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Intracellular copper [Cu(I)] has been hypothesized to play role in the differentiation of the neurons. This necessitates understanding the role of Cu(I) not only in the neurons but also in the glia considering their anatomical proximity, contribution towards ion homeostasis, and neurodegeneration. In this study, we did a systematic investigation of the changes in the cellular copper homeostasis during neuronal and glial differentiation and the pathways triggered by them. Our study demonstrates increased mRNA for the plasma membrane copper transporter CTR1 leading to increased Cu(I) during the neuronal (PC-12) differentiation. ATP7A is retained in the trans-Golgi network (TGN) despite high Cu(I) demonstrating its utilization towards the neuronal differentiation. Intracellular copper triggers pathways essential for neurite generation and ERK1/2 activation during the neuronal differentiation. ERK1/2 activation also accompanies the differentiation of the foetal brain derived neuronal progenitor cells. The study demonstrates that ERK1/2 phosphorylation is essential for the viability of the neurons. In contrast, differentiated C-6 (glia) cells contain low intracellular copper and significant downregulation of the ERK1/2 phosphorylation demonstrating that ERK1/2 activation does not regulate the viability of the glia. But ATP7A shows vesicular localization despite low copper in the glia. In addition to the TGN, ATP7A localizes into RAB11 positive recycling endosomes in the glial neurites. Our study demonstrates the role of copper dependent ERK1/2 phosphorylation in the neuronal viability. Whereas glial differentiation largely involves sequestration of Cu(I) into the endosomes potentially (i) for ready release and (ii) rendering cytosolic copper unavailable for pathways like the ERK1/2 activation.

Significance: Recent advances in nonlinear optics in neuroscience have focused on using two ultrafast lasers for activity imaging and optogenetic stimulation. Broadband femtosecond light sources can obviate the need for multiple lasers by spectral separation for chromatically targeted excitation. Aim: We present a photonic crystal fiber (PCF)-based supercontinuum source for spectrally resolved two-photon (2P) imaging and excitation of GCaMP6s and C1V1-mCherry, respectively. Approach: A PCF is pumped using a 20-MHz repetition rate femtosecond laser to generate a supercontinuum of light, which is spectrally separated, compressed, and recombined to image GCaMP6s (930 nm excitation) and stimulate the optogenetic protein, C1V1-mCherry (1060 nm excitation). Galvanometric spiral scanning is employed on a single-cell level for multiphoton excitation and high-speed resonant scanning is employed for imaging of calcium activity. Results: Continuous wave lasers were used to verify functionality of optogenetic activation followed by directed 2P excitation. Results from these experiments demonstrate the utility of a supercontinuum light source for simultaneous, single-cell excitation and calcium imaging. Conclusions: A PCF-based supercontinuum light source was employed for simultaneous imaging and excitation of calcium dynamics in brain tissue. Pumped PCFs can serve as powerful light sources for imaging and activation of neural activity, and overcome the limited spectra and space associated with multilaser approaches.

Significance: Wide-field measurement of cellular membrane dynamics with high spatiotemporal resolution can facilitate analysis of the computing properties of neuronal circuits. Quantum microscopy using a nitrogen-vacancy (NV) center is a promising technique to achieve this goal. Aim: We propose a proof-of-principle approach to NV-based neuron functional imaging. Approach: This goal is achieved by engineering NV quantum sensors in diamond nanopillar arrays and switching their sensing mode to detect the changes in the electric fields instead of the magnetic fields, which has the potential to greatly improve signal detection. Apart from containing the NV quantum sensors, nanopillars also function as waveguides, delivering the excitation/emission light to improve sensitivity. The nanopillars also improve the amplitude of the neuron electric field sensed by the NV by removing screening charges. When the nanopillar array is used as a cell niche, it acts as a cell scaffolds which makes the pillars function as biomechanical cues that facilitate the growth and formation of neuronal circuits. Based on these growth patterns, numerical modeling of the nanoelectromagnetics between the nanopillar and the neuron was also performed. Results: The growth study showed that nanopillars with a 2-μm pitch and a 200-nm diameter show ideal growth patterns for nanopillar sensing. The modeling showed an electric field amplitude as high as ≈1.02×1010 mV/m at an NV 100 nm from the membrane, a value almost 10 times the minimum field that the NV can detect. Conclusion: This proof-of-concept study demonstrated unprecedented NV sensing potential for the functional imaging of mammalian neuron signals.

Animal models of stroke are used extensively to study the mechanisms involved in the acute and chronic phases of recovery following stroke. A translatable animal model that closely mimics the mechanisms of a human stroke is essential in understanding recovery processes as well as developing therapies that improve functional outcomes. We describe a photo-thrombosis stroke model that is capable of targeting a single distal pial branch of the middle cerebral artery with minimal damage to the surrounding parenchyma in awake head-fixed mice. Mice are implanted with chronic cranial windows above one hemisphere of the brain that allow optical access to study recovery mechanisms for over a month following occlusion. Additionally, we study the effect of laser spot size used for occlusion and demonstrate that a spot size with small axial and lateral resolution has the advantage of minimizing unwanted photodamage while still monitoring macroscopic changes to cerebral blood flow during photothrombosis. We show that temporally guiding illumination using real-time feedback of blood flow dynamics also minimized unwanted photodamage to the vascular network. Finally, through quantifiable behavior deficits and chronic imaging we show that this model can be used to study recovery mechanisms or the effects of therapeutics longitudinally. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.

Neuron cells consist of the soma or cell body, axons, dendritic arbor with multiple branches, and dendritic spines which are the substrates for memory storage and synaptic transmission. Detriments in neuron morphology are suggested to play a key role in cognitive impairments following brain irradiation. Multiple molecular mechanisms are involved in the regulation and stability of neuron morphology, while the effects of radiation on these processes have not been studied extensively. In this report, we consider possible biological targets in neurons for energy deposition (ED) by charged particles that could lead to neuron morphology detriments, and the resulting dose and radiation quality dependence of such detriments. The track structures of heavy ions including high charge and energy (HZE) particles consists of core of high-ED events and a penumbra of sparse ED from δ-ray electrons produced in ionization of target molecules. We consider the role of track structure relative to possible targets causative in the degradation of morphology.

Pointing is one of the communicative actions that infants acquire during their first year of life. Based on a hypothesis that early pointing is triggered by emergent reaching behavior toward objects placed at out‐of‐reach distances, we proposed a neural network model that acquires reaching without explicit representation of ‘targets’. The proposed model controls a two‐joint arm in a horizontal plane, and it learns a loop of internal forward and inverse transformations; the former predicts the visual feedback of hand position and the latter generates motor commands from the visual input through random generation of the motor commands. In the proposed model, the motor output and visual input were represented by broadly tuned neural units. Even though explicit ‘targets’ were not presented during learning, the simulation successfully generated reaching toward visually presented objects at within‐reach and out‐of‐reach distances.

Toll-like receptors (TLRs) are members of the pattern recognition receptor family that detect components of foreign pathogens or endogenous molecules released in response to injury. Recent studies demonstrate that TLRs also have a functional role in regulating neuronal proliferation in the developing brain. This study investigated cellular expression of TLR3 using immunohistochemistry on human brain tissue. The tissue sections analysed contained anterior and lateral periventricular white matter from the frontal and parietal lobes in post-mortem neonatal cases with a postmenstrual age range of 23.6-31.4 weeks. In addition to preterm brains without overt pathology (control), preterm pathology cases with evidence of white matter injuries (WMI) were also examined. In order to identify TLR-positive cells, we utilized standard double-labelling immunofluorescence co-labelling techniques and confocal microscopy to compare co-expression of TLR3 with a neuronal marker (NeuN) or with glial markers (GFAP for astrocytes, Iba-1 for microglia and Olig2 for oligodendrocytes). We observed an increase in the neuronal (28 vs. 17%) and astroglial (38 vs. 21%) populations in the WMI group compared to controls in the anterior regions of the periventricular white matter in the frontal lobe. The increase in neurons and astrocytes in the WMI cases was associated with an increase in TLR3 immunoreactivity. This expression was significantly increased in the astroglia. The morphology of the TLR3 signal in the control cases was globular and restricted to the perinuclear region of the neurons and astrocytes, whilst in the cases of WMI, both neuronal, axonal and astroglial TLR3 expression was more diffuse (i.e., a different intracellular distribution) and could be detected along the extensions of the processes. This study demonstrates for the first time that neurons and glial cells in human neonatal periventricular white matter express TLR3 during development. The patterns of TLR3 expression were altered in the presence of WMI, which might influence normal developmental processes within the immature brain. Identifying changes in TLR3 expression during fetal development may be key to understanding the reduced volumes of grey matter and impaired cortical development seen in preterm infants.

Background and Objective: Could a normal – but persistent – stress response to impeded axonal transport lead to late-onset Alzheimer’s disease (AD)? Our results offer an affirmative answer, suggesting a mechanism for the abnormal production of amyloid-β (Aβ), triggered by the slowed axonal transport at old age. We hypothesize that Aβ precursor protein (APP) is a sensor at the endoplasmic reticulum (ER) that detects, and signals to the nucleus, abnormalities in axonal transport. When persistently activated, due to chronically slowed-down transport, this signaling pathway leads to accumulation of Aβ within the ER. Methods and Results: We tested this hypothesis with the neuronal cell line CAD. We show that, normally, a fraction of APP is transported into neurites by recruiting kinesin-1 via the adaptor protein, Fe65. Under conditions that block kinesin-1-dependent transport, APP, Fe65 and kinesin-1 accumulate in the soma, and form a complex at the ER. This complex recruits active c-Jun N-terminal kinase (JNK), which phosphorylates APP at Thr668. This phosphorylation increases the cleavage of APP by the amyloidogenic pathway, which generates Aβ within the ER lumen, and releases Fe65 into the cytoplasm. Part of the released Fe65 translocates into the nucleus, likely to initiate a gene transcription response to arrested transport. Prolonged arrest of kinesin-1-dependent transport could thus lead to accumulation and oligomerization of Aβ in the ER. Conclusion: These results support a model where the APP:Fe65 complex is a sensor at the ER for detecting the increased level of kinesin-1 caused by halted transport, which signals to the nucleus, while concomitantly generating an oligomerization-prone pool of Aβ in the ER. Our hypothesis could thus explain a pathogenic mechanism in AD.

The collagen 2.3 and 3.6 promoters have been used to drive Cre expression for generation of conditional transgenic mutant mice. Within the bone, Col3.6 is expressed by mesenchymal precursor cells and their downstream progeny, while Col2.3 is more osteoblast specific. Our generation of transgenic mice with Col2.3-Cre- and Col3.6-Cre-driven deletion of the long-form leptin receptor (ObRb) necessitated a thorough analysis of the nonspecific expression of these promoters in the central nervous system. Both Col2.3 and Col3.6 were capable of forcing loxP recombination in the brain as demonstrated by EGFP expression in ROSA reporter mice. Expression of Col2.3 was limited to the central base of the brain near the third ventricle. In contrast, robust expression of Col3.6 was noted throughout the brain, centering near the distal third ventricle, third ventricle, and aqueduct. We subsequently analyzed the colocalization of leptin-responsive P-Stat3 neurons with Col3.6-expressing neurons. Approximately 5–10% colocalization was noted in leptin-responsive brain areas such as the arcuate nucleus, dorsal medial hypothalamus, ventral premammillary nucleus, and lateral hypothalamus. Injection of 3.6Cre+F/F ObRb knockout mice with leptin confirmed the presence of an intact P-Stat3 response that was dampened in the lateral hypothalamus (p < 0.050). This test was done to explore the contribution of neural leptin signaling to the bone phenotype of the 3.6Cre+F/F mice. Our analysis indicates that neural ObRb deletion, while present, is likely not the sole driver of femoral changes through traditional sympathetic circuits.

The monovalent cation lithium partially exerts its effects by activating neurotrophic and neuroprotective cellular cascades. Here, we discuss the effects of lithium on oxidative stress, programmed cell death (apoptosis), inflammation, glial dysfunction, neurotrophic factor functioning, excitotoxicity, and mitochondrial stability. In particular, we review evidence demonstrating the action of lithium on cyclic adenosine monophosphate (cAMP)-mediated signal transduction, cAMP response element binding activation, increased expression of brain-derived neurotrophic factor, the phosphatidylinositide cascade, protein kinase C inhibition, glycogen synthase kinase 3 inhibition, and B-cell lymphoma 2 expression. Notably, we also review data from clinical studies demonstrating neurotrophic effects of lithium. We expect that a better understanding of the clinically relevant pathophysiological targets of lithium will lead to improved treatments for those who suffer from mood as well as neurodegenerative disorders.

Background: Human immunodeficiency virus (HIV) leucoencephalopathy (HIVL) is an uncommon and rapidly progressive form of AIDS dementia complex (ADC) that has remained poorly understood. Tumour necrosis factor α (TNFα), which has been implicated in the pathogenesis of ADC, is predominantly localised in macrophages in the HIV infected brain, although in vitro studies indicate that neurones can express this cytokine. Objective: To examine the clinical/neuroradiological features of HIVL and the expression of TNFα in HIVL. Methods: Six patients who presented with rapidly progressive dementia within four to 12 weeks of the primary manifestation of their HIV infection were evaluated. Clinical history, treatment regimens, and imaging studies were reviewed, and brain samples from three of the patients were studied by means of immunohistochemistry. Results: Imaging studies showed diffuse bilateral deep white matter changes in all six patients. Clinical and imaging abnormalities improved in five of the six patients within weeks after initiation of antiretroviral treatment. Brain biopsies of two showed pronounced microglia/macrophage activation, but only scant viral protein (gp41) expression. Staining for TNFα was found in microglia/macrophages, and surprisingly, in neurones also. Postmortem analysis of a third patient also showed TNFα expression in neurones of the frontal cortex and basal ganglia. Conclusion: This study provides the first demonstration of staining for TNFα in the neurones of the HIV infected brain, and suggests that the process underlying this rapidly progressive form of ADC may reflect indirect mechanisms mediated by host factors, particularly TNFα.

Most afferent signals from the viscera do not give rise to conscious experience and yet they participate in the complex neural control of visceral functions. Surprisingly little information is available on the origin, morphology, and receptor functional characteristics of the nerve endings of most primary afferent neurones to the digestive tract. This review deals with the morphological nature of the afferent neurones that supply the gastrointestinal tract specifically.

Biologists have long been interested in both the regularities and the deviations in the relationship between brain, development, ecology, and behavior between taxa. We first examine some basic information about the observed ranges of fundamental changes in developmental parameters (i.e. neurogenesis timing, cell cycle rates, and gene expression patterns) between taxa. Next, we review what is known about the relative importance of different kinds of developmental mechanisms in producing brain change, focusing on mechanisms of segmentation, local and general features of neurogenesis, and cell cycle kinetics. We suggest that a limited set of developmental alterations of the vertebrate nervous system typically occur and that each kind of developmental change may entail unique anatomical, functional, and behavioral consequences for the organism. Thus, neuroecologists who posit a direct mapping of brain size to behavior should consider that not any change in brain anatomy is possible.

The motor systems that generate feeding-related behaviors of gastropod mollusks provide exceptional opportunities for increasing our understanding of neural homologies and the evolution of neural networks. This report examines the neural control of feeding in Helisoma trivolvis, a pulmonate snail that ingests food by rasping or scraping material from the substrate, and Aplysia californica, an opisthobranch sea slug that feeds by using a grasping or seizing motion. Two classes of neurons that are present in the buccal ganglia of both species are considered: (1) clusters of peptidergic mechanoafferent cells that transmit sensory information from the tongue-like radula/odontophore complex to the central motor circuit; and (2) sets of octopamine-immunoreactive interneurons that are intrinsic to the feeding network. We review evidence that suggests homology of these cell types and propose that their roles have been largely conserved in the control of food-scraping and food-grasping consummatory behaviors. We also consider significant differences in the feeding systems of Aplysia and Helisoma that are associated with the existence of radular closure in Aplysia, an action that does not occur in Helisoma. It is hypothesized that a major adaptation in the innervation patterns of analogous, possibly homologous muscles could distinguish the food-scraping versus food-grasping species. It appears that although core CPG elements have been largely conserved in this system, the neuromuscular elements that they regulate have been more evolutionarily labile.

This paper presents a biologically inspired, hardware-realisable spiking neuron model, which we call the Temporal Noisy-Leaky Integrator (TNLI). The dynamic applications of the model as well as its applications in Computational Neuroscience are demonstrated and a learning algorithm based on postsynaptic delays is proposed. The TNLI incorporates temporal dynamics at the neuron level by modelling both the temporal summation of dendritic postsynaptic currents which have controlled delay and duration and the decay of the somatic potential due to its membrane leak. Moreover, the TNLI models the stochastic neurotransmitter release by real neuron synapses (with probabilistic RAMs at each input) and the firing times including the refractory period and action potential repolarisation. The temporal features of the TNLI make it suitable for use in dynamic time-dependent tasks like its application as a motion and velocity detector system presented in this paper. This is done by modelling the experimental velocity selectivity curve of the motion sensitive H1 neuron of the visual system of the fly. This application of the TNLI indicates its potential applications in artificial vision systems for robots. It is also demonstrated that Hebbian-based learning can be applied in the TNLI for postsynaptic delay training based on coincidence detection, in such a way that an arbitrary temporal pattern can be detected and recognised. The paper also demonstrates that the TNLI can be used to control the firing variability through inhibition with 80% inhibition to concurrent excitation, firing at high rates is nearly consistent with a Poisson-type firing variability observed in cortical neurons. It is also shown with the TNLI, that the gain of the neuron (slope of its transfer function) can be controlled by the balance between inhibition and excitation, the gain being a decreasing function of the proportion of inhibitory inputs. Finally, in the case of perfect balance between inhibition and excitation, i.e. where the average input current is zero, the neuron can still fire as a result of membrane potential fluctuations. The firing rate is then determined by the average input firing rate. Overall this work illustrates how a hardware-realisable neuron model can capitalise on the unique computational capabilities of biological neurons. © 2002 Elsevier Science Ltd. All rights reserved. 15 7 891 908 Cited By :27

Background: Spinocerebellar ataxia type 1 (SCA1) is one of the autosomal dominant neurodegenerative disorders commonly linked to pathological expansion of the CAG repeat of the relevant gene. Nuclear inclusions and neurodegeneration are both triggered by this pathological expansion of the CAG/polyglutamine repeat on ataxin-1, but it remains to be determined whether or not nuclear inclusion formation is associated with accelerated neurodegeneration. Objective: To examine the influence of nuclear inclusions on nuclear size and deformity in human brains from patients suffering from SCA1. Material: Pontine sections of brains obtained at necropsy from seven patients with SCA1 and five controls. Methods: The size and deformity of each neuronal nucleus was quantified. Nuclei with and without inclusions were examined separately to assess the possible influence of nuclear inclusions on neurodegeneration. Results: Nuclear shrinkage and deformity were more marked in SCA1 brains than in controls. This shrinkage was attenuated in neurones containing nuclear inclusions. Conclusions: The existence of nuclear inclusions in SCA1 is presumably linked to a mechanism that attenuates rather than accelerates nuclear shrinkage. This in vivo finding may provide a clue to constructing a rational therapeutic strategy for combating neurodegeneration associated with nuclear inclusions.

Objectives: Current models of basal ganglia dysfunction in Parkinson9s disease suggest a pivotal role of subthalamic nucleus (STN) hyperactivity. There is a direct excitatory output to the globus pallidus internus (GPi), which in turn hyperinhibits the motor thalamus and leads to a lack of cortical facilitation. The model, however, does not address the reciprocal influence of GPi on STN activity. Methods: Measurement of immediate changes in STN single cell activity after GPi deep brain stimulation (DBS). Results: An opposite effect of GPi DBS in the dorsal versus ventral STN was found. There was an almost exclusive reduction of firing rate in the dorsal region of the STN, whereas the cells in the ventral region exhibited facilitation similar to the recordings from the substantia nigra pars reticulata. Conclusion: Although these findings require confirmation, they suggest that the current theories of GPi DBS action, which do not include a GPi-STN modulation, are most likely incomplete.

This paper describes a suite of routines using IgorPro, a powerful analysis and graphing software package for the Macintosh computer, to enhance the ability to analyze, manipulate, and display data recorded with the Discovery™ acquisition software marketed by DataWave Technologies. The routines are able to time-align fast and slow data channels, and are especially useful for analyses that involve both neural and behavioral data. The software was designed for eyeblink conditioning and vocalization experiments, but it can easily be used for analyzing other types of neurobehavioral data. The data are first prepared on the PC with routines that inspect the header of the data file and translate the data file into a compact binary format that can be read by IgorPro. An option is also available to splice out data from unnecessary portions of an intertrial interval. The new file is then put on the Macintosh computer for display and analysis by IgorPro. These routines enable both neural and behavioral data to be quickly and easily reduced, manipulated, and statistically and graphically summarized.

When soluble proteins in cytosolic fractions of rat soleus muscles are 32P-phosphorylated in vitro by an ATP:protein phosphotransferase reaction, the major substrate is a 56-kilodalton (56K) protein. As we have also reported previously, the onset and development of increased 32P-phosphorylation of this 56K protein, which are observed after the soleus is denervated, temporally correlate with the denervation period and length of the distal nerve stump [Held et al, 1983]. Conclusive evidence which identifies this neuroregulated muscle protein as the regulatory subunit of cyclic AMP-dependent protein kinase type II (R-II) is presented in this paper. The 56K soleus protein and purified bovine heart R-II were 32P-phosphorylated and subjected to limited proteolysis with bovine pancreas trypsin. After resolution of the generated 32P-phosphopeptides by SDS slab PAGE and visualization by autoradiography, no tryptic products were observed from the 56K soleus protein which were not also produced by proteolysis of the purified R-II. These tryptic phosphopeptides included 39, 16.5, and 12K fragments which retained the autophosphorylation site of R-II. After denervation, the 32P-phosphorylation of the 56K soleus protein and of the 39K tryptic peptide product were comparably increased. The identification of the neuroregulated 56K soleus protein as R-II was also confirmed by Western blotting with a specific anti-R-II sera. Taken together, our results demonstrate that the previously observed neuroregulation of the 32P-phosphorylation of the 56K soleus protein is identifiable with some alteration which affects the intramolecular 32P-autophosphorylation of R-II.

Polyclonal antibodies directed against squid opsin were used in immunocytochemical and immunoblot experiments to identify a rhodopsin-like protein in photosensitive neurons of Aplysia. Aldehyde-fixed abdominal and cerebral ganglia were embedded in paraffin for peroxidase anti-peroxidase analysis or used whole for immunofluorescence studies. Ganglia were embedded in Lowicryl K4M for electron-microscope immunocytochemistry. In both the cerebral and abdominal ganglia, light-microscope immunocytochemical results showed reaction product deposited around the neuronal cell periphery corresponding in position to the lipochondria. In the abdominal ganglion, the giant cell R2, located in the right rostral quarter, and neurons in the right caudal quarter were consistently labeled with anti-opsin. Electron-microscopic studies demonstrated ferritin-labeling of the lipochondria in R2 and other immunoreactive neurons. Immunoblot analysis of R2 and cerebral neuron extracts was used to identify two prominent immunoreactive protein bands at 85 000 and 67 500 molecular weight.