Biology subjects

Kondrakiewicz, K.

Publications and source records attributed to Kondrakiewicz, K..

5 recordsLinked to original sources

bioRxiv2025

Behavioral orienting but not novelty activates dopamine neurons

Novel stimuli have a profound impact on brain function and behavior. They evoke attention, arousal and sensory exploration and induce synaptic plasticity in brain regions related to learning and memory. Many of these effects have been attributed to novelty-evoked activation of the dopaminergic midbrain and dopamine (DA) release in major projection targets in the striatum. However, it remains controversial if individual DA neurons respond to novel stimuli. To address this question, we recorded and manipulated DA neurons in mice exposed to novel and familiar odors while monitoring orienting behaviors including exploratory sniffing, facial movements, and pupil dilation. We found that DA neurons were activated by orienting behaviors, rather than by novelty itself. Moreover, their activity was causally involved in generating the orienting responses. Finally, we identified a major input region to the dopaminergic midbrain which couples orienting to DA firing. Activity in the mediodorsal pons (mdPons) correlated tightly with sniffing and facial movements. Consequently, optogenetic stimulation of glutamatergic mdPons neurons induced both orienting and DA firing. Our findings suggest that DA neurons do not respond to novelty per se but are activated through descending glutamatergic projections from the mdPons. This mechanism links salient sensory events to DA release, providing a basis for novelty-evoked exploration and plasticity.

neuroscience↗

bioRxiv2025

The anterior olfactory nucleus mediates curious exploration evoked by novel odors

The spontaneous exploratory reaction to novel stimuli reflects a fundamental form of curiosity, which is widely observed in the animal kingdom. How sensory systems mediate the recognition of novel stimuli to evoke exploration is not well understood. To address this question, we presented novel and familiar olfactory stimuli to head-restrained mice, while measuring novelty-evoked exploratory behaviors. In parallel, we recorded neural activity in primary olfactory cortical structures, the anterior olfactory nucleus (AON) or the anterior piriform cortex (aPCx). Novelty strongly modulated odor responses in the AON, but only weakly in the aPCx. Pharmacological and chemogenetic inactivation of the AON but not the aPCx disrupted exploratory responses. During long-term habituation over multiple days, sensory representations were drifting in the AON whereas they became stable within one day in the aPCx. Our findings suggest that AON and aPCx play distinct roles in novelty-evoked exploration. While the AON mediates the immediate reaction to novel stimuli, the aPCx exhibits stable stimulus representations, consistent with supporting odor memory.

neuroscience↗

bioRxiv2023

Local contribution to the somatosensory evoked potentials in rat's thalamus

Local Field Potential (LFP), despite its name, often reflects remote activity. Depending on the orientation and synchrony of their sources, both oscillations and more complex waves may passively spread in brain tissue over long distances and be falsely interpreted as local activity at such distant recording site. Current Source Density method was proposed to recover locally active currents from multi-site LFP recordings. Here we use a model-based kernel CSD (kCSD) to study the contribution of local and distant currents to LFP recorded with dense multichannel probes from rat thalamic nuclei and barrel cortex, activated by whisker stimulation. We show that the evoked potential wave seen in the thalamic nuclei around 7-15 ms post-stimulus has a substantial negative component reaching from cortex. This component can be analytically removed and truly local thalamic LFP, with purely thalamic contributions, can be recovered reliably using kCSD. In particular, concurrent recordings from the cortex are not essential for reliable thalamic CSD estimation. Proposed framework can be used to analyse LFP from other brain areas and has consequences for general LFP interpretation and analysis. 1 BRIEF SUMMARYWhile recording LFP simultaneously in multiple structures, we often see significant correlations between the observed waves. A natural question is if they are propagated passively from one structure to another or if they are simultaneously generated by different, separated sets of sources. We argue this can be answered reliably using CSD analysis. We focus on the case of thalamic and cortical recordings in the somatosensory system in response to whisker stimulation where we observe significant correlations between early thalamic and cortical responses to whisker deflection.

neuroscience↗

bioRxiv2020

What we can and what we cannot see with extracellular multielectrodes

Extracellular recording is an accessible technique used in animals and humans to study the brain physiology and pathology. As the number of recording channels and their density grows it is natural to ask how much improvement the additional channels bring in and how we can optimally use the new capabilities for monitoring the brain. Here we show that for any given distribution of electrodes we can establish exactly what information about current sources in the brain can be recovered and what information is strictly unobservable. We demonstrate this in the general setting of previously proposed kernel Current Source Density method and illustrate it with simplified examples as well as using evoked potentials from the barrel cortex obtained with a Neuropixels probe and with compatible model data. Author SummaryEvery set of measurements is a window into reality rendering its incomplete or distorted picture. It is often difficult to relate the obtained representation of the world to underlying ground truth. Here we show, for brain electrophysiology, for arbitrary experimental setup (distribution of electrodes), and arbitrary analytical setup (function space of current source densities), that one can identify distributions of current sources which can be recovered precisely, and those which are invisible in the system. This shows what is and what is not observable in the studied system for a given setup, allows to improve the analysis results by modifying analytical setup, and facilitates interpretation of the measured sets of LFP, ECoG and EEG recordings.

neuroscience↗

bioRxiv2020

More than a feeling: central amygdala mediates social transfer of information about proximity of danger

To survive, an animal must adequately respond to challenges presented by the environment. Social animals can learn about danger from fear of conspecifics which allows them to avoid predation and other threats without costly, first-hand experience. However, it remains unclear as to whether animals can transmit specific information that helps an individual avoid harm or whether the transmitted social signals simply increase vigilance in a non-specific manner. Here we demonstrate that animals can select appropriate defensive strategies in a novel environment depending on cues from the conspecific and, using opsins targeted to behaviorally activated neurons, identify distinct neuronal circuits in the central amygdala (CeA) that are crucial for choosing a context-appropriate reaction. The identified circuits differ in molecular markers and patterns of connectivity. Thus, we show that social signals carry explicit information about proximity of danger, necessary for choosing a context-appropriate reaction, and that the choosing process is mediated by the CeA circuits.

neuroscience↗