25.04.2026, Saturday, 10:00-11:30
Chair: Aleksandra Trenk
Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Cracow, Poland
10:00 Krzysztof Maćkiewicz
BioTechMed Center, Multimedia Systems Department, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, Gdansk, Poland
Department of Animal and Human Physiology, Faculty of Biology, University of Gdansk, Gdansk, Poland
"Alternative adaptive social strategies emerge during a sequential spatial memory task in rats"
Understanding how spatial memory guides behavior in social contexts requires experimental paradigms that combine precise task structure with interactive environments.
Here we present an automated, interactive environment (the Switchboard Test) designed to study sequential spatial memory in rats and to examine how such memory is expressed and adapted during social interaction. The system enables training and testing of location- and sequence-specific responses, with adjustable parameters including spatial layout, sequence length, cues, timing, and reward size.
Rats were individually trained to memorize a specific sequence of three button presses and became experts in the task. Expert rats (n = 16; two per cage across eight cages) were subsequently tested in pairs with cagemate experts (8 pairs, 9 days), with all possible expert–expert inter-cage pairings (112 pairs, 3 days each), and with naïve rats either from the same cage or from different cages (28 pairs each). Behavioral events were combined with video-based position tracking and individual identification, enabling detailed analysis of joint behavior.
Our apparatus and task enabled rats to deploy ethologically relevant social strategies, including cooperation, temporal segregation, and conflict resolution, which they must learn and refine over repeated interactions to succeed in a social context within an environment with a single reward dispensing area.
Such testing may be useful for identifying individuals with reduced ability to operate in a social context during sequential instrumental tasks, and for studying social hierarchies emerging in an interactive, dynamic environment.
FINANCIAL SUPPORT: National Science Centre, Polonez Bis: 2022/47/P/NZ4/03358 and Gdansk University of Technology, IDUB grant: 1/1/2024/IDUB/I.1B/Pt.
10:15 Joanna Yadav
Department of Neurophysiology and Chronobiology,
Jagiellonian University, Cracow, Poland; Doctoral School of Exact and Natural Sciences, Cracow, Poland
"The nucleus incertus – modulatory node in aversion-processing circuits"
Aversion- and fear-related responses support learning and survival. In humans, impaired regulation of these behaviors contributes to psychiatric and stress-related disorders. The nucleus incertus (NI) is implicated in stress-related processing and projects to key aversion-processing nodes, including the lateral habenula (LHb) and its major efferent target, the rostromedial tegmental nucleus (RMTg).
The aim of the study was to characterize the functional connectivity and anatomical organization of nucleus incertus projections to aversion-processing brain regions, with particular emphasis on lateralization.
To map circuit anatomy, we unilaterally injected (i) retrograde viral tracers expressing fluorescent reporters into the RMTg of adult Sprague-Dawley rats and, in separate animals, (ii) anterograde reporter vectors into the NI. Brain tissue was subsequently examined using fluorescent microscope. To test functional connectivity, we recorded RMTg multi-unit activity in urethane-anesthetized rats during optogenetic stimulation of NI neurons after bilateral RMTg delivery of a retrograde Cre vector and NI delivery of a Cre-dependent opsin.
Retrograde tracing revealed bilateral NI projection to the RMTg. Anterograde tracing showed NI fibers innervating both the RMTg and the LHb, including features of this innervation that have not been described before. No robust modulation of RMTg multi-unit activity was detected during NI optogenetic stimulation under urethane anesthesia, suggesting that NI→RMTg influence may be state-dependent and attenuated in an anaesthetized preparation.
Beyond the canonical LHb-RMTg pathway, the NI provides an additional modulatory input to aversion-related circuits. Incorporating NI contributions may refine circuit-level models of aversion and stress processing.
FINANCIAL SUPPORT: Preludium 21 2022/45/N/NZ4/03171
10:30 Sylwia Drabik
Department of Neurophysiology and Chronobiology, Jagiellonian University, Cracow, Poland; Doctoral School of Exact and Natural Sciences, Cracow, Poland
"Recruitment of the Interpeduncular Nucleus–Ventral Hippocampus Pathway During Social Stress"
Social stress elevates brain nerve growth factor (NGF) levels, reshaping the activity of stress-sensitive circuits. The midbrain interpeduncular nucleus (IPN), a regulator of anxiety and social behaviour shows a robust expression of the NGF receptor TrkA and sends dense projections to the ventral hippocampus (vHPC); a key hub for social and anxiety-related signalling and an important NGF source.
Despite this anatomical link, its behavioural relevance and mechanistic role of the IPN–vHPC pathway remain unclear. Accordingly, we sought to define the electrophysiological properties and possible functional role of IPN neurons innervating the vHPC.
Molecular characterization of IPN neurons was performed using RNAscope in situ hybridization. Viral based tract tracing was employed to map IPN-vHPC innervation. Electrophysiological whole cell patch clamp and multielectrode array recordings were used to verify IPN neurons’ sensitivity to NGF. To examine behavioral engagement of the circuit, resident-intruder paradigm followed up by assessment of neuronal activation was carried out.
RNAscope analysis revealed that TrkA-expressing IPN neurons are mainly located in rostral, intermediate, and lateral subnuclei, aligning with viral tracing data identifying vHPC-projecting cells in these areas. Patch-clamp recordings from anterior IPN slices showed no detectable response to NGF. Electrophysiological recordings with optogenetic tagging of IPN neurons innervating vHPC, revealed a small subset of identified neurons responding to NGF with inward currents. Multielectrode array recordings showed heterogeneous effects of NGF, of IPN neurons. Social stress exposure in the resident-intruder test resulted in the increased c-Fos expression in IPN cells.
Our findings reveal that the IPN-vHPC circuit is enriched in TrkA-expressing subregions, exhibits selective and heterogeneous sensitivity to NGF, and is engaged during social stress, supporting its role in modulating stress-related behaviors.
FINANCIAL SUPPORT: Funding: National Science Centre, Poland (UMO 2021/41/N/NZ4/04499; UMO-2023/49/B/NZ4/01885
10:45 Julia Sepielak-Świderska
Laboratory of Molecular Basis of Behavior, Nencki Institute of Experimental Biology, Warsaw, Poland
"Neural Mechanisms of Spatial Choice: DCA1 Plasticity, Cue Processing & Behavioral Variability"
Hippocampal synaptic plasticity, in particular long-term potentiation (LTP), has long been considered a central mechanism underlying spatial memory. However, recent evidence from studies in genetically modified mice has challenged this concept, proposing instead that hippocampal plasticity may play a role in spatial decision-making (Bannerman et al., 2012).
To examine the molecular and behavioural determinants of spatial choice, we designed a fully automated behavioural platform that enables continuous tracking of mouse locomotion and navigation. The system comprises three interconnected corridors outfitted with video monitoring, visual and auditory cue modules, automated doors, and liquid reward delivery, allowing animals to explore freely while acquiring rewards.
Using this paradigm, we assessed spatial decision-making in male and female C57BL/6 mice and observed no sex differences in overall performance. We systematically evaluated the contributions of motivational state, cue modality, reward distance, and dorsal CA1 (dCA1) synaptic plasticity. Plasticity was disrupted via lentiviral shRNA-mediated knockdown of the synaptic scaffold protein PSD-95.
Food restriction enhanced motivation, learning efficiency, and choice dynamics, while closer reward placement accelerated acquisition. Cue manipulations in males showed that removal of visual cues impaired performance. PSD-95-dependent dCA1 plasticity emerged as a key regulator of attentional engagement and decision-making strategies. Notably, animals could be segregated into high-, intermediate-, and low-performing subgroups, indicating inherent differences in decision strategies. To further investigate the neural correlates underlying performance variability between groups, whole-brain c-Fos immunostaining across serial sections was performed.
Collectively, these results elucidate how hippocampal plasticity, environmental information, and individual variability interact to shape spatial decision-making.
FINANCIAL SUPPORT: National Science Centre 2020/38/A/NZ4/00483 to K. Radwańska
11:00 Monika Puchalska
Laboratory of Molecular Basis of Behavior, Nencki Institute of Experimental Biology, Warsaw, Poland
"Lateralised neuronal networks of reward seeking across mouse lifespan"
Reward seeking behaviors are supported by distributed neuronal networks that functional organisation evolves throughout aging. Understanding age-dependent differences in neuronal basis of behavior is crucial for elucidating the mechanisms underlying cognitive decline and age-related neurological disorders.
The aim of this study is to investigate how lateralised neural circuits underlying reward seeking are shaped across mouse lifespan.
This study investigates neuronal networks of social learning in mice across different age groups using IntelliCage automated behavioral system, whole brain iDISCO clearing coupled with c-Fos immunostaining and chemogenetic manipulations.
We observed significant variations in behavior between young (3-5 months old) and old (>18 months old) mice, particularly in exploratory activity, social behaviors, learning and memory tasks. Further, iDISCO analysis revealed age-related differences in the activation patterns of brain regions associated with olfactory and cognitive functions. In particular, we observed strong lateralization of old mice brain activity in hippocampal and amygdalar areas. This phenomenon was much less pronounced in young animals. Chemogenetic manipulations confirmed specific engagement of the left, but not right, medial nucleus of the amygdala in social preference and learning again only in old, but not young, mice.
Our study demonstrates that spontaneous behavioral strategies employed by mice in order to find reward change as animals age, and this process is accompanied by evolving brain network activity. In particular, we show for the first time that mouse brain activity is strongly lateralised and this process progresses over time.
FINANCIAL SUPPORT: This work is supported by the National Science Centre MAESTRO Grant (2020/38/A/NZ4/00483) to K.R.
11:15 Martyna Marzec
Department of Neurophysiology and Chronobiology, Jagiellonian University,, Cracow, Poland; Doctoral School of Exact and Natural Sciences, Cracow, Poland
"From Superior Colliculus to Striatum: a lateralized pathway linking visual space to dopamine and orienting"
Midbrain dopaminergic (DA) neurons in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) shape action selection through dopamine release in the striatum. Transient hemispheric imbalances in dopaminergic signaling can bias directional behaviours. The superior colliculus (SC) conveys spatially organized multisensory information to VTA/SNc, but the extent to which this input supports lateralized dopaminergic output and biases orienting movements remains unclear.
We aimed to define the anatomical organization and functional lateralization of the SC→VTA/SNc→striatum pathway in rats, and to determine how unilateral visual stimulation differentially modulates DA neurons activity and hemispheric dopamine dynamics in rat.
Anatomical connectivity was examined using viral tract-tracing. In vivo extracellular single-unit recordings from VTA/SNc DA neurons were performed during pharmacological disinhibition of the SC combined with uniocular light stimulation. Striatal DA dynamics were quantified using fiber photometry. The behavioural relevance of this circuit was assessed using pathway-specific optogenetic stimulation during custom-made orienting test.
Tract-tracing revealed pronounced lateralization and topographic organization within the circuit, with SNc DA neurons receiving SC input preferentially innervating the ipsilateral dorsal striatum. Uniocular stimulation predominantly evoked excitatory responses in VTA/SNc DA neurons. Although firing rates didn’t show a consistent hemispheric bias, striatal dopamine release was significantly higher contralateral to the stimulated eye. Optogenetic activation of the pathway induced bias in animals’ orienting behaviour.
These results indicate that lateralized visual input differentially modulates dopamine signals through anatomically asymmetric SC to midbrain dopaminergic circuit. This pathway may provide a mechanism by which spatial sensory information may bias action selection.
