Naked Scientists: Wireless retinal implant, pristine early-universe star, injectable HIV PrEP, and corvid language comprehension

This episode investigates four science frontiers. First, a 2 millimeter by 2 millimeter retinal implant, powered by infrared light, helps people with age-related macular degeneration read text again, albeit with limited resolution but stable over years. Second, the NHS moves toward long-acting injectable HIV PrEP using cabotegravir, expanding protection to those who struggle with daily pills. Third, astronomers identify a metal-poor red giant that acts as a near-pristine fossil from the early universe, offering fresh clues about first stars. Fourth, Cambridge researchers show rooks that understand human speech and even follow vocal commands, revealing remarkable generalized cognition. The podcast also explains how ATP and phosphocreatine limit high-intensity exercise effort.

Wireless retinal implant advances for age-related macular degeneration

In the first segment, the Naked Scientists discuss a breakthrough in retinal prosthetics. A tiny 2 millimeter by 2 millimeter chip, implanted beneath the retina, receives an infrared image from a camera worn on glasses. The device is powered and driven by infrared light, so there is no external power cable. The platform converts the image into electrical stimulation of the overlying retinal cells, bypassing degenerated photoreceptors to supply a usable visual signal. In the study, 38 patients with age-related macular degeneration achieved reading capability improvements that are stable for more than four years, although the acuity corresponds to roughly 20 meters of what a healthy eye would see from 100 meters. The speaker notes that while the pixel count is modest (378 pixels, roughly 100 microns per pixel), high refresh rates can help the brain reconstruct more detailed scenes, leveraging the brain's tendency to integrate rapid, repeated frames into a coherent image. A key takeaway is the externalized power supply, which reduces surgical complexity and may enhance device longevity, making this approach potentially more suitable for younger patients with other forms of retinal degeneration. A clinician (Robert McLaren) explains the underlying biology: photoreceptors in the center of the retina are lost in AMD, while the rest of the visual pathway remains intact, so the goal is to stimulate remaining retinal neurons in lieu of photoreceptors. Quote "The power comes from the infrared light that's shone on this implant" - Dr. Robert McLaren, Professor of Ophthalmology, University of Oxford.

Long-acting injectable HIV PrEP in the UK

The discussion shifts to public health, focusing on cabotegravir as an injectable pre-exposure prophylaxis (PrEP) for HIV with two months of protection per dose, contrasting with daily oral regimens like TDF-FTC. The UK Health Security Agency outlines that this option could increase uptake among people who struggle with daily adherence, provide discretion, and reach those who might face barriers to conventional PrEP. The NHS faces a high ongoing burden of HIV prevention but points to substantial declines in new diagnoses since the widespread rollout of daily PrEP, especially among gay and bisexual men. Economic considerations are addressed, noting NICE's cost-effectiveness assessments and the higher upfront cost of injectable PrEP versus daily tablets, while emphasizing potential healthcare savings by preventing infections. The ambition is to accelerate progress toward eliminating new HIV cases by 2030, using a combination approach that includes daily PrEP, injectable PrEP, regular testing, and condoms. Quote "injectable cabotegravir prep provides protection from HIV for 2 months" - Hamish Mohammed, UK Health Security Agency.

Pristine star as a window into the early universe

The program next surveys a remarkable star, SDSS JO 7157334, a red giant about 85,000 light-years away and roughly 9 to 10 billion years old, with minimal heavy elements. This near-pristine star serves as a rare observational proxy for the first generations of stars that formed from hydrogen and helium, before heavier elements enriched the cosmos. Spectroscopy reveals the star’s chemical fingerprint, showing the absence or extreme paucity of metals like iron and carbon, a key to understanding primordial star formation. The star is thought to originate from the outskirts of the Milky Way, likely tied to the Magellanic Clouds, and may trace back to a massive Population III-like progenitor in a previous generation. The interview underscores that such stars provide critical constraints on stellar formation, cooling mechanisms, and the physics of the early universe, offering a glimpse into how the first stars and galaxies transformed the cosmos. Quote "So one big takeaway is just the fact that it is possible to learn about the very, very early universe by looking at the galaxies around us" - Matt Bothwell, space scientist and author.

Corvid cognition: rooks understand speech and follow commands

The episode turns to animal cognition with Nicky Clayton, who demonstrates that rooks can understand human commands, respond to spoken instructions, and even follow voices when taught with a reward-based system. Training rooks requires patience to establish trust, often over a year, but once trust is established, the birds rapidly master tasks such as selecting color targets or responding to spoken cues. The rooks’ learning speed and problem-solving flexibility are highlighted as evidence of generalized cognition not hard-wired by natural selection to a single task. The discussion compares these wild birds to dogs, noting that rooks are not domesticated yet can acquire a versatile set of cognitive tools, including language comprehension, which underscores the sophistication of corvid intelligence. Quote "they understand human commands" - Nicky Clayton, Professor of Ethology, University of Cambridge.

Muscle energy systems and the limits of human performance

In the final segment, a question about why you cannot perform an 11th push-up is addressed by detailing the energy systems of muscle. ATP is the immediate energy carrier, with a small cellular pool kept replenished by phosphocreatine and anaerobic glycolysis. The breakdown of phosphocreatine releases inorganic phosphate, contributing to fatigue, and hydrogen ions generated during glycolysis lower muscle pH, also contributing to fatigue; calcium release from the sarcoplasmic reticulum is impeded by inorganic phosphate, reducing contraction efficiency. The explanation highlights how fatigue arises from biochemical byproducts and energy depletion during high-intensity efforts, illustrating the differences between biological systems and machines. Quote "ATP is crucial for keeping us and all life for that matter, alive" - Andy Jones, Professor of Applied Physiology, University of Exeter.