Does Cerebral Hemispheric Laterality Control Swallow Performance?

Diffusion tensor imaging (DTI) studies have demonstrated white matter microstructural differences between the left and right hemispheres of the brain. However, the basis of these hemispheric asymmetries is not yet understood in terms of the biophysical properties of white matter microstructure, especially in children. There are reports of altered hemispheric white matter lateralization in ASD; however, this has not been studied in other related neurodevelopmental disorders such as sensory processing disorder (SPD). Firstly, we postulate that biophysical compartment modeling of diffusion MRI (dMRI), such as Neurite Orientation Dispersion and Density Imaging (NODDI), can elucidate the hemispheric microstructural asymmetries observed from DTI in children with neurodevelopmental concerns. Secondly, we hypothesize that sensory over-responsivity (SOR), a common type of SPD, will show altered hemispheric lateralization relative to children without SOR. Eighty-seven children (29 females, 58 males), ages 8–12 years, presenting at a community-based neurodevelopmental clinic were enrolled, 48 with SOR and 39 without. Participants were evaluated using the Sensory Processing 3 Dimensions (SP3D). Whole brain 3 T multi-shell multiband dMRI (b = 0, 1,000, 2,500 s/mm2) was performed. Tract Based Spatial Statistics were used to extract DTI and NODDI metrics from 20 bilateral tracts of the Johns Hopkins University White-Matter Tractography Atlas and the lateralization Index (LI) was calculated for each left–right tract pair. With DTI metrics, 12 of 20 tracts were left lateralized for fractional anisotropy and 17/20 tracts were right lateralized for axial diffusivity. These hemispheric asymmetries could be explained by NODDI metrics, including neurite density index (18/20 tracts left lateralized), orientation dispersion index (15/20 tracts left lateralized) and free water fraction (16/20 tracts lateralized). Children with SOR served as a test case of the utility of studying LI in neurodevelopmental disorders. Our data demonstrated increased lateralization in several tracts for both DTI and NODDI metrics in children with SOR, which were distinct for males versus females, when compared to children without SOR. Biophysical properties from NODDI can explain the hemispheric lateralization of white matter microstructure in children. As a patient-specific ratio, the lateralization index can eliminate scanner-related and inter-individual sources of variability and thus potentially serve as a clinically useful imaging biomarker for neurodevelopmental disorders.

Brain correlates of stuttering and syllable production: a PET performance-correlation analysis

Although the left and right human cerebral hemispheres differ both functionally and anatomically, little is known about the environmental or genetic factors that govern central nervous system asymmetry. Nevertheless, cerebral asymmetry is strongly correlated with handedness, and handedness does have a significant genetic component. To explore the relative contribution of environmental and genetic influences on cerebral asymmetry, we examined the volumes of left and right cerebral cortex in a large cohort of aging identical and fraternal twins and explored their relationship to handedness. Cerebral lobar volumes had a major genetic component, indicating that genes play a large role in changes in brain volume that occur with aging. Shared environment, which likely represents in utero events, had about twice the effect on the left hemisphere as on the right, consistent with less genetic control over the left hemisphere. To test the major genetic models of handedness and cerebral asymmetry, twin pairs were divided into those with two right handers and those with at least one left hander (nonright handers). Genetic factors contributed twice the influence to left and right cerebral hemispheric volumes in right-handed twin pairs, suggesting a large decrement in genetic control of cerebral volumes in the nonright-handed twin pairs. This loss of genetic determination of the left and right cerebral hemispheres in the nonright-handed twin pairs is consistent with models postulating a right-hand/left-hemisphere-biasing genetic influence, a "right-shift" genotype that is lost in nonright handers, resulting in decreased cerebral asymmetry.

In contradiction to the crossing of all retinal fibers in the lateral-eye species, the retinal fibers of binocular vision in frontal-eye species run either ipsilaterally or cross the midline twice to terminate the ipsilateral cerebral hemisphere.[1][1] It is hypothesized that carrying separated

Objective To investigate the effects of inhalation of isoflurane at different time points on hypoxic-ischemic brain injury in neonatal rats.Methods One hundred and eighty 7-day-old Sprague-Dawley rats,weighing 12-16 g,were randomly divided into 6 groups (n =30 each):sham operation group (group Ⅰ),cerebral hypoxia/ischemia (H/I) group (group Ⅱ),and inhalation of isoflurane at different time point groups (groups Ⅲ-Ⅵ).Brain ischemia was induced by double ligation of left common carotid artery followed by inhalation of 8 ％ O2 + 92 ％ N2 for 2 h at 37 ℃.In groups Ⅲ,Ⅳ,Ⅴ and Ⅵ 1.5 ％ isoflurane was inhaled for 30 min starting from 0,3,6,12 h after H/I respectively,while the rats were exposed to 30％ O2 and 70％ N2 only in groups Ⅰ and Ⅱ.The survival rate at 7 days after H/I was recorded.The animals were sacrificed at 7 days after H/I.The brains were removed and the right and left cerebral hemispheres (CH) were weighed separately.The ratio between left/right CH was calculated.The density of normal neurons in ventral posterior inferior thalamic nucleus and posterior cingulate cortex in left and right CH were measured and the ratio of the density of normal neurons in the left to right CH was calculated.Results Compared with group Ⅰ,the weight of left cerebral hemisphere,ratio between left/right CH,and ratio of the density of normal neurons in the left to right CH were significantly decreased in other five groups (P ＜ 0.05).Compared with group Ⅱ,the weight of left cerebral hemisphere,ratio between left/right CH,and ratio of the density of normal neurons in the left to right CH were significantly increased in groups Ⅲ,Ⅳand Ⅴ (P ＜ 0.05).There were no significant differences in the indices nentioned above among groups Ⅲ,Ⅳand Ⅴ (P ＞ 0.05).There was no significant difference in the survival rate among groups Ⅱ-Ⅵ (P ＞ 0.05).Conclusion Inhalation of 1.5％ isoflurane for 30 min within 6 h after cerebral H/I can reduce the cerebral injury in neonatal rats. Key words: Isoflurane; Hypoxia-ischemia, brain; Infant, newborn

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Objective To explore the developmental characteristics of white matter volume in autism spectrum disorder (ASD) children longitudinal. Methods From May 2011 to September 2014, 37 ASD children (ASD group) and 27 developmental delays (DD) children (control group) were treated at the Child Mental Health Research Center, Nanjing Brian Hospital Affiliated of Nanjing Medical University, and the children whose age, gender and developmental quotient matched with the ASD children were scanned by structure magnetic resonance imaging (sMRI) at the age of 2-3 years old and 4-5 years old respectively.Region of interest(ROI) technology was adopted to investigate the change of the cerebrum white and the sub-lobes structure white matter volume with time.Then the correlation between clinical symptoms and brain white matter volume changes was analyzed. Results Among the 2-3 years old, compared with the control group, the white matter volume of the total brain[(383 521.84±6 427.57) mm3vs. (364 014.06±6 856.97) mm3], the left cerebral hemisphere [(191 609.35±3 206.60) mm3vs. (181 695.89±3 389.54) mm3], temporal lobe [(41 860.49±816.38) mm3vs. (39 444.18±834.85) mm3] and the right temporal lobe [(21 312.79±414.07) mm3vs. (20 084.22±412.13) mm3] were significantly larger in the ASD group, and the differences were statistically significant (all P 0.05). Among the 4-5 years old, compared with the control group, the white matter volumes of the total brain[(417 651.42±6 443.86) mm3vs. (394 317.27±6 404.86) mm3], left cerebral hemisphere [(208 714.16±3 214.61) mm3vs. (197 192.82±3 262.02) mm3], right cerebral hemisphere [(208 937.26±3 242.09) mm3vs. (7 124.45±3 193.13) mm3], frontal lobe [(107 107.46±1 681.99) mm3vs. (100 326.19±1 883.24) mm3], left frontal lobe [(54 569.63±846.85) mm3vs. (51 177.25±979.09) mm3], right frontal lobe [(52 537.83±841.99) mm3vs. (49 148.94±928.31) mm3], temporal lobe [(45 189.75±833.29) mm3vs.(42 487.73±786.27) mm3], left temporal lobe [(22 204.21±411.77) mm3vs. (20 922.90±418.46) mm3], and right temporal lobe [(22 985.54±426.93) mm3vs. (21 564.83±378.78) mm3] were significantly larger in the ASD group, and the differences were statistically significant (all P 0.05). For longitudinal analysis, there was a significant difference in the white matter volume between the whole brain, left cerebral hemisphere, right cerebral hemisphere, frontal lobe, left frontal lobe, right frontal lobe, temporal lobe, left temporal lobe, right temporal lobe and the differences were statistically significant(F=5.521, 5.533, 5.459, 5.830, 5.800, 5.723, 4.857, 4.418, 5.159, all P<0.05). There was a positive correlation between the changes of the volume of whole brain, the white matter volume in the whole brain, bilateral cerebral hemisphere, frontal lobe, parietal lobe, right parietal lobe and Childhood Autism Rating Scale(r=0.367, 0.343, 0.321, 0.349, 0.296, 0.308, 0.351, all P<0.05). Conclusions Among the 2-3 years old, the white matter volume of the brain regions have been increased significantly in ASD.Among the 4-5 years old, the increase of the white matter volume of the brain regions implicated more widely which mainly concentrated in the frontal and temporal lobe in ASD.The severity of the clinical symptoms of ASD may be associated with the white matter volume of the total brain, bilateral cerebral hemisphere, frontal lobe, parietal lobe and right parietal lobe. Key words: Autism spectrum disorder; White matter; Volume; Magnetic resonance imaging; Longitudinal study

The study of cerebral specialization in persons with Down syndrome (DS) has revealed an anomalous pattern of organization. Specifically, persons with DS elicit a right cerebral hemisphere lateralization for receptive language and a left cerebral hemisphere lateralization for the production of simple and complex movements: a pattern quite different from the left hemisphere lateralization typically characterizing the aforementioned processes in the non-DS population. It is thought that the putative separation between speech perception and movement planning systems as well as the cost of interhemispheric integration impedes verbal-motor behaviours in persons with DS. Moreover, morphological anomalies of callosal structure may further amplify between-hemisphere communication difficulties in the DS population. In the present investigation, we employed a behavioural technique (i.e. the Poffenberger paradigm; Poffenberger) to determine whether global anomalies of callosal structure further amplify deficits in interhemispheric communication. Fourteen individuals with DS and 25 chronological age-matched and gender-equated participants without intellectual disability performed a visuomotor reaction time (RT) test with their left or right hand to visual stimuli appearing left or right of visual fixation. Typically it is reported that responses to visual stimuli appearing ipsilateral to the responding hand (i.e. the uncrossed condition) are faster than responses wherein visual stimuli and responding hand are contralaterally mapped (i.e. the crossed condition). The increased RT associated with the crossed condition is reported on the order of 4 ms and has been interpreted to reflect the physiological result of interhemispheric transmission. Not surprisingly persons with DS exhibited slower and more variable RTs relative to control counterparts. In addition, a reliable RT advantage favouring the uncrossed conditions was observed among control participants but not persons with DS. In keeping with the extant literature, RT performance of the DS group was slower and more variable than control counterparts. This finding has been interpreted to reflect an 'adaptive reaction' wherein the perceptual-motor abilities of persons with DS are not optimized to respond to externally paced stimuli. In terms of evaluating interhemispheric transmission via the Poffenberger paradigm, our results show the finite measures of explicit brain-behaviour relations characterizing so-called healthy controls are not always tenable in the DS population. Indeed, we believe such a finding underpins the aforementioned 'adaptive reaction' exemplifying preferred movement control in persons with DS.

Introduction: Problems with attention are common in patients with cerebral small vessel disease (CSVD). The normal human brain exhibits functional and structural asymmetry. However, it is unknown whether there is lateralization of attention in patients with CSVD.Objective: This study aims to investigate attention separately in both cerebral hemispheres in patients with CSVD using the computer-based Lateralized Attention Network Test—Revised (LANT-R).Methods: The total number of subjects included was 58, which includes the CSVD (N = 35) and healthy control (HC, N = 23) groups. All subjects completed the LANT-R paradigm and neuropsychological background tests.Results: The results indicate that there is an left hemisphere (LH) lateralization in orienting network efficiency in the HC group. However, this lateralization was not apparent in the CSVD group. Furthermore, the difference between groups was significant (interaction P = 0.02). In addition, the scores of subjects in the CSVD group are lower in several cognitive domains, including attention function, memory function, information processing speed, and executive function, compared with the controls.Conclusion: Patients with CSVD change in the lateralization of attention compared with the normal elderly. The decrease in attention in patients with CSVD might be caused by the reduced ability of selecting useful information in the LH.

Diacylglycerols (DGs) were found to be asymmetrically distributed between the two cerebral hemispheres of rat brain. The left cerebral hemisphere (LCH) contained 100% more DG than the right cerebral hemisphere (RCH). The lateralization was enhanced in animals subjected to depolarization induced by a single electroconvulsive shock (ECS). During the acute phase of the convulsion, the DG pool increased in both hemispheres, with the LCH attaining a concentration 180% higher than the RCH. Stearate and arachidonate were the principal DG-acyl groups accumulated in the RCH, whereas in the LCH stearate and palmitate were mainly involved. After the last of a series of five shocks (one per day) the lateralization of the "DG response" was less accentuated during the acute phase of the ECS. Whereas DG release was drastically reduced in the LCH, in the RCH it was minimally affected. The DG sidedness after five shocks was nevertheless maintained at the level of arachidonate-containing DGs, which showed a higher accumulation in the LCH than in the RCH. The kinetics of DG removal showed a rapid phase during the first minute following a single or five ECSs. Total DG levels returned to basal values in the RCH, whereas in the LCH they remained slightly increased with respect to the initial levels 1 min after the convulsive episode. Minimal changes occurred in the subsequent 4 min. Chronic ECS altered the endogenous DG content and composition. Thus, 24 h after the last of four ECSs, total levels of DGs diminished by 40% in the RCH, whereas they remained unchanged in the LCH.(ABSTRACT TRUNCATED AT 250 WORDS)

Inflammatory lipid mediators derived from arachidonic acid (AA) and docosahexaenoic acid (DHA) modify the pathophysiology of brain ischemia. The goal of this work was to investigate the formation of eicosanoids and docosanoids generated from AA and DHA, respectively, during no-flow cerebral ischemia. Rats were subjected to head-focused microwave irradiation 5 min following decapitation (complete ischemia) or prior to decapitation (controls). Brain lipids were extracted and analyzed by reverse-phase liquid chromatography-tandem mass spectrometry. After complete ischemia, brain AA, DHA, and docosapentaenoic acid concentrations increased 18-, 5- and 4-fold compared with controls, respectively. Prostaglandin E(2) (PGE(2)) and PGD(2) could not be detected in control microwaved rat brain, suggesting little endogenous PGE(2)/D(2) production in the brain in the absence of experimental manipulation. Concentrations of thromboxane B(2), E(2)/D(2)-isoprostanes, 5-hydroxyeicosatetraenoic acid (5-HETE), 5-oxo-eicosatetraenoic acid, and 12-HETE were significantly elevated in ischemic brains. In addition, DHA products such as mono-, di- and trihydroxy-DHA were detected in control and ischemic brains. Monohydroxy-DHA, identified as 17-hydroxy-DHA and thought to be the immediate precursor of neuroprotectin D(1), was 6.5-fold higher in ischemic than in control brain. The present study demonstrated increased formation of eicosanoids, E(2)/D(2)-IsoPs, and docosanoids following cerebral ischemia. A balance of these lipid mediators may mediate immediate events of ischemic injury and recovery.

51 children with localized cerebral lesions were investigated with the British Ability Scales, Wechsler test, Porteus Mazes, Conners Teacher Rating Scale, and computerized tomography. The extent of the lesions was quantitatively determined. The IQ was 10 points lower in the left hemispheric lesions, although the right hemispheric lesions were larger. When corrected for size of lesions, the IQ is 17 points higher (p less than 0.05) in children with right than with left hemispheric early lesions. The children with left hemispheric lesions had also significantly more behavioural problems (Conners Scale). Children with bilateral lesions had 15 points lower IQ than those with unilateral lesions, although from the slightly larger extent one could expect only 3 points difference. There was no influence of hemiparesis or of epilepsy of the IQ independent of the extent of lesion. There was more plasticity of the hemisphere than of the lobes as shown by Wisconsin Card Sorting data. The higher density of mental capacities in the left cerebral hemisphere of man is explained by more efficient programs, and more dense packing of functions due to more training of the left cerebral hemisphere.

Anatomical Asymmetries Versus Variability of Language Areas of the Brain

Two different experimental procedures were used to examine (a) information-processing differences between two groups of subjects (Cs versus Vs) identified by the form of their conditioned eyeblinks; (b) information-processing differences between the right and left cerebral hemispheres; and (c) parallels between hypothesized C-V differences and right-left hemisphere differences. In the first experiment, the evocative command words BLINK and DON'T BLINK served as positive and negative conditioned stimuli. It was found that Vs gave more conditioned eyeblinks than Cs and that differential eyelid conditioning of Vs more than Cs was influenced by the semantic content of the stimuli. More importantly, the conditioning performance of Cs was more influenced by the semantic attributes of the stimuli when they were presented directly to the right visual field (left hemisphere) than when they were presented directly to the left visual field (right hemisphere). In contrast, the conditioning performance of Vs was equally influenced by the semantic attributes regardless of which hemisphere received direct stimulation. A second experiment was designed to determine whether such hemisphere-of-presentation differences for Cs versus Vs could also be obtained in a very different task. Subjects classified as Cs or Vs during a differential eyelid conditioning task then performed two same-different reaction time (RT) tasks that required discrimination of complex polygons in one case and the names of letters in another. On each RT trial both stimuli of a pair appeared briefly either in the center, left, or right visual field. For both Cs and Vs RTs to complex polygon pairs averaged 20 msec faster on left visual field trials than on right visual field trials, consistent with current hypotheses about right-hemisphere specialization for visuospatial processing. In contrast, the results for letter pairs generally confirmed the C-V differences found in Experiment 1. That is, the right visual field (left-hemisphere) advantage for these verbal stimuli was once again larger for Cs than for Vs. The present results suggest that the two groups of subjects (Cs versus Vs) differ qualitatively in the modes of information processing that they typically employ. The results also suggest that these different modes of processing are related to aspects of cerebral hemisphere organization and that even right-handed individuals may differ from each other in the extent to which each cerebral hemisphere is mobilized for a given experimental task. Such individual differences must be incorporated into both models of classical eyelid conditioning and models of cerebral hemisphere specialization.

Objective To find the sensitive parameters for evaluating the cerebral CT perfusion changes in patients before and after carotid endarterectomy (CEA). Methods Between November 2015 and April 2017,the data of 27 patients who underwent CEA and conducted CT perfusion(CTP) examination before and after the operation were analyzed retrospectively.The different perfusion parameters of the cerebral hemisphere in different areas were analyzed before and after the operation.Absolute perfusion parameters include:cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) and time to peak (TTP);relative perfusion parameters include: rCBV, rCBF, rMTT and rTTP;relative to brainstem perfusion parameters include:sCBV, sCBF, sMTT and sTTP.Paired sample t test (normal distribution of quantitative data) was used to analyze the parameters differences before and after the operation. Results The postoperative perfusion parameters of the operated side cerebral hemisphere compared with the preoperative:(1)The absolute perfusion parameters:the decreased of TTP in frontal lobe,anterior watershed region,middle cerebral artery territory and basal ganglia region[preoperative (22.4±3.0) s, (23.0±3.1) s, (23.2±2.2) s, (21.9±2.7) s,postoperative (20.1±2.4) s, (20.5±2.7) s, (20.7±2.8) s, (19.5±2.8) s] had statistical significance(t values were 2.437, 2.504, 2.882, 2.431, P<0.05).(2)The relative perfusion parameters:the decreased of rMTT in middle cerebral artery territory and basal ganglia region(preoperative 1.18±0.44, 1.06±0.22, postoperative 1.04±0.33, 0.97±0.16) and the decreased of rTTP in middle cerebral artery territory and basal ganglia region(preoperative 1.07±0.15, 1.04±0.05, postoperative 1.00±0.13, 0.97±0.06) had statistical significance(t values were 2.235, 2.244, 2.245, 2.268, P<0.05).(3)The relative to brainstem perfusion parameters:the decreased of sCBV in middle cerebral artery territory(preoperative 1.08±0.16, postoperative 0.98±0.15), the increased of sCBF in frontal lobe and middle cerebral artery territory(preoperative 1.07±0.19, 1.00±0.21,postoperative 1.17±0.21, 1.09±0.20),the decreased of sMTT in middle cerebral artery territory and basal ganglia region(preoperative 1.27±0.29, 0.94±0.11,postoperative 1.05±0.05, 0.86±0.10),the decreased sTTP in frontal lobe,anterior watershed region,middle cerebral artery territory and basal ganglia region(preoperative 1.05±0.05, 1.07±0.06, 1.10±0.08, 1.02±0.03, postoperative 0.97±0.05, 0.96±0.06, 0.98±0.07, 0.95±0.01) had statistical significance(t values were 2.882,-2.995,-2.737, 2.172, 2.425, 2.249, 2.263, 2.806, 3.267, P<0.05). Conclusion CTP is significant to evaluate the changes of cerebral perfusion in patients who underwent CEA. The relative to brainstem parameters are more valuable than relative parameters and absolute parameters in judging the perfusion changes after CEA. Key words: Endarterectomy, carotid; Tomography, X-ray computed; Perfusion imaging; Brain stem; Relative perfusion parameters