Posterior Cerebrum Research Articles

Regional cerebral blood flow correlated with aphasia in dementia of the Alzheimer's type and frontotemporal lobar degeneration.

Individuals with neurocognitive disorders such as dementia of the Alzheimer's type (DAT) and frontotemporal lobar degeneration sometimes show characteristic language dysfunctions. As neurocognitive disorders progress, different types of aphasia may present. To evaluate the disease‑related changes of language functions, and to determine the correlation between the regional cerebral blood flow (rCBF) and language dyfunctions in patients with DAT or the behavioral variant of frontotemporal dementia (bvFTD) or semantic dementia (SD), we used a scale for speech and reading impairment in Japanese (the Standard Language Test for Aphasia [SLTA]), and perfusion single photon emission computed tomography, and we analyzed the relationships among them. Significant differences were identified among the DAT, SD, and bvFTD groups in the SLTA subscales concerning kanji (morphographic) words. There were positive correlations between the SLTA subscales concerning kanji words and the rCBF in left temporo‑occipital regions. The patients with bvFTD showed relative rCBF preservation in the posterior cerebrum compared with the DAT and SD patients. Our results indicate that aphasia for Japanese kanji words might be related to the dysfunction of temporo‑occipital regions, and they suggest that in patients with bvFTD, preserving the CBF in the posterior cerebrum might help maintain the ability to handle morphographic words such as kanji.

Teaching Neuro Images : MRI findings in X-linked adrenoleukodystrophy

A 6-year-old boy presented with 4 months progressive verbal comprehension difficulties, declining school performance, strabismus, and visual impairment. General examination noted moderate hypotension and hyperpigmented skin. Pertinent neurologic examination abnormalities included difficulty with comprehension, decreased visual acuity (20/50 bilaterally), disconjugate gaze, bilateral dysmetria, and unsteady gait. CSF protein was elevated (1.82 g/L). Brain MRI showed posterior cerebrum and brainstem abnormalities consistent with adrenoleukodystrophy1 (figure). Morning cortisol was decreased (21 nM) and adrenocorticotrophic hormone stimulation test confirmed adrenal insufficiency. Diagnosis was confirmed by very long chain fatty acid analysis (elevated C26:0/C22:0 and C24:0/C22:0 ratios) and identification of pathogenic ABCD1 mutation.

Tentorium cerebelli formation during human embryonic and early fetal development.

The morphologies of the fetal tentorium cerebelli (TC) and brain influence each other during development. This study aimed to analyze and more comprehensively understand the three-dimensional morphogenesis of the TC and fetal brain. We examined magnetic resonance imaging from 64 embryonic and fetal specimens (crown-rump length range, 9.2-225 mm). During the embryonic period, the lateral folds of the TC elongated to traverse the middle part of the midbrain. The TC and falx cerebri appeared separated, and no invaginations at the parieto-occipital region were observed. In the early fetal period, the cerebrum covered approximately half of the midbrain. The separation of the dural limiting layer at the parieto-occipital region widened from the posterior cerebrum to the cranial cerebellum. The lateral folds of the TC were spread between its tip, continuous with the falx cerebri, and its base plane, located between the midbrain and rostral hindbrain. Differences in the TC components' growth directions gradually diminished as the cerebrum covered the midbrain. We observed rotation of the TC at its median section according to its growth, which ceased in the middle fetal period. The brainstem and cerebellum extended inferiorly via differential growth, with the cerebrum covering them superiorly. The morphology of the TC curved to conform to the cerebellar and cerebral surfaces. Our present study suggests that factors affecting TC morphology differ between the early and middle fetal periods. Present data provided a more comprehensive view of TC formation according to developmental stage.

Therapeutic hypothermia demonstrates sex-dependent improvements in motor function in a rat model of neonatal hypoxic ischemic encephalopathy

Therapeutic hypothermia demonstrates sex-dependent improvements in motor function in a rat model of neonatal hypoxic ischemic encephalopathy

Variation in brain volume in nine populations and three taxa of the African striped mouse Rhabdomys.

Brain size can vary between populations in different environments because of different selection pressures on behaviours, such as learning and memory, related to spatial, social and environmental differences. We investigated the variation in total and broad-scale regional brain size in the murid rodent genus Rhabdomys from different environments. We assessed taxon-, population- and sex-level differences in total and regional brain volume in three populations each of three taxa (arid-occurring Rhabdomys pumilio and mesic-occurring Rhabdomys dilectus chakae and R. d. dilectus) originating across southern Africa. We μCT-scanned crania obtained from museums in South Africa and used digital software to create endocasts and extract total endocranium and regional volumes: olfactory bulb, anterior cerebrum, posterior cerebrum, cerebellum volume and petrosal volume. Total endocranial volume scaled with basal skull length and all-region volumes scaled with total endocranial volume. We found taxon-, and population-level differences in total endocranial volume. Relative anterior and posterior cerebrum volume did not differ significantly between taxa or populations, but relative cerebellum volume was larger in arid populations than mesic populations. Relative olfactory bulb volume was larger in mesic R. dilectus than in the R. pumilio, but petrosal lobule volume was larger in R. pumilio populations than in R. dilectus. Males had larger total endocranial volumes than females. Drivers of larger total endocranial volumes in R. pumilio are not immediately clear from our results. Environmental seasonality of food availability, cognitive buffering and locomotion may all correlate with total endocranial volume size, whereas the influence of sociality cannot be excluded. The environment and degree of semi-arboreality are likely driving variation in cerebellum, olfactory bulb and petrosal lobule volumes.

Interleukin‐17 Impairs Cerebrovascular Function, Increases Blood‐Brain‐Barrier Permeability, and Induces Cerebral Edema in Pregnant Rats

Cerebrovascular events account for ~40% of all preeclamptic/eclamptic‐related deaths and can induce neurological complications. While placental ischemia can impair cerebrovascular function in women with preeclampsia (PE) and rats which develop a PE‐like syndrome, the placental‐derived factors mediating these effects are elusive. Although pro‐inflammatory cytokines, including Interleukin‐17 (IL‐17), are increased by placental ischemia, it is not known whether IL‐17 disrupts cerebrovascular function during pregnancy. Therefore, we tested the hypothesis that infusion of IL‐17 during pregnancy impairs cerebral blood flow (CBF) autoregulation and myogenic tone, while also promoting increased regional blood‐brain‐barrier (BBB) permeability and brain water content (BWC). Pregnant Sprague Dawley rats were infused with recombinant IL‐17 (150 pg/day) via mini‐osmotic pump (i.p.) from gestational days 14–19. Cerebral blood flow was measured by laser Doppler flowmetry and myogenic tone was assessed in isolated middle cerebral arteries (MCA) by pressure‐flow myography. BWC was determined by quantifying dry:wet weight ratio and BBB permeability was measured by Evans blue extravasation. As previously shown, IL‐17 increased MAP (112 ± 2.5 vs 99.7 ± 2.8 mmHg; p<0.01) compared to pregnant control rats. CBF was significantly greater in IL‐17‐treated pregnant rats at 180 mmHg (187 ± 19 vs 149 ± 22%; p<0.05) and 190 mmHg (215 ± 18 vs 160 ± 23%; p<0.01) compared to pregnant control rats. Myogenic tone peaked at 125 mmHg in the MCA of IL‐17‐treated rats and declined thereafter, forming an inverted‐U curve in response to increases in intraluminal pressure. In contrast, myogenic tone peaked at 175 mmHg in control pregnant rats, forming a hyperbolic curve, which suggests that myogenic responses are blunted at high arterial pressures in IL‐17‐treated rats. BWC tended to increase in the cortex (80.5 ± 0.2 vs. 79.5 ± 0.4%, p = 0.054) and striatum (77.6 ± 0.8 vs. 75.1 ± 1.4%, p = 0.062), and was significantly increased in the posterior cerebrum (79.7 ± 0.4 vs. 77.8 ± 0.5%, p< 0.01) and cerebrum (79.8 ± 0.3 vs. 78.8 ± 0.1%, p< 0.01) of IL‐17‐treated rats. IL‐17 increased BBB permeability in the cortex only (0.017 ± 0.002 vs 0.012 ± 0.002, p<0.05). These data suggest that increases in circulating IL‐17 during pregnancy could contribute to cerebrovascular dysfunction leading to impaired CBF control and myogenic responses, cerebral edema, and increased BBB permeability. IL‐17 may be a potential therapeutic target to prevent or ameliorate neurological impairment in preeclampsia. Future studies examining whether blockade of IL‐17 in placental ischemic rats could prevent cerebrovascular dysfunction may provide valuable insight into the role of cytokines on cerebrovascular health during pregnancy.Support or Funding InformationFunding: R01HL12186106, R01HL136684‐02, R01HL136684, P01HL051971, P20GM104357, 5U54GM115428, T32HL105324, and 19POST34450074.

IMPACT OF MEMORY TRAINING WITH METAMEMORY CONCEPT IN THE ELDERLY WITH SUBJECTIVE MEMORY COMPLAINTS

IMPACT OF MEMORY TRAINING WITH METAMEMORY CONCEPT IN THE ELDERLY WITH SUBJECTIVE MEMORY COMPLAINTS

Effect of cervical manipulation on vertebral artery and cerebral haemodynamics in patients with chronic neck pain: a crossover randomised controlled trial

ObjectiveIt is hypothesised that cervical manipulation may increase the risk of cerebrovascular accidents. We aimed to determine whether cervical spine manipulation is associated with changes in vertebral artery and cerebrovascular...

Postpartum Changes in Microglia Density and Activation in a Rat Model of Superimposed Preeclampsia

Microglia are the primary immune cells of the central nervous system, surveying the microenvironment and responding to cell injury or tissue damage. The Dahl Salt Sensitive (Dahl‐S) rat model of superimposed preeclampsia (PE) has preexisting hypertension and chronic kidney disease and exhibits characteristic symptoms of PE during pregnancy. Preexisting cardiovascular and renal disease increase the risk of superimposed PE, which further increases risk of maternal complications. Recently, we showed that the rat model of placental ischemia (induced preeclampsia) has increased posterior cortical microglia activation 2 months postpartum. However, whether superimposed PE exacerbates postpartum microglia activation is not known. Because the Dahl‐S rat has increased peripheral inflammation (increased circulating TNFα) during pregnancy and exacerbated hypertension and proteinuria with subsequent pregnancies, we hypothesized that the Dahl‐S model has increased microglia activation after two pregnancies. Dahl‐S rats were randomly assigned to virgin (DSV) or postpartum (DSP) groups (n=3 per group). Postpartum rats were mated twice (3 and 5 months of age) and brains were collected at 8 months of age. Posterior cerebrum was cryo‐sectioned and immuno‐stained using ionized calcium binding adapter molecule (Iba1). Microglia density and morphology were analyzed using ImageJ in 3 images per region and averaged per rat. There was no difference in microglia density (number of Iba1+ microglia per image) in the hippocampus (10±2 in DSV vs. 9±1 in DSP) or cortex (7±1 in DSV vs. 7±2 in DSP). DSP rats had higher proportion of hippocampal Type 3 (78% vs. 62% in DSV) and fewer Type 4 (5% vs. 22% in DSV) microglia (p<0.05). DSP had fewer hippocampal amoeboid (activated) microglia and higher cortical ramified (surveying) microglia compared to DSV (Figure). Taken together, history of superimposed preeclampsia symptoms in DSP rats does not induce exacerbated microglia activation suggesting that pregnancy is either protective to the brain or that following damage, microglia fail to activate, contributing to incomplete repair processes. These hypotheses will be tested in future studies. Future studies will also determine cortical and hippocampal cytokine levels and astrocyte activation in the postpartum Dahl‐S rats.Support or Funding InformationNIH R00HL129192, R25HL121042, 5T32HL105324‐09, R01HL134711This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Brain structural changes after multi-strategic metamemory training in older adults with subjective memory complaints: A randomized controlled trial.

BackgroundMetamemory is the process of monitoring and controlling one's memory. Improving metamemory may reduce the memory problem in old age. We hypothesized that metamemory training (MMT) would improve cognition in older adults with subjective memory complaints and change the brain region related to metacognition.MethodWe recruited and randomized older adults to the multi‐strategic memory training of 10 weekly 90‐min sessions, based on the metamemory concept or usual care. Cognitive tests including the Elderly Verbal Learning Test, Simple Rey Figure Test, Digit Span, Spatial Span, Categorical Fluency, and the Boston Naming Test were done in 201 participants, together with magnetic resonance imaging (MRI) in 49 participants before and after training.ResultsA total of 112 in the training group and 89 in the control group participated. The training group had a significant increase in long‐term delayed free recall, categorical fluency, and the Boston Naming test. In MRI, the mean diffusivity of the bundles of axon tracts passing from the frontal lobe to the posterior end of the lateral sulcus decreased in the training group.ConclusionThese results indicate that the MMT program has a positive impact on enhancing older people’ cognitive performance. Improved white matter integrity in the anterior and posterior cerebrum and increased cortical thickness of prefrontal regions, which related to metacognition, possibly suggest that the effects of the MMT would be induced via the enhancement of cognitive control.

Abstract P263: Interleukin-17 Infusion Promotes Cerebral Edema and Increased Blood Brain Barrier Permeability in Pregnant Rats

While cerebrovascular abnormalities such as cerebral edema and increased blood-brain barrier (BBB) permeability are a common complication of (pre)eclampsia, the exact mechanisms underlying these abnormalities remain unclear. One potential mechanism could be increased Interleukin-17 (IL-17), a pro-inflammatory cytokine that is increased in both preeclampsia patients and the rat model of placental ischemia created by reducing uterine perfusion pressure. While IL-17 has been linked to the pathogenesis of preeclampsia, its effect on cerebrovascular function during pregnancy is unknown. Thus, we tested the hypothesis that increasing circulating IL-17 during pregnancy promotes regional increases in brain water content and BBB permeability. Recombinant mouse IL-17 (150 pg/day) was infused via mini-osmotic pump (i.p) from gestational day 14 to 19 in pregnant rats (n = 5-7 per group). Brain water content was assessed using the dry weight to wet weight ratio and BBB permeability was assessed by quantifying Evans blue extravasation into the anterior cerebrum, hippocampus, cortex, striatum, posterior cerebrum, and cerebrum. As reported previously, IL-17 infusion resulted in a significant increase in mean arterial pressure (119 ± 3 vs. 104 ± 4 mmHg in normal pregnant group; p = 0.010). Water content tended to be increased in the cortex (80.5 ± 0.2 vs. 79.5 ± 0.4%, p = 0.054) and striatum (77.6 ± 0.8 vs. 75.1 ± 1.4%, p = 0.062) and was significantly increased in the posterior cerebrum (79.7 ± 0.4 vs. 77.8 ± 0.5%, p = 0.007) and cerebrum (79.8 ± 0.3 vs. 78.8 ± 0.1%, p = 0.005) of the IL-17 treated group. BBB permeability was increased only in the cortex (0.017 ± 0.002 vs 0.012 ± 0.002, p = 0.046) of rats receiving IL-17 infusion. These data suggest that increased IL-17 during pregnancy contributes to edema formation and increased BBB permeability in the cerebral cortex and may be a therapeutic target in preeclampsia. Future studies will determine whether reducing IL-17 levels in placental ischemic rats will prevent these cerebrovascular changes.

Placental ischemia increases seizure susceptibility and cerebrospinal fluid cytokines.

Eclampsia is diagnosed in preeclamptic patients who develop unexplained seizures and/or coma during pregnancy or postpartum. Eclampsia is one of the leading causes of maternal and infant morbidity and mortality, accounting for ∼13% of maternal deaths worldwide. Little is known about the mechanisms contributing to the pathophysiology of eclampsia, partly due to the lack of suitable animal models. This study tested the hypothesis that placental ischemia, induced by reducing utero-placental perfusion, increases susceptibility to seizures, cerebrospinal fluid (CSF) inflammation, and neurokinin B (NKB) expression in brain and plasma. Pentylenetetrazol (PTZ), a pro-convulsive drug, was injected into pregnant and placental ischemic rats (40 mg/kg, i.p.) on gestational day 19 followed by video monitoring for 30 min. Seizure scoring was blindly conducted. Placental ischemia hastened the onset of seizures compared to pregnant controls but had no effect on seizure duration. Placental ischemia increased CSF levels of IL-2, IL-17, IL-18 and eotaxin (CCL11), had no effect on plasma NKB; however, PTZ increased plasma NKB in both pregnant and placental ischemic rats. NKB was strongly correlated with latency to seizure in normal pregnant rats (R2 = 0.88 vs. 0.02 in placental ischemic rats). Lastly, NKB decreased in the anterior cerebrum in response to placental ischemia and PTZ treatment but was unchanged in the posterior cerebrum. These data demonstrate that placental ischemia is associated with increased susceptibility to seizures and CSF inflammation; thus provides an excellent model for elucidating mechanisms of eclampsia-like symptoms. Further studies are required to determine the role of CSF cytokines/chemokines in mediating increased seizure susceptibility.

Placental ischemia-induced increases in brain water content and cerebrovascular permeability: role of TNF-α.

Cerebrovascular complications and increased risk of encephalopathies are characteristic of preeclampsia and contribute to 40% of preeclampsia/eclampsia-related deaths. Circulating tumor necrosis factor-α (TNF-α) is elevated in preeclamptic women, and infusion of TNF-α into pregnant rats mimics characteristics of preeclampsia. While this suggests that TNF-α has a mechanistic role to promote preeclampsia, the impact of TNF-α on the cerebral vasculature during pregnancy remains unclear. We tested the hypothesis that TNF-α contributes to cerebrovascular abnormalities during placental ischemia by first infusing TNF-α in pregnant rats (200 ng/day ip, from gestational day 14 to 19) at levels to mimic those reported in preeclamptic women. TNF-α increased mean arterial pressure (MAP, P < 0.05) and brain water content in the anterior cerebrum (P < 0.05); however, TNF-α infusion had no effect on blood-brain barrier (BBB) permeability in the anterior cerebrum or posterior cerebrum. We then assessed the role of endogenous TNF-α in mediating these abnormalities in a model of placental ischemia induced by reducing uterine perfusion pressure followed by treatment with the soluble TNF-α receptor (etanercept, 0.8 mg/kg sc) on gestational day 18. Etanercept reduced placental ischemia-mediated increases in MAP, anterior brain water content (P < 0.05), and BBB permeability (202 ± 44% in placental ischemic rats to 101 ± 28% of normal pregnant rats). Our results indicate that TNF-α mechanistically contributes to cerebral edema by increasing BBB permeability and is an underlying factor in the development of cerebrovascular abnormalities associated with preeclampsia complicated by placental ischemia.

Placental Ischemia Impairs Cerebral Blood Flow Autoregulation and Increases Blood‐Brain Barrier Permeability in Pregnant Rats

Cerebrovascular events contribute to ~40% of preeclampsia/eclampsia related deaths, and neurological symptoms are common among preeclamptic patients. We previously reported that placental ischemia, induced by reducing utero‐placental perfusion pressure, leads to impaired cerebrovascular myogenic reactivity and cerebral edema in the pregnant rat. Whether the impaired myogenic reactivity is associated with altered cerebral blood flow (CBF) autoregulation and the edema is due to altered blood‐brain barrier (BBB) permeability is unclear. Therefore, we tested the hypothesis that placental ischemia leads to impaired CBF autoregulation and a disruption of the BBB. CBF autoregulation, measured in vivo by laser Doppler flowmetry, was significantly impaired in placental ischemic rats compared to normal pregnant rats. Brain water content was increased in the anterior cerebrum of placental ischemic rats and BBB permeability, assayed using the Evans blue extravasation method, was also increased in the anterior cerebrum. The expression of the tight junction proteins: claudin‐1 was increased in the posterior cerebrum while zonula occludens‐1, and occludin, were not significantly altered in either the anterior or posterior cerebrum. These results are consistent with the hypothesis that placental ischemia mediates anterior cerebral edema through impaired CBF autoregulation and the associated increased transmission of pressure to microvessels, resulting in increased BBB permeability and cerebral edema.

A Case of Posterior Reversible Leukoencephalopathy Syndrome Following Poststreptococcal Glomerulonephritis

Posterior reversible leukoencephalopathy syndrome is a clinical radiographic syndrome of many causative factors. Sudden onset headache, vomiting, altered mental status, blurred vision and seizures are main symptoms shown in posterior reversible leukoencephalopathy syndrome. In addition, it typically shows radiological findings of edema in the white matter of posterior cerebrum, being in commonly bilateral but asym­metric. We report a case of poststreptococcal glomerulonephritis (PSGN) presenting as posterior reversible leukoencephalopathy syndrome. Immediate control of hypertension resulted in rapid and complete neurological recovery.

Placental ischemia in pregnant rats impairs cerebral blood flow autoregulation and increases blood-brain barrier permeability.

Cerebrovascular events contribute to ~40% of preeclampsia/eclampsia‐related deaths, and neurological symptoms are common among preeclamptic patients. We previously reported that placental ischemia, induced by reducing utero‐placental perfusion pressure, leads to impaired myogenic reactivity and cerebral edema in the pregnant rat. Whether the impaired myogenic reactivity is associated with altered cerebral blood flow (CBF) autoregulation and the edema is due to altered blood–brain barrier (BBB) permeability remains unclear. Therefore, we tested the hypothesis that placental ischemia leads to impaired CBF autoregulation and a disruption of the BBB. CBF autoregulation, measured in vivo by laser Doppler flowmetry, was significantly impaired in placental ischemic rats. Brain water content was increased in the anterior cerebrum of placental ischemic rats and BBB permeability, assayed using the Evans blue extravasation method, was increased in the anterior cerebrum. The expression of the tight junction proteins: claudin‐1 was increased in the posterior cerebrum, while zonula occludens‐1, and occludin, were not significantly altered in either the anterior or posterior cerebrum. These results are consistent with the hypothesis that placental ischemia mediates anterior cerebral edema through impaired CBF autoregulation and associated increased transmission of pressure to small vessels that increases BBB permeability leading to cerebral edema.

The Procyonid Social Club: Comparison of Brain Volumes in the Coatimundi (Nasua nasua, N. narica), Kinkajou (Potos flavus), and Raccoon (Procyon lotor)

The present study investigated whether increased relative brain size, including regional brain volumes, is related to differing behavioral specializations exhibited by three member species of the family Procyonidae. Procyonid species exhibit continuums of behaviors related to social and physical environmental complexities: the mostly solitary, semiarboreal and highly dexterous raccoons (Procyon lotor); the exclusively arboreal kinkajous (Potos flavus), which live either alone or in small polyandrous family groups, and the social, terrestrial coatimundi (Nasua nasua, N. narica). Computed tomographic (CT) scans of 45 adult skulls including 17 coatimundis (9 male, 8 female), 14 raccoons (7 male, 7 female), and 14 kinkajous (7 male, 7 female) were used to create three-dimensional virtual endocasts. Endocranial volume was positively correlated with two separate measures of body size: skull basal length (r = 0.78, p < 0.01) and basicranial axis length (r = 0.45, p = 0.002). However, relative brain size (total endocranial volume as a function of body size) varied by species depending on which body size measurement (skull basal length or basicranial axis length) was used. Comparisons of relative regional brain volumes revealed that the anterior cerebrum volume consisting mainly of frontal cortex and surface area was significantly larger in the social coatimundi compared to kinkajous and raccoons. The dexterous raccoon had the largest relative posterior cerebrum volume, which includes the somatosensory cortex, in comparison to the other procyonid species studied. The exclusively arboreal kinkajou had the largest relative cerebellum and brain stem volume in comparison to the semi arboreal raccoon and the terrestrial coatimundi. Finally, intraspecific comparisons failed to reveal any sex differences, except in the social coatimundi. Female coatimundis possessed a larger relative frontal cortical volume than males. Social life histories differ in male and female coatimundis but not in either kinkajous or raccoons. This difference may reflect the differing social life histories experienced by females who reside in their natal bands, and forage and engage in antipredator behavior as a group, while males disperse upon reaching adulthood and are usually solitary thereafter. This analysis in the three procyonid species supports the comparative neurology principle that behavioral specializations correspond to an expansion of neural tissue involved in that function.

1033 Central Neurogenic Hyperventilation May Cause Metabolic Alkalosis in Mitochondrial Encephalopathy

BackgroundThe differential diagnosis of respiratory alkalosis (RA) includes a state called central neurogenic hyperventilation (CNH). In the few reported cases of CNH the etiology was a stimulation of the respiratory...

Effect of Pregnancy on Autoregulation of Cerebral Blood Flow in Anterior Versus Posterior Cerebrum

Severe preeclampsia and eclampsia are associated with brain edema that forms preferentially in the posterior cerebral cortex possibly because of decreased sympathetic innervation of posterior cerebral arteries and less effective autoregulation during acute hypertension. In the present study, we examined the effect of pregnancy on the effectiveness of cerebral blood flow autoregulation using laser Doppler flowmetry and edema formation by wet:dry weight in acute hypertension induced by phenylephrine infusion in the anterior and posterior cerebrum from nonpregnant (n=8) and late-pregnant (n=6) Sprague-Dawley rats. In addition, we compared the effect of pregnancy on sympathetic innervation by tyrosine hydroxylase staining of posterior and middle cerebral arteries (n=5-6 per group) and endothelial and neuronal NO synthase expression using quantitative PCR (n=3 per group). In nonpregnant animals, there was no difference in autoregulation between the anterior and posterior cerebrum. However, in late-pregnant animals, the threshold of cerebral blood flow autoregulation was shifted to lower pressures in the posterior cerebrum, which was associated with increased neuronal NO synthase expression in the posterior cerebral cortex versus anterior. Compared with the nonpregnant state, pregnancy increased the threshold of autoregulation in both brain regions that was related to decreased expression of endothelial NO synthase. Lastly, acute hypertension during pregnancy caused greater edema formation in both brain cortices that was not attributed to changes in sympathetic innervation. These findings suggest that, although pregnancy shifted the cerebral blood flow autoregulatory curve to higher pressures in both the anterior and posterior cortices, it did not protect from edema during acute hypertension.

Pride Diaries: Sex, Brain Size and Sociality in the African Lion (Panthera leo) and Cougar (Puma concolor)

The purpose of this study was to examine if differences in social life histories correspond to intraspecific variation in total or regional brain volumes in the African lion (Panthera leo) and cougar (Puma concolor). African lions live in gregarious prides usually consisting of related adult females, their dependent offspring, and a coalition of immigrant males. Upon reaching maturity, male lions enter a nomadic and often, solitary phase in their lives, whereas females are mainly philopatric and highly social throughout their lives. In contrast, the social life history does not differ between male and female cougars; both are solitary. Three-dimensional virtual endocasts were created using computed tomography from the skulls of 14 adult African lions (8 male, 6 female) and 14 cougars (7 male, 7 female). Endocranial volume and basal skull length were highly correlated in African lions (r = 0.59, p < 0.05) and in cougars (r = 0.67, p < 0.01). Analyses of total endocranial volume relative to skull length revealed no sex differences in either African lions or cougars. However, relative anterior cerebrum volume comprised primarily of frontal cortex and surface area was significantly greater in female African lions than males, while relative posterior cerebrum volume and surface area was greater in males than females. These differences were specific to the neocortex and were not found in the solitary cougar, suggesting that social life history is linked to sex-specific neocortical patterns in these species. We further hypothesize that increased frontal cortical volume in female lions is related to the need for greater inhibitory control in the presence of a dominant male aggressor.