scholarly journals Evolutionary learning in the brain by heterosynaptic plasticity

2021 ◽  
Author(s):  
Zedong Bi ◽  
Guozhang Chen ◽  
Dongping Yang ◽  
Yu Zhou

The way in which the brain modifies synapses to improve the performance of complicated networks remains one of the biggest mysteries in neuroscience. Existing proposals lack sufficient experimental support, and neglect inter-cellular signaling pathways ubiquitous in the brain. Here we show that the heterosynaptic plasticity between hippocampal or cortical pyramidal cells mediated by diffusive nitric oxide and astrocyte calcium wave, together with flexible dendritic gating of somatostatin interneurons, implies an evolutionary algorithm (EA). In simulation, this EA is able to train deep networks with biologically plausible binary weights in MNIST classification and Atari-game playing tasks up to performance comparable with continuous-weight networks trained by gradient-based methods. Our work leads paradigmatically fresh understanding of the brain learning mechanism.

1999 ◽  
Vol 17 (1) ◽  
pp. 45-55 ◽  
Author(s):  
A.E.-D El-Husseini ◽  
J Williams ◽  
P.B Reiner ◽  
S Pelech ◽  
S.R Vincent

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Isela Álvarez-González ◽  
Scarlett Camacho-Cantera ◽  
Patricia Gómez-González ◽  
Michael J. Rendón Barrón ◽  
José A. Morales-González ◽  
...  

AbstractWe evaluated the duloxetine DNA damaging capacity utilizing the comet assay applied to mouse brain and liver cells, as well as its DNA, lipid, protein, and nitric oxide oxidative potential in the same cells. A kinetic time/dose strategy showed the effect of 2, 20, and 200 mg/kg of the drug administered intraperitoneally once in comparison with a control and a methyl methanesulfonate group. Each parameter was evaluated at 3, 9, 15, and 21 h postadministration in five mice per group, except for the DNA oxidation that was examined only at 9 h postadministration. Results showed a significant DNA damage mainly at 9 h postexposure in both organs. In the brain, with 20 and 200 mg/kg we found 50 and 80% increase over the control group (p ≤ 0.05), in the liver, the increase of 2, 20, and 200 mg/kg of duloxetine was 50, 80, and 135% in comparison with the control level (p ≤ 0.05). DNA, lipid, protein and nitric oxide oxidation increase was also observed in both organs. Our data established the DNA damaging capacity of duloxetine even with a dose from the therapeutic range (2 mg/kg), and suggest that this effect can be related with its oxidative potential.


2021 ◽  
Vol 37 (1) ◽  
Author(s):  
Yeon Ho Yoo ◽  
Dae Won Kim ◽  
Bai Hui Chen ◽  
Hyejin Sim ◽  
Bora Kim ◽  
...  

Abstract Background Aging is one of major causes triggering neurophysiological changes in many brain substructures, including the hippocampus, which has a major role in learning and memory. Thioredoxin (Trx) is a class of small redox proteins. Among the Trx family, Trx2 plays an important role in the regulation of mitochondrial membrane potential and is controlled by TrxR2. Hitherto, age-dependent alterations in Trx2 and TrxR2 in aged hippocampi have been poorly investigated. Therefore, the aim of this study was to examine changes in Trx2 and TrxR2 in mouse and rat hippocampi by age and to compare their differences between mice and rats. Results Trx2 and TrxR2 levels using Western blots in mice were the highest at young age and gradually reduced with time, showing that no significant differences in the levels were found between the two subfields. In rats, however, their expression levels were the lowest at young age and gradually increased with time. Nevertheless, there were no differences in cellular distribution and morphology in their hippocampi when it was observed by cresyl violet staining. In addition, both Trx2 and TrxR2 immunoreactivities in the CA1-3 fields were mainly shown in pyramidal cells (principal cells), showing that their immunoreactivities were altered like changes in their protein levels. Conclusions Our current findings suggest that Trx2 and TrxR2 expressions in the brain may be different according to brain regions, age and species. Therefore, further studies are needed to examine the reasons of the differences of Trx2 and TrxR2 expressions in the hippocampus between mice and rats.


2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yong-Peng Yu ◽  
Xiang-Lin Chi ◽  
Li-Jun Liu

Gases such as nitric oxide (NO) and carbon monoxide (CO) play important roles both in normal physiology and in disease. Recent studies have shown that hydrogen sulfide (H2S) protects neurons against oxidative stress and ischemia-reperfusion injury and attenuates lipopolysaccharides (LPS) induced neuroinflammation in microglia, exhibiting anti-inflammatory and antiapoptotic activities. The gas H2S is emerging as a novel regulator of important physiologic functions such as arterial diameter, blood flow, and leukocyte adhesion. It has been known that multiple factors, including oxidative stress, free radicals, and neuronal nitric oxide synthesis as well as abnormal inflammatory responses, are involved in the mechanism underlying the brain injury after subarachnoid hemorrhage (SAH). Based on the multiple physiologic functions of H2S, we speculate that it might be a promising, effective, and specific therapy for brain injury after SAH.


Parasitology ◽  
1996 ◽  
Vol 113 (6) ◽  
pp. 559-565 ◽  
Author(s):  
M. K. S. Gustafsson ◽  
A. M. Lindholm ◽  
N. B. Terenina ◽  
M. Reuter

SUMMARYThe free radical nitric oxide (NO), which is synthesized by nitric oxide synthase (NOS), has recently been discovered to function as a neuronal messenger. The presence of NOS was detected in the nervous system of adult Hymenolepis diminuta with NADPH-diaphorase (NADPH-d) histochemistry. The NADPH-d histochemical reaction is regarded as a selective marker for NOS in neuronal tissue. NADPH-d staining was observed in nerve fibres in the main and minor nerve cords and the transverse ring commissures, and in cell bodies in the brain commissure, along the main nerve cords, in the suckers and the rostellar sac. NADPH-d staining was also observed in the wall of the internal seminal vesicle and the genital atrium. The pattern of NADPH-d staining was compared with that of the 5-HT immunoreactive nervous elements. The NADPH-d staining reaction and the 5-HT immunoreactivity occur in separate sets of neurons. This is the first time the NADPH-d reaction has been demonstrated in the nervous system of a flatworm, indicating that NOS is present and that NO can be produced at this level of evolution.


1997 ◽  
Vol 17 (10) ◽  
pp. 1089-1096 ◽  
Author(s):  
Kazunori Toyoda ◽  
Kenichiro Fujii ◽  
Setsuro Ibayashi ◽  
Tetsuhiko Nagao ◽  
Takanari Kitazono ◽  
...  

We tested the hypothesis that nitric oxide (NO) plays a role in CBF autoregulation in the brain stem during hypotension. In anesthetized rats, local CBF to the brain stem was determined with laser-Doppler flowmetry, and diameters of the basilar artery and its branches were measured through an open cranial window during stepwise hemorrhagic hypotension. During topical application of 10−5 mol/L and 10−4 mol/L Nω-nitro-L-arginine (L-NNA), a nonselective inhibitor of nitric oxide synthase (NOS), CBF started to decrease at higher steps of mean arterial blood pressure in proportion to the concentration of L-NNA in stepwise hypotension (45 to 60 mm Hg in the 10−5 mol/L and 60 to 75 mm Hg in the 10−4 mol/L L-NNA group versus 30 to 45 mm Hg in the control group). Dilator response of the basilar artery to severe hypotension was significantly attenuated by topical application of L-NNA (maximum dilatation at 30 mm Hg: 16 ± 8% in the 10−5 mol/L and 12 ± 5% in the 10−4 mol/L L-NNA group versus 34 ± 4% in the control group), but that of the branches was similar between the control and L-NNA groups. Topical application of 10−5 mol/L 7-nitro indazole, a selective inhibitor of neuronal NOS, did not affect changes in CBF or vessel diameter through the entire pressure range. Thus, endothelial but not neuronal NO seems to take part in the regulation of CBF to the the brain stem during hypotension around the lower limits of CBF autoregulation. The role of NO in mediating dilatation in response to hypotension appears to be greater in large arteries than in small ones.


Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Joseph Francis ◽  
Li Yu ◽  
Anuradha Guggilam ◽  
Srinivas Sriramula ◽  
Irving H Zucker

3-Hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors (statins) have been shown to reduce the incidence of myocardial infarction independent of their lipid-lowering effects. Nitric oxide (NO) in the central nervous system contributes to cardiovascular regulatory mechanisms. Imbalance between nitric oxide (NO) and superoxide anion (O 2 . − ) in the brain may contribute to enhanced sympathetic drive in heart failure (HF). This study was done to determine whether treatment with atorvastatin (ATS) ameliorates the imbalance between NO and O 2 . − production in the brain stem and contributes to improvement of left ventricular (LV) function. Methods and Results: Myocardial infarction (MI) was induced by ligation of the left coronary artery or sham surgery. Subsequently, mice were treated with ATS (10 μg/kg) (MI + ATS), or vehicle (MI + V). After 5 weeks, echocardiography revealed left ventricular dilatation in MI mice. Realtime RT-PCR indicated an increase in the mRNA expression of the LV hypertrophy markers, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Neuronal NOS (nNOS) and endothelial NOS (eNOS) mRNA expression were significantly reduced, while that of NAD(P)H oxidase subunit (gp91phox) expression was elevated in the brain stem of MI mice. Compared with sham-operated mice, ATS-treated mice showed reduced cardiac dilatation, decreased ANP and BNP in the LV. ATS also reduced gp91phox expression and increased nNOS mRNA expression in the brain stem, while no changes in eNOS and iNOS were observed. Conclusion: These findings suggest that ATS reduces oxidative stress and increases neuronal NOS in the brain stem, and improves left ventricular function in heart failure.


2000 ◽  
Vol 279 (6) ◽  
pp. H2786-H2796 ◽  
Author(s):  
Shaohua Ye ◽  
Pantea Mozayeni ◽  
Michael Gamburd ◽  
Huiqin Zhong ◽  
Vito M. Campese

Increased sympathetic nervous system (SNS) activity plays a role in the genesis of hypertension in rats with chronic renal failure (CRF). The rise in central SNS activity is mitigated by increased local expression of neuronal nitric oxide synthase (NOS) mRNA and NO2/NO3 production. Because interleukin (IL)-1β may activate nitric oxide in the brain, we have tested the hypothesis that IL-1β may modulate the activity of the SNS via regulation of the local expression of neuronal NOS (nNOS) in the brain of CRF and control rats. To this end, we first found that administration of IL-1β in the lateral ventricle of control and CRF rats decreased blood pressure and norepinephrine (NE) secretion from the posterior hypothalamus (PH) and increased NOS mRNA expression. Second, we observed that an acute or chronic injection of an IL-1β-specific antibody in the lateral ventricle raised blood pressure and NE secretion from the PH and decreased NOS mRNA abundance in the PH of control and CRF rats. Finally, we measured the IL-1β mRNA abundance in the PH, locus coeruleus, and paraventricular nuclei of CRF and control rats by RT-PCR and found it to be greater in CRF rats than in control rats. In conclusion, these studies have shown that IL-1β modulates the activity of the SNS in the central nervous system and that this modulation is mediated by increased local expression of nNOS mRNA.


1996 ◽  
Vol 76 (1) ◽  
pp. 193-244 ◽  
Author(s):  
P. B. Persson

It is generally held that the role of a specific control element can only be understood within its physiological environment. The reviewed studies make it clear that there is a potent interplay between locally produced substances such as adenosine, nitric oxide, prostaglandins, and various others all interacting with the central level of control. This can occur at central sites (e.g., nitric oxide in the brain) or in the periphery (e.g., neural influence on autoregulation). The interactions are more or less pronounced during specific physiological challenges. Furthermore, several of these interactions are altered under pathological circumstances, and in some cases, the interactions seem to maintain or even augment the severity of disease. When more than three parameters participate in an interaction, the resulting regulation may become extremely complex. If these parameters are nonlinearly coupled with each other, the only way to shed light onto the nature of control network is by treating it as a black box. With the use of spectral analysis or nonlinear methods, it is possible to disentangle the fundamental nature of the system in terms of the complexity and stability. Therefore, modern developments in cardiovascular physiology utilizing these techniques, some of which are derived from the "chaos theory," are reviewed.


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