Clinical studyVolumetric analysis of a specific language region – the planum temporale
Introduction
The planum temporale (PT) represents a triangular structure on the upper surface of the superior temporal gyrus within the sylvian fissure.1 Geschwind and Levitsky2 examined 100 post-mortem brains and noted a longer left PT in 65%. They proposed that the significantly larger left PT may be compatible with functional asymmetry. In the language-dominant hemisphere, the PT coincides with part of Wernicke’s area and functional neuroimaging has demonstrated a role in phonological processing.3 The region is represented by Brodmann area 42.4 Cytoarchitecturally it is believed to consist of secondary auditory cortex.5 Little is known about the morphological changes in the PT that must occur with cognitive and behavioural development.
Initial MR studies of length and surface area demonstrated leftward asymmetry.[6], [7], [8], [9], [10], [11], [12], [13] MRI volume studies of this region[14], [15], [16], [17], [18], [19], [20], [21], [22] have demonstrated variable results in average PT volumes (900 mm3 to 5650 m3) as well as hemispheric asymmetry for control subjects. Differing techniques of volumetric analysis, image acquisition, slice thickness and border definitions were observed in these studies.
In this study, we propose a reproducible method for image acquisition and measurement of PT volumes as well as measuring the PT volume in healthy children.
Section snippets
Materials and methods
Forty-two healthy children (23 males; 19 females; age range, 4.2–15.7 years) were recruited and consent was obtained from parents after standard ethics procedures. Handedness details were obtained for all children. Trained MRI technicians scanned the subjects on a Philips ACS-NT 1.5T machine (Children’s Hospital at Westmead, Sydney) (Philips Medical Systems Australia, North Ryde, NSW, Australia) with the head in the neutral position inside the head coil. A head cradle inside the head coil with
Results
Statistical analyses were performed using the statistical software package SPSS for Windows (Version 10, SPSS Inc., Chicago, IL). The paired t-test was used to compare coronal and sagittal volumes obtained in the preliminary 10 controls. Measurements of the PT volumes for a given patient on two separate occasions, by the same investigator, were used to assess reproducibility of the technique. Pearson’s correlation coefficient was used to quantify the association between the first and second
Methodology
Previous investigators have suggested measurements of the PT were best performed in the coronal plane as it provided direct assessment of the full depth of the sylvian fissure.5 The limitation however, lies posteriorly when the PT angles upward.33 This can be appreciated in the upper images of Fig. 2, Fig. 3. The limitation of the sagittal plane is most laterally when posterior tributaries of the sylvian fissure appear to be a continuation of the PT.33 This is demonstrated in Fig. 4, Fig. 5.
Acknowledgements
The authors would like to thank Mr Allan Kemp and Professor John Morris for their assistance in this study. Dr L. Vadlamudi was the Glaxo-Wellcome Epilepsy Society of Australia Fellow.
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Cited by (8)
A systematic literature review of sex differences in childhood language and brain development
2018, NeuropsychologiaCitation Excerpt :In terms of structural asymmetry, one study reported greater leftward asymmetry of the planum temporale in females than males aged between 3 and 14 years (Preis et al., 1999 and see also leroy et al., 2015), although the authors caution that unpublished data using a larger sample found no such difference. In line with this work, Vadlamudi et al. (2006) did not find any sex differences in the asymmetry of the planum temporale in children between 4 and 16 years. The corpus callosum is the major commissural fiber bundle that inter-connects the two cerebral hemispheres.
Sex differences in the relationship between planum temporale asymmetry and corpus callosum morphology in chimpanzees (Pan troglodytes): A combined MRI and DTI analysis
2016, NeuropsychologiaCitation Excerpt :In the current study, we examined the relationship between individual variation in asymmetries in the planum temporale (PT) and variation in CC surface area in a sample of chimpanzees. The PT is the flat bank of tissue that lies posterior to Heschl's gyrus and overlaps with Wernicke's area, a region historically linked to speech comprehension, among other functions (Dorsaint-Pierre et al., 2006; Galaburda 1984; Galaburda et al., 1987; Galaburda and Sanides, 1980; Goulven and Tzourio-mazoyer, 2004; Josse, Mazoyer, Crivello and Tzourio-Mazoyer, 2003; Shapleske et al., 1999; Vadlamudi et al., 2006; Xu et al., 2006). Numerous studies in humans have shown that the PT, at least when measured using region of interest approaches, is larger in the left compared to right hemisphere in typically developing individuals (Knaus et al., 2006; Shapleske et al., 1999; Sommer et al., 2008).
Regional variation, hemispheric asymmetries and gender differences in pericortical white matter
2011, NeuroImageCitation Excerpt :Language dominance is thought to reflect underlying structural differences between the two hemispheres, and asymmetries in local gyral and sulcal anatomy have been reported in many cortical regions (Galaburda et al., 1978; Keller et al., 2007; Van Essen, 2005). However, the regions that show the largest cortical-surface asymmetries vary in different studies (Lyttelton et al., 2009; Vadlamudi et al., 2006) and often correlate poorly with functional measures of language dominance (Dorsaint-Pierre et al., 2006; Eckert et al., 2006; Josse et al., 2009) where the Wada test (Wada and Rasmussen, 2007) suggests that more than 90% of neurologically normal right-handed subjects have left hemisphere language dominance (Moddel et al., 2009; Rasmussen and Milner, 1977). Hemispheric asymmetries in fiber tract properties appear to correlate closely with language dominance.
The brain has sex
2015, Medicina Fluminensis