bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aging-Related Hyperexcitability in CA3 Pyramidal Neurons Is Mediated by Enhanced A-Type K+Channel Function and Expression
Authors: Simkin Dina , Hattori Shoai , Ybarra Natividad , Musial Timothy F. , Buss Eric W. , Richter Hannah , Oh M. Matthew , Nicholson Daniel A. , Disterhoft John F. 
Published: September 2015

Aging-related impairments in hippocampus-dependent cognition have been attributed to maladaptive changes in the functional properties of pyramidal neurons within the hippocampal subregions. Much evidence has come from work on CA1 pyramidal neurons, with CA3 pyramidal neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing in the hippocampal circuit. Here, we use whole-cell current-clamp to demonstrate that aged rat (29–32 months) CA3 pyramidal neurons fire significantly more action potentials (APs) during theta-burst frequency stimulation and that this is associated with faster AP repolarization (i.e., narrower AP half-widths and enlarged fast afterhyperpolarization). Using a combination of patch-clamp physiology, pharmacology, Western blot analyses, immunohistochemistry, and array tomography, we demonstrate that these faster AP kinetics are mediated by enhanced function and expression of Kv4.2/Kv4.3 A-type K+channels, particularly within the perisomatic compartment, of CA3 pyramidal neurons. Thus, our study indicates that inhibition of these A-type K+channels can restore the intrinsic excitability properties of aged CA3 pyramidal neurons to a young-like state.SIGNIFICANCE STATEMENTAge-related learning deficits have been attributed, in part, to altered hippocampal pyramidal neuronal function with normal aging. Much evidence has come from work on CA1 neurons, with CA3 neurons receiving comparatively less attention despite its age-related hyperactivation being postulated to interfere with spatial processing. Hence, we conducted a series of experiments to identify the cellular mechanisms that underlie the hyperexcitability reported in the CA3 region. Contrary to CA1 neurons, we demonstrate that postburst afterhyperpolarization is not altered with aging and that aged CA3 pyramidal neurons are able to fire significantly more action potentials and that this is associated with faster action potential repolarization through enhanced expression of Kv4.2/Kv4.3 A-type K+channels, particularly within the cell bodies of CA3 pyramidal neurons.
Peripheral Neuropathy Induces HCN Channel Dysfunction in Pyramidal Neurons of the Medial Prefrontal Cortex
Authors: Cordeiro Matos Steven , Zhang Zizhen , Séguéla Philippe 
Published: September 2015

Neuropathic pain is a debilitating condition for which the development of effective treatments has been limited by an incomplete understanding of its molecular basis. The cationic currentIhmediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels plays an important role in pain by facilitating ectopic firing and hyperexcitability in DRG neurons, however little is known regarding the role ofIhin supraspinal pain pathways. The medial prefrontal cortex (mPFC), which is reported to be involved in the affective aspects of pain, exhibits high HCN channel expression. Using the spared nerve injury (SNI) model of neuropathic pain in Long–Evans rats and patch-clamp recordings in layer II/III pyramidal neurons of the contralateral mPFC, we observed a hyperpolarizing shift in the voltage-dependent activation ofIhin SNI neurons, whereas maximalIhremained unchanged. Accordingly, SNI mPFC pyramidal neurons exhibited increased input resistance and excitability, as well as facilitated glutamatergic mGluR5-mediated persistent firing, compared with sham neurons. Moreover, intracellular application of bromo-cAMP abolished the hyperpolarizing shift in the voltage-dependent activation ofIhobserved in SNI neurons, whereas protein kinase A (PKA) inhibition further promoted this shift in both SNI and sham neurons. Behaviorally, acute HCN channel blockade by local injection of ZD7288 in the mPFC of SNI rats induced a decrease in cold allodynia. These findings suggest that changes in the cAMP/PKA axis in mPFC neurons underlie alterations to HCN channel function, which can influence descending inhibition of pain pathways in neuropathic conditions.SIGNIFICANCE STATEMENTRecent studies investigating the role of the medial prefrontal cortex (mPFC) in neuropathic pain have led to an increased awareness of how affective and cognitive factors can influence pain perception. It is therefore imperative that we advance our understanding of the involvement of supraspinal pain pathways. Our electrophysiological and behavioral results support an important role for hyperpolarization-activated cyclic nucleotide-gated channels and the cAMP/protein kinase A signaling axis in promoting hyperexcitability and persistent firing in pyramidal neurons of the mPFC in neuropathic animals. These findings offer novel insights, with potential therapeutic implications, into pathophysiological mechanisms underlying the abnormal contribution of layer II/III prefrontal pyramidal neurons to chronic pain states.
Hunger States Control the Directions of Synaptic Plasticity via Switching Cell Type-Specific Subunits of NMDA Receptors
Authors: Qi Yong , Yang Yunlei 
Published: September 2015

It remains largely unknown whether and how hunger states control activity-dependent synaptic plasticity, such as long-term potentiation (LTP) and long-term depression (LTD). We here report that both LTP and LTD of excitatory synaptic strength within the appetite control circuits residing in hypothalamic arcuate nucleus (ARC) behave in a manner of hunger states dependence and cell type specificity. For instance, we find that tetanic stimulation induces LTP at orexigenicagouti-related protein(AgRP) neurons inad libitumfed mice, whereas it induces LTD in food-deprived mice. In an opposite direction, the same induction protocol induces LTD at anorexigenicpro-opiomelanocortin(POMC) neurons in fed mice but weak LTP in deprived mice. Mechanistically, we also find that food deprivation increases the expressions of NR2C/NR2D/NR3-containing NMDA receptors (NMDARs) at AgRP neurons that contribute to the inductions of LTD, whereas it decreases their expressions at POMC neurons. Collectively, our data reveal that hunger states control the directions of activity-dependent synaptic plasticity by switching NMDA receptor subpopulations in a cell type-specific manner, providing insights into NMDAR-mediated interactions between energy states and associative memory.SIGNIFICANCE STATEMENTBased on the experiments performed in this study, we demonstrate that activity-dependent synaptic plasticity is also under the control of energy states by regulating NMDAR subpopulations in a cell type-specific manner. We thus propose a reversible memory configuration constructed from energy states-dependent cell type-specific bidirectional conversions of LTP and LTD. Together with the distinct functional roles played by NMDAR signaling in the control of food intake and energy states, these findings reveal a new reciprocal interaction between energy states and associative memory, one that might serve as a target for therapeutic treatments of the energy-related memory disorders or vice versa.
Conditional Knock-Out of Vesicular GABA Transporter Gene from Starburst Amacrine Cells Reveals the Contributions of Multiple Synaptic Mechanisms Underlying Direction Selectivity in the Retina
Authors: Pei Zhe , Chen Qiang , Koren David , Giammarinaro Benno , Acaron Ledesma Hector , Wei Wei 
Published: September 2015

Direction selectivity of direction-selective ganglion cells (DSGCs) in the retina results from patterned excitatory and inhibitory inputs onto DSGCs during motion stimuli. The inhibitory inputs onto DSGCs are directionally tuned to the antipreferred (null) direction and therefore potently suppress spiking during motion in the null direction. However, whether direction-selective inhibition is indispensable for direction selectivity is unclear. Here, we selectively eliminated the directional tuning of inhibitory inputs onto DSGCs by disrupting GABA release from the presynaptic interneuron starburst amacrine cell in the mouse retina. We found that, even without directionally tuned inhibition, direction selectivity can still be implemented in a subset of On-Off DSGCs by direction-selective excitation and a temporal offset between excitation and isotropic inhibition. Our results therefore demonstrate the concerted action of multiple synaptic mechanisms for robust direction selectivity in the retina.SIGNIFICANCE STATEMENTThe direction-selective circuit in the retina has been a classic model to study neural computations by the brain. An important but unresolved question is how direction selectivity is implemented by directionally tuned excitatory and inhibitory mechanisms. Here we specifically removed the direction tuning of inhibition from the circuit. We found that direction tuning of inhibition is important but not indispensable for direction selectivity of DSGCs' spiking activity, and that the residual direction selectivity is implemented by direction-selective excitation and temporal offset between excitation and inhibition. Our results highlight the concerted actions of synaptic excitation and inhibition required for robust direction selectivity in the retina and provide critical insights into how patterned excitation and inhibition collectively implement sensory processing.
Interareal Spike-Train Correlations of Anterior Cingulate and Dorsal Prefrontal Cortex during Attention Shifts
Authors: Oemisch Mariann , Westendorff Stephanie , Everling Stefan , Womelsdorf Thilo 
Published: September 2015

The anterior cingulate cortex (ACC) and prefrontal cortex (PFC) are believed to coactivate during goal-directed behavior to identify, select, and monitor relevant sensory information. Here, we tested whether coactivation of neurons across macaque ACC and PFC would be evident at the level of pairwise neuronal correlations during stimulus selection in a spatial attention task. We found that firing correlations emerged shortly after an attention cue, were evident for 50–200 ms time windows, were strongest for neuron pairs in area 24 (ACC) and areas 8 and 9 (dorsal PFC), and were independent of overall firing rate modulations. For a subset of cell pairs from ACC and dorsal PFC, the observed functional spike-train connectivity carried information about the direction of the attention shift. Reliable firing correlations were evident across area boundaries for neurons with broad spike waveforms (putative excitatory neurons) as well as for pairs of putative excitatory neurons and neurons with narrow spike waveforms (putative interneurons). These findings reveal that stimulus selection is accompanied by slow time scale firing correlations across those ACC/PFC subfields implicated to control and monitor attention. This functional coupling was informative about which stimulus was selected and thus indexed possibly the exchange of task-relevant information. We speculate that interareal, transient firing correlations reflect the transient coordination of larger, reciprocally interacting brain networks at a characteristic 50–200 ms time scale.SIGNIFICANCE STATEMENTOur manuscript identifies interareal spike-train correlations between primate anterior cingulate and dorsal prefrontal cortex during a period where attentional stimulus selection is likely controlled by these very same circuits. Interareal correlations emerged during the covert attention shift to one of two peripheral stimuli, proceeded on a slow 50–200 ms time scale, and occurred between putative pyramidal and putative interneurons. Spike-train correlations emerged particularly for cell pairs tuned to similar contralateral target locations, thus indexing the interareal coordination of attention-relevant information. These findings characterize a possible way by which prefrontal and anterior cingulate cortex circuits implement their control functions through coordinated firing when macaque monkeys select and monitor relevant stimuli for goal-directed behaviors.
Losing Neutrality: The Neural Basis of Impaired Emotional Control without Sleep
Authors: Simon Eti Ben , Oren Noga , Sharon Haggai , Kirschner Adi , Goldway Noam , Okon-Singer Hadas , Tauman Rivi , Deweese Menton M. , Keil Andreas , Hendler Talma 
Published: September 2015

Sleep deprivation has been shown recently to alter emotional processing possibly associated with reduced frontal regulation. Such impairments can ultimately fail adaptive attempts to regulate emotional processing (also known as cognitive control of emotion), although this hypothesis has not been examined directly. Therefore, we explored the influence of sleep deprivation on the human brain using two different cognitive–emotional tasks, recorded using fMRI and EEG. Both tasks involved irrelevant emotional and neutral distractors presented during a competing cognitive challenge, thus creating a continuous demand for regulating emotional processing. Results reveal that, although participants showed enhanced limbic and electrophysiological reactions to emotional distractors regardless of their sleep state, they were specifically unable to ignore neutral distracting information after sleep deprivation. As a consequence, sleep deprivation resulted in similar processing of neutral and negative distractors, thus disabling accurate emotional discrimination. As expected, these findings were further associated with a decrease in prefrontal connectivity patterns in both EEG and fMRI signals, reflecting a profound decline in cognitive control of emotion. Notably, such a decline was associated with lower REM sleep amounts, supporting a role for REM sleep in overnight emotional processing. Altogether, our findings suggest that losing sleep alters emotional reactivity by lowering the threshold for emotional activation, leading to a maladaptive loss of emotional neutrality.SIGNIFICANCE STATEMENTSleep loss is known as a robust modulator of emotional reactivity, leading to increased anxiety and stress elicited by seemingly minor triggers. In this work, we aimed to portray the neural basis of these emotional impairments and their possible association with frontal regulation of emotional processing, also known as cognitive control of emotion. Using specifically suited EEG and fMRI tasks, we were able to show that sleep deprivation alters emotional reactivity by triggering enhanced processing of stimuli regarded previously as neutral. These changes were further accompanied by diminished frontal connectivity, reduced REM sleep, and poorer performance. Therefore, we suggest that sleep loss alters emotional reactivity by lowering the threshold for emotional activation, leading to a maladaptive loss of emotional neutrality.
Perceptual Salience and Reward Both Influence Feedback-Related Neural Activity Arising from Choice
Authors: Lou Bin , Hsu Wha-Yin , Sajda Paul 
Published: September 2015

For day-to-day decisions, multiple factors influence our choice between alternatives. Two dimensions of decision making that substantially affect choice are the objective perceptual properties of the stimulus (e.g., salience) and its subjective value. Here we measure EEGs in human subjects to relate their feedback-evoked EEG responses to estimates of prediction error given a neurally derived expected value for each trial. Unlike in traditional reinforcement learning paradigms, in our experiment the reward itself is not probabilistic; rather, it is a fixed value, which, when combined with the variable stimulus salience, yields uncertainty in the choice. We find that feedback-evoked event-related potentials (ERPs), specifically those classically termed feedback-related negativity, are modulated by both the reward level and stimulus salience. Using single-trial analysis of the EEG, we show stimulus-locked EEG components reflecting perceived stimulus salience can be combined with the level of reward to create an estimate of expected reward. This expected reward is used to form a prediction error that correlates with the trial-by-trial variability of the feedback ERPs for negative, but not positive, feedback. This suggests that the valence of prediction error is more important than the valence of the actual feedback, since only positive rewards were delivered in the experiment (no penalty or loss). Finally, we show that these subjectively defined prediction errors are informative of the riskiness of the subject's choice on the subsequent trial. In summary, our work shows that neural correlates of stimulus salience interact with value information to yield neural representations of subjective expected reward.SIGNIFICANCE STATEMENTHow we make perceptual decisions depends on sensory evidence and the value of our options. These two factors often interact to yield subjective decisions; i.e., individuals integrate sensory evidence and value to form their own estimates of expected reward. Here, we use electroencephelography to identify trial-by-trial neural activity of perceived stimulus salience, showing that this activity can be combined with the value of choice options to form a representation of expected reward. Our results provide insight into the neural processing governing the interaction between salience and value and the formation of subjective expected reward and prediction error. This work is potentially important for identifying neural markers of abnormal sensory/value processing, as is seen in some cases of psychiatric illnesses.
ComplementC3-Deficient Mice Fail to Display Age-Related Hippocampal Decline
Authors: Shi Qiaoqiao , Colodner Kenneth J. , Matousek Sarah B. , Merry Katherine , Hong Soyon , Kenison Jessica E. , Frost Jeffrey L. , Le Kevin X. , Li Shaomin , Dodart Jean-Cosme , Caldarone Barbara J. , Stevens Beth , Lemere Cynthia A. 
Published: September 2015

The complement system is part of the innate immune response responsible for removing pathogens and cellular debris, in addition to helping to refine CNS neuronal connections via microglia-mediated pruning of inappropriate synapses during brain development. However, less is known about the role of complement during normal aging. Here, we studied the role of the central complement component, C3, in synaptic health and aging. We examined behavior as well as electrophysiological, synaptic, and neuronal changes in the brains ofC3-deficient male mice (C3KO) compared with age-, strain-, and gender-matched C57BL/6J (wild-type, WT) control mice at postnatal day 30, 4 months, and 16 months of age. We found the following: (1) region-specific and age-dependent synapse loss in aged WT mice that was not observed inC3KO mice; (2) age-dependent neuron loss in hippocampal CA3 (but not in CA1) that followed synapse loss in aged WT mice, neither of which were observed in agedC3KO mice; and (3) significantly enhanced LTP and cognition and less anxiety in agedC3KO mice compared with aged WT mice. Importantly, CA3 synaptic puncta were similar between WT andC3KO mice at P30. Together, our results suggest a novel and prominent role for complement protein C3 in mediating aged-related and region-specific changes in synaptic function and plasticity in the aging brain.SIGNIFICANCE STATEMENTThe complement cascade, part of the innate immune response to remove pathogens, also plays a role in synaptic refinement during brain development by the removal of weak synapses. We investigated whether complement C3, a central component, affects synapse loss during aging. Wild-type (WT) andC3knock-out (C3KO) mice were examined at different ages. The mice were similar at 1 month of age. However, with aging, WT mice lost synapses in specific brain regions, especially in hippocampus, an area important for memory, whereasC3KO mice were protected. AgedC3KO mice also performed better on learning and memory tests than aged WT mice. Our results suggest that complement C3, or its downstream signaling, is detrimental to synapses during aging.
PKR Inhibition Rescues Memory Deficit and ATF4 Overexpression in ApoE ε4 Human Replacement Mice
Authors: Segev Yifat , Barrera Iliana , Ounallah-Saad Hadile , Wibrand Karin , Sporild Ida , Livne Adva , Rosenberg Tali , David Orit , Mints Meshi , Bramham Clive R. , Rosenblum Kobi 
Published: September 2015

Sporadic Alzheimer's disease (AD) is an incurable neurodegenerative disease with clear pathological hallmarks, brain dysfunction, and unknown etiology. Here, we tested the hypothesis that there is a link between genetic risk factors for AD, cellular metabolic stress, and transcription/translation regulation. In addition, we aimed at reversing the memory impairment observed in a mouse model of sporadic AD. We have previously demonstrated that the most prevalent genetic risk factor for AD, the ApoE4 allele, is correlated with increased phosphorylation of the translation factor eIF2α. In the present study, we tested the possible involvement of additional members of the eIF2α pathway and identified increased mRNA expression of negative transcription factor ATF4 (aka CREB2) both in human and a mouse model expressing the human ApoE4 allele. Furthermore, injection of a PKR inhibitor rescued memory impairment and attenuated ATF4 mRNA increased expression in the ApoE4 mice. The results propose a new mechanism by which ApoE4 affects brain function and further suggest that inhibition of PKR is a way to restore ATF4 overexpression and memory impairment in early stages of sporadic AD.SIGNIFICANCE STATEMENTATF4 mRNA relative quantities are elevated in ApoE4 allele carriers compared with noncarrier controls. This is true also for the ApoE ε4 human replacement mice. ApoE4 mice injected with PKR inhibitor (PKRi) demonstrate a significant reduction in ATF4 expression levels 3 h after one injection of PKRi. Treatment of ApoE4 human replacement mice with the PKRi before learning rescues the memory impairment of the ApoE4 AD model mice. We think that these results propose a new mechanism by which ApoE4 affects brain function and suggest that inhibition of PKR is a way to restore memory impairment in early stages of sporadic AD.
„Ród ruski”, „ród wareski” i narodowość staroruska
Authors: Musin Aleksander 
Published: September 2015

Studia nad dziejami dawnej Rusi charakteryzują się obecnie uwzględnianiem różnorodności poszczególnych jej regionów, co stanowi pewne odejście od ukształtowanego w drugiej połowie XIX wieku założenia o „jednolitej narodowości staroruskiej”. Zakładało one istnienie wspólnego przodka dzisiejszych Rosjan, Ukraińców oraz Białorusinów. Nowe ustalenia na temat czynników wpływających na konsolidację staroruskiego społeczeństwa wymagają od badacza – w celu dokonania przekonującego rozstrzygnięcia problemu zbiorowej samoidentyfikacji w średniowieczu – sięgnięcia po te zabytki piśmiennictwa, w których ujawnić się mogły explicite historyczne podstawy dokonywania przez zbiorowości ludzkie dawnej Rusi identyfikacji swoich członków lub wzajemnego przeciwstawiania się sobie. Specyficzna struktura państwa staroruskiego składającego się z „włości” kijowskiej i nowogrodzkiej oraz pojawiające się w zabytkach piśmienniczych określenia typu „ród ruski”, „ród wareski” każą zastanowić się nad znaczeniem i konotacjami, jakie niesie ze sobą projektowana „narodowość staroruska”.