Victor A. Kulikov

Automated measurement of spatial preference in the open field test with transmitted lighting.

New modification of the open field was designed to improve automation of the test. The main innovations were: (1) transmitted lighting and (2) estimation of probability to find pixels associated with an animal in the selected region of arena as an objective index of spatial preference. Transmitted (inverted) lighting significantly ameliorated the contrast between an animal and arena and allowed to track white animals with similar efficacy as colored ones. Probability as a measure of preference of selected region was mathematically proved and experimentally verified. A good correlation between probability and classic indices of spatial preference (number of region entries and time spent therein) was shown. The algorithm of calculation of probability to find pixels associated with an animal in the selected region was implemented in the EthoStudio software. Significant interstrain differences in locomotion and the central zone preference (index of anxiety) were shown using the inverted lighting and the EthoStudio software in mice of six inbred strains. The effects of arena shape (circle or square) and a novel object presence in the center of arena on the open field behavior in mice were studied.

Application of 3-D imaging sensor for tracking minipigs in the open field test.

BACKGROUND The minipig is a promising model in neurobiology and psychopharmacology. However, automated tracking of minipig behavior is still unresolved problem. NEW METHOD The study was carried out on white, agouti and black (or spotted) minipiglets (n=108) bred in the Institute of Cytology and Genetics. New method of automated tracking of minipig behavior is based on Microsoft Kinect 3-D image sensor and the 3-D image reconstruction with EthoStudio software. The algorithms of distance run and time in the center evaluation were adapted for 3-D image data and new algorithm of vertical activity quantification was developed. RESULTS The 3-D imaging system successfully detects white, black, spotted and agouti pigs in the open field test (OFT). No effect of sex or color on horizontal (distance run), vertical activities and time in the center was shown. Agouti pigs explored the arena more intensive than white or black animals, respectively. The OFT behavioral traits were compared with the fear reaction to experimenter. Time in the center of the OFT was positively correlated with fear reaction rank (ρ=0.21, p<0.05). Black pigs were significantly more fearful compared with white or agouti animals. COMPARISON WITH EXISTING METHOD The 3-D imaging system has three advantages over existing automated tracking systems: it avoids perspective distortion, distinguishes animals any color from any background and automatically evaluates vertical activity. CONCLUSION The 3-D imaging system can be successfully applied for automated measurement of minipig behavior in neurobiological and psychopharmacological experiments.

Association between tryptophan hydroxylase-2 genotype and the antidepressant effect of citalopram and paroxetine on immobility time in the forced swim test in mice

Tryptophan hydroxylase-2 (TPH2) is the rate limiting enzyme of serotonin synthesis in the brain. The 1473G allele of the C1473G polymorphism in mTPH2 gene is associated with reduced enzyme activity and serotonin synthesis rate in the mouse brain. Here, the influence of the 1473G allele on the antidepressant effect of selective serotonin reuptake inhibitors (SSRIs), citalopram (2.5 or 5.0mg/kg) and paroxetine (5.0 or 10.0mg/kg), in the forced swim test was studied using B6-1473G and B6-1473C congenic mouse lines with the 1473G (decreased TPH2 activity) or 1473C (normal TPH2 activity) alleles, respectively, transferred to the genome of C57BL/6 mouse strain. Paroxetine (5.0 or 10.0mg/kg) and citalopram (2.5 or 5.0mg/kg) decreased immobility time in B6-1473C mice, while both doses of paroxetine and 2.5mg/kg of citaloprame did not alter immobility time in B6-1473G mice. However, 5.0mg/kg of citalopram reduced immobility in B6-1473G mice. The results provided genetic evidence of moderate association between 1473G allele and reduced sensitivity to SSRIs in mice.

Effects of LPS and serotonergic drugs on hygienic behavior in mice.

Hygienic self-grooming is a behavioral adaptation for removing litter particles and pathogenic agents from animal fur and skin. We studied contribution of brain serotonin system into mechanisms regulating hygienic behavior in intact mice and mice with LPS(lipopolysaccharide)-induced sickness. A spot of fluorescent dye was applied on the back of a mouse, and the decrease in its fluorescence served as an index of fur cleaning efficiency estimated using original classifier algorithm. Agonist of 5-HT(₁A) receptor (8-OH-DPAT) or 5-HT(₂A/₂C) receptor (DOI) attenuated fur cleaning at a dose of 1 mg/kg but not of 0.2 mg/kg. MAO-A inhibitor clorgyline decreased hygienic self-grooming at a dose of 10 but not of 5 mg/kg. SSRI paroxetine had no effect while fluoxetine diminished hygienic behavior at the higher dose used (20 mg/kg). Inhibitory effect of LPS treatment (50 μg/kg) on fur cleaning was not altered by administration of p-MPPI (5-HT(₁A) receptor antagonist, 1mg/kg) or DOI (1mg/kg) while 8-OH-DPAT (1 mg/kg) produced additive effect. The results suggest the involvement of 5-HT(₁A) and 5-HT(₂A/₂C) brain serotonin receptors and MAO-A in the inhibition of hygienic behavior in mice. However, LPS-induced depression of fur cleaning appeared to be mediated via different mechanisms and enhanced by 5-HT(₁A) receptor activation.

Spatial learning in the Morris water maze in mice genetically different in the predisposition to catalepsy: the effect of intraventricular treatment with brain-derived neurotrophic factor.

Hereditary catalepsy in mice is accompanied with volume reduction of some brain structures and high vulnerability to inflammatory agents. Here an association between hereditary catalepsy and spatial learning deficit in the Morris water maze (MWM) in adult mouse males of catalepsy-resistant AKR, catalepsy-prone CBA and AKR.CBA-D13Mit76 (D13) strains was studied. Recombinant D13 strain was created by means of the transfer of the CBA-derived allele of the major gene of catalepsy to the AKR genome. D13 mice showed a low MWM performance in the acquisition test and high expression of the gene coding proinflammatory interleukin-6 (Il-6) in the hippocampus and cortex compared with mice of the parental AKR and CBA strains. An acute ivc administration of 300 ng of brain derived neurotrophic factor (BDNF) normalized the performance in the MWM, but did not decrease the high Il-6 gene expression in the brain of D13 mice. These results indicated a possible association between the hereditary catalepsy, MWM performance, BDNF and level of Il-6 mRNA in the brain, although the relation between these characteristics seems to be more complex. D13 recombinant mice with deficit of spatial learning is a promising model for study of the genetic and molecular mechanisms of learning disorders as well as for screening potential cognitive enhancers.

Method of estimation of turbulence characteristic scales

We propose an optical method that uses phase data of a laser beam obtained from a Shack-Hartmann sensor to estimate both the inner and outer scales of turbulence. The method is based on the sequential analysis of normalized correlation functions of Zernike coefficients. It allows the exclusion C(n)(2) from the analysis and reduces the solution of a two-parameter problem to a sequential solution of two single-parameter problems. The method has been applied to estimate the outer and inner scales of turbulence induced in the water cell.

Estimation of turbulent parameters based on the intensity scintillations of the laser beam propagated through a turbulent water layer

The inner scale and the refractive-index structure parameter Cn2 are estimated by the intensity scintillations of the laser beam propagated through the turbulent water layer. The laser beam scintillations caused by underwater propagation can be described in the framework of a turbulence model with accounting of the inner scale. An intensity field has been observed at a 2 m distance when the laser beam passed through a water convective cell with a characteristic Rayleigh number of about 108. Similar intensity fields were simulated by using the split-step method. Characteristics of the experimentally obtained and numerically simulated intensity fields are compared and analyzed. A simple method of the turbulent parameter estimation is proposed.

Method of abandoned object detection based on a sequence of depth images

A new method of abandoned object detection based on analyzing a sequence of depth images is proposed, and algorithms of real-time determination of the quasi-stationary background and abandoned objects are developed. The efficiency of the proposed algorithms is compared with that of the algorithm based on analyzing brightness images..

Behavioral phenotyping of mice deficient in the tumor necrosis factor

The tumor necrosis factor (TNF) is a cytokine exerting both homeostatic and pathophysiological roles in the central nervous system (CNS). It has been demonstrated that TNF plays roles in diseases such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis. Nevertheless, the roles of TNF in the CNS under normal physiological conditions have been poorly studied. A novel mouse strain with the TNF deficiency (TNFKO) was developed in S.A. Nedospasov’s laboratory at the Engelhardt Institute of Molecular biology of the Russian Academy of Sciences in a C57Bl/6 (WT) background. In our study, we compared the behavior of TNFKO and WT adult mice in a battery of tests: open field, elevated plus-maze, and the forcedswim test. We showed that TNF deficiency had no effect on locomotor activity or exploration in the openfield test. At the same time, in this test, TNFKO mice spent more time in the center of the arena, but had a higher level of defecation and lower rearing duration. This result indicates that, in the open-field conditions, TNFKO mice show disorientation rather than anxiety-like behavior. There were no differences between TNFKO and WT in the anxiety level in the elevated plus-maze test or in depressive-like behavior in the forced-swim test. These data suggest that the TNF deficiency leads to changes in neurofunctional interactions that alter the mouse’s response to mild stress in the open-field test.

Fast algorithm of detection of boundary points in images

A method of detecting boundary points in brightness images, based on subpixel calculation of the brightness difference, is proposed. In a fragment 4×4 pixels in size, this method allows calculating 12 directions of the jump in brightness; the algorithm complexity is ∼34N atomic operations. The method considered is compared with available methods of detection of boundary points in the image. The algorithm proposed is demonstrated to be more stable to the “salt and pepper” noise, ensures more stable determination of the brightness jump direction, and provides a more intense response to the signal. An application of the method is noted.