Biology subjects

Karakose-Akbiyik, S.

Publications and source records attributed to Karakose-Akbiyik, S..

4 recordsLinked to original sources

bioRxiv2026

Postnatal maturation of putamen microstructure accompanies topographic white matter connectivity and altered circuits in autism

The putamen is a major hub of the basal ganglia that emerges early in gestation. However, whether its mature organization is established before birth or emerges postnatally remains unknown. Using cross-sectional and longitudinal quantitative MRI (R1 and R2*, related to tissue density and iron, respectively) and diffusion MRI, we characterized the development of putamen's microstructure and its white matter connectivity with cortex from birth to 12 months and compared their trajectories with those in adults. Despite its prenatal emergence, the putamen undergoes substantial postnatal development. R1 increases from birth to 12 months, producing a prominent anterior-posterior gradient, whereas R2* increases primarily between age one and adulthood, producing a medial-lateral gradient. Cortico-putamen white matter connectivity is diffuse in infants but becomes topographic in adults, with anterior putamen linked to frontal cortex and posterior putamen to sensorimotor cortex. In autism spectrum disorder, this organization is largely preserved and accompanied by increased anterior putamen-prefrontal connectivity. Our findings reveal distinct spatial developmental trajectories of putamen microstructure and cortical connectivity providing a developmental framework for understanding the organization of the putamen in infancy, which has implications for assessing neurodevelopmental disorders of the basal ganglia.

neuroscience↗

bioRxiv2026

Spatial organization of neural responses to physical and agentive movement dynamics is reflected in intrinsic functional connectivity

Making sense of dynamic scenes requires interpreting the movements of inanimate objects governed by external physical forces and the actions of animate agents pursuing endogenous goals. Prior research has identified regions preferring physical or agentive movement, but their spatial organization relative to one another remains unclear. We used fMRI and within-individual analyses to examine neural responses during a motion prediction task in which two dots moved either according to physical forces (physical condition) or in coordinated, self-propelled ways suggesting intentional action (agentive condition). Resting-state data from the same participants independently characterized functional connectivity. Preferential responses to physical and agentive movement were interdigitated across frontal, parietal, and temporal cortices. Regions sharing a preference were intrinsically connected even when widely separated, while regions with opposing preferences belonged to separate networks even when adjacent. Together, these results reveal that differences between physical and agentive dynamics are not confined to local task-evoked preferences but are embedded within the brain's broader functional organization.

neuroscience↗

bioRxiv2025

Dissociation between physical reasoning and tool use in individuals with left hemisphere brain damage

Many everyday tasks, from chopping vegetables to catching a ball, require understanding both how objects respond to physical forces and how to use them effectively. These capacities, tool use and physical reasoning, are often assumed to rely on shared cognitive and neural mechanisms. At some level, this correspondence is expected: using an object typically requires understanding its physical properties. However, both capacities are complex and multicomponential, so the relationship between them may vary across levels of representation and task demands. Here, we asked whether third-person physical reasoning about object dynamics can dissociate from tool use (i.e., performing a tools typical action, such as using a hammer to drive a nail) in individuals with left-hemisphere stroke. We tested 11 patients, five of whom showed impairments in tool use. Physical reasoning was assessed using a novel collection of tasks probing judgments about mass, velocity, and timing across static and dynamic scenes. Tool use was evaluated using a classic gesture-to-sight task, a pantomime-based measure in which participants are shown pictures of familiar tools and asked to demonstrate how each would be used. We identified an individual-level dissociation: patient I.A.* showed impairment in gesturing the use of objects despite preserved physical reasoning, often outperforming neurotypical controls. This pattern was complemented by patient N.P., who showed the reverse profile, with intact tool use gestures but difficulties in some physical reasoning tasks. These findings suggest that the ability to reason about the physical world and tool use can dissociate behaviorally and be independently disrupted by brain damage. This challenges the view that physical reasoning and tool use draw on the same underlying cognitive and neural mechanisms and suggests that at least some of their components are distinct.

neuroscience↗

bioRxiv2023

The role of agentive and physical forces in the neural representation of motion events

How does the brain represent information about motion events in relation to agentive and physical forces? In this study, we investigated the neural activity patterns associated with observing animated actions of agents (e.g., an agent hitting a chair) in comparison to similar movements of inanimate objects that were either shaped solely by the physics of the scene (e.g., gravity causing an object to fall down a hill and hit a chair) or initiated by agents (e.g., a visible agent causing an object to hit a chair). Using fMRI-based multivariate pattern analysis, this design allowed testing where in the brain the neural activity patterns associated with motion events change as a function of, or are invariant to, agentive versus physical forces behind them. Cross-decoding revealed a shared neural representation of animate and inanimate motion events that is invariant to agentive or physical forces in regions spanning frontoparietal and posterior temporal cortices. In contrast, the right lateral occipitotemporal cortex showed higher sensitivity to agentive events, while the left dorsal premotor cortex was more sensitive to information about inanimate object events that were solely shaped by the physics of the scene.

neuroscience↗