of illness onset and its differ-1136 ence between the sexes may be related to the timing of 1137 maturation of myelinated white matter tracts, particularly 1138 the corpus callosum (Crow et al, 2007).…”

Section: Age Of Onset and Illness Durationmentioning

confidence: 99%

“…As has 588 also been found for the hippocampus, the few studies of 589 cell size have provided more consistency, with normal 590 or slightly reduced neuron size being a common result 591(Rajkowska et al, 1998). In the prefrontal cortex,Sweet et al, 2003) have been found in the planum tem-608 porale, and a size reduction of the largest pyramidal neu-609 rons has been found in the left hemisphere but not the 610 right(Simper et al, 2011). It has been suggested that 611 these findings implicate impaired feed-forward connec-612 tions(Sweet et al, 2003) and altered interhemispheric 613 connections(Simper et al, 2011) in schizophrenia.…”

mentioning

confidence: 99%

“…In the prefrontal cortex,Sweet et al, 2003) have been found in the planum tem-608 porale, and a size reduction of the largest pyramidal neu-609 rons has been found in the left hemisphere but not the 610 right(Simper et al, 2011). It has been suggested that 611 these findings implicate impaired feed-forward connec-612 tions(Sweet et al, 2003) and altered interhemispheric 613 connections(Simper et al, 2011) in schizophrenia. The 614 balance of findings (both increased and decreased neu-615 ron densities) is consistently mixed, as with the literature 616 on the frontal lobe.…”

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confidence: 99%

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The neuropathology of schizophrenia: A selective review of past studies and emerging themes in brain structure and cytoarchitecture

2015

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The relationship between callosal axons and cortical neurons in the planum temporale: Alterations in schizophrenia

Cited by 15 publications

References 27 publications

The hypothesis of neuronal interconnectivity as a function of brain sizeâ€”a general organization principle of the human connectome

The hypothesis of neuronal interconnectivity as a function of brain sizeâ€”a general organization principle of the human connectome

Interhemispheric transcallosal connectivity between the left and right planum temporale predicts musicianship, performance in temporal speech processing, and functional specialization

The neuropathology of schizophrenia: A selective review of past studies and emerging themes in brain structure and cytoarchitecture

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