Biology subjects

Pusch, R.

Publications and source records attributed to Pusch, R..

5 recordsLinked to original sources

bioRxiv2025

Contingency violation in extinction learning

In extinction learning, contextual renewal occurs when an extinguished behavior reemerges after a context change. A key question is how stimuli become integrated as contextual cues. While contingency, the predictive relationship between stimuli and outcomes; is known to be important, its precise contribution remains unclear. Using a ABA renewal design with pigeons in operant chambers, we systematically violated contingency by probabilistically reinforcing responses during extinction. Our results show that partial violations of contingency modulated extinction learning but did not abolish contextual renewal. Instead, pigeons developed meta-learning strategies, adapting their behavior across sessions to optimize reward despite extinction conditions. These findings highlight that context formation is sensitive to contingency levels, but also that animals can flexibly reorganize their learning strategies when contingency is unstable.

animal behavior and cognition↗

bioRxiv2025

Divide and conquer: How avian 'prefrontal' and hippocampal neurons process extinction learning in complementary ways

Context-dependent extinction learning enables organisms to acquire an inhibition of responding to cues that no longer signal reward in specific environmental settings. Both the hippocampus and the prefrontal cortex play key but complementary roles in encoding extinction. To understand what drives the differential contributions of these two structures, we recorded single-unit responses from the pigeon hippocampus (HPC) and the prefrontal nidopallium caudolaterale (NCL), while the animals were engaged in a repeated appetitive ABA extinction learning paradigm. HPC carried more information about experimental phases (acquisition (context A), extinction (context B), and renewal (context A)) than NCL. In addition, hippocampal neurons with mixed selectivity integrated all contextual stimuli and conditioned cues, thereby possibly enabling context integration into phase-dependent extinction events. The mixed selectivity pattern of NCL neurons differed: They encoded all relevant task parameters separately, thereby possibly enabling the weighing and deciding between response alternatives. Repeatedly testing the same animals over many months enabled us to reveal that the activity of NCL neurons increasingly became predictive of the number of responses that animals made during renewal. Thus, NCL neurons possibly assumed a meta-learning ability that enabled a behavioral adaption to the deeper task structure that always followed the sequence of acquisition[->]extinction[->]renewal. Our results make it likely that different processing strategies of hippocampus and prefrontal NCL enable a differential encoding of experimental phase, context, decision-making, and meta-learning during extinction learning.

neuroscience↗

bioRxiv2021

Working memory performance is tied to stimulus complexity

1.Working memory is the cognitive capability to maintain and process information over short periods. Behavioral and computational studies have shown that visual information is associated with working memory performance. However, the underlying neural correlates remain unknown. To identify how visual information affects working memory performance, we conducted behavioral experiments and single unit recordings in the avian prefrontal analog, the nidopallium caudolaterale (NCL). Complex pictures featuring luminance, spatial and color information, were associated with higher working memory performance compared to uniform gray pictures in conjunction with distinct neural coding patterns. For complex pictures, we found a multiplexed neuronal code displaying visual and value-related features that switched to a representation of the upcoming choice during a delay period. When processing gray stimuli, NCL neurons did not multiplex and exclusively represented the choice already during stimulus presentation and throughout the delay period. The prolonged representation possibly resulted in a decay of the memory trace ultimately leading to a decrease in performance. In conclusion, we found that high stimulus complexity is associated with neuronal multiplexing of the working memory representation possibly allowing a facilitated read-out of the neural code resulting in enhancement of working memory performance.

neuroscience↗

bioRxiv2021

Digital embryos - A novel technical approach to investigate perceptual categorization in pigeons (Columba livia) using machine learning

Pigeons are classic model animals to study perceptual category learning. A theoretical understanding of the cognitive mechanisms of categorization requires a careful consideration of the employed stimulus material. Optimally, stimuli should not consist of real-world objects that might be associated with prior experience. The number of exemplars should be theoretically infinite and easy to produce. In addition, the experimenter should have the freedom to produce 2D- and 3D-versions of the stimuli and, finally, the stimulus set should provide the opportunity to identify the diagnostic elements that the animals use. To this end, we used the approach of "virtual phylogenesis" of "digital embryos" to produce two stimulus sets of objects that meet these criteria. In our experiment pigeons learned to categorize these stimuli in a forced-choice procedure. In addition, we used peck tracking to identify where on the stimulus the animals pecked to signal their choice. Pigeons learned the task and transferred successfully to novel exemplars. Using a k-nearest neighbor classifier, we were able to predict the presented stimulus class based on pecking location indicating that pecks are related to features of interest. We further identified potential strategies of the pigeons through this approach, namely that they were either learning one or two categories to discriminate between stimulus classes. These strategies remained stable during category transfer, but differed between individuals indicating that categorization learning is not limited to a single learning strategy.

animal behavior and cognition↗

bioRxiv2020

Complex dynamics of choice during operant extinction and a simple associative learning account

Extinction learning, the process of ceasing an acquired behavior in response to altered reinforcement contingencies, is not only essential for survival in a changing environment, but also plays a fundamental role in the treatment of pathological behaviors. During therapy and other forms of training involving extinction, subjects are typically exposed to several sessions with a similar structure. The effects of this repeated exposure are not well understood. Here, we studied the behavior of pigeons across several sessions of a discrimination learning task in context A, extinction in context B, and a return to context A to test the context-dependent return of the learned responses (ABA renewal). By focusing on individual learning curves across animals, we uncovered a session-dependent variability of behavior: (1) During extinction, pigeons preferred the unrewarded alternative choice in one-third of the sessions, predominantly during the first one. (2) In later sessions, abrupt transitions of behavior at the onset of context B emerged, and (3) the renewal effect decayed as sessions progressed. We show that the observed results can be parsimoniously accounted for by a computational model based only on associative learning between stimuli and actions. Our work thus demonstrates the critical importance of studying the trial-by-trial dynamics of learning in individual sessions, and the power of "simple" associative learning processes.

animal behavior and cognition↗