Biology subjects

Szumiec, Łukasz

Publications and source records attributed to Szumiec, Łukasz.

5 recordsLinked to original sources

bioRxiv2025

Individual and social contributions to learning of mice in Intellicages: the general framework and mean field theory

Reinforcement learning enables the adaptation of behaviors to changes in the environment. Models of reinforcement learning based on using previous experience to guide future choices enable balancing exploitation of opportunities and exploring the options and provide accurate predictions of animal behavior in simple instrumental tasks. However, they fail to account for the critical advantage we and other animals have, namely the ability not only to learn from our own choices but also from observing the outcomes of choices made by others. Here, we propose a new conceptual, analytical, and computational framework combining point processes with reinforcement learning models for the description, analysis and modeling of individual and group effects of mice learning reward placement. We show that marked point processes provide a natural language to describe behavior of group housed mice. We show how different reinforcement models of the behavior, including group effects, can be studied effectively in this framework, using example experiments. With this framework we show that the group effects (peer pressure) are twice stronger than individual learning.

animal behavior and cognition↗

bioRxiv2025

Modeling social influence as a reinforcer reveals varying individual learning strategies and the group's structure

In a social context, knowledge can be gained through observation and imitation, but in a numerous group, social influence can also be contradictory and confusing. The mechanisms of social learning in groups have not been fully characterized, partly due to the lack of adequate mathematical description. Using the known reinforcing property of social influence we introduce a reinforcement learning model which can account for social effects at the group and individual level. We use it to reveal pairwise influence relations and the overall learning strategies in a reversal learning task applied to a cohort of mice housed in an Intellicage. Animals make an efficient use of social influence when the goal of the group agrees with their own, but switch to an individual learning scheme when these goals are misaligned. They also exhibit varied decision rules depending on their own motivational state, and a selectivity in assimilating social information depending on the state of their conspecifics.

animal behavior and cognition↗

bioRxiv2025

L-DOPA induces spatially discrete changes in gene expression in the forebrain of mice with a progressive loss of dopaminergic neurons

L-3,4-Dihydroxyphenylalanine (L-DOPA) is effective at alleviating motor impairments in Parkinsons disease (PD) patients but has mixed effects on nonmotor symptoms and causes adverse effects after prolonged treatment. Here, we analyzed the spatial profile of L-DOPA-induced gene expression in the forebrain of mice with an inducible progressive loss of dopaminergic neurons (the TIF-IADATCreERT2 strain), with a focus on the similarities and differences in areas relevant to different PD symptoms. The animals received a 14-day L-DOPA treatment, and 1 h after the final drug injection, a spatial transcriptome analysis was performed on coronal forebrain sections. A total of 121 genes were identified as being regulated by L-DOPA. We found that the treatment had widespread effects extending beyond the primary areas involved in dopamine-dependent movement control. An unsupervised clustering analysis of the transcripts recapitulated the forebrain anatomy and indicated both ubiquitous and region-specific effects on transcription. The changes were most pronounced in layers 2/3 and 5 of the dorsal cortex and the dorsal striatum, where a robust increase in the abundance of activity-regulated transcripts, including Fos, Egr1, and Junb, was observed. Conversely, transcripts with a decreased abundance, e.g., Plekhm2 or Pgs1, were identified primarily in the piriform cortex, the adjacent endopiriform nucleus, and the claustrum. Taken together, our spatial analysis of L-DOPA-induced alterations in gene expression reveals the anatomical complexity of treatment effects, identifying novel genes affected by the drug, as well as molecular activation in brain areas relevant to the nonmotor symptoms of PD.

neuroscience↗

bioRxiv2023

Nonmotor symptoms associated with progressive loss of dopaminergic neurons in a mouse model of Parkinson's disease

Parkinsons disease (PD) is characterized by three main motor symptoms: bradykinesia, rigidity and tremor. PD is also associated with diverse nonmotor symptoms that may develop in parallel or precede motor dysfunctions, ranging from autonomic system dysfunctions and impaired sensory perception to cognitive deficits and depression. Here, we examine the role of the progressive loss of dopaminergic transmission in behaviors related to the nonmotor symptoms of PD in a mouse model of the disease (the TIF-IADATCreERT2 strain). We found that in the period from 5 to 12 weeks after the induction of a gradual loss of dopaminergic neurons, mild motor symptoms became detectable, including changes in the distance between paws while standing as well as the step cadence and sequence. Male mutant mice showed no apparent changes in olfactory acuity, no anhedonia-like behaviors, and normal learning in an instrumental task; however, a pronounced increase in the number of operant responses performed was noted. Similarly, female mice with progressive dopaminergic neuron degeneration showed normal learning in the probabilistic reversal learning task and no loss of sweet-taste preference, but again, a robustly higher number of choices were performed in the task. In both males and females, the higher number of instrumental responses did not affect the accuracy or the fraction of rewarded responses. Taken together, these data reveal discrete, dopamine-dependent nonmotor symptoms that emerge in the early stages of dopaminergic neuron degeneration.

neuroscience↗

bioRxiv2022

A robust method for measuring social reward in adult mice

Social interactions can be and often are rewarding. The effect of social contact strongly depends on circumstances, and the reward may be driven by varied motivational processes, ranging from parental or affiliative behaviors to investigation or aggression. Reward associated with nonreproductive interactions in rodents is measured using the social conditioned place preference (sCPP) paradigm, where a change in preference for an initially neutral context confirms reinforcing effects of social contact. Here, we revised the sCPP method and reexamined social reward in adult female mice. Contrary to earlier studies, we found that robust rewarding effects of social contact could be detected in adult (14-week-old) female C57BL/6 mice when the sCPP task was refined to remove confounding factors. Strikingly, the rewarding effects of social interaction were only observed among female siblings who remained together from birth. Contact with same-age nonsiblings was not rewarding even after 8 weeks of cohousing. Other factors critical for the social reward effect in the sCPP paradigm included the number of conditioning sessions and the inherent preference for contextual cues. Thus, we show that social interaction is rewarding in adult female mice, but this effect strictly depends on the familiarity of the interaction partners. Furthermore, by identifying confounding factors, we provide a behavioral model to study the mechanisms underlying the rewarding effects of nonreproductive social interaction in adult mice.

animal behavior and cognition↗