Biology subjects

Albantakis, L.

Publications and source records attributed to Albantakis, L..

4 recordsLinked to original sources

bioRxiv2025

Reduced inter-subject functional connectivity during movies in autism: Replicability across cross-national fMRI datasets

BackgroundAutism is a neurodevelopmental disorder characterized by repetitive behaviors and difficulties in social communication and interaction. Previous research has shown that these symptoms are linked to idiosyncratic behavioral and brain activity patterns while viewing natural social events in movies. This study aimed to investigate the replicability of brain activity idiosyncrasy in autistic individuals by comparing their inter-subject functional connectivity (ISFC) with that of neurotypical individuals. MethodsWe tested for ISFC differences between autistic and neurotypical groups using functional magnetic resonance imaging (fMRI) data from two independent datasets from Germany (Nneurotypical = 25, 7 Males, 18 Females; Nautism = 22, 12 Males, 10 Females) and Finland (Nneurotypical = 19, Nautism = 18; All males). Participants watched short movie stimuli, and pairwise ISFCs were computed across 273 brain regions. Group differences were evaluated using subject-wise permutation tests for each dataset. ResultsIn both datasets, the autistic group showed lower ISFCs compared to the neurotypical group, specifically between visual regions (e.g., occipital gyrus, cuneus) and parietal regions (e.g., superior and inferior parietal lobules), as well as between visual regions and frontal regions (e.g., inferior frontal gyrus, precentral gyrus). ISFC was higher in the Finnish autistic group in temporal regions associated with sound and speech processing. ConclusionsThe study confirmed the replicability of reduced ISFCs in autistic individuals during naturalistic movie-watching, especially between visual and parietal/frontal brain regions. These findings reinforce the utility of ISFC and naturalistic movie-watching paradigm in studying neural connectivity alterations in autism.

neuroscience↗

bioRxiv2024

From micro to macro units: a mathematical framework for identifying the causal grain of a system from its intrinsic perspective

Integrated information theory (IIT) aims to account for the quality and quantity of consciousness in physical terms. According to IIT, a substrate of consciousness must be a system of units that is a maximum of intrinsic, irreducible cause-effect power, quantified by integrated information ({varphi}s). Moreover, the grain of each unit must be the one-- from micro (finer) to macro (coarser)--that maximizes the systems intrinsic irreducibility (i.e., maximizes{varphi} s). The units that maximize{varphi} s are called the intrinsic units of the system. This work extends the mathematical framework of IIT 4.0 to assess cause-effect power at different grains and thereby determine a systems intrinsic units. Using simple, simulated systems, we show that the cause-effect power of a system of macro units can be higher than the cause-effect power of the corresponding micro units. Two examples highlight specific kinds of macro units, and how each kind can increase cause-effect power. The implications of the framework are discussed in the broader context of IIT, including how it provides a foundation for tests and inferences about consciousness.

systems biology↗

bioRxiv2019

How cognitive and environmental constraints influencethe reliability of simulated animats in groups

Evolving in groups can either enhance or reduce an individuals task performance. Still, we know little about the factors underlying group performance, which may be reduced to three major dimensions: (a) the individuals ability to perform a task, (b) the dependency on environmental conditions, and (c) the perception of, and the reaction to, other group members. In our research, we investigated how these dimensions interrelate in simulated evolution experiments using adaptive agents equipped with Markov brains (\"animats\"). We evolved the animats to perform a spatial-navigation task under various evolutionary setups. The last generation of each evolution simulation was tested across modified conditions to evaluate and compare the animats reliability when faced with change. Moreover, the complexity of the evolved Markov brains was assessed based on measures of information integration. We found that, under the right conditions, specialized animats were as reliable as animats already evolved for the modified tasks, that interaction between animats was dependent on the environment and on the design of the animats, and that the task difficulty influenced the correlation between the performance of the animat and its brain complexity. Generally, our results suggest that the interrelation between the aforementioned dimensions is complex and their contribution to the groups task performance, reliability, and brain complexity varies, which points to further dependencies. Still, our study reveals that balancing the group size and individual cognitive abilities prevents over-specialization and can help to evolve better reliability under unknown environmental situations.\n\nAuthor SummaryThe ability to adapt to environmental changes is an essential attribute of organisms which have had evolutionary success. We designed a simulated evolution experiment to better understand the relevant features of such organisms and the conditions under which they evolve: First, we created diverse groups of cognitive systems by evolving simulated organisms (\"animats\") acting in groups on a spatial-navigation task. Second, we post-evolutionary tested the final evolved animats in new environments-not encountered before- in order to test their reliability when faced with change. Our results imply that the ability to generalize to environments with changing task demands can have complex dependencies on the cognitive design and sensor configuration of the organism itself, as well as its social or environmental conditions.

animal behavior and cognition↗

bioRxiv2017

Unifying concepts of biological function from molecules to ecosystems.

The concept of function arises at all levels of biological study and is often loosely and variously defined, especially within ecology. This has led to ambiguity, obscuring the common structure that unites levels of biological organisation, from molecules to ecosystems. Here we build on already successful ideas from molecular biology and complexity theory to create a precise definition of biological function which spans scales of biological organisation and can be quantified in the unifying currency of biomass, enabling comparisons of functional effectiveness (irrespective of the specific function) across the field of ecology. We give precise definitions of ecological and ecosystem function that bring clarity and precision to studies of biodiversity-ecosystem function relationships and questions of ecological redundancy. To illustrate the new concepts and their unifying power, we construct a simple community-level model with nutrient cycling and animal-plant mutualism, emphasising the importance of its network structure in determining overall functioning. This type of network structure is that of an autocatalytic set of functional relationships, which also appears at biochemical, cellular and organism levels of organisation, creating a nested hierarchy. This enables a common and unifying concept of function to apply from molecular interaction networks up to the global ecosystem.

ecology↗