Biology subjects

Skalaban, L. J.

Publications and source records attributed to Skalaban, L. J..

7 recordsLinked to original sources

bioRxiv2026

The hippocampus and cortical memory networks have an inflection point in middle childhood

Decades of developmental memory research has mainly reported linear and protracted changes in both human hippocampal function and connectivity between the hippocampus and cortex. While foundational, very few studies have interrogated the reliability of hippocampal signals across age, and how this coincides with (or diverges from) age-related changes in connectivity to broader cortical networks supporting multiple memory systems. Here, utilizing movie-watching fMRI data in children 3 to 12 years and adults, we assessed hippocampal response stability using an inter-subject functional correlation (ISFC) approach, and then measured functional connectivity between the hippocampus and the Posterior Medial (PM) - Anterior Temporal (AT) cortical memory networks proposed to support episodic-like (PM) and semantic-like (AT) memory respectively. Results showed that hippocampal responses are stable in the youngest children, but bifurcate in 7 year olds, with half the subjects correlating most highly with younger and half with older age groups. Likewise, we found that while functional connectivity within the AT network is stable across development, connections between the anterior hippocampus and this network did not reach adult levels until around 7 years. Thus, while brain networks supporting semantic memory may be in place early, interactions with the hippocampus may not develop until after middle childhood, with an inflection point around 7 years of age.

neuroscience↗

bioRxiv2026

Habitual digital media use and the brain: a meta-analysis

Research on the relationship between digital media and neurocognitive function has blossomed with the rising digital age and advent of social media, producing a growing literature focused on how technological developments may be affecting users brains. Much of the science has focused on the involvement of specific brain systems that support reward (e.g., nucleus accumbens, orbitofrontal cortex), cognitive control (e.g., lateral prefrontal, anterior cingulate), and socio-emotional processes (e.g., temporo-parietal junction) and why they might be especially relevant to digital media engagement. However, a broad and systematic analysis of the consistency of findings across neuroimaging studies has not yet been published. Here, we conducted a coordinate-based meta-analysis based on published structural and functional MRI studies exploring habitual digital media engagement. Adopting a granular approach to summation of this literature, we use Activation Likelihood Estimation (ALE) and find that the most consistent effects arise in the anterior insular cortex, a region implicated in the integration of social and emotional information that has not been frequently highlighted in the prior literature on digital media effects in the brain. This discovery encourages reconsideration of how the brain is likely to affect, and be affected by, digital media engagement and online behavior.

neuroscience↗

bioRxiv2021

Neural event segmentation of continuous experience in human infants

How infants experience the world is fundamental to understanding their cognition and development. A key principle of adult experience is that, despite receiving continuous sensory input, we perceive this input as discrete events. Here we investigate such event segmentation in infants and how it differs from adults. Research on event cognition in infants often uses simplified tasks in which (adult) experimenters help solve the segmentation problem for infants by defining event boundaries or presenting discrete actions/vignettes. This presupposes which events are experienced by infants and leaves open questions about the principles governing infant segmentation. We take a different, data-driven approach by studying infant event segmentation of continuous input. We collected whole-brain fMRI data from awake infants (and adults, for comparison) watching a cartoon and used a hidden Markov model to identify event states in the brain. We quantified the existence, timescale, and organization of multiple event representations across brain regions. The adult brain exhibited a known hierarchical gradient of event timescales, from shorter events in early visual regions to longer events in later visual and associative regions. In contrast, the infant brain only represented longer events, even in early visual regions, with no timescale hierarchy. The boundaries defining these infant events only partially overlapped with boundaries defined from adult brain activity and behavioral judgments. These findings suggest that events are organized differently in infants, with longer timescales and more stable neural patterns, even in sensory regions. This may indicate greater temporal integration and reduced temporal precision during dynamic, naturalistic perception. Significance StatementSensory input is continuous and yet humans perceive discrete events. This event segmentation has been studied in adults by asking them to indicate natural breaks in continuous input. This classic parsing task is impossible in infants who cannot understand or follow instructions. We circumvent this barrier by testing how the infant brain parses. We applied a computational model to rare awake fMRI data from infants to identify how their brains transitioned between stable states during a cartoon. Whereas adults showed a gradient in event timescales, from shorter events in sensory regions to longer events in associative regions, infants persistently segmented fewer, longer events across the cortical hierarchy. These findings provide new neuroscientific insight into how infants represent their environment.

neuroscience↗

bioRxiv2020

Retinotopic organization of visual cortex in human infants

Vision develops rapidly during infancy, yet how visual cortex is organized during this period is unclear. One possibility is that the retinotopic organization of visual cortex emerges gradually as perceptual abilities improve. This may result in a hierarchical maturation of visual areas from striate to extrastriate cortex. Another possibility is that retinotopic organization is present from early infancy. This early maturation of area boundaries and tuning could scaffold further developmental changes. Here we test the functional maturity of infant visual cortex by performing retinotopic mapping with fMRI. Infants aged 5-23 months had retinotopic maps, with alternating preferences for vertical and horizontal meridians indicative of area boundaries from V1 to V4, and an orthogonal gradient of preferences from high to low spatial frequencies indicative of growing receptive field sizes. Although present in the youngest infants, these retinotopic maps showed subtle agerelated changes, suggesting that early maturation undergoes continued refinement.

neuroscience↗

bioRxiv2020

Attention recruits frontal cortex in human infants

Young infants learn about the world by overtly shifting their attention to perceptually salient events. In adults, attention recruits several brain regions spanning the frontal and parietal lobes. However, these regions are thought to have a protracted maturation and so it is unclear whether they are recruited in infancy and, more generally, how infant attention is supported by the brain. We used event-related fMRI with 24 awake behaving infants 3-12 months old while they performed a child-friendly attentional cuing task. A target was presented to either the left or right of the infants fixation and eye-tracking was used to measure the latency with which they saccaded to the target. To manipulate attention, a brief cue was presented before the target in three conditions: on the same side as the upcoming target (valid), on the other side (invalid), or on both sides (neutral). All infants were faster to look at the target on valid versus invalid trials, with valid faster than neutral and invalid slower than neutral, indicating that the cues effectively captured attention. We then compared the fMRI activity evoked by these trial types. Regions of adult attention networks activated more strongly for invalid than valid trials, particularly frontal regions such as anterior cingulate cortex. Neither behavioral nor neural effects varied by infant age within the first year, suggesting that these regions may function early in development to support the reorienting of attention. Together, this furthers our mechanistic understanding of how the infant brain controls the allocation of attention.

neuroscience↗

bioRxiv2020

Evidence of hippocampal learning in human infants

The hippocampus is essential for human memory. Thus, memory deficiencies in infants are often attributed to hippocampal immaturity. However, the functionality of the infant hippocampus has never been tested directly. Here we report that the human hippocampus is indeed active in infancy. We recorded hippocampal activity using fMRI while awake infants aged 3-24 months viewed sequences of objects. Greater activity was observed when the order of the sequence contained regularities that could be learned compared to when the order was random. The involvement of the hippocampus in such statistical learning, with additional recruitment of the medial prefrontal cortex, is consistent with findings from adults. These results suggest that the hippocampus supports the important ability of infants to extract the structure of their environment through experience.

neuroscience↗

bioRxiv2020

How to read a baby's mind: Re-imagining fMRI for awake, behaving infants

Thousands of functional magnetic resonance imaging (fMRI) studies have provided important insight into the human brain. However, only a handful of these studies tested infants while they were awake, because of the significant and unique methodological challenges involved. We report our efforts over the past five years to address these challenges, with the goal of creating methods for infant fMRI that can reveal the inner workings of the developing, preverbal mind. We use these methods to collect and analyze two fMRI datasets obtained from infants during cognitive tasks, released publicly with this paper. In these datasets, we explore data quantity and quality, task-evoked activity, and preprocessing decisions to derive and evaluate recommendations for infant fMRI. We disseminate these methods by sharing two software packages that integrate infant-friendly cognitive tasks and behavioral monitoring with fMRI acquisition and analysis. These resources make fMRI a feasible and accessible technique for cognitive neuroscience in human infants.

neuroscience↗