Biology subjects

Insel, N.

Publications and source records attributed to Insel, N..

4 recordsLinked to original sources

bioRxiv2026

Social Approach Dynamics in Freely-Moving Rat Dyads are Not Impacted by Lesions to the Retrosplenial Cortex

Social interaction in rodents can involve a dynamic interplay of approach and withdrawal movements, requiring the brain to rapidly update information about where others are and where they may intend to go. In mammals, the posterior parietal cortex (PPC) and adjacent, reciprocally-connected retrosplenial cortex (RSC) are high-level hubs for spatial information processing. To test the role of these regions in dynamic social approach, we evaluated rats' relative orientation, movement, and position (ROMP) with a freely-moving social-stimulus rat following bilateral lesions to the PPC or anterior RSC. RSC animals showed overall more and faster movements, and greater attention to environment boundaries across multiple behavioral conditions (open field, social, object, static social, and dynamic object) compared with sham-lesioned controls. Increased attention to boundaries was correlated with reduced orienting to a social stimulus; however, this appeared to have little observable impact on the social interactions themselves. Rear-sniffing was lower in RSC rats, but only during the latter half of the 10 minute social exposures, and there were no detected differences in the dynamics of their social approach compared with sham controls. PPC lesion spread was more limited, and social behavior was mostly indistinguishable from sham controls, though this group was more likely to chase the dynamic object. Results suggest that social approach within short (peripersonal) distances is largely accomplished through sensorimotor adjustments that do not require higher-level, spatial-predictive processing taking place in the RSC.

animal behavior and cognition↗

bioRxiv2021

Variability of social interactions in new versus established relationships in female degus

When an organism explores a new environment or stimulus it varies its behavior to ensure proper sampling. As contingencies are learned, variance can give-way to routines and stereotypies. This phenomenon is common across species but has not been well studied in the social domain, in which the stimulus an animal investigates, another individual, may react negatively to unexpected behaviors. Here we investigate the effects of social familiarity on interaction variability in degus, female members of which are predisposed to form relationships with new, same-sex individuals. Degus were presented with a series of 20 minute, dyadic "reunion" sessions across days, interleaving exposures to familiar and unfamiliar same-sex conspecifics. We found that session-to-session variability in males was higher between strangers compared with cagemates, suggesting males may establish relationships by testing different social roles. In contrast, following an initial exposure, female strangers showed lower session-to-session change compared with cagemates, potentially establishing new relationships by maintaining behavioral norms. Social novelty did not appear to affect variability of interaction timing within a session. Given ecological pressures on female degus to form large, stable social networks, the data are consistent with the notion that higher behavioral variability across encounters is maladaptive for establishing cooperative peer relationships.

animal behavior and cognition↗

bioRxiv2020

Disambiguating stress-buffering and relationship-renewal in reunions between female degus

Many animals become more motivated to interact after a period of isolation. This phenomenon may involve general drives, e.g. for social touch or companionship, as well as drives that are specific to particular peers, and which ultimately serve to reestablish relationships between the individuals. Female degus are known to be affiliative with multiple other individuals, including unrelated and unfamiliar conspecifics, offering an opportunity to study social motivation independent from exclusive pair-bonds or overt, same-sex competition. We attempted to disentangle factors driving peer interaction by examining reunion behavior across several social isolation and separation manipulations. High levels of interaction were observed between adult females who had been separated even without isolation, revealing a drive to re-establish relationships with specific peers. The content of separation-only reunions differed from isolation, with the latter involving more early-session interaction, higher levels of allogrooming before rear-sniffing, and a higher ratio of chitter vocalizations. To assess whether post-isolation behavior was related to stress, we examined reunions following a non-social (footshock) stressor. Like isolation, footshock increased early-session interactions, but did not increase allogrooming before rear-sniffing or chittering, as compared with controls. To test whether separation-only reunion behavior shared qualities with relationship formation, we also examined reunions of new (stranger) dyads. Strangers exhibited higher levels of interaction than cagemates, with particularly high levels of late-session rear-sniffing. Like separation-only reunions, strangers showed more non-chitter vocalizations and lower levels of allogrooming before rear-sniffing. Across experiments, an exploratory clustering method was used to identify vocalizations that differed between conditions. This yielded promising leads for future investigation, including a chaff-type syllable that may have been more common during relationship renewal. Overall, results are consistent with the hypothesis that female degu reunions are supported by both general and peer-stimulus specific drives, expressed through the structure of physical and vocal interactions over time.

animal behavior and cognition↗

bioRxiv2017

Relevance learning via inhibitory plasticity and its implications for schizophrenia

Symptoms of schizophrenia may arise from a failure of cortical circuits to filter-out irrelevant inputs. Schizophrenia has also been linked to disruptions to cortical inhibitory interneurons, consistent with the possibility that in the normally functioning brain, these cells are in some part responsible for determining which inputs are relevant and which irrelevant. Here, we develop an abstract but biologically plausible neural network model that demonstrates how the cortex may learn to ignore irrelevant inputs through plasticity processes affecting inhibition. The model is based on the proposal that the amount of excitatory output from a cortical circuit encodes expected magnitude of reward or punishment (\"relevance\"), which can be trained using a temporal difference learning mechanism acting on feed-forward inputs to inhibitory interneurons. The model exhibits learned irrelevance and blocking, which become impaired following disruptions to inhibitory units. When excitatory units are connected to a competitive-learning output layer, the relevance code is capable of modulating learning and activity. Accordingly, the combined network is capable of recapitulating published experimental data linking inhibition in frontal cortex with fear learning and expression. Finally, the model demonstrates how relevance learning can take place in parallel with other types of learning, through plasticity rules involving inhibitory and excitatory components respectively. Altogether, this work offers a theory of how the cortex learns to selectively inhibit inputs, providing insight into how relevance-assignment problems may emerge in schizophrenia.

neuroscience↗