scholarly journals Dynamic contrast enhancement and flexible odor codes

2017 ◽  
Author(s):  
Srinath Nizampatnam ◽  
Debajit Saha ◽  
Rishabh Chandak ◽  
Baranidharan Raman
Keyword(s):  
Contrast Enhancement ◽  
Antennal Lobe ◽  
Dependent Manner ◽  
Evoked Responses ◽  
Computational Logic ◽  
Behavioral Experiments ◽  
Dynamic Contrast Enhancement ◽  
Sensory Stimuli ◽  
Temporal Features ◽  
The Stability

ABSTRACTSensory stimuli evoke spiking activities patterned across neurons and time that are hypothesized to encode information about their identity. Since the same stimulus can be encountered in a multitude of ways, how stable or flexible are these stimulus-evoked responses? Here, we examined this issue in the locust olfactory system. In the antennal lobe, we found that both spatial and temporal features of odor-evoked responses varied in a stimulus-history dependent manner. The response variations were not random, but allowed the antennal lobe circuit to enhance the uniqueness of the current stimulus. Nevertheless, information about the odorant identity became confounded due to this contrast-enhancement computation. Notably, a linear logical classifier (OR-of-ANDs) that can decode information distributed in flexible subsets of neurons generated predictions that matched results from our behavioral experiments. In sum, our results reveal a simple computational logic for achieving the stability vs. flexibility tradeoff in sensory coding.

Intranasal administration of mitochondria improves spatial memory in olfactory bulbectomized mice

2021 ◽  
pp. 153537022110568
Author(s):  
Natalia V Bobkova ◽  
Daria Y Zhdanova ◽  
Natalia V Belosludtseva ◽  
Nikita V Penkov ◽  
Galina D Mironova
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Spatial Memory ◽  
Intranasal Administration ◽  
Brain Structures ◽  
Brain Regions ◽  
Dependent Manner ◽  
Behavioral Experiments ◽  
Hippocampal Cell Culture ◽  
The Brain

Here, we found that functionally active mitochondria isolated from the brain of NMRI donor mice and administrated intranasally to recipient mice penetrated the brain structures in a dose-dependent manner. The injected mitochondria labeled with the MitoTracker Red localized in different brain regions, including the neocortex and hippocampus, which are responsible for memory and affected by degeneration in patients with Alzheimer's disease. In behavioral experiments, intranasal microinjections of brain mitochondria of native NMRI mice improved spatial memory in the olfactory bulbectomized (OBX) mice with Alzheimer’s type degeneration. Control OBX mice demonstrated loss of spatial memory tested in the Morris water maze. Immunocytochemical analysis revealed that allogeneic mitochondria colocalized with the markers of astrocytes and neurons in hippocampal cell culture. The results suggest that a non-invasive route intranasal administration of mitochondria may be a promising approach to the treatment of neurodegenerative diseases characterized, like Alzheimer's disease, by mitochondrial dysfunction.

Nicotine Suppression of Gustatory Responses of Neurons in the Nucleus of the Solitary Tract

2006 ◽  
Vol 96 (4) ◽  
pp. 1877-1886 ◽  
Author(s):  
Christopher T. Simons ◽  
Yves Boucher ◽  
Mirela Iodi Carstens ◽  
E. Carstens
Keyword(s):  
Monosodium Glutamate ◽  
Plasma Extravasation ◽  
Dependent Manner ◽  
Evoked Responses ◽  
Solitary Tract ◽  
Depressant Effect ◽  
Tongue Surface ◽  
Single Unit Recordings ◽  
Gustatory Neurons ◽  
Dose Dependent

This study investigated effects of nicotine applied to the tongue surface on responses of gustatory neurons in the nucleus of the solitary tract (NTS) in rats. In pentobarbital-anesthetized rats, single-unit recordings were made from NTS units responsive to one or more tastants (sucrose, NaCl, citric acid, monosodium glutamate, quinine). Application of nicotine (0.87, 8.7, or 600 mM) excited gustatory NTS units and significantly attenuated NTS unit responses to their preferred tastant in a dose-dependent manner. The depressant effect of nicotine was equivalent regardless of which tastant best excited the NTS unit. Nicotinic excitation of NTS units and depression of their tastant-evoked responses were both significantly attenuated by the nicotinic antagonist mecamylamine, which itself did not excite NTS units. In rats with bilateral trigeminal ganglionectomy, nicotine still excited nearly all NTS units but no longer depressed tastant-evoked responses. Nicotine did not elicit plasma extravasation when applied to the tongue. The results indicate that nicotine directly excites NTS units by gustatory nerves and inhibits their tastant-evoked responses by a nicotinic acetylcholine receptor-mediated excitation of trigeminal afferents that inhibit NTS units centrally.

scholarly journals Molecular mechanisms for microtubule length regulation by kinesin-8 and XMAP215 proteins

2014 ◽  
Vol 4 (6) ◽  
pp. 20140031 ◽  
Author(s):  
Louis Reese ◽  
Anna Melbinger ◽  
Erwin Frey
Keyword(s):  
Molecular Motors ◽  
Molecular Mechanisms ◽  
Molecular Motor ◽  
Mutual Exclusion ◽  
High Growth ◽  
Dependent Manner ◽  
Dynamic Regulation ◽  
Filament Dynamics ◽  
Length Regulation ◽  
The Stability

The cytoskeleton is regulated by a plethora of enzymes that influence the stability and dynamics of cytoskeletal filaments. How microtubules (MTs) are controlled is of particular importance for mitosis, during which dynamic MTs are responsible for proper segregation of chromosomes. Molecular motors of the kinesin-8 protein family have been shown to depolymerize MTs in a length-dependent manner, and recent experimental and theoretical evidence suggests a possible role for kinesin-8 in the dynamic regulation of MTs. However, so far the detailed molecular mechanisms of how these molecular motors interact with the growing MT tip remain elusive. Here we show that two distinct scenarios for the interactions of kinesin-8 with the MT tip lead to qualitatively different MT dynamics, including accurate length control as well as intermittent dynamics. We give a comprehensive analysis of the regimes where length regulation is possible and characterize how the stationary length depends on the biochemical rates and the bulk concentrations of the various proteins. For a neutral scenario, where MTs grow irrespective of whether the MT tip is occupied by a molecular motor, length regulation is possible only for a narrow range of biochemical rates, and, in particular, limited to small polymerization rates. By contrast, for an inhibition scenario, where the presence of a motor at the MT tip inhibits MT growth, the regime where length regulation is possible is extremely broad and includes high growth rates. These results also apply to situations where a polymerizing enzyme like XMAP215 and kinesin-8 mutually exclude each other from the MT tip. Moreover, we characterize the differences in the stochastic length dynamics between the two scenarios. While for the neutral scenario length is tightly controlled, length dynamics is intermittent for the inhibition scenario and exhibits extended periods of MT growth and shrinkage. On a broader perspective, the set of models established in this work quite generally suggest that mutual exclusion of molecules at the ends of cytoskeletal filaments is an important factor for filament dynamics and regulation.

BDNF-Induced Facilitation of Afferent-Evoked Responses in Lamina II Neurons Is Reduced After Neonatal Spinal Cord Contusion Injury

2005 ◽  
Vol 94 (3) ◽  
pp. 1798-1804 ◽  
Author(s):  
Sandra M. Garraway ◽  
Aileen J. Anderson ◽  
Lorne M. Mendell
Keyword(s):  
Nmda Receptor ◽  
Dorsal Root ◽  
Dependent Manner ◽  
Evoked Responses ◽  
Patch Clamp Technique ◽  
Synaptic Facilitation ◽  
Trkb Receptors ◽  
Contusion Injury ◽  
Nmda Receptor Function ◽  
Spinal Cord Contusion

We previously reported that brain-derived neurotrophic factor (BDNF), a pronociceptive neurotransmitter, induces synaptic facilitation of excitatory postsynaptic current (EPSC) in lamina II neurons of neonatal rats up to P14 in a N-methyl-d-aspartate (NMDA) receptor-dependent manner. Here we used the patch-clamp technique to study synaptic and NMDA-evoked responses in transverse spinal slices in the lumbar enlargement as well as the ability of BDNF to modify these responses from 1 day to 6 wk after neonatal contusion. In older uninjured animals (>P14), BDNF continued to evoke synaptic facilitation although superfusion of NMDA (in TTX) induced inward current of significantly smaller amplitude than that observed in younger rats. After contusion injury, BDNF was unable to facilitate dorsal root-evoked EPSCs in lamina II neurons despite the finding that NMDA-evoked currents were only slightly smaller than those observed in age-matched uninjured animals. These findings suggest that although BDNF-induced facilitation of the AMPA/kainate receptor-mediated response to dorsal root stimulation is maintained in the mature dorsal horn from intact rats, BDNF may no longer elicit these pronociceptive actions after neonatal contusion injury. The lack of change in NMDA-evoked currents in contused cords suggests that diminished NMDA receptor function is not the major cause of the decline in BDNF action after contusion. It seems more likely that diminished trkB expression and enhanced expression of truncated trkB receptors in the contused cord play a significant role in determining the reduced effect of BDNF under these conditions.

scholarly journals DIFFERENTIAL DIAGNOSTICS OF BREAST PATHOLOGY USING CONTRAST ENHANCEMENT PATTERNS IN CONTRAST-ENHANCED SPECTRAL MAMMOGRAPHY

2020 ◽  
Vol 66 (3) ◽  
pp. 252-261
Author(s):  
Roksana Ulyanova ◽  
A. Chernaya ◽  
Petr Krivorotko ◽  
Sergey Novikov ◽  
Sergey Kanaev ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Contrast Enhancement ◽  
World Literature ◽  
Differential Diagnostics ◽  
Diagnostic Feature ◽  
Benign Lesions ◽  
Intravenous Contrast ◽  
Dynamic Contrast Enhancement ◽  
Contrast Enhanced ◽  
Detailed Assessment

Dual-energy contrast-enhanced spectral mammography (CESM) is a new promising method for visualizing pathological changes in breast, which combines digital mammography and a functional assessment of vascularization using intravenous contrast ehnancement. According to accumulated experience CESM is well tolerated by patients and is similar to magnetic resonance imaging with dynamic contrast enhancement (MRI with DCE), but at the same time, CESM is more affordable and can be performed in patients with contraindications for MRI. However, few studies have been conducted to evaluate the role of CESM. In the world literature, interpretation of contrast images is based only on the degree of accumulation of the contrast agent, but we propose a more detailed assessment of the structure of the hypervascular lesions by highlighting the contrast enhancement patterns. Objective: to determine the diagnostic effectiveness of CESM using the contrast enhancement patterns in malignant and benign lesions. Materials and methods. 239 women with suspicious for breast cancer lesions were examined from August 2018 to December 2019. The mean age of the women was 51 years. 322 lesions were revealed, 149 (46.3%) were malignant, 173 (53.7%) were benign. All lesions were histologically confirmed. As a result of the analysis of our data, 9 types of contrast enhancement patterns were distinguished: reticulate, granular, annular, diffuse-spherical, lacunar, cloud-like, heterogeneous-annular, point, cotton-like. Results. Using an additional diagnostic feature - contrast enhancement patterns in lesions, increased the sensitivity of CESM from 91.3% to 98.0% (p=0.26), specificity from 80.3% to 93, 6% (p=0.013), accuracy from 85.4 to 95.7% (p=0.004) in comparison with using of only one feature of contrast enhancement intensity in the differential diagnosis of malignant and benign lesions. Conclusion: thus, this approach of interpreting subtraction images allows to increase the efficiency of CESM in diagnosis of breast cancer.

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