Biology subjects

Spriggs, M.

Publications and source records attributed to Spriggs, M..

3 recordsLinked to original sources

bioRxiv2024

Human brain changes after first psilocybin use

Psychedelics have robust effects on acute brain function and long-term behavior but whether they also cause enduring functional and anatomical brain changes is unknown. In a placebo-controlled, within-subjects, electroencephalography, and magnetic resonance imaging study in 28 healthy, entirely psychedelic-naive participants, anatomical and functional brain changes were detected from one-hour to one-month after a single high-dose (25 mg) of psilocybin. Increases in cognitive flexibility, psychological insight, and well-being were seen at one-month. Diffusion imaging done before and one-month after 25mg psilocybin revealed decreased axial diffusivity bilaterally in prefrontal-subcortical tracts that correlated with decreased brain network modularity over the same time period. Decreased modularity also correlated with improved well-being. Increased cortical signal entropy at 1- and 2-hours post-dosing predicted improved psychological well-being at one-month. Next-day psychological insight mediated the entropy to well-being relationship. All effects were exclusive to 25mg psilocybin; no effects occurred with a 1mg psilocybin placebo dose.

neuroscience↗

bioRxiv2023

Exploring archaeogenetic studies of dental calculus to shed light on past human migrations in Oceania

The Pacific islands have experienced multiple waves of human migrations, providing a case study for exploring the potential of using the microbiome to study human migration. We performed a metagenomic study of archaeological dental calculus from 103 ancient individuals, originating from 12 Pacific islands and spanning a time range of [~]3000 years. Oral microbiome DNA preservation in calculus is far higher than that of human DNA in archaeological bone from the Pacific, and comparable to that seen in calculus from temperate regions. Variation in the microbial community composition was minimally driven by time period and geography within the Pacific, while comparison with samples from Europe, Africa, and Asia reveal the microbial communities of Pacific calculus samples to be distinctive. Phylogenies of individual bacterial species in Pacific calculus reflect geography. Archaeological dental calculus shows potential to yield information about past human migrations, complementing studies of the human genome.

microbiology↗

bioRxiv2018

Population Turnover in Remote Oceania Shortly After Initial Settlement

Ancient DNA analysis of three individuals dated to ~3000 years before present (BP) from Vanuatu and one ~2600 BP individual from Tonga has revealed that the first inhabitants of Remote Oceania (\"First Remote Oceanians\") were almost entirely of East Asian ancestry, and thus their ancestors passed New Guinea, the Bismarck Archipelago, and the Solomon Islands with minimal admixture with the Papuan groups they encountered [1]. However, all present-day populations in Near and Remote Oceania harbor 25-100% Papuan ancestry, implying that there must have been at least one later stream of migration eastward from Near Oceania. We generated genome-wide data for 14 ancient individuals from Efate and Epi Islands in Vanuatu ranging from 3,000-150 BP, along with 185 present-day Vanuatu individuals from 18 islands. We show that people of almost entirely Papuan ancestry had arrived in Vanuatu by 2400 BP, an event that coincided with the end of the Lapita cultural period, changes in skeletal morphology, and the cessation of long-distance trade between Near and Remote Oceania [2]. First Remote Oceanian ancestry subsequently increased via admixture but remains at 10-20% in most islands. Through a fine-grained comparison of ancestry profiles in Vanuatu and Polynesia with diverse groups in Near Oceania, we find that Papuan ancestry in Vanuatu is consistent with deriving from the Bismarck Archipelago instead of the geographically closer Solomon Islands. Papuan ancestry in Polynesia also shows connections to the ancestry profiles present in the Bismarck Archipelago but is more similar to Tolai from New Britain and Tutuba from Vanuatu than to the ancient Vanuatu individuals and the great majority of present-day Vanuatu populations. This suggests a third eastward stream of migration from Near to Remote Oceania bringing a different type of Papuan ancestry.

genetics↗