Biology subjects

Shaked, A.

Publications and source records attributed to Shaked, A..

5 recordsLinked to original sources

bioRxiv2022

Connectomics of the Octopus vulgaris vertical lobe provides insight into conserved and novel principles of a memory acquisition network

We present the first analysis of the connectome of the vertical lobe (VL) of Octopus vulgaris, a brain structure mediating acquisition of long-term memory in this behaviorally advanced mollusk. Serial section electron microscopy revealed new types of interneurons, cellular components of extensive modulatory systems and multiple synaptic motifs. The sensory input to the VL is conveyed via ~1,800,000 axons that sparsely innervate two parallel and interconnected feedforward networks formed by the two types of amacrine interneurons (AM), simple AMs (SAMs) and complex AMs (CAMs). SAMs make up 89.3% of the ~25,000,000 VL cells, each receiving a synaptic input from only a single input neuron on its non-bifurcating primary neurite, suggesting that each input neuron is represented in only ~12 SAMs. This synaptic site is likely a "memory site" as it is endowed with LTP. The CAMs, a newly described AM type, comprise 1.6% of the VL cells. Their bifurcating neurites integrate multiple inputs from the input axons and SAMs. While the SAM network appears to feedforward sparse "memorizable" sensory representations into the VL output layer, the CAMs appear to monitor global activity and feedforward a balancing inhibition for "sharpening" the stimulus-specific VL output. While sharing morphological and wiring features with circuits supporting associative learning in other animals, the VL has evolved a unique circuit that enables associative learning based strictly on feedforward information flow.

neuroscience↗

bioRxiv2022

Disentangling the Neural Correlates of Agency, Ownership and Multisensory Processing

The experience of the self as an embodied agent in the world is an essential aspect of human consciousness. This experience arises from the feeling of control over ones bodily actions, termed the Sense of Agency (SoA), and the feeling that the body belongs to the self, Body Ownership (BO). Despite long-standing philosophical and scientific interest in the relationship between the body and brain, the neural systems involved in SoA and BO and especially their interactions, are not yet understood. In this preregistered study using the Moving Rubber Hand Illusion inside an MR-scanner, we aimed to uncover the relationship between BO & SoA in the human brain. Importantly, by using both visuomotor and visuotactile stimulations and measuring online trial-by-trial fluctuations in the illusion magnitude, we were able to disentangle brain systems related to objective sensory stimulation and subjective judgments of the bodily-self. Our results indicate that at both the behavioral and neural levels, BO and SoA are strongly interrelated. Multisensory regions in the occipital and fronto-parietal regions encoded convergence of sensory stimulation conditions. However, the subjective judgments of bodily-self were also related to BOLD fluctuations in regions not activated by the sensory conditions such as the insular cortex and precuneus. Our results highlight the convergence of multisensory processing in specific neural systems for both BO and SoA with partially dissociable regions for subjective judgments in regions of the default mode network.

neuroscience↗

bioRxiv2021

Neural Representation of the Relational Self from Infancy to Adulthood

Investigations into the neural underpinnings of the "self" highlight its complexity and multi-dimensionality and emphasize that various aspects of the self are sustained by different neural systems. Here, we focused on the Relational Self, a dimension denoting the self-within-attachment-relationships that taps the continuity of attachment across individual development and affiliative bonds. Mothers and children were followed across two decades and videotaped in naturalistic interactions at three ages: infancy (3-6 months), childhood (9-12 years), and young adulthood (18-24 years). During fMRI scanning, young adults were exposed to videos of their own mother-child interactions from the three ages versus matched unfamiliar interactions. Relational Self-stimuli elicited greater activations across preregistered nodes of the human caregiving network, including thalamus-to-brainstem, amygdala, hippocampus, ACC, insula, and temporal cortex. Critically, Relational Self-stimuli were age-invariant in most regions of interest despite large variability of stimuli across multiple self-related features, such as similarity, temporal distance, affect, or mentalization, and Bayesian analysis indicated strong evidence for lack of age-related differences. PPI analysis demonstrated that Relational Self-stimuli elicited tighter connectivity between the ACC and insula. Greater child social engagement during interaction with mother correlated with higher ACC and insula response to Relational Self-stimuli. Findings highlight an important novel dimension in the neural representation of the self, suggest that the Relational Self may be sustained by a paralimbic interface integrating exteroceptive and interoceptive self-related signals, and demonstrate overlap in the attachment network of parents and children, lending support to perspectives on the continuity of attachment and self across the individuals developmental history. Significance StatementDescribing the neural underpinnings of the "self" is inherently complex due to the multi-dimensionality of the construct. Following mothers and children from infancy to adulthood, we focused on the Relational Self, a dimension denoting the self-within-attachment-relationships, and exposed young adults to own versus unfamiliar mother-child interactions across their relational history. Relational Self stimuli triggered greater activations in the human caregiving network, including thalamus-to-brainstem, amygdala, hippocampus, ACC, insula, and temporal cortex, were age-invariant, and elicited tighter connectivity between ACC and insula, creating a paralimbic interface of interoception-exteroception sustaining the Relational Self. Findings highlight a novel dimension in the neural representation of the self and lend support to perspectives emphasizing the cross-generational transmission of attachment and its continuity across the individuals developmental history.

neuroscience↗

bioRxiv2019

NASH patient liver derived organoids exhibit patient specific NASH phenotypes and drug responses.

To determine if patient liver derived organoids can in principle be a useful experimental model for non alcoholic staetohepatitis (NASH), we derived to our knowledge for the first time bipotent ductal organoids from endstage NASH patient livers, and for comparison from normal donor livers. We found that all tested NASH liver derived organoids exhibited a profound failure to dedifferentiate from the hepatic state back to the biliary state, consistent with the known poor regenerative capacity of NASH livers. Indeed, RNAseq on all tested NASH organoid populations confirmed down regulation of multiple cell cycle pathways. NASH liver derived hepatically differentiated organoids can slowly expand as monolayers, significantly simplifying microscopic quantitation: The monolayers show variable, but overall significantly increased lipid droplet accumulation in response to free fatty acids. Transcriptome analysis of NASH organoids reveals strong upregulation of a wide variety of pro inflammatory pathways in a NASH patient specific manner. Surprisingly, NASH liver derived organoids are highly diverse not only regarding their cytochrome cytochrome p450 metabolism and inflammatory response, but also react differentially to known antisteatotic, anti inflammatory and antifibrotic drugs, raising the possibility of using NASH patient liver biopsy derived organoids for personalized drug screening and therapy.\n\nOne Sentence SummaryNASH patient liver derived organoids replicate NASH liver phenotypes in a patient specific manner and exhibit profound differences in their response to drugs that are currently used in NASH clinical trials.

cell biology↗

bioRxiv2018

Genetic And Epigenetic Fine Mapping Of Complex Trait Associated Loci In The Human Liver

Deciphering the impact of genetic variation on gene regulation is fundamental to understanding common, complex human diseases. Although histone modifications are important markers of gene regulatory regions of the genome, any specific histone modification has not been assayed in more than a few individuals in the human liver. As a result, the impacts of genetic variation that direct histone modification states in the liver are poorly understood. Here, we generate the most comprehensive genome-wide dataset of two epigenetic marks, H3K4me3 and H3K27ac, and annotate thousands of putative regulatory elements in the human liver. We integrate these findings with genome-wide gene expression data collected from the same human liver tissues and high-resolution promoter-focused chromatin interaction maps collected from human liver-derived HepG2 cells. We demonstrate widespread functional consequences of natural genetic variation on putative regulatory element activity and gene expression levels. Leveraging these extensive datasets, we fine-map a total of 77 GWAS loci that have been associated with at least one complex phenotype. Our results contribute to the repertoire of genes and regulatory mechanisms governing complex disease development and further the basic understanding of genetic and epigenetic regulation of gene expression in the human liver tissue.

genetics↗