Neuropsychiatric and Cognitive Symptoms: Two Sides of the Same Coin?

Neuropsychiatric symptoms (NPS) are increasingly being recognized as clinical markers for incipient dementia in Alzheimer's disease (AD dementia). NPS may reinforce cognitive impairment or decline and vice versa. Although NPS are frequent already in mild cognitive impairment, their mechanisms are poorly understood. It is unclear if they share biological mechanisms with cognitive symptoms and how they are associated to structural brain changes, but evidence suggests associations of NPS to cerebral atrophy. An additional NPS dimension in AD dementia concepts might add valuable information to detect patients at risk for AD dementia.

Heritability of cerebral blood flow in adolescent and young adult twins: an arterial spin labeling perfusion imaging study

Blood perfusion is a fundamental physiological property of all organs and is closely linked to brain metabolism. Genetic factors were reported to have important influences on cerebral blood flow. However, the profile of genetic contributions to cerebral blood flow in adolescents or young adults was underexplored. In this study, we recruited a sample of 65 pairs of same-sex adolescent or young adult twins undergoing resting arterial spin labeling imaging to conduct heritability analyses. Our findings indicate that genetic factors modestly affect cerebral blood flow in adolescents or young adults in the territories of left anterior cerebral artery and right posterior cerebral artery, with the primary contribution being to the frontal regions, cingulate gyrus, and striatum, suggesting a profile of genetic contributions to specific brain regions. Notably, the regions in the left hemisphere demonstrate the highest heritability in most regions examined. These results expand our knowledge of the genetic basis of cerebral blood flow in the developing brain and emphasize the importance of regional analysis in understanding the heritability of cerebral blood flow. Such insights may contribute to our understanding of the underlying genetic mechanism of brain functions and altered cerebral blood flow observed in youths with brain disorders.

Neurophysiological measures of auditory sensory processing are associated with adaptive behavior in children with Autism Spectrum Disorder

BACKGROUND

Atypical auditory cortical processing is consistently found in scalp electrophysiological and magnetoencephalographic studies of Autism Spectrum Disorder (ASD), and may provide a marker of neuropathological brain development. However, the relationship between atypical cortical processing of auditory information and adaptive behavior in ASD is not yet well understood.

METHODS

We sought to test the hypothesis that early (100-175 ms) auditory processing in ASD is related to everyday adaptive behavior through the examination of auditory event-related potentials (AEPs) in response to simple tones and Vineland Adaptive Behavior Scales in a large cohort of children with ASD (N = 84), aged 6-17, and in age- and IQ- matched neurotypically (NT) developing controls (N = 132).

RESULTS

Statistical analyses revealed significant group differences in early AEPs over temporal scalp regions (150-175 ms), and the expected rightward lateralization of the AEP (100-125 ms and 150-175 ms) to tonal stimuli in both groups. Lateralization of the AEP (150-175 ms) was significantly associated with adaptive functioning in the socialization domain.

CONCLUSIONS

These results lend support to the hypothesis that atypical processing of sensory information is related to everyday adaptive behavior in autism.

A morphometric analysis of the circumolivary fiber bundle of the human brainstem

The circumolivary fiber bundle (CFB) is considered to be an anatomical variation, which can be found on the surface of the human medulla oblongata. The macroscopical fiber bundle runs downwards from either the anterior median fissure, the pyramid, or both, around the inferior pole of the olive and turns upwards to reach the restiform body of the inferior cerebellar peduncle. Multiple fiber systems feed the constitution of the CFB (collateral corticospinal fibers, fibers connecting to the reticular formation, anterior external arcuate fibers). With this examination we provide a systematic analysis of the frequency of occurrence (6.14%), size, and laterality of the CFB. Including all three fiber bundle parts (descending part, genu, and ascending part), the left-sided sizes were increased. Likewise, the appearance of an unilateral left-sided CFB could be detected in more than 60% of our cases. Our morphometrical analysis currently covers the largest sample of investigated brainstem sides (n = 489) so far. This investigation should widen the perspective on how anatomists, neuroradiologists, and neurosurgeons expect the anterolateral surface of the human medulla oblongata.

Changes in and asymmetry of the proteome in the human fetal frontal lobe during early development

Inherent hemispheric asymmetry is important for cognition, language and other functions. Describing normal brain and asymmetry development during early development will improve our understanding of how different hemispheres prioritize specific functions, which is currently unknown. Here, we analysed developmental changes in and asymmetry of the proteome in the bilateral frontal lobes of three foetal specimens in the late first trimester of pregnancy. We found that during this period, the difference in expression between gestational weeks (GWs) increased, and the difference in asymmetric expression decreased. Changes in the patterns of protein expression differed in the bilateral frontal lobes. Our results show that brain asymmetry can be observed in early development. These findings can guide researchers in further investigations of the mechanisms of brain asymmetry. We propose that both sides of the brain should be analysed separately in future multiomics and human brain mapping studies.

Proteomic analysis of human early fetal brain tissue is undertaken to investigate bilateral developmental changes of protein expression and left-right asymmetries of protein expression.

Comparative Analysis of Lateral Preferences in Patients With Resistant Schizophrenia

BACKGROUND

Schizophrenia is a chronic brain disorder of diverse etiology and clinical presentation. Despite the expansion of treatment methods, between 30 and 50% of cases remain resistant to treatment. In patients with schizophrenia, specifics in the dominant lateralization in the brain function have been discovered. This gave a reason to seek the relation between functional lateralization and the effect of treatment.

METHODS

Of the 105 people observed with schizophrenia, 45 (42.9%) were treatment resistant, and 60 (57.1%) were considered responders. We compared functional lateralization (hand, foot, and eye) between the two groups. Handedness was ascertained by using the Edinburgh Handedness Inventory. The assessment was made at 12 weeks of treatment.

RESULTS

Of all patients with schizophrenia, 41.89% have mixed lateralization, 53.34% are right winged, and 4.76% of the patients are left winged. Resistance of the symptoms shows that 26 (57.78%) are cross-dominated, 18 (40%) are right winged, and 1 (2.22%) is left winged. In patients with clinical remission, 18 (30%) are of mixed dominance, 38 (63.33%) are right winged, and 4 (6.66%) are left winged. From the results for the separate lateralization of the hand, foot, and eye, we found a significant difference only in terms of the dominance of the eye. In 44 (41.9%) of the patients, we found dominance of the left eye. In patients with resistance, the percentage established by us is higher-at 26 (57.8%). These results indicate that the increased percentage of mixed dominance in patients with schizophrenia is mainly due to left-sided lateralization of the eye, especially in those with resistance to treatment.

CONCLUSION

We find an increased number of patients with cross-dominance left eye dominance in patients with schizophrenia. Cross-dominance and left eye dominance are associated with a higher probability of symptom resistance than other forms of lateralization (left-handed or right-handed). The high percentage of cross-dominance is due to the high percentage of left-sided dominance of the eye.

Disrupted Asymmetry of Inter- and Intra-Hemispheric Functional Connectivity at Rest in Medication-Free Obsessive-Compulsive Disorder

Disrupted functional asymmetry of cerebral hemispheres may be altered in patients with obsessive-compulsive disorder (OCD). However, little is known about whether anomalous brain asymmetries originate from inter- and/or intra-hemispheric functional connectivity (FC) at rest in OCD. In this study, resting-state functional magnetic resonance imaging was applied to 40 medication-free patients with OCD and 38 gender-, age-, and education-matched healthy controls (HCs). Data were analyzed using the parameter of asymmetry (PAS) and support vector machine methods. Patients with OCD showed significantly increased PAS in the left posterior cingulate cortex, left precentral gyrus/postcentral gyrus, and right inferior occipital gyrus and decreased PAS in the left dorsolateral prefrontal cortex (DLPFC), bilateral middle cingulate cortex (MCC), left inferior parietal lobule, and left cerebellum Crus I. A negative correlation was found between decreased PAS in the left DLPFC and Yale-Brown Obsessive-compulsive Scale compulsive behavior scores in the patients. Furthermore, decreased PAS in the bilateral MCC could be used to distinguish OCD from HCs with a sensitivity of 87.50%, an accuracy of 88.46%, and a specificity of 89.47%. These results highlighted the contribution of disrupted asymmetry of intra-hemispheric FC within and outside the cortico-striato-thalamocortical circuits at rest in the pathophysiology of OCD, and reduced intra-hemispheric FC in the bilateral MCC may serve as a potential biomarker to classify individuals with OCD from HCs.

The right thalamus may play an important role in anesthesia-awakening regulation in frogs

Background

Previous studies have shown that the mammalian thalamus is a key structure for anesthesia-induced unconsciousness and anesthesia-awakening regulation. However, both the dynamic characteristics and probable lateralization of thalamic functioning during anesthesia-awakening regulation are not fully understood, and little is known of the evolutionary basis of the role of the thalamus in anesthesia-awakening regulation.

Methods

An amphibian species, the South African clawed frog (Xenopus laevis) was used in the present study. The frogs were immersed in triciane methanesulfonate (MS-222) for general anesthesia. Electroencephalogram (EEG) signals were recorded continuously from both sides of the telencephalon, diencephalon (thalamus) and mesencephalon during the pre-anesthesia stage, administration stage, recovery stage and post-anesthesia stage. EEG data was analyzed including calculation of approximate entropy (ApEn) and permutation entropy (PE).

Results

Both ApEn and PE values differed significantly between anesthesia stages, with the highest values occurring during the awakening period and the lowest values during the anesthesia period. There was a significant correlation between the stage durations and ApEn or PE values during anesthesia-awakening cycle primarily for the right diencephalon (right thalamus). ApEn and PE values for females were significantly higher than those for males.

Discussion

ApEn and PE measurements are suitable for estimating depth of anesthesia and complexity of amphibian brain activity. The right thalamus appears physiologically positioned to play an important role in anesthesia-awakening regulation in frogs indicating an early evolutionary origin of the role of the thalamus in arousal and consciousness in land vertebrates. Sex differences exist in the neural regulation of general anesthesia in frogs.

Lateralization of gene expression in the honeybee brain during olfactory learning

In the last decade, it has been demonstrated that brain functional asymmetry occurs not only in vertebrates but also in invertebrates. However, the mechanisms underlying functional asymmetry remain unclear. In the present study, we trained honeybees of the same parentage and age, on the proboscis extension reflex (PER) paradigm with only one antenna in use. The comparisons of gene expression between the left and right hemispheres were carried out using high throughput sequencing. Our research revealed that gene expression in the honeybee brain is also asymmetric, with more genes having higher expression in the right hemisphere than the left hemisphere. Our studies show that during olfactory learning, the left hemisphere is more responsible for long term memory and the right hemisphere is more responsible for the learning and short term memory.

Association between symptoms of psychosis and reduced functional connectivity of auditory cortex

We have previously reported altered functional asymmetry of the primary auditory cortex (Heschl's gyrus) of patients with schizophrenia (SZ) and their relatives during auditory processing. In this study, we investigated whether schizophrenia patients have altered intrinsic functional organization of Heschl's gyrus (HG) during rest. Using functional magnetic resonance imaging (fMRI), we measured functional connectivity between bilateral HG and the whole brain in 24 SZ patients, 22 unaffected first-degree relatives and 24 matched healthy controls. SZ patients and relatives showed altered functional asymmetry in HG and altered connectivity between temporal and limbic areas in the auditory network during resting-state in comparison with healthy controls. These changes in functional connectivity correlated with predisposition towards hallucinations in patients and relatives and with acute positive symptoms in patients. The results are in line with the results from task-related and symptom-mapping studies that investigated the neural correlates of positive symptoms, and suggest that individual psychopathology is associated with aberrant intrinsic organization of auditory regions in schizophrenia. This might be evidence that reduced hemispheric lateralization and reduced functional connectivity of the auditory network are trait markers of schizophrenia.

The brain-heart connection: frontal cortex and left ventricle angiotensinase activities in control and captopril-treated hypertensive rats-a bilateral study

The model of neurovisceral integration suggests that the frontal cortex (FC) and the cardiovascular function are reciprocally and asymmetrically connected. We analyzed several angiotensinase activities in the heart left ventricle (VT) of control and captopril-treated SHR, and we search for a relationship between these activities and those determined in the left and right FC. Captopril was administered in drinking water for 4 weeks. Samples from the left VT and from the left and right FC were obtained. Soluble and membrane-bound enzymatic activities were measured fluorometrically using arylamides as substrates. The weight of heart significantly decreased after treatment with captopril, mainly, due to the reduction of the left VT weight. In the VT, no differences for soluble activities were observed between control and treated SHR. In contrast, a generalized significant reduction was observed for membrane-bound activities. The most significant correlations between FC and VT were observed in the right FC of the captopril-treated group. The other correlations, right FC versus VT and left FC versus VT in controls and left FC versus VT in the captopril group, were few and low. These results confirm that the connection between FC and cardiovascular system is asymmetrically organized.