Biology subjects

Anokhin, K.

Publications and source records attributed to Anokhin, K..

6 recordsLinked to original sources

bioRxiv2026

Context-bridged associative learning: linking neutral tone engram to fear through shared context

In associative fear learning, weak or temporally constrained training may fail to link a conditioned stimulus (CS) with an aversive unconditioned stimulus (US), particularly when the contextual representation is impaired (the immediate shock deficit). Here, we systematically tested behavioral conditions that enable linking of an initially neutral auditory memory trace to an aversive episode. Male C57BL/6 mice were studied in four experiments manipulating (i) preexposure to a CS tone, (ii) the duration of context exploration before immediate footshock, and (iii) whether CS memory was tested in a novel or a familiar-like context. A 5 s tone followed immediately by footshock did not induce reliable fear to either the CS or the training context. CS preexposure three days before conditioning did not facilitate CS aversive memory when animals were tested in a completely novel context. However, robust facilitation emerged when the CS memory was tested in a context similar to the preexposure/conditioning one, indicating strong contextual gating of CS retrieval. Extending context exploration before shock enabled CS fear learning, but reduced (and even reversed) the effect of CS preexposure, consistent with latent inhibition. Together, these results delineate behavioral constraints for linking an initially neutral cue memory to an aversive event and highlight contextual control over the coupling and expression of cue memory traces.

neuroscience↗

bioRxiv2025

Co-allocation of distinct contextual memories within a wide time window temporal dynamics and neuronal co-reactivation during retrieval

Recent studies have shown that a shared neuronal ensemble in the hippocampus links distinct contextual memories encoded within a certain time window (specifically, 5 hours, 2 and 7 days). Here we explored the temporal dynamics of two contextual (neutral and aversive) memories linking and analysed neuronal ensembles in the hippocampus, amygdala and different cortical regions reactivated during retrieval. Firstly, we have found that memories integrated across different time-points including several hours, days and weeks but not if learning phases was separated by short-term and very long-term time intervals. Secondly, we have demonstrated a higher neuronal co-reactivation in the hippocampus and amygdala during retrieval in case of memories integration that supports the hypothesis that shared neuronal ensembles link distinct memories. Finally, we have elicited that proportions of reactivated neuronal ensembles in these brain regions are greater in case of contextual memories integration.

neuroscience↗

bioRxiv2022

Plasticity facilitates rapid evolution

Developmental plasticity enables organisms to cope with new environmental challenges. If deploying such plasticity is costly in terms of time or energy, the same adaptive behavior could subsequently evolve through piecemeal genomic reorganisation that replaces the requirement to acquire that adaptation by individual plasticity. Here we report a new dimension to the way in which plasticity can drive evolutionary change leading to ever greater complexity in biological organization. Our model deploys the concept of partially overlapping functional systems. We found that plasticity accelerated dramatically the evolutionary accumulation of adaptive systems in model organisms with relatively low rates of mutation. The effect of plasticity on the evolutionary growth of complexity was even greater when the number of elements needed to construct a functional system was increased. These results suggest that as the difficulty of challenges from the environment become greater, so plasticity exerts an ever more powerful role in meeting those challenges and in opening up new avenues for the subsequent evolution of complex adaptations.

animal behavior and cognition↗

bioRxiv2021

Spatiotemporal 3D image registration for mesoscale studies of brain development.

Comparison of brain samples representing different developmental stages often necessitates registering the samples to common coordinates. Although the available software tools are successful in registering 3D images of adult brains, registration of perinatal brains remains challenging due to rapid growth-dependent morphological changes and variations in developmental pace between animals. To address these challenges, we propose a multi-step algorithm for the registration of perinatal brains. First, we optimized image preprocessing to increase the algorithms sensitivity to mismatches in registered images. Second, we developed an attention-gated simulated annealing (Monte Carlo) procedure capable of focusing on the differences between perinatal brains. Third, we applied classical multidimensional scaling (CMDS) to align ("synchronize") brain samples in time, accounting for individual development paces. We tested this multi-step algorithm on 28 samples of whole-mounted perinatal mouse brains (P0 - P9) and observed accurate registration results. Our computational pipeline offers a runtime of several minutes per brain on a personal computer and automates brain registration tasks including mapping brain data to atlases, comparison of averaged experimental groups, and monitoring brain development dynamics.

neuroscience↗

bioRxiv2020

The Laplacian eigenmaps dimensionality reduction of fMRI data for discovering stimulus-induced changes in the resting-state brain activity

The resting brain at wakefulness is active even in the absence of goal-directed behavior or salient stimuli. However, patterns of this resting-state (RS) activity can undergo alterations following exposure to meaningful stimuli. This study aimed to develop an unbiased method to detect such changes in the RS activity after exposure to emotionally meaningful stimuli. For this purpose, we used functional magnetic resonance imaging (fMRI) of RS brain activity before and after the acquisition and extinction of experimental conditioned fear. A group of healthy volunteers participated in three fMRI sessions: a RS before fear conditioning, a fear extinction session, and a RS immediately after fear extinction. The fear-conditioning paradigm consisted of three neutral visual stimuli paired with a partial reinforcement by a mild electric current. We used both linear and non-linear dimensionality reduction approaches to distinguish between the initial RS and the RS after stimuli exposure. The principal component analysis (PCA) as a linear dimensionality reduction method did not differentiate these states. Using the non-linear Laplacian eigenmaps manifold learning method, we were able to show significant differences between the two RSs at the level of individual participants. This detection was further improved by smoothing the BOLD signal with the wavelet multiresolution analysis. The developed method can improve the discrimination of functional states collected in longitudinal fMRI studies.

neuroscience↗

bioRxiv2018

Experience-specific anterograde amnesia: memory reacquisition deficit phenomenon and its characterization in the vertebrate learning model

A common assumption from experiments that interfere with memory consolidation is that the resultant amnesia returns the brain of an animal to a tabula rasa state with respect to disturbed experience. However, recent studies in terrestrial snail classical conditioning revealed an odd phenomenon: animals were unable to relearn conditioned avoidance of specific food after this memory had been impaired by protein-synthesis inhibitors or N-methyl-D-aspartate (NMDA) receptor antagonists. Here we examined whether such specific memory reacquisition deficit can also be observed in vertebrate learning. We trained day-old chicks in a one-trial passive avoidance task by presenting them a bead of a specific color covered with a repellent substance, methyl anthranilate. Training was preceded by administration of the protein synthesis inhibitor anisomycin or the NMDA receptor antagonist MK-801. Both drugs produced permanent amnesia, and no spontaneous recovery of memory was observed. A second training was given to the amnestic animals either using a bead of the same color (retraining) or a new color (novel training). The interval between the first and second training was 2 or 24 h, and the retention test was given from 30 min to 48 h after the second training. Retraining of the amnestic chicks with the bead that was presented during the initial training failed to produce new avoidance memory for this stimulus at all the between-training and training-to-test intervals. This memory reacquisition deficit was specific and was not transferred to a new conditioned stimulus, which was readily learned. We suggest that such pharmacologically induced experience-specific anterograde amnesia might reflect general properties of normal memory allocation, and we discuss its possible neural bases.

neuroscience↗