Proteomics reveal rat hippocampal lateral asymmetry

Correlational Study of Aminopeptidase Activities between Left or Right Frontal Cortex versus the Hypothalamus, Pituitary, Adrenal Axis of Spontaneously Hypertensive Rats Treated with Hypotensive or Hypertensive Agents

It has been suggested that the neuro-visceral integration works asymmetrically and that this asymmetry is dynamic and modifiable by physio-pathological influences. Aminopeptidases of the renin-angiotensin system (angiotensinases) have been shown to be modifiable under such conditions. This article analyzes the interactions of these angiotensinases between the left or right frontal cortex (FC) and the same enzymes in the hypothalamus (HT), pituitary (PT), adrenal (AD) axis (HPA) in control spontaneously hypertensive rats (SHR), in SHR treated with a hypotensive agent in the form of captopril (an angiotensin-converting enzyme inhibitor), and in SHR treated with a hypertensive agent in the form of the L-Arginine hypertensive analogue L-NG-Nitroarginine Methyl Ester (L-NAME). In the control SHR, there were significant negative correlations between the right FC with HPA and positive correlations between the left FC and HPA. In the captopril group, the predominance of negative correlations between the right FC and HPA and positive correlations between the HPA and left FC was maintained. In the L-NAME group, a radical change in all types of interactions was observed; particularly, there was an inversion in the predominance of negative correlations between the HPA and left FC. These results indicated a better balance of neuro-visceral interactions after captopril treatment and an increase in these interactions in the hypertensive animals, especially in those treated with L-NAME.

Lateralization of the hippocampus: A review of molecular, functional, and physiological properties in health and disease

The hippocampus is a part of the brain's medial temporal lobe that is located under the cortex. It belongs to the limbic system and helps to collect and transfer information from short-term to long-term memory, as well as spatial orientation in each mammalian brain hemisphere. After more than two centuries of research in brain asymmetry, the hippocampus has attracted much attention in the study of brain lateralization. The hippocampus is very important in cognitive disorders, related to seizures and dementia, such as epilepsy and Alzheimer's disease. In addition, the motivation to study the hippocampus has increased significantly due to the asymmetry in the activity of the left and right hippocampi in healthy people, and its disruption during some neurological diseases. After a general review of the hippocampal structure and its importance in related diseases, the asymmetry in the brain with a focus on the hippocampus during the growth and maturation of healthy people, as well as the differences created in patients at the molecular, functional, and physiological levels are discussed. Most previous work indicates that the hippocampus is lateralized in healthy people. Also, lateralization at different levels remarkably changes in patients, and it appears that the most complex cognitive disorder is caused by a new dominant asymmetric system.

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.

Changes in the level of fatty acids in the brain of rats during memory acquisition

Memory acquisition is accompanied by many cellular and molecular processes, and it is not always clear what role they play. Fatty acids (FAs) are known to be important for cognitive functions, but the details of their involvement in memory processes remain unknown. We investigated FAs in the prefrontal cortex and hippocampus of rats trained to perform a task with food reinforcement. The learning consisted of two training sessions, each of which included 10 trials. The results showed that such training altered individual FAs in the brains. The most significant changes were in the prefrontal cortex, where an increase in the level of many FAs occurred, especially after the second training session: palmitic (16:0), stearic (18:0), docosahexaenoic (22:6, n-3), arachidonic (22:4, n-6), docosapentaenoic (22:5, n-6) acids. Changes in the fatty acid level after training in rats were detected only in the left hippocampus, where the levels of palmitic, docosapentaenoic, and docosahexaenoic acids changed. The changes in the right hippocampus were not significant. In both the prefrontal cortex and the left hippocampus, 72 h after training, all FAs returned to control levels. We believe that the main role of a reversible increase in FA levels during memory acquisition is to support and protect cellular processes involved in memory acquisition. Consolidation of memory traces, which occurs mainly in the neocortex, requires protection from external influences, to which FAs makes a significant contribution. They are able to improve neuronal plasticity, enhance local blood flow, improve mitochondrial processes, and suppress pro-inflammatory signals.

Paradoxical Enhancement of Spatial Learning Induced by Right Hippocampal Lesion in Rats

The left–right hemispheric differences in some brain functions are well known in humans. Among them, savant syndrome has unique features, such as exceptional abilities in vision, memory, computation, and music, despite brain abnormalities. In cases of acquired savant and transient savant, brain damage or inhibition is often seen in the left hemisphere, suggesting a link between left hemispheric dysfunction and these talents. On the other hand, some functional left–right differences have been reported in rodent brains, and therefore, unilateral damage in rodents may also result in savant-like enhancements. In the present study, we examined the effects of hippocampal damage on spatial learning in rats with left, right, or bilateral hippocampal lesion. The results showed that learning performance was impaired in the bilateral lesion group, and there was no significant difference in the left lesion group, while performance was enhanced in the right lesion group. These results suggest that damage to the right hippocampus in rats may lead to savant-like enhancement in learning and memory. The construction of the savant model through these results will contribute to the neuroscientific elucidation of the paradoxical phenomenon observed in savants, that some abilities are enhanced despite their brain dysfunction.

Disconnection between Rat’s Left and Right Hemisphere Impairs Short-Term Memory but Not Long-Term Memory

Split-brain experiments, which have been actively conducted since the twentieth century, have provided a great deal of insight into functional asymmetry and inter-hemispheric interactions. However, how communication between the left and right hemispheres directly contributes to memory formation is still poorly understood. To address this issue, we cut the rat commissural fibers prior to performing behavioral tests, which consisted of two short-term and two long-term memory tasks. The result showed that cutting the commissural fibers impairs short-term memory but not long-term memory. This suggests that the left-right hemispheric interaction through the commissural fibers contributes to the appropriate formation of short-term memory, but not that of long-term memory. Our findings would help to elucidate dynamic memory formation between the two hemispheres and contribute to the development of therapeutics for some neurological diseases which cause a reduction in the inter-hemispheric interaction.

Hippocampal asymmetry and regional dispersal of nAChRs alpha4 and alpha7 subtypes in the adult rat

To better comprehend the relationship between left/right (L/R) differences and hippocampus functions is necessary knowledge of lateral asymmetry and regional distribution. This research was design to examine hippocampal L/R asymmetry and regional distribution profile of the alpha7 and alpha4 subtypes of nicotinic acetylcholine receptors (nAChRs) in the adult rat. 10-12-week-old twenty-four male wistar rats were randomly selected. After removing the brains, immunohistochemistry, real-time PCR, and western blot methods were applied to distinguish the presence of the receptors in the hippocampus. Outcomes stated that the mentioned receptors expression profile was spatial-dependent. As, the hippocampal dispersal of alpha7 and alpha4 subtypes in the left hippocampus (LH) was remarkably maximum compare with the right hippocampus (RH) (p = 0.001, p = 0.005 respectively). Furthermore, the alpha7 optical density (OD) was not significantly different in the diverse regions in hippocampus of adult rat (p = 0.057), while the maximum OD of the alpha4 was detected in the hippocampal dentate gyrus and CA3 regions of LH (p = 0.007, p = 0.009 respectively) and the minimum OD was in the CA1 of the RH (p = 0.019). In real time PCR evaluation, there is a significantly higher expression of alpha7 and alpha4 in LH compared to RH (p = 0.043, p = 0.049 respectively), also, for western blot (p = 0.042, p = 0.030 respectively). According to present data, the alpha7 and alpha4 nAChR subtypes expression profile demonstrated lateral asymmetry, the uniform regional dispersal for alpha7 and different regional dispersal for alpha4 in the adult rat hippocampus.

Effect of Gender on Development of Hippocampal Subregions From Childhood to Adulthood

The hippocampus is known to be comprised of several subfields, but the developmental trajectories of these subfields are under debate. In this study, we analyzed magnetic resonance imaging (MRI) data from a cross-sectional sample (198 healthy Chinese) using an automated segmentation tool to delineate the development of the hippocampal subregions from 6 to 26 years of age. We also examined whether gender and hemispheric differences influence the development of these subregions. For the whole hippocampus, the trajectory of development was observed to be an inverse-u. A significant increase in volume with age was found for most of the subregions, except for the L/R-parasubiculum, L/R-fimbria, and L-HATA. Gender-related differences were also found in the development of most subregions, especially for the hippocampal tail, CA1, molecular layer HP, GC-DG, CA3, and CA4, which showed a consistent increase in females and an early increase followed by a decrease in males. A comparison of the average volumes showed that the right whole hippocampus was significantly larger, along with the R-presubiculum, R-hippocampal-fissure, L/R-CA1, and L/R-molecular layer HP in males in comparison to females. Additionally, the average volume of the right hemisphere was shown to be significantly larger for the hippocampal tail, CA1, molecular layer HP, GC-DG, CA3, and CA4. However, for the presubiculum, parasubiculum, and fimbria, the left side was shown to be larger. In conclusion, the hippocampal subregions appear to develop in various ways from childhood to adulthood, with both gender and hemispheric differences affecting their development.

In vivo magnetic resonance imaging reveals the effect of gonadal hormones on morphological and functional brain sexual dimorphisms in adult sheep

Sex differences in the brain and behavior are produced by the perinatal action of testosterone, which is converted into estradiol by the enzyme aromatase in the brain. Although magnetic resonance imaging (MRI) has been widely used in humans to study these differences, the use of animal models, where hormonal status can be properly manipulated, is necessary to explore the mechanisms involved. We used sheep, a recognized model in the field of neuroendocrinology, to assess brain morphological and functional sex differences and their regulation by adult gonadal hormones. To this end, we performed voxel-based morphometry and a resting-state functional MRI approach to assess sex differences in gonadally intact animals. We demonstrated significant sex differences in gray matter concentration (GMC) at the level of the gonadotropic axis, i.e., not only within the hypothalamus and pituitary but also within the hippocampus and the amygdala of intact animals. We then performed the same analysis one month after gonadectomy and found that some of these differences were reduced, especially in the hypothalamus and amygdala. By contrast, we found few differences in the organization of the functional connectome between males and females either before or after gonadectomy. As a whole, our study identifies brain regions that are sexually dimorphic in the sheep brain at the resolution of the MRI and highlights the role of gonadal hormones in the maintenance of these differences.

The role of anti-inflammatory cytokines in memory processing in a healthy brain

The purpose of the work was to study the role of anti-inflammatory cytokines in memory processing in a healthy brain. Wistar rats were trained to perform a task with positive (food) reinforcement; and then the task performance was tested after intraventricular injection of IL-10 or TGF-β1. A microinjection into the brain of either of the two cytokines did not affect the performance of the task and did not have an anti-amnesic effect when the retrieval was deteriorated with scopolamine. In addition, endogenous levels of IL-10 and TGF-β1 were determine in the prefrontal cortex and in the hippocampus after one and two training sessions, consisting of 10 runs each. The level of IL-10 did not change after training both in the prefrontal cortex and in the hippocampus. Endogenous level of TGF-β1 increased in the neocortex after the first training session, the second session, and recovered to the normal level three days after training. In contrast, in the hippocampus, the level of TGF-β1 was decreased: maximally after the first training session in the right hippocampus and after the second training session in the left one. Given the role of the prefrontal cortex in memory processing, we assume that a specific increase of TGF-β1 in the prefrontal cortex may indicate involvement in memory trace consolidation.

Brain Lateralization in Mice Is Associated with Zinc Signaling and Altered in Prenatal Zinc Deficient Mice That Display Features of Autism Spectrum Disorder

A number of studies have reported changes in the hemispheric dominance in autism spectrum disorder (ASD) patients on functional, biochemical, and morphological level. Since asymmetry of the brain is also found in many vertebrates, we analyzed whether prenatal zinc deficient (PZD) mice, a mouse model with ASD like behavior, show alterations regarding brain lateralization on molecular and behavioral level. Our results show that hemisphere-specific expression of marker genes is abolished in PZD mice on mRNA and protein level. Using magnetic resonance imaging, we found an increased striatal volume in PZD mice with no change in total brain volume. Moreover, behavioral patterns associated with striatal lateralization are altered and the lateralized expression of dopamine receptor 1 (DR1) in the striatum of PZD mice was changed. We conclude that zinc signaling during brain development has a critical role in the establishment of brain lateralization in mice.

Mapping orbitofrontal-limbic maturation in non-human primates: A longitudinal magnetic resonance imaging study

Brain development involves spatiotemporally complex microstructural changes. A number of neuropsychiatric disorders are linked to the neural processes of development and aging. Thus, it is important to understanding the typical developmental patterns of various brain structures, which will help to define critical periods of vulnerability for neural maturation, as well as anatomical mechanisms of brain structure-related neuropathology. In this study, we used magnetic resonance imaging to assess development of the orbitofrontal cortex, cingulate cortex, amygdala, and hippocampus in a non-human primate species, the common marmoset (Callithrix jacchus). We collected a total of 114 T2-weighted and 91 diffusion-weighted scans from 23 animals from infancy to early adulthood. Quantitative and qualitative evaluation of age-related brain growth patterns showed non-linear structural developmental changes in all measured brain regions, consistent with reported human data. Overall, robust volumetric growth was observed from 1 to 3 months of age (from infancy to the early juvenile period). This rapid brain growth was associated with the largest decrease in mean, axial, and radial diffusivities of diffusion tensor imaging in all brain regions, suggesting an increase in the number and size of cells, dendrites, and spines during this period. After this developmental period, the volume of various brain regions steadily increased until adolescence (7-13 months of age, depending on the region). Further, structural connectivity derived from tractography data in various brain regions continuously changed from infancy to adolescence, suggesting that the increase in brain volume was related to continued axonal myelination during adolescence. Thereafter, the volume of the cortical regions decreased considerably, while there was no change in subcortical regions. Familial factors, rather than sex, contributed the development of the front-limbic brain regions. Overall, this study provides further data on the factors and timing important for normal brain development, and suggest that the common marmoset is a useful animal model for human neural development.

Left-right functional asymmetry of ventral hippocampus depends on aversiveness of situations

Many studies suggest that animals exhibit lateralized behaviors during aversive situations, and almost all animals exhibit right hemisphere-dominant behaviors associated with fear or anxiety. However, which brain structure in each hemisphere underlies such lateralized function is unclear. In this study, we focused on the hippocampus and investigated the effects of bilateral and unilateral lesions of the ventral hippocampus (VH) on anxiety-like behavior using the successive alleys test. We also examined the expression of c-fos in the VH, which was induced by an aversive situation. Results revealed that consistent right VH dominance trended with the anxiety level. Weaker anxiety induced both right and left VH functions, whereas stronger anxiety induced right VH function. From these results, we conclude that animals are able to adaptively regulate their behaviors to avoid aversive stimuli by changing the functional dominance of their left and right VH.

Hippocampal asymmetry: differences in the left and right hippocampus proteome in the rat model of temporal lobe epilepsy

The hippocampus is a complex brain structure and undergoes severe sclerosis and gliosis in temporal lobe epilepsy (TLE) as the most common type of epilepsy. The key features of the TLE may be reported in chronic animal models of epilepsy, such as pilocarpine model. Therefore, the current study was conducted in a rat pilocarpine model of acquired epilepsy. Two-dimensional gel electrophoresis based proteomic technique was used to compare the proteome map of the left and right hippocampus in both control and epileptic rats. Generally, 95 differentially expressed spots out of 1300 spots were identified in the hippocampus proteome using MALDI-TOF-TOF/MS. Within identified proteins, some showed asymmetric expression related to the mechanisms underlying TLE imposed by pilocarpine. Assessment of lateralization at the molecular level demonstrated that expression of proteins involved in dopamine synthesis was significantly more in the right hippocampus than the left one. In the epileptic model, reduction in dopamine pathway proteins was accompanied by an increase in the expression of proteins involved in polyamine synthesis, referring to a new regulating mechanism. Our results revealed changes in the laterality of protein expression due to pilocarpine-induced status epilepticus that could present some new proteins as potential candidates for antiepileptic drug design.

BIOLOGICAL SIGNIFICANCE

In the current study, two-dimensional gel electrophoresis (2-DE) based proteomic technique was used to profile changes in the left and right hippocampus proteome after pilocarpine induced status epilepticus. Spots of proteome maps for two hemispheres were excised and identified with MALDI-TOF-TOF/MS. Analysis of proteome map of the left and right hippocampus revealed a lateralization at the molecular level, in which the expression of proteins involved in dopamine synthesis and release were significantly more in right hippocampi than the left ones in the normal rats. Also, the expression of proteins involved in polyamine synthesis significantly increased in epileptic hippocampus (considerably higher in right hippocampi), whilst the proteins which included in dopamine pathways were decreased. Our results revealed changes in the laterality of protein expression due to pilocarpine-induced status epilepticus that could present some new proteins as potential candidates for antiepileptic drug design.

Autophagy does not lead to the asymmetrical hippocampal injury in chronic stress

Chronic stress results in hippocampal injury, and impairs learning and memory ability of animals. However the cellular mechanisms underlying cell death within hippocampus remain elusive. The present employed the rat model of chronic unpredicted mild stress (CUMS) and examined the cellular mechanism responsible for learning and memory impairments. The results showed that in correlation to the decreased ability in novelty cognition and reverse learning, CUMS led to loss of CA3 neurons in hippocampus, especially in the right hippocampus. Interestingly, autophagy contributed to the cell loss but was asymmetrical on both sides. This suggested that CUMS resulted in asymmetrical hippocampal injuries, which is not fully determined by autophagy.

Proteomics reveals intersexual differences in the rat brain hippocampus

It is widely accepted that intersexual differences occur in cognitive domains, e.g., in spatial learning and memory. The hippocampus plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. However, it still remains unknown whether the hippocampal proteomic profiling differs between males and females. In this study, we investigated the intersexual differences in protein expression of hippocampi using the two-dimensional electrophoresis analysis. In all, 33 differentially expressed proteins were characterized by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry and validated by Western-blotting analysis. In line with Western-blotting validation, the proteomic identification revealed the overexpression of glial fibrillary acidic protein in female rats' hippocampi, and the overexpression of both creatine kinase B-type and DRP-2 in male rats' hippocampi. The intersexual differences in hippocampal proteomic profiling are probably closely related to those in spatial learning and memory abilities.

Hippocampal asymmetry: differences in structures and functions

The structural asymmetry of bilateral hippocampus in mammals has been well recognized. Recent findings highlighted the accompanying functional asymmetries, as well as the molecular differences of the hippocampus. The present paper summarized these recent advances in understanding the hippocampal asymmetries at molecular, circuit and functional levels. Additionally, the addition of new neurons to the hippocampal circuit during adulthood is asymmetrical. We conclude that these differences in molecules and structures of bilateral hippocampus determined the variances in functionality between the two sides.

Effects of an early experience of reward through maternal contact or its denial on laterality of protein expression in the developing rat hippocampus

Laterality is a basic characteristic of the brain which is detectable early in life. Although early experiences affect laterality of the mature brain, there are no reports on their immediate neurochemical effects during neonatal life, which could provide evidence as to the mechanisms leading to the lateralized brain. In order to address this issue, we determined the differential protein expression profile of the left and right hippocampus of 13-day-old rat control (CTR) pups, as well as following exposure to an early experience involving either receipt (RER) or denial (DER) of the expected reward of maternal contact. Proteomic analysis was performed by 2-dimensional polyacrylamide gel electrophoresis (PAGE) followed by mass spectroscopy. The majority of proteins found to be differentially expressed either between the three experimental groups (DER, RER, CTR) or between the left and right hemisphere were cytoskeletal (34%), enzymes of energy metabolism (32%), and heat shock proteins (17%). In all three groups more proteins were up-regulated in the left compared to the right hippocampus. Tubulins were found to be most often up-regulated, always in the left hippocampus. The differential expression of β-tubulin, β-actin, dihydropyrimidinase like protein 1, glial fibrillary acidic protein (GFAP) and Heat Shock protein 70 revealed by the proteomic analysis was in general confirmed by Western blots. Exposure to the early experience affected brain asymmetry: In the RER pups the ratio of proteins up-regulated in the left hippocampus to those in the right was 1.8, while the respective ratio was 3.6 in the CTR and 3.4 in the DER. Our results could contribute to the elucidation of the cellular mechanisms mediating the effects of early experiences on the vulnerability for psychopathology, since proteins shown in our study to be differentially expressed (e.g. tubulins, dihydropyrimidinase like proteins, 14-3-3 protein, GFAP, ATP synthase, α-internexin) have also been identified in proteomic analyses of post-mortem brains from psychiatric patients.

Exercise influences hippocampal plasticity by modulating brain-derived neurotrophic factor processing

Exercise has been shown to impact brain plasticity and function by involving the action of brain-derived neurotrophic factor (BDNF); however, mechanisms involved are poorly understood. Two types of BDNF coexist in the brain, the precursor (proBDNF) and its mature product (mBDNF), which preferentially bind specific receptors and exert distinct functions. It is crucial to understand how exercise affects crucial steps in the BDNF processing and signaling to evaluate therapeutic applications. We found that 7 days of voluntary exercise increased both pro and mature BDNF in the rat hippocampus. Exercise also increased the activity of tissue-type plasminogen activator (tPA), a serine proteinase shown to facilitate proBDNF cleavage into mBDNF. The blockade of tPA activity reduced the exercise effects on proBDNF and mBDNF. The tPA blocking also inhibited the activation of TrkB receptor, and the TrkB signaling downstream effectors phospho-ERK, phospho-Akt, and phospho-CaMKII. The blocking of tPA also counteracted the effects of exercise on the plasticity markers phospho-synapsin I and growth-associated protein 43 (GAP-43). These results indicate that the effects of exercise on hippocampal plasticity are dependent on BDNF processing and subsequent TrkB signaling, with important implications for neuronal function.

The association between financial hardship and amygdala and hippocampal volumes: results from the PATH through life project

This study examined whether middle-aged adults exposed to poverty in childhood or current financial hardship have detectable brain differences from those who have not experienced such adversity. Structural magnetic resonance imaging (MRI) was conducted as one aspect of the Personality and Total Health (PATH) through life study: a large longitudinal community survey measuring the health and well-being of three cohorts from south-eastern Australia. This analysis considers data from 431 middle-aged adults in the aged 44-48 years at the time of the interview. Volumetric segmentation was performed with the Freesurfer image analysis suite. Data on socio-demographic circumstances, mental health and cognitive performance were collected through the survey interview. Results showed that, after controlling for well-established risk factors for atrophy, adults who reported financial hardship had smaller left and right hippocampal and amygdalar volumes than those who did not report hardship. In contrast, there was no reliable association between hardship and intra-cranial volume or between childhood poverty and any of the volumetric measures. Financial hardship may be considered a potent stressor and the observed results are consistent with the view that hardship influences hippocampal and amygdalar volumes through hypothalamic-pituitary-adrenal axis function and other stress-related pathways.

Osteopontin expression during early cerebral ischemia-reperfusion in rats: enhanced expression in the right cortex is suppressed by acetaminophen

Osteopontin (OPN) is a pleiotropic protein implicated in various inflammatory responses including ischemia-reperfusion (I-R) injury. Two distinct forms of the protein have been identified: an extensively studied secreted form (sOPN) and a less-well-known intracellular form (iOPN). Studies have shown that increased OPN expression parallels the time course of macrophage infiltration into injured tissue, a late event in the development of cerebral infarcts. sOPN has been suggested to promote remodeling of the extracellular matrix in the brain; the function of iOPN may be to facilitate certain signal transduction processes. Here, we studied OPN expression in adult male Sprague-Dawley rats subjected to global forebrain I-R injury. We found iOPN in the cytoplasm of both cortices and the hippocampus, but unexpectedly only the right cortex exhibited a marked increase in the iOPN level after 45 min of reperfusion. Acetaminophen, a drug recently shown to decrease apoptotic incidence, caspase-9 activation, and mitochondrial dysfunction during global I-R, significantly inhibited the increase in iOPN protein in the right cortex, suggesting a role for iOPN in the response to I-R injury in the right cortex.