The hot cross bun sign in corticobasal degeneration.

The hot cross bun (HCB) sign encompasses a cross-shaped hyperintensity area in the pons on axial T2-weighted magnetic resonance imaging (MRI). The HCB sign is characteristic of multiple system atrophy (MSA) and has occasionally been observed in other neurological disorders. Here, we report an autopsied case of corticobasal degeneration (CBD) that showed the HCB sign. A female patient presented with progressive gait disturbance and cognitive impairment at the age of 60 years. A neurological examination revealed dysarthria, muscle rigidity of the limbs, akinesia, truncal ataxia, urinary incontinence, and dementia. The HCB sign was observed on a brain MRI at the age of 65 years, and a clinical diagnosis of possible MSA was made. She died of pneumonia at the age of 67 years. A postmortem observation, provided neuropathological findings characteristic of CBD, including the presence of astrocytic plaques, pretangles, neuropil threads, and ballooned neurons in association with four-repeat-tau aggregation. Interestingly, the pons displayed severe neuronal loss and astrogliosis that were prominent in the pontine and raphe nuclei. Myelin sheath depletion was prominent in the transverse fibers of the pontine base and the myelinated fibers of the pontine tegmentum in contrast to relative sparing of the pontine corticospinal tract and medial lemniscus. The cerebellar dentate nucleus exhibited neuronal loss and grumose degeneration. Western blot analysis of sarkosyl-insoluble fractions from brain tissue lysates using an anti-phosphorylated tau antibody identified immunoreactive signal bands in approximately 37-40, 43, 64, and 68 kDa, consistent with CBD. Genetic analysis did not reveal any known pathogenic mutations in the microtubule-associated protein tau gene (MAPT). Our case was characterized by the HCB sign and concordant neuropathological changes in the pons. CBD should be considered an underlying pathology of the HCB sign, even though the pontocerebellar changes would be unusual in CBD cases.

MAPT subhaplotypes in corticobasal degeneration: assessing associations with disease risk, severity of tau pathology, and clinical features.

The microtubule-associated protein tau (MAPT) H1 haplotype is the strongest genetic risk factor for corticobasal degeneration (CBD). However, the specific H1 subhaplotype association is not well defined, and it is not clear whether any MAPT haplotypes influence severity of tau pathology or clinical presentation in CBD. Therefore, in the current study we examined 230 neuropathologically confirmed CBD cases and 1312 controls in order to assess associations of MAPT haplotypes with risk of CBD, severity of tau pathology (measured as semi-quantitative scores for coiled bodies, neurofibrillary tangles, astrocytic plaques, and neuropil threads), age of CBD onset, and disease duration. After correcting for multiple testing (P < 0.0026 considered as significant), we confirmed the strong association between the MAPT H2 haplotype and decreased risk of CBD (Odds ratio = 0.26, P = 2 × 10-12), and also observed a novel association between the H1d subhaplotype and an increased CBD risk (Odds ratio = 1.76, P = 0.002). Additionally, although not statistically significant after correcting for multiple testing, the H1c haplotype was associated with a higher risk of CBD (Odds ratio = 1.49, P = 0.009). No MAPT haplotypes were significantly associated with any tau pathology measures, age of CBD onset, or disease duration. Though replication will be important and there is potential that population stratification could have influenced our findings, these results suggest that several MAPT H1 subhaplotypes are primarily responsible for the strong association between MAPT H1 and risk of CBD, but that H1 subhaplotypes are unlikely to play a major role in driving tau pathology or clinical features. Our findings also indicate that similarities in MAPT haplotype risk-factor profile exist between CBD and the related tauopathy progressive supranuclear palsy, with H2, H1d, and H1c displaying associations with both diseases.

Circadian Modulation of Neurons and Astrocytes Controls Synaptic Plasticity in Hippocampal Area CA1.

Most animal species operate according to a 24-h period set by the suprachiasmatic nucleus (SCN) of the hypothalamus. The rhythmic activity of the SCN modulates hippocampal-dependent memory, but the molecular and cellular mechanisms that account for this effect remain largely unknown. Here, we identify cell-type-specific structural and functional changes that occur with circadian rhythmicity in neurons and astrocytes in hippocampal area CA1. Pyramidal neurons change the surface expression of NMDA receptors. Astrocytes change their proximity to synapses. Together, these phenomena alter glutamate clearance, receptor activation, and integration of temporally clustered excitatory synaptic inputs, ultimately shaping hippocampal-dependent learning in vivo. We identify corticosterone as a key contributor to changes in synaptic strength. These findings highlight important mechanisms through which neurons and astrocytes modify the molecular composition and structure of the synaptic environment, contribute to the local storage of information in the hippocampus, and alter the temporal dynamics of cognitive processing.

The brain structure of selected trypanorhynch tapeworms.

The brain architecture in four species of tapeworms from the order Trypanorhyncha has been studied. In all species, the brain consists of paired anterior and lateral lobes, and an unpaired central lobe. The anterior lobes connect by dorsal and ventral semicircular commissures; the central and lateral lobes connect by a median and an X-shaped crisscross commissure. In the center of the brain, five well-developed compact neuropils are present. The brain occupies a medial position in the scolex pars bothrialis. The ventral excretory vessels are situated outside the lateral lobes of the brain; the dorsal excretory vessels are located inside the brain and dorsal to the median commissure. The brain gives rize four anterior proboscis nerves and four posterior bulbar nerves with myelinated giant axons (GAs). The cell bodies of the GAs are located within the X-commissure and in the bulbar nerves. Highly developed serotonergic neuropils are present in the anterior and lateral lobes; numerous 5-HT neurons are found in the brain lobes including the central unpaired lobe. The X-cross commissure consists of the α-tub-immunoreactive and 5-HT-IR neurites. Eight ultrastructural types of neurons were found in the brain of the three species investigated. In addition, different types of synapses were present in the neuropils. Glial cells ensheath the brain lobes, the neuropils, the GAs, and the bulbar nerves. Glia cell processes form complex branching patterns of thin cytoplasmic sheets sandwiched between adjacent neural processes and filling the space between neurons. Multilayer myelin-like envelopes and a mesaxon-like structure have been found in Trypanorhyncha nervous system. We compared the brain architecture of Trypanorhyncha with that of an early basal cestode taxon, that is, Diphyllobothriidea, and present a hypothesis about the homology of the anterior brain lobes in order Trypanorhyncha; and the lateral lobes and median commissure are homologous brain structures within Eucestoda.

Fine structure of the nervous system of Cercaria parvicaudata Stunkard & Shaw, 1931 (Digenea, Renicolidae).

The biology of free-living and parasitic Platyhelminthes is diverse. Taking into account the widespread prevalence of parasitic flatworms, Digenea is the least studied group regarding the fine structure of nervous system especially of the cercarial life stage. Here, we present a description of the fine structure of central nervous system (CNS) and two types of uniciliate sensory papillae of xiphidiocercaria Cercaria parvicaudata (Microphalloidea, Renicolidae). The present study documents that C. parvicaudata has a complex nervous system that includes a well-developed ganglion with a cortex of perikarya and glia-like sheaths, myelin-like structures within one of the dorsal nerve cords and four types of polarized synapses between neurites. Different types of neurons in the CNS could not be distinguished on ultrastructural level due to high similarity in their fine structure. Shared polarized synapses with high electron density of presynaptic components are numerous in the neuropile and nerve cords of this larva. Within the larval body, we detected specialized "support" processes that relate to different tissues. Some "support" processes are also closely related to the nervous system of C. parvicaudata, where they are considered as glia-like structures. In this case, the fine structure of glia-like "support" cells of C. parvicaudata differs from those described as glia-like cells in adult flatworms. We suggest a wide prevalence of glia-like cells among cercariae, as well as the fact that glia-like structures in digenean nervous systems can develop from various nonneuronal tissues.

High-Accuracy Detection of Neuronal Ensemble Activity in Two-Photon Functional Microscopy Using Smart Line Scanning.

Two-photon functional imaging using genetically encoded calcium indicators (GECIs) is one prominent tool to map neural activity. Under optimized experimental conditions, GECIs detect single action potentials in individual cells with high accuracy. However, using current approaches, these optimized conditions are never met when imaging large ensembles of neurons. Here, we developed a method that substantially increases the signal-to-noise ratio (SNR) of population imaging of GECIs by using galvanometric mirrors and fast smart line scan (SLS) trajectories. We validated our approach in anesthetized and awake mice on deep and dense GCaMP6 staining in the mouse barrel cortex during spontaneous and sensory-evoked activity. Compared to raster population imaging, SLS led to increased SNR, higher probability of detecting calcium events, and more precise identification of functional neuronal ensembles. SLS provides a cheap and easily implementable tool for high-accuracy population imaging of neural GCaMP6 signals by using galvanometric-based two-photon microscopes.

Fast near-whole-brain imaging in adult Drosophila during responses to stimuli and behavior.

Whole-brain recordings give us a global perspective of the brain in action. In this study, we describe a method using light field microscopy to record near-whole brain calcium and voltage activity at high speed in behaving adult flies. We first obtained global activity maps for various stimuli and behaviors. Notably, we found that brain activity increased on a global scale when the fly walked but not when it groomed. This global increase with walking was particularly strong in dopamine neurons. Second, we extracted maps of spatially distinct sources of activity as well as their time series using principal component analysis and independent component analysis. The characteristic shapes in the maps matched the anatomy of subneuropil regions and, in some cases, a specific neuron type. Brain structures that responded to light and odor were consistent with previous reports, confirming the new technique's validity. We also observed previously uncharacterized behavior-related activity as well as patterns of spontaneous voltage activity.

No difference in the prevalence of Alzheimer-type neurodegenerative changes in the brains of suicides when compared with controls: an explorative neuropathologic study.

Suicide ranks among the leading causes of death for individuals of all ages with highest rates in the elderly. The cause of suicide is considered a multifactorial phenomenon. A variety of neurodegenerative diseases, notably Alzheimer's disease, or, more recently, tauopathies as frontotemporal lobar degeneration or chronic traumatic encephalopathy, has been suggested as risk factor for suicide. Accordingly, we hypothesized that neurodegenerative changes typical of these diseases should be more prevalent in the brains of suicides when compared with controls. Suicides from the German federal state of Hamburg (n = 162) were compared with age- and sex-matched controls who died of other cause. Neuropathological assessment included semiquantitative analysis of neuritic plaques and neurofibrillary tangles visualized with silver stains; in addition, quantitative immunohistochemical analysis of ß-amyloid load and counts of tau-positive neurofibrillary tangles and neuropil threads was done. Univariate analysis and multivariable conditional logistic regression models did not show an effect of any parameter associated with the odds of committing suicide. On the contrary, after stratification for age, older suicide victims (over 48 years) showed lower ß-amyloid loads when compared to controls in the univariate analysis (suicides: 4.7 ± 12.9; controls: 9.9 ± 20.9; p = 0.031; r = - 0.17). In conclusion, neuropathological characteristics of Alzheimer's disease and common tauopathies associated with age seem to be of limited relevance for suicides. However, intact cognition when planning and carrying out complex acts may be of importance in the context of suicide.

Brainstem tau pathology in Alzheimer's disease is characterized by increase of three repeat tau and independent of amyloid ß.

INTRODUCTION: Alzheimer-type neuropil threads (NTs) and neurofibrillary tangles (NFTs) are comprised of either 4 repeat (4R)-tau, 3 repeat (3R)-tau, or a mixture of both. In the hippocampus, the number of NFTs, and the proportion of 3R tau progressively increases. If this preferential accumulation of 3R tau also occurs in the brainstem, it may be fundamentally related to progression of Alzheimer pathology. METHODS: Midbrain and pontine sections of brainstems from 23 cases (Braak-NFT stages I/II: 8, III/IV: 8, and V/VI: 7) were double immunofluorolabeled for 4R and 3R tau. High-resolution (0.645 µm/pixel), in-focus snapshots were tiled to cover entire brain sections using a virtual slide system. Each lesion was classified by size (NT < 200 µm2 < NFT) and staining profile (3R/4R). In addition, the localization and quantity of amyloid ß (Aß) deposits were examined in adjacent sections for comparison with tau. RESULTS: The data sets obtained from approximately 286 gigabytes of image files consisted of 847,763 NTs and 7859 NFTs. The proportion of 3R tau-positive NTs and NFTs in the midbrain, and 3R tau-positive NTs in the pons gradually increased with advancing NFT stages, while the proportion of 3R tau-positive NFTs in the pons was already elevated at early stages. Aß deposits were absent at NFT stages I/II, and when present at later stages, their regional distribution was different from that of tau. These observations suggest that a progressive increase in the proportion of 3R tau occurs independently of Aß deposits. CONCLUSIONS: This is the first quantitative analysis of NFTs and NTs in the human brainstem. We demonstrate that the proportion of 3R tau in the brainstem neurofibrillary changes increases with disease progression. Because this phenomenon is shared between the brainstem and the hippocampus, this increase may be fundamental to the pathogenesis of Alzheimer disease.

Novel Phospho-Tau Monoclonal Antibody Generated Using a Liposomal Vaccine, with Enhanced Recognition of a Conformational Tauopathy Epitope.

The microtubule-associated protein Tau is an intrinsically unfolded, very soluble neuronal protein. Under still unknown circumstances, Tau protein forms soluble oligomers and insoluble aggregates that are closely linked to the cause and progression of various brain pathologies, including Alzheimer's disease. Previously we reported the development of liposome-based vaccines and their efficacy and safety in preclinical mouse models for tauopathy. Here we report the use of a liposomal vaccine for the generation of a monoclonal antibody with particular characteristics that makes it a valuable tool for fundamental studies as well as a candidate antibody for diagnostic and therapeutic applications. The specificity and affinity of antibody ACI-5400 were characterized by a panel of methods: (i) measuring the selectivity for a specific phospho-Tau epitope known to be associated with tauopathy, (ii) performing a combination of peptide and protein binding assays, (iii) staining of brain sections from mouse preclinical tauopathy models and from human subjects representing six different tauopathies, and (iv) evaluating the selective binding to pathological epitopes on extracts from tauopathy brains in non-denaturing sandwich assays. We conclude that the ACI-5400 antibody binds to protein Tau phosphorylated at S396 and favors a conformation that is typically present in the brain of tauopathy patients, including Alzheimer's disease.

An Autopsy Proven Child Onset Chronic Traumatic Encephalopathy

Here we present an autopsy case of chronic traumatic encephalopathy (CTE) in a 36-year-old man. He had a history of febrile seizures at the age of four and was severely demented at age 10 when he was admitted to a mental hospital. He had suffered repetitive self-harm, such as frequent banging of the head on the wall in his hospital record, but he had no clear history between the ages of four and ten. Autopsy revealed global cerebral atrophy, including the basal ganglia, thalamus, hippocampus, amygdala, mammilary bodies and lateral geniculate bodies. This case showed typical pathological features of CTE. Phosphorylated tau (p-tau)-positive neurofibrillary tangles (NFTs) and neuropil threads (NT) we are widely distributed in the brain, especially in the depth of the cerebral sulci. NFT and NT were also found in the basal ganglia, thalamus, amygdala and brainstem. Scanty β-amyloid deposits were found in the motor and sensory cortices, but α-synuclein was completely negative in the brain. This example showed that CTE can occur in young ages and that even children can experience CTE dementia.

Epidemiological pathology of Tau in the ageing brain: application of staging for neuropil threads (BrainNet Europe protocol) to the MRC cognitive function and ageing brain study.

INTRODUCTION: Deposition of abnormally phosphorylated tau (phospho-tau) occurs in Alzheimer's disease but also with brain ageing. The Braak staging scheme focused on neurofibrillary tangles, but abundant p-tau is also present in neuropil threads, and a recent scheme has been proposed by the BrainNet Europe consortium for staging tau pathology based on neuropil threads. We determined the relationship of threads to tangles, and the value of staging for threads in an unselected population-representative ageing brain cohort. We also determined the prevalence of astroglial tau pathologies, and their relationship to neuronal tau. Phospho-tau pathology was determined by immunohistochemistry (AT8 antibody) in the MRC-CFAS neuropathology cohort. Neuropil threads were staged using the BrainNet Europe protocol for tau pathology, and compared with Braak tangle stages. Astroglial tau pathology was assessed in neo-cortical, mesial temporal and subcortical areas. RESULTS: Cases conformed well to the hierarchical neuropil threads staging of the BrainNet Europe protocol and correlated strongly with Braak staging (r=0.84, p < 0.001). Based on the areas under the receiver operator curves (AUC), incorporating either threads or tangle staging significantly improved dementia case identification to a similar degree over age alone (Braak stage X (2)(1)=10.1, p=0.002; BNE stage X (2)(1)=9.7, p=0.002). Thorn-shaped astrocytes, present in 40 % of cases, were most common in mesial temporal lobe, then brainstem, and were associated with subpial tau-positive neurites (mesial temporal: X (2)(1)=61.3, p < 0.001; brainstem: X (2)(1)=47.9, p < 0.001). Adding thorn astrocytes did not improve dementia prediction (AUC: X (2)(1)=0.77, p=0.381), but there was a weak relationship between numbers of areas involved and staging for threads or tangles (r=0.17, p=0.023). Neuropil threads develop hierarchically in parallel with neurofibrillary tangles. CONCLUSIONS: The BrainNet Europe staging protocol is straightforward to apply, and offers similar predictive value for dementia to Braak tangle staging. Astroglial tauopathy, particularly thorn shaped astrocyte formation, does not relate to dementia status, but the association with phospho-tau neurites may suggest a pathogenic relationship to neuronal tau pathology.

Immunohistochemical analysis of hippocampal butyrylcholinesterase: Implications for regional vulnerability in Alzheimer's disease.

Studies of acetylcholine degrading enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in Alzheimer's disease (AD) have suggested their potential role in the development of fibrillar amyloid-ß (Aß) plaques (amyloid plaques). A recent genome-wide association study analysis identified a novel association between genetic variations in the BCHE locus and amyloid burden. We studied BChE immunoreactivity in hippocampal tissue sections from AD and control cases, and examined its relationship with amyloid plaques, neurofibrillary tangles (NFT), dystrophic neurites (DN) and neuropil threads (NT). Compared to controls, AD cases had greater BChE immunoreactivity in hippocampal neurons and neuropils in CA2/3, but not in the CA1, CA4 and dentate gyrus. The majority of amyloid plaques (> 80%, using a pan-amyloid marker X-34) contained discrete neuritic clusters which were dual-labeled with antibodies against BChE and phosphorylated tau (clone AT8). There was no association between overall regional BChE immunoreaction intensity and amyloid plaque burden. In contrast to previous reports, BChE was localized in only a fraction (~10%) of classic NFT (positive for X-34). A similar proportion of BChE-immunoreactive pyramidal cells were AT8 immunoreactive. Greater NFT and DN loads were associated with greater BChE immunoreaction intensity in CA2/3, but not in CA1, CA4 and dentate gyrus. Our results demonstrate that in AD hippocampus, BChE accumulates in neurons and plaque-associated neuritic clusters, but only in a small proportion of NFT. The association between greater neurofibrillary pathology burden and markedly increased BChE immunoreactivity, observed selectively in CA2/3 region, could reflect a novel compensatory mechanism. Since CA2/3 is generally considered more resistant to AD pathology, BChE upregulation could impact the cholinergic modulation of glutamate neurotransmission to prevent/reduce neuronal excitotoxicity in AD hippocampus.

Resilience of precuneus neurotrophic signaling pathways despite amyloid pathology in prodromal Alzheimer's disease.

BACKGROUND: Reduction of precuneus choline acetyltransferase activity co-occurs with greater beta-amyloid (Aß) in Alzheimer's disease (AD). Whether this cholinergic deficit is associated with alteration in nerve growth factor (NGF) signaling and its relation to Aß plaque and neurofibrillary tangle (NFT) pathology during disease onset is unknown. METHODS: Precuneus NGF upstream and downstream signaling levels relative to Aß and NFT pathology were evaluated using biochemistry and histochemistry in 62 subjects with a premortem diagnosis of non-cognitively impaired (NCI; n = 23), mild cognitive impairment (MCI; n = 21), and mild to moderate AD (n = 18). RESULTS: Immunoblots revealed increased levels of proNGF in AD subjects but not MCI subjects, whereas cognate receptors were unchanged. There were no significant differences in protein level for the downstream survival kinase-signaling proteins Erk and phospho-Erk among groups. Apoptotic phospho-JNK, phospho-JNK/JNK ratio, and Bcl-2 were significantly elevated in AD subjects. Soluble Aß1-42 and fibrillar Aß measured by [(3)H] Pittsburgh compound-B ([(3)H]PiB) binding were significantly higher in AD subjects compared with MCI and NCI subjects. The density of plaques showed a trend to increase, but only 6-CN-PiB-positive plaques reached significance in AD subjects. AT8-positive, TOC-1-positive, and Tau C3-positive NFT densities were unchanged, whereas only AT8-positive neuropil thread density was statistically higher in AD subjects. A negative correlation was found between proNGF, phospho-JNK, and Bcl-2 levels and phospho-JNK/JNK ratio and cognition, whereas proNGF correlated positively with 6-CN-PiB-positive plaques during disease progression. CONCLUSIONS: Data indicate that precuneus neurotrophin pathways are resilient to amyloid toxicity during the onset of AD.

[Autopsy case of frontotemporal lobar degeneration with motor neuron disease associated with numerous diffuse plaques, pretangles and neuropil threads].

We report an autopsy case of dementia associated with amyotrophic lateral sclerosis (ALS) in a 73-year-old female. She developed memory impairment at the age of 68 years. Atrophy of her hand muscles was noted at the age of 71 years. She was not aware of her memory impairment or muscle weakness, and was loquacious and euphoric. She was clinically diagnosed as having Alzheimer disease (AD) complicated by ALS with dementia/frontotemporal lobar degeneration with motor neuron disease (ALS-D/FTLD-MND). A neuropathological study confirmed the presence of features of sporadic ALS. Furthermore, severe neuronal loss involving the subiculum and the rostral portion of the medial side of the temporal pole cortex was detected, and TAR DNA-binding protein-43-positive-neuronal cytoplasmic inclusions were identified in the granule cells of the dentate gyrus. These findings were compatible with the pathological features of ALS-D/FTLD-MND. Although many pretangles, neuropil threads and senile plaques were revealed in the degenerated areas, there were few neurofibrillary tangles and typical plaques (Braak stage III, C). Further discussion is required to determine whether AD with ALS-D/FTLD-MND is different from typical AD. This case might be helpful for diagnosing similar cases in the future.

Caspase-6 as a novel early target in the treatment of Alzheimer's disease.

A recent paradigm shift appears to be underway on what scientists believe to be the cause of Alzheimer's disease (AD). The amyloid hypothesis has dominated the field of basic research for the last 25 years, and although these massive efforts have culminated in efficient removal of amyloid from the brains of patients, the absence of beneficial effects for the patient have been greatly disappointing. This has created a shift in the focus on amyloid to a much greater focus on Tau protein, in the hope that preventing tangle formation may inhibit or delay the progression of AD. Although there are promising developments in this area of research, diversifying our efforts to identify novel early targets by understanding the upstream molecular mechanisms that lead to, or occur with, neurofibrillary tangle and plaque formation may provide more efficient therapies against AD. Among many areas in development, an emphasis on the role of caspase-6 (Casp6) activity in early neurodegenerative mechanisms brings hope of a novel target against AD. Casp6 activity is intimately associated with the pathologies that define AD, correlates well with lower cognitive performance in aged individuals, and is involved in axonal degeneration in several cellular and in vivo animal models. This is a review of the evidence showing the relevance of Casp6 activation as an early event that could be inhibited to prevent the progression of AD.

Alzheimer's disease: pathogenesis and prevention.

Tau lesions (pretangles, neuropil threads, neurofibrillary tangles) in select neuronal types are essential to the pathogenesis of Alzheimer's disease. Pretangle formation marks the beginning of the pathological process and is of particular interest because it is temporally closer to the prevailing conditions that induce the pathological process underlying Alzheimer's disease in contrast to late-stage disease. However, not all pretangles convert into neurofibrillary tangles. We propose that the development of tau lesions in Alzheimer's disease is traceable to differences between early- versus late-maturing oligodendrocytes and to the exceptionally protracted myelination of late-developing portions of the human brain. Conclusions drawn from these considerations should encourage development of new preventative and disease-modifying strategies.

Division of labor in the hyperdiverse ant genus Pheidole is associated with distinct subcaste- and age-related patterns of worker brain organization.

The evolutionary success of ants and other social insects is considered to be intrinsically linked to division of labor among workers. The role of the brains of individual ants in generating division of labor, however, is poorly understood, as is the degree to which interspecific variation in worker social phenotypes is underscored by functional neurobiological differentiation. Here we demonstrate that dimorphic minor and major workers of different ages from three ecotypical species of the hyperdiverse ant genus Pheidole have distinct patterns of neuropil size variation. Brain subregions involved in sensory input (optic and antennal lobes), sensory integration, learning and memory (mushroom bodies), and motor functions (central body and subesophageal ganglion) vary significantly in relative size, reflecting differential investment in neuropils that likely regulate subcaste- and age-correlated task performance. Worker groups differ in brain size and display patterns of altered isometric and allometric subregion scaling that affect brain architecture independently of brain size variation. In particular, mushroom body size was positively correlated with task plasticity in the context of both age- and subcaste-related polyethism, providing strong, novel support that greater investment in this neuropil increases behavioral flexibility. Our findings reveal striking levels of developmental plasticity and evolutionary flexibility in Pheidole worker neuroanatomy, supporting the hypothesis that mosaic alterations of brain composition contribute to adaptive colony structure and interspecific variation in social organization.

Enhancement of native and phosphorylated TDP-43 immunoreactivity by proteinase K treatment following autoclave heating.

TDP-43 is a major disease protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with TDP-43 (FTLD-TDP). To evaluate the effectiveness of proteinase K (PK) treatment in antigen retrieval for native and phosphorylated TDP-43 protein, we examined the temporal cortex and spinal cord from patients with sporadic ALS and FTLD-TDP and control subjects. PK treatment following heat retrieval enhanced the immunoreactivity for native TDP-43 in controls as well as for native and phosphorylated TDP-43 in ALS and FTLD-TDP. A significant number of TDP-43-positive neuropil threads were demonstrated in lesions, in which routine immunohistochemistry revealed that the predominant inclusions are cytoplasmic. This retrieval method is the best of immunohistochemical techniques for demonstrating TDP-43 pathology, especially in the neuropil.