Do Invertebrates Have Emotions?

Anecdotally, it’s difficult to watch some of the more intelligent animals navigating the world or interacting with one another without concluding that they have emotions. However, empirically studying whether or not that’s true has proven difficult, as finding a definitive answer to a big philosophical question by means of lab experiments is not an easy task. While there’s growing evidence that primates and some other vertebrates have emotional states, researchers debate whether the same is true for animals further removed from humans, such as octopuses, and also debate what it means to have an emotional state versus an internal feeling in the first place. “I think it’s easier for people to say, ‘Oh, my dog has emotions,’ but harder for people to recognize emotions in a crab, for instance. It’s a very automatic response,” University of York philosopher Kristin Andrews tells The Scientist. “But then you have to be careful of anthropomorphizing and making sure you’re not just projecting your own feelings [onto the animal].”

An octopus in an experimental chamber

How Neurons in a Dish Learned to Play “Pong”

Is Pong the most complicated game in the world? Maybe not, but is it complex enough that it requires a brain to master? Also no, according to a biotech company called Cortical Labs, which trained a culture of neurons on a dish to master (a modified, simplified version of) the game. DishBrain, as the system is called, is evidence that neurons—not a whole brain—are capable of learning and therefore of sentience as well, argues research published in Neuron this October. Use of the word “sentience” was a controversial choice, experts say, but Cortical Labs Chief Scientific Officer Brett Kagan says he expected his paper to be controversial. Still, he sees DishBrain, which trains neurons to learn Pong by stimulating them with either connectivity-fostering or disrupting inputs based on whether they hit or missed the ball, as evidence that biological neurons can be harnessed to better understand intelligence and recreate it virtually. “Can this be a new way of thinking about what neurons are?” asks Kagan. “Are they just part of human and animal biology? Or can they be a new biomaterial for intelligence? . . . Why try and mimic what you can harness?”

illuminated neural connections

Neurons Damaged in Dementia Recognize Interruptions to Patterns

Understanding Alzheimer’s disease and other forms of dementia has remained a top research priority for neuroscientists, with the goal of helping those with the conditions live more comfortably and those who may develop them have their symptoms delayed, prevented, or treated. So studies that uncover entirely new mechanisms through which neurodegenerative diseases impair brain function—such as this one, published in The Journal of Neuroscience this March—are always exciting. In the experiment, researchers found that people with dementia had a harder time noticing deviations from a pattern (in this case, the rhythm and pace of a beeping noise) than people without the condition. They also identified the cluster of neurons responsible for the ability to notice when a pattern breaks, finding that it’s often damaged and malfunctioning in multiple forms of dementia. “Ultimately, we want to accelerate the development of new treatment[s] to help people in everyday life,” study coauthor and University of Cambridge clinical neuroscientist James Rowe tells The Scientist. “Drugs that can help to tune this fundamental function of the brain . . . can help people affected from dementia in their everyday life.”

image of brain made from colorful stacked slices

Retching Mice Reveal the Brain Circuit Behind Vomiting

This article was a favorite among The Scientist’s editorial staff, and also formed the basis of a metaphor about undying scientific curiosity and fascination in our former editor-in-chief Bob Grant’s final editorial for the magazine. In the study, published in Cell this November, researchers identified the neurological pathway in mice’s gut-brain axis that triggers vomiting—despite the fun fact that mice actually can’t vomit at all. Instead, the researchers triggered distinct “retching” behaviors in the mice and identified a way to prevent the nausea-linked behavior from occurring—a development they say may help cancer patients manage the side effects of chemotherapy.

Glioblastoma Cells Imitate Immature Neurons to Invade the Brain

The human body goes to extreme lengths to protect the brain, from physically limiting access via the blood-brain barrier to surrounding its precious neurons with dedicated support and immune cells. And yet, cancer finds its way in. Research published in Cell this July helps to explain how, and it involves a fair amount of biological trickery. It turns out that glioblastoma cells, a highly invasive and incurable cancer, spread throughout the brain by disguising themselves as immature neurons in need of support. The cells, the study finds, even receive synaptic transmissions from existing neurons in the brain, which then foster further growth and spread of the incognito tumors. As Peter Hau, a University Hospital Regensburg neurooncologist who didn’t work on the study, tells The Scientist, “this research will quickly fuel in several translational approaches and will certainly help to develop therapies in these devastating tumors.”

See “Our Favorite Neuroscience Stories of 2021