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Harris Kaplan

@harriskaplan

Neurobiologist working on how the infant brain controls behavior Postdoc in @dulaclab.bsky.social @ Harvard PhD was in the Zimmer lab @ IMP, Vienna

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24.09.2023
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Latest posts by Harris Kaplan @harriskaplan

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Cell Type-Specific Hormonal Signaling Configures Hypothalamic Circuits for Parenting Parenting behavior emerges from hormonally sensitive circuits, but how distinct circuit components are affected by, and contribute to, sex and state dependent changes in infant caregiving remains uncl...

New paper alert!!...🀩 Led by @blogeman.bsky.social, we identify how cell type-specific hormonal responses in the hypothalamus tunes parenting behavior in males and females 🐭🧠🍼. Highlights in thread πŸ‘‡ 1/6

www.biorxiv.org/content/10.6...

13.12.2025 14:01 πŸ‘ 73 πŸ” 32 πŸ’¬ 1 πŸ“Œ 0

I am thrilled to share our latest work led by @zurisullivan.bsky.social in collaboration with @moffittlab.bsky.social ! We find that the brain encodes distinct, pathogen-specific sickness states across behavior, physiology, neural activity, and gene expression 1/6

www.biorxiv.org/content/10.6...

09.12.2025 12:04 πŸ‘ 82 πŸ” 23 πŸ’¬ 2 πŸ“Œ 2
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MCB Researchers Highlighted in Nature Publication Series - Harvard University - Department of Molecular & Cellular Biology Researchers from the Brain Initiative Cell Census Network (BICCN) will release an extraordinary series of 16 manuscripts in Nature on November 5.. This collection, made possible by large […]

MCB Researchers Highlighted in Nature Publication Series 🧠 πŸ§ͺ🧬 #AcademicSky #higherEd
www.mcb.harvard.edu/department/n... @dulaclab.bsky.social @rachellegaudet.bsky.social @harvardbrainsci.bsky.social @nature.com @harriskaplan.bsky.social

05.11.2025 23:06 πŸ‘ 12 πŸ” 5 πŸ’¬ 0 πŸ“Œ 1
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A cell type in the visual system that receives feedback about limb movement Hartman et al. describe a cell type in the Drosophila visual system that is activated during head grooming through visual and non-visual signals arising from foreleg movements. These neurons inhibit a...

New paper from our lab! This was such a fun project to be a part of - proof that sometimes following a spurious observations down the rabbit hole leads to awesome findings.

www.cell.com/current-biol...

17.07.2025 15:08 πŸ‘ 48 πŸ” 19 πŸ’¬ 3 πŸ“Œ 2
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Animal behavior changes considerably over postnatal development. How do such changes relate to the development of underlying neuronal circuits? On Friday, 7/25, 3pm, join hosts Drs. Marco Rizzo & Tamara Markovic as they welcome @harvard.edu's Dr. @harriskaplan.bsky.social to #MSNseminars & Find out!

17.07.2025 17:40 πŸ‘ 1 πŸ” 3 πŸ’¬ 0 πŸ“Œ 0
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Finally, this work was supported by the NIH BICCN, Nomis Foundation, @jcchildsfund.bsky.social, @hhmi.org, and others. Thank you!

05.03.2025 22:04 πŸ‘ 4 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0

Thanks to all co-authors, within the @dulaclab.bsky.social - @blogeman.bsky.social, Tate Yawitz, Mustafa Talay, and Changwoo Seo, and collaborators: Kai Zhang & Bing Ren, Celine Santiago & David Ginty, and Noor Sohail, Serhiy Naumenko, & Shannan Ho Sui.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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In summary, we described the molecular programs that make up preoptic area cell type development, and showed how the maturation of these cell types depends in part on external inputs.

05.03.2025 22:04 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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We also did a deep dive into (1) the development of signaling pathways important for various hypothalamic functions, such as sleep and social behavior, and (2) the emergence of sex differences in gene expression.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Adults showed only subtle differences in gene expression, indicating that cell types eventually β€œcatch up” in their maturation. Future work will address whether these gene expression differences cause any of the dramatic effects on social behavior previously reported in adult Trpc2 mutants.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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We found that this difference amounts to a transient developmental delay in the maturation of preoptic area cell types.

05.03.2025 22:04 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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To address this, we sequenced the POA in mutant mice impaired in various sensory modalities. This revealed little to no effect of bodily touch, olfaction, cold sensation or vision. However, in Trpc2 mutants, which lack pheromone sensation through the vomeronasal organ, many cell types were affected.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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However, it’s possible that the causality is the other way around: cell types may mature in response to other changes in the animal. For example, early life social experience can have long-lasting impacts on sociality into adulthood, suggesting the existence of critical periods in early life.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

This suggests that the timing of gene expression changes correlates with the timing of changes in the behavior that the cell type is involved in. While these data are intriguing, future work must be done to show how these gene expression changes relate to changes in cell type function.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Cell types involved in social behavior matured especially late, consistent with social behavior changing dramatically with puberty. Cell types involved in sleep showed major changes from P10 to P18, which is the same time as dramatic changes in sleep behavior in mice.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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This revealed diverse maturation trajectories. Some cell types matured gradually, others more non-linearly. Some matured early, others late. We found that these differences depend in part on the cell type’s sub-regional location within the preoptic area, its function, and the sex of the animal.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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While cell type identity is diversified very early on, cell types are not yet mature – their gene expression differs from their adult states. We asked whether different cell types mature along distinct trajectories, by measuring similarity to the adult state at each younger age.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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When does this diversity first emerge? We sequenced at E14, an age where ~half of the POA cells are dividing progenitors, and the other half are newborn neurons. These data revealed that diversification occurs rapidly upon neurogenesis.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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To quantify this, we used CCA-based label transfer, and found that indeed each E16 cell type maps onto just a single adult cell type. This indicates that the full complement of ~150 cell types is already diversified well before birth.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Each cell type's developmental trajectory appeared as a gradient in UMAP space. This intriguingly suggested that cell types are diversified very early in life – as early as embryonic day 16 (E16), based on the grouping of those cells with adult cell types.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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The dataset is massive: 200,000 cells and ~150 cell types, ~25% of which have known behavioral annotations thanks to previous work by many labs, such as @dulaclab.bsky.social work on parenting or social drive (recently published by @dingliu.bsky.social). Maybe you can spot your favorite cell type!

05.03.2025 22:04 πŸ‘ 2 πŸ” 1 πŸ’¬ 1 πŸ“Œ 0
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Preoptic cell types have been defined using single-cell RNA-seq in adults, so we used snRNA-seq to ask whether we can identify these cell types early in life, and how they might differ molecularly from adult cell types.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

These cell types have been studied extensively in adults, but not earlier. Social behavior and homeostasis change dramatically with age. For example, infants meet homeostatic needs like thirst or warmth through social interactions, so these cell types may function differently early in life.

05.03.2025 22:04 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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We focused on the mouse hypothalamic preoptic area (POA), a brain region containing genetically defined cell types that have been linked to specific social behaviors, such as parenting, and homeostatic functions, such as sleep.

05.03.2025 22:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Sensory input, sex and function shape hypothalamicΒ cellΒ type development - Nature Paired transcriptomic and chromatin accessibility profiling are used to examine the developmental trajectories of neuronal populations in the hypothalamic preoptic region, including cell types with ke...

I’m excited to share our publication from @dulaclab.bsky.social in @nature.com, where we illuminate the development of hypothalamic cell types involved in a broad range of functions, from social behaviors to thirst, thermoregulation, and sleep. Highlights below! 🧡

www.nature.com/articles/s41...

05.03.2025 22:04 πŸ‘ 34 πŸ” 10 πŸ’¬ 2 πŸ“Œ 3

Delighted to share our new work just out today, led by terrific postdoc in the lab @harriskaplan.bsky.social: the development of instinct at the single cell level. Thread to follow shortly
www.nature.com/articles/s41...

05.03.2025 16:44 πŸ‘ 36 πŸ” 8 πŸ’¬ 3 πŸ“Œ 1
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In our new paper @dulaclab.bsky.social, we investigated a fundamental question in social neuroscience: the origin of "sociality" (the need of being together) at the levels of behavior, neuron type, neural circuit and sensory modulation. (Detailed digest below) (1/7)
www.nature.com/articles/s41...

27.02.2025 16:05 πŸ‘ 46 πŸ” 12 πŸ’¬ 2 πŸ“Œ 5

Please look at the 🧡 from @dingliu.bsky.social summarizing our discovery of brain-wide circuits controlling the emergence and satiation of social drive during social isolation vs grouping

27.02.2025 16:30 πŸ‘ 25 πŸ” 7 πŸ’¬ 1 πŸ“Œ 0

Obviously we don't need to wonder about Zuckerberg's moral compass or pecuniary interests here, we've known who this guy is forever. The question of why leaders of institutions like HHMI / universities would be so silent/compliant is more complicated.

19.02.2025 18:26 πŸ‘ 26 πŸ” 9 πŸ’¬ 3 πŸ“Œ 0
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We have to stand up for science! Anyone who can join these rallies and believes that US science must be protected should come! @standupforscience.bsky.social

15.02.2025 19:51 πŸ‘ 233 πŸ” 105 πŸ’¬ 7 πŸ“Œ 2