Attribution of Biases of Interhemispheric Temperature Contrast in CMIP6 Models

One of the basic characteristics of Earth's modern climate is that the Northern Hemisphere(NH) is climatologically warmer than the Southern Hemisphere(SH). Here, model performances of this basic state are examined using simulation results from 26 CMIP6 models. Results show that the CMIP6 models underestimate the contrast in interhemispheric surface temperatures on average(0.8 K for CMIP6 mean versus 1.4 K for reanalysis data mean), and that there is a large intermodel spread, ranging from -0.7 K to 2.3 K. A box model energy budget analysis shows that the contrast in interhemispheric shortwave absorption at the top of the atmosphere, the contrast in interhemispheric greenhouse trapping, and the crossequatorial northward ocean heat transport, are all underestimated in the multimodel mean. By examining the intermodel spread, we find intermodel biases can be tracked back to biases in midlatitude shortwave cloud forcing in AGCMs. Models with a weaker interhemispheric temperature contrast underestimate the shortwave cloud reflection in the SH but overestimate the shortwave cloud reflection in the NH, which are respectively due to underestimation of the cloud fraction over the SH extratropical ocean and overestimation of the cloud liquid water content over the NH extratropical continents.Models that underestimate the interhemispheric temperature contrast exhibit larger double ITCZ biases, characterized by excessive precipitation in the SH tropics. Although this intermodel spread does not account for the multimodel ensemble mean biases, it highlights that improving cloud simulation in AGCMs is essential for simulating the climate realistically in coupled models.

Functional topography of the corpus callosum investigated by DTI and f MRI

This short review examines the most recent functional studies of the topographic organization of the human corpus callosum, the main interhemispheric commissure. After a brief description of its anatomy, development, microstructure, and function, it examines and discusses the latest findings obtained using diffusion tensor imaging(DTI) and tractography(DTT) and functional magnetic resonance imaging(f MRI), three recently developed imaging techniques that have significantly expanded and refined our knowledge of the commissure. While DTI and DTT have been providing insights into its microstructure, integrity and level of myelination, f MRI has been the key technique in documenting the activation of white matter fibers, particularly in the corpus callosum. By combining DTT and f MRI it has been possible to describe the trajectory of the callosal fibers interconnecting the primary olfactory, gustatory, motor, somatic sensory, auditory and visual cortices at sites where the activation elicited by peripheral stimulation was detected by fMRI. These studies have demonstrated the presence of callosal fiber tracts that cross the commissure at the level of the genu, body, and splenium, at sites showing f MRI activation. Altogether such findings lend further support to the notion that the corpus callosum displays a functional topographic organization that can be explored with f MRI.

On the Interrelation between Spring Bihemispheric Circulations at Middle and High Latitudes

Bihemispheric atmospheric interaction and teleconnection allow us to deepen our understanding of large-scale climate and weather variability. This study uses 1979-2017 spring NCEP reanalysis to show that there is interrelation between bihemispheric circulations at the extratropics. This is regarded as a significant negative correlation between the Antarctic and the Arctic regional surface air pressure anomalies, which is induced by interhemispheric oscillation (IHO) of the atmospheric mass. The spatial pattern of IHO is characterized by antiphase extratropical airmass anomalies and geopotential height anomalies from the troposphere to stratosphere between the Southern and Northern Hemisphere. IHO is closely related to stronger bihemispheric low-frequency signals such as Antarctic Oscillation and Arctic Oscillation, thereby demonstrating that IHO can be interpreted as a tie in linking these two dominant extratropical circulations of both hemispheres. IHO is associated with a strong meridional teleconnection in zonal winds from the middle-high troposphere to the lower stratosphere, with the wind anomalies in the form of alternate positive-negative wavy bands extending from the Antarctic to Arctic region, which act as a possible approach to interactions between the bihemispheric atmospheric mass. It is argued that IHO-related omega angular momentum anomalies led by the extratropical atmosphere cause the meridional teleconnection of relative angular momenta, thereby giving rise to the zonal wind anomalies. The modeling of GFDL and UKMO as components of the CMIP5 project have been verified, achieving the related IHO structure shown in the present paper.

Glacial Thermohaline Circulation and Climate:Forcing from the North or South?

Based on the evidence available from both observations and model simulations, the author proposes a view that may provide a unified interpretation of the North Atlantic thermohaline variability. Because of the slow response time of the Southern Ocean （millennia） and the relatively faster response time of the North Atlantic （centuries）, the North Atlantic thermohaline circulation is controlled predominantly by the climate forcing over the Southern Ocean at the long glacial cycle timescales, but by the North Atlantic climate forcing at the short millennial timescaies.

Description of interhemispheric disconnection syndrome in a patient with Marchiafava-Bignami disease

Interhemispheric disconnection syndrome (IDS), described by Sperry, Gazzaniga and Bogen, is characterized by the presence of visual and tactile anomia, absence of interhemispheric transference of unilateral somatosensory stimulation of both hands, hemialexia and unilateral left-side apraxia. Subsequently, changes were also observed in the sensory interhemispheric transfer and in tests of crossed motor control. In Marchiafava-Bignami disease (MBD) there have been descriptions of partial IDS. The aim is to describe the dissociations in IDS that are presented in a patient with MBD, using a specialized assessment methodology. Patient and Method: A 54-year-old patient, righthanded, with 11 years of schooling, presented with antecedent chronic alcoholism. Neuropsychological tests were administered for general assessment along with specific tests of interhemispheric transference. Results: Borderline changes were found in visual memory, visual-constructive abilities and attention and executive functioning. In tasks of interhemispheric transference the patient showed changes in: the imitation of hand poses;inter-manual pressure point localization (tactile stimulation);reading aloud of words by visual hemifield;and movement control. Conclusion: Our patient showed a wide lesion of the Corpus Callosum (CC) with relative preservation of the splenium, accompanied by partial disconnection syndrome in the context of a global cognitive deterioration from his chronic alcoholism.

Sea Surface Temperature Anomaly and Precipitation Distribution in the Alagoas State of the Brazilian Northeast

Precipitation data of 17 pluviometrical stations in the Alagoas State of the Brazilian Northeast and global spatial distribution of the Sea Surface Temperature Anomaly (SSTA) were analyzed for the period of 1981-2007. Techniques of constructing composite charts for SSTA fields are used to study the interrelation between the ocean thermal state with precipitation more than 50 mm/24 h, 20 mm/24 h or without precipitation for six ambient regions of the state. The student test is used for estimating statistical characteristics of the composites. Synoptic-scale pattern analyses of the composites reveal strikingly different spatial distribution of SSTA within each composite. The El Niño Southern Oscillation cycle refers to the coherent, large-scale fluctuation of ocean temperatures. At the highest ambient regions during heavy precipitation days, more intensive SSTA was observed. The lowest anomalies were observed for all types of precipitation in the semi-arid region. Quantile analyses of NCEP/NCAR indexes of SSTA distribution, such as NATL, SATL, TROP and RNASA were used too. Positive SSTA values in tropical regions are associated with the highest possibility of precipitation formation. The SST interhemispheric north-south gradient in equatorial regions of the North and South Atlantic has direct influence on the precipitation formation in the Alagoas State.

Lagged Coherence of Photon Emissions and Spectral Power Densities between the Cerebral Hemispheres of Human Subjects during Rest Conditions: Phase Shift and Quantum Possibilities

Photon counts about 15 cm from the left and right sides of the head while subjects sat quietly during baseline conditions within a hyper-dark chamber were measured by photomultiplier units. Lag/lead analyses for photon emissions between the two hemispheres indicated a weak but statistically significant correlation between the amplitude fluctuations that were separated by about 800 to 900 ms. Analyses of the spectral power densities of photon amplitude variations from the left and right hemispheres revealed peak values between 2 and 3 Hz which were equivalent to a difference of about 900 ms. The radiant flux densities were estimated to be in the order of 10?12 W?m?2 and to include the equivalence of about 107 neurons. Our calculations, which accounted for the small magnitude of the strength of the interhemispheric coefficients, suggest that the coherence could be strongly correlated with processes associated with the unmyelinated axons with diameters between 400 to 800 nm, the visible wavelengths, within the corpus callosum. When the ratio of the phase shift was applied to the Aharanov-Bohm equation, the time required for a photon-related electron to be within a cerebral magnetic field was the same duration as a single orbit of an electron and a photon’s traversal latency across a neuronal plasma membrane. We suggest that the peak photon decoherence between the two cerebral hemispheres may reveal a neuronal-quanta substrate to the conditions associated with consciousness.

Interhemispheric atmospheric mass oscillation and its relation to interannual variations of the Asian monsoon in boreal summer

Using NCEP/NCAR reanalysis and precipitation records of Chinese stations, we have investigated the relationship of interhemispheric oscillation of air mass (IHO) with global lower-level circulation and monsoon anomalies in boreal summer. Our results show that the summer IHO explains a greater portion of variance in the abnormal distribution of atmospheric mass over 30°S-60°N as well as the Antarctic. The IHO strongly correlates to the variations of sea level pressure (SLP) in these regions. It is shown that IHO has some influences on both atmospheric mass transports and water vapor fluxes over 30°S-60°N in association with three anomalous cyclonic circulations over land areas of the eastern hemisphere, which is in close relation to the changes in summer monsoon intensity in eastern Asia and western Africa. Composites of summer rainfall anomalies in China for high and low IHO-index years indicate that the eastern Asian summer monsoon is more intense, with positive precipitation anomaly centers in northern and northeastern parts of China, as opposed to the negative center over the mid-lower reaches of the Yangtze River (MLRYR) in stronger IHO years. In weak IHO years, a feeble summer monsoon appears in eastern Asia, leading to positive center of precipitation anomalies displaced into the MLRYR. Furthermore, a teleconnection in wind fields between the western African and eastern Asian monsoon regions was observed in the middle and higher troposphere in the scenario of IHO. The anomalous cyclonic (anticyclonic) circulations along the path of this Africa-East Asia teleconnection were found to be just over the diabatic heating (cooling) centers, suggesting that diabatic forcings are responsible for the formation of this Africa-East Asia teleconnection.

Interhemispheric Subdural Empyema Secondary to Sinusitis in an Adolescent Girl

To the Editor:With the advent of antibiotics application,intracranial complications of paranasal sinusitis,including meningitis, intracranial abscess,subdural empyema (SDE),epidural abscess, cavernous sinus thrombosis,and thrombosis of other dural sinuses, have become uncommon. However,SDE is still a life-threatening disease entity.It is defined as a purulent collection between dura mater and arachnoid.The most common cause of SDE is sinusitis.Other causes include meningitis,otitis media,operative infection,head trauma,and bacteremic seeding of previous subdural hematoma, Here,we present a rapidly progressive case ofinterhemispheric SDE following sinusitis.Clinicians should be aware of SDE when the patient presents with headache and fever,and neuroimaging manifests as a dilated subdural space especially in adolescent with sinusitis.

Reduced homotopic interhemispheric connectivity in psychiatric disorders:evidence for both transdiagnostic and disorder specific features

There is considerable interest in the significance of structural and functional connections between the two brain hemispheres in terms of both normal function and in relation to psychiatric disorders.In recent years,many studies have used voxel mirrored homotopic connectivity analysis of resting state data to investigate the importance of connectivity between homotopic regions in the brain hemispheres in a range of neuropsychiatric disorders.The current review summarizes findings fromthese voxel mirrored homotopic connectivity studies in individuals with autism spectrum disorder,addiction,attention deficit hyperactivity disorder,anxiety and depression disorders,and schizophrenia,aswell as disorders such as Alzheimer’s disease,mild cognitive impairment,epilepsy,and insomnia.Overall,other than attention deficit hyperactivity disorder,studies across psychiatric disorders report decreased homotopic resting state functional connectivity in the default mode,attention,salience,sensorimotor,social cognition,visual recognition,primary visual processing,and reward networks,which are often associated with symptom severity and/or illness onset/duration.Decreased homotopic resting state functional connectivity may therefore represent a transdiagnostic marker for general psychopathology.In terms of disorder specificity,the extensive decreases in homotopic resting state functional connectivity in autism differ markedly from attention deficit hyperactivity disorder,despite both occurring during early childhood and showing extensive co-morbidity.A pattern of more posterior than anterior regions showing reductions in schizophrenia is also distinctive.Going forward,more studies are needed to elucidate the functions of these homotopic functional connections in both health and disorder and focusing on associations with general psychopathology,and not only on disorder specific symptoms.

Preliminary study of inter-hemispheric resting-state mirror functional homotopy in drug-naive patients with obsessive-compulsive disorder

Objective To explore the pattern of inter-hemispheric resting-state mirror functional homotopy in the drugnaive obsessive-compulsive disorder(OCD).Methods Twenty patients with OCD meeting the DSM-Ⅳ-TR criteria and 20 gender-,age-,education-matched healthy subjects participated in the resting-state brain functional magnetic resonance imaging scan.The Y-BOCS,HAMD1 7 and HAMA were used to assess the clinical symptoms(i.e.obsessive,compulsive,depressive and anxiety symptoms).Based on the data processing & analysis for(resting-state)brain imaging(DPABI)software,a voxel-mirrored homotopic connectivity(VMHC)approach was used to explore the pattern of inter-hemispheric resting-state mirror functional homotopy in OCD;partial correlation analysis was used to analyze the relationship between the whole brain VMHC value and clinical symptoms in OCD.Results Compared with the controls,the OCD patients showed decreased VMHC values in the orbitofrontal cortex(0.76±0.23 vs.0.39±0.13,t=-5.46,P<0.01,gaussian random field corrected,two-tailed);the VMHC value of bilateral dorsolateral prefrontal cortex was negatively correlated with obsessive thought(r=-0.912,P<0.01,Bonferroni correction).Conclusion Reduced interhemispheric resting-state functional homotopy in the orbitofrontal cortex is observed in OCD patients,and the interhemispheric resting-state functional homotopy in the bilateral dorsolateral prefrontal cortex may be related with obsessive thought of OCD patients.