Optogenetic Stimulation of CA1 Pyramidal Neurons at Theta Enhances Recognition Memory in Brain Injured Animals.

The hippocampus plays a prominent role in learning and memory formation. The functional integrity of this structure is often compromised after traumatic brain injury (TBI), resulting in lasting cognitive dysfunction. The activity of hippocampal neurons, particularly place cells, is coordinated by local theta oscillations.

Dopaminergic regulation of hippocampal plasticity, learning, and memory.

The hippocampus is responsible for encoding behavioral episodes into short-term and long-term memory. The circuits that mediate these processes are subject to neuromodulation, which involves regulation of synaptic plasticity and local neuronal excitability. In this review, we present evidence to demonstrate the influence of dopaminergic neuromodulation on hippocampus-dependent memory, and we address the controversy surrounding the source of dopamine innervation.

Impaired Experience-Dependent Refinement of Place Cells in a Rat Model of Alzheimer's Disease.

Background: Hippocampal place cells play an integral role in generating spatial maps. Impaired spatial memory is a characteristic pathology of Alzheimer's disease (AD), yet it remains unclear how AD influences the properties of hippocampal place cells.

Objective: To record electrophysiological activity in hippocampal CA1 neurons in freely-moving 18-month-old male TgF344-AD and age-matched wild-type (WT) littermates to examine place cell properties.

The complex nature of financial market microstructure: the case of a stock market crash.

This paper uses multivariate Hawkes processes to model the transactions behavior of the US stock market as measured by the 30 Dow Jones Industrial Average individual stocks before, during and after the 36-min May 6, 2010, Flash Crash. The basis for our analysis is the excitation matrix, which describes a complex network of interactions among the stocks. Using high-frequency transactions data, we find strong evidence of self- and asymmetrically cross-induced contagion and the presence of fragmented trading venues.

Mild Traumatic Brain Injury Decreases Spatial Information Content and Reduces Place Field Stability of Hippocampal CA1 Neurons.

Both clinical and experimental studies have reported that mild traumatic brain injury (mTBI) can result in cognitive impairments in the absence of overt brain damage. Whether these impairments result from neuronal dysfunction/altered plasticity is an area that has received limited attention. In this study, we recorded activity of neurons in the cornu Ammonis (CA)1 subfield of the hippocampus in sham and mild lateral fluid percussion injured (mFPI) rats while these animals were performing an object location task.

Repeated mild traumatic brain injury produces neuroinflammation, anxiety-like behaviour and impaired spatial memory in mice.

Primary Objective: Repeated traumatic brain injuries (rmTBI) are frequently associated with debilitating neuropsychiatric conditions such as cognitive impairment, mood disorders, and post-traumatic stress disorder. We tested the hypothesis that repeated mild traumatic brain injury impairs spatial memory and enhances anxiety-like behaviour.

Research Design: We used a between groups design using single (smTBI) or repeated (rmTBI) controlled cranial closed skull impacts to mice, compared to a control group.

Dopamine receptor activity participates in hippocampal synaptic plasticity associated with novel object recognition.

Physiological and behavioral evidence supports that dopamine (DA) receptor signaling influences hippocampal function. While several recent studies examined how DA influences CA1 plasticity and learning, there are fewer studies investigating the influence of DA signaling to the dentate gyrus. The dentate gyrus receives convergent cortical input through the perforant path fiber tracts and has been conceptualized to detect novelty in spatial memory tasks.

Dopamine Regulates Aversive Contextual Learning and Associated In Vivo Synaptic Plasticity in the Hippocampus.

Dopamine release during reward-driven behaviors influences synaptic plasticity. However, dopamine innervation and release in the hippocampus and its role during aversive behaviors are controversial. Here, we show that in vivo hippocampal synaptic plasticity in the CA3-CA1 circuit underlies contextual learning during inhibitory avoidance (IA) training.

Dopamine and norepinephrine receptors participate in methylphenidate enhancement of in vivo hippocampal synaptic plasticity.

Attention-deficit hyperactive disorder (ADHD) is the most commonly studied and diagnosed psychiatric disorder in children. Methylphenidate (MPH, e.g.

Immobility responses between mouse strains correlate with distinct hippocampal serotonin transporter protein expression and function.

Mouse strain differences in immobility and in sensitivity to antidepressants have been observed in the forced swimming test (FST) and the tail suspension test (TST). However, the neurotransmitter systems and neural substrates that contribute to these differences remain unknown. To investigate the role of the hippocampal serotonin transporter (5-HTT), we measured baseline immobility and the immobility responses to fluoxetine (FLX) in the FST and the TST in male CD-1, C57BL/6, DBA and BALB/c mice.

Evaluation of fecal α1-proteinase inhibitor concentrations in cats with idiopathic inflammatory bowel disease and cats with gastrointestinal neoplasia.

Idiopathic inflammatory bowel disease (IBD) and gastrointestinal lymphoma are common disorders in cats. The aim of this study was to evaluate fecal α(1)-PI concentrations, a marker of gastrointestinal protein loss, in cats with histopathological evidence of gastrointestinal inflammation or gastrointestinal neoplasia. Fecal and serum samples were obtained from 20 cats with chronic gastrointestinal disease in which endoscopic biopsies were performed.

Posterior parietal cortex dynamically ranks topographic signals via cholinergic influence.

The hypothesis to be discussed in this review is that posterior parietal cortex (PPC) is directly involved in selecting relevant stimuli and filtering irrelevant distractors. The PPC receives input from several sensory modalities and integrates them in part to direct the allocation of resources to optimize gains. In conjunction with prefrontal cortex, nucleus accumbens, and basal forebrain cholinergic nuclei, it comprises a network mediating sustained attentional performance.

Neurophysiology of Nicotine Addiction.

Tobacco use is a major health problem, and nicotine is the main addictive component. Nicotine binds to nicotinic acetylcholine receptors (nAChR) to produce its initial effects. The nAChRs subtypes are composed of five subunits that can form in numerous combinations with varied functional and pharmacological characteristics.

Low frequency oscillations in rat posterior parietal cortex are differentially activated by cues and distractors.

The posterior parietal cortex (PPC) is hypothesized to detect visual cues among competing distractors. Anatomical and neurophysiologic evidence indicates that the rat PPC is part of a network of brain areas involved in directed attention, specifically when new task parameters or conditions are introduced. Here, we test the hypothesis that changes in the local field potential (LFP) of the PPC of rats performing a sustained attention task reflect aspects of detection.

Cholinergic optimization of cue-evoked parietal activity during challenged attentional performance.

The detection of salient or instrumental stimuli and the selection of cue-evoked responses are mediated by a fronto-parietal network that is modulated by cholinergic inputs originating from the basal forebrain. Visual cues that guide behavior are more strongly represented in the posterior parietal cortex (PPC) than are similar cues that are missed or task-irrelevant. Although the crucial role of cholinergic inputs in cue detection has been demonstrated by lesion studies, the role of PPC neurons in the cholinergic modulation of cue detection is unclear.

Comparison of endoscopic and full-thickness biopsy specimens for diagnosis of inflammatory bowel disease and alimentary tract lymphoma in cats.

Objective: To evaluate the accuracy of endoscopic biopsy (EB) specimens for diagnosis of alimentary tract lymphosarcoma in cats.

Design: Prospective study.

Animals: 22 cats with inflammatory bowel disease (IBD) or alimentary tract lymphosarcoma.

Serum and urine concentrations of trypsinogen-activation peptide as markers for acute pancreatitis in cats.

The purpose of this study was to compare the clinical utility of the serum concentration of feline trypsin-like immunoreactivity (fTLI), the plasma and urine concentrations of trypsinogen-activation peptide (TAP), and the ratio of the urine TAP and creatinine concentrations (TAP:Cr) in the diagnosis of feline acute pancreatitis. We used 13 healthy cats and 10 cats with a diagnosis of acute pancreatitis. The mean serum fTLI and plasma TAP concentrations were significantly higher in the cats with acute pancreatitis than in the healthy cats (P < 0.

Four cats with fungal rhinitis.

Fungal rhinitis is uncommon in the cat and cases of nasal aspergillosis-penicilliosis have been rarely reported. Signs of fungal rhinitis include epistaxis, sneezing, mucopurulent nasal discharge and exophthalmos. Brachycephalic feline breeds seem to be at increased risk for development of nasal aspergillosis-penicilliosis.

Clinical effects of short-term oral budesonide on the hypothalamic-pituitary-adrenal axis in dogs with inflammatory bowel disease.

Six dogs were entered into a 30-day, prospective, nonrandomized, uncontrolled clinical trial evaluating the effects of an oral preparation of budesonide on the hypothalamic-pituitary-adrenal (HPA) axis during therapeutic management of active inflammatory bowel disease. Oral budesonide, at a dose of 3 mg/m(2), was administered once daily. Upon entry and completion of the trial, serum basal cortisol, adrenocorticotropic (ACTH)-stimulated cortisol, endogenous ACTH concentration, serum alkaline phosphatase (SAP) activity, and urine specific gravity were evaluated, as well as owner assessment of glucocorticoid-associated side effects.

Maintenance of gastrointestinal endoscopes.

Endoscopes are used for visualization and biopsy of gastrointestinal lesions, as well as therapeutic procedures, such as foreign body retrieval. In the past, they were primarily used in large institutional settings where specialized personnel could focus on their maintenance. Today, they are becoming increasingly common in general practice.

Optimal fecal assessment.

Fecal testing is a common component of most gastrointestinal work-ups. A multitude of diagnostic techniques are available for identifying parasites and pathogens, or showing abnormalities of flora. Optimal fecal assessment involves careful formulation of a differential list based on signalment, history, and clinical signs.