The Speaker News Journal

Jellyfish are able to detect the direction of ocean currents, according to recent research by a joint team of environmental scientists. The team studied the movements and of free-ranging barrel-jellyfish and found that the animals are “incredibly advanced in their orientation abilities.”

“Most people who have spent time on the coast will have seen jellyfish and probably assume they are simple animals that just drift with ocean currents,” Dr. Graeme Hays, professor at Deakin University’s School of Life and Environmental Sciences and an author of the study, told The Speaker.

“Our work shows this is not necessarily the case, and instead jellyfish can show remarkable abilities to sense currents, change their swimming behaviour accordingly, and hence maintain their position in preferred areas. These abilities contribute to the massive blooms of jellyfish that are widely being reported around the world.”

The team collected data using GPS loggers that were placed both on the jellyfish and on floats on the ocean’s surface. The researchers then created a model of jellyfish behavior that took into account ocean currents.

From the research, the team has formed a clearer picture of the lives of individual and groups of jellyfish.

“We now know that jellyfish are not simply passive drifters, but instead can make complex movements that help maintain massive blooms which have been seen in many places around the world.”

The research will help efforts to manage these blooms, which can involve hundreds to millions of jellyfish for months-long periods and which can be troublesome when they clog fishing nets or sting beachgoers.

How jellyfish are detecting the currents remains unknown, but Hays provided us with an educated guess about what he believes is the most likely answer: that the jellyfish are able to sense the shear of the water.

“Most probably the jellyfish are using the fact that the currents change slightly with depth–current shear. So this means that different parts of the body of the jellyfish are experiencing slightly different currents. It is probably this difference in current flow across their body that the jellyfish can perceive, allowing them to detect the current flow and modify their swimming accordingly.”

The report, “Current-oriented swimming by jellyfish and its role in bloom maintenance,” was completed by Graeme Hays, Sylvie Vandenabeele and Sabrina Fossette, and was published in the journal Current Biology.

By Sid Douglas

Photos by Graeme Hays

Schizophrenia has been known to be associated with a dearth of neural connections in the prefrontal cortex (PFC). The onset of the disease, which often takes place in a person’s early 20s, may be associated with something quite different, however. A joint research team analyzed MRI data from a group of individuals who had recently experienced their first psychotic episode and found that excessive communication within the PFC — rather than a lack of signals — seems to produce abnormal internal states in schizophrenics.

“It is already appreciated by the research community that schizophrenia is likely a ‘dynamic’ neurodevelopmental illness. The reported effects suggest that perhaps following illness onset — which typically occurs in late teens and early 20s — there may be an abnormal elevation in neural activity in certain areas,” Dr. Alan Anticevic, assistant professor of psychiatry at Yale and lead author on the paper, told The Speaker.

The PFC is the frontal lobe of the brain, responsible for higher-order thinking, and has been implicated as a major site of functional impairment in schizophrenia and other severe menal illnesses. Specifically, schizophrenia has been linked in numerous studies with deficits in PFC funcional connectivity, structure and activation.

However, PFC functional connectivity during early-course schizophrenia has not yet been characterized.

The joint Yale-Sichuan University team examined the MRI’s of 129 individuals who had recently undergone their first psychotic episode and who had not yet been medicated.

They found evidence of increased PFC connectivity in these patients.

They also tested for hypoconnectivity, and while not finding evidence for this in the PFC, they did detect evidence for hypoconnectivity at the whole-brain level. Generally, the team found, early-course schizophrenia was associated with more severe elevation in PFC connection strength.

“Typically schizophrenia, especially in its more chronic stages, is associated with abnormal reductions in neural activity and connections across the PFC,” Anticevic told us. “The reported effects in part call into question this view by showing that at certain illness stages there seems to be prevailing elevation in PFC connectivity. However, this elevation is likely to be abnormal as it predicted symptoms. This finding may map well onto some emerging theories suggesting that early illness stages may be associated with an abnormal spike in glutamate — a key excitatory neurotransmitter that is present throughout the brain.”

This effect was also captured by a sophisticated mathematical model Anticevic’s group is developing in collaboration with Dr. John Murray at NYU. “This ‘computational psychiatry’ approach helps us to mathematically formalize hypothesized disease mechanisms at the cellular level” Anticevic added. In turn, the team can relate these neurobiologically plausible modeling predictions to their neuroimaging effects.

The team also found that PFC hyperconnectivity normalized for some patients over time, and that this predicted symptom improvement.

Anticevic noted the challenge of attempting to answer the question of what was is happening neurobiologically when PFC hyperactivity is normalized in some individuals diagnosed with schizophrenia in response to treatment, but provided an educated guess.

“We currently don’t have a deep mechanistic understanding of this problem. However, one possibility is that somehow medication is ‘normalizing’ the abnormal elevation in excitation and inhibition balance in local cortical circuits that may be responsible for the hyperactivity. One possible mechanism at the neural system level may involve the interplay of domaine and glutamate between the dorsal striatum and prefrontal cortex, which is the pathway where medication may expert its key effects.”

“We hope to demonstrate that alterations occurring in people who suffer from schizophrenia are likely ‘dynamic,'” concluded Anticevic. “In addition, we hope to demonstrate how the combination of leading neuroimaging approaches and our mathematical models can help us understand these dynamics to develop better therapies for the earliest stages of the illness when intervention is critical.”

The report, “Early-Course Unmedicated Schizophrenia Patients Exhibit Elevated Prefrontal Connectivity Associated with Longitudinal Change,” was completed by Alan Anticevic, Xinyu Hu, Yuan Xiao, Junmei Hu, Fei Li, Feng Bi, Michael W. Cole, Aleksandar Savic, Genevieve J. Yang, Grega Repovs, John D. Murray, Xiao-Jing Wang, Xiaoqi Huang, Su Lui, John H. Krystal, and Qiyong Gong, and was published in the Journal of Neuroscience.

Photos: the Yale-Sichuan University team

An accidental discovery made by researchers testing the weight-bearing capacities of a small bird in the Tennessee mountains has shed light on how birds’ senses–notably their ability to hear very low infrasounds characteristic of large storms–allow the animals to avert meteorological catastrophes.

“I think this is just one newly discovered example of the many ways other animals perceive and interact with their environment that are different from how we humans work, Dr. Henry Streby of Beissinger Lab at UC Berkeley, the lead author of the study, told The Speaker.

“We tend to assume other animals are hearing, seeing, and smelling things the same way we do, but we know many other animals sense things far outside of the range of our senses. It is difficult to imagine what goes on in a bird’s brain; they hear higher and lower frequency sounds that we do and they see in a much wider light spectrum and a more complicated color space than we do. Our study, and others tracking migratory birds, are starting to show some of the ways birds can use their impressive senses to get around and stay safe from weather and other dangers.”

The team was working in the Cumberland Mountains of eastern Tennessee, testing the weight-bearing capacity of a small bird.

“A golden-winged warbler weighs only 9 grams, which is less than the mass of 2 US nickles or one British Pound coin,” Streby described his subject. They wanted to know if the bird could carry geolocators on their backs.

Around 24 hours before a large storm blew into the area, spawning 84 tornadoes and killing at least 25 people, the warblers unexpectedly picked up and moved 1,500 kilometers in five days. The team was able to monitor their movements because of the devices they had saddled some of the birds with.

Streby qualified that he couldn’t say with certainty that the birds flew in large groups.

“Our sample of birds carrying tracking devices was quite small, but we suspect they were not the only ones that left,” Streby said. “Although these movements seem impressive, and they occurred outside of the birds’ normal migration period, they were well within the known capabilities of these birds. The birds in this population regularly make similar long distance movements during their spring and fall migration to and from Colombia.”

However, the timing and character of the birds’ movements led the researchers to conclude that a mass temporary relocation took place when the birds sensed that the massive storm was headed their way.

“People have been studying this species on the breeding grounds for decades, but we only just started tracking their migration during this study,” Streby told us.

“Movements like this have not been reported before, and we did not see anything like this during the previous year with this population or with another population we were tracking that was not in the storm’s path. So, basically, we have an extraordinary large-scale movement away from the breeding grounds and back again, that correlates perfectly with the timing of this enormous and powerful storm. Avoiding the storm is the most likely explanation.”

The warbler, like other birds, are particularly attuned to hearing weather, Streby explained. “We know birds are particularly attuned to these very low infrasounds, and we know that large tornado producing storms create infrasound in the exact same frequency range, but nobody had put the two together until this report.”

Next, the team will undertake a further phase of their research, which is expanding in unpredicted ways–they will be collecting data from hundreds of migrating birds, and the team is looking forward to new unexpected developments.

“In 2015, we will be marking more than 400 birds of this species and a closely related species at 16 sites across their entire breeding range. Our goal is to find out where all of these populations spend the winter and where the important resting and refueling places are along their migration routes. These species are of high conservation concern and we are hoping to better understand the challenges they face during all aspects of their annual cycle. We did not intend to study how these birds respond to extreme weather events, but if they encounter any storms like the one from 2014, or maybe have to fly around a hurricane during migration, or something else completely unexpected, I’m excited to see what they do.

“We shouldn’t assume animals perceive their environment the same way we do,” Streby said. “We are lucky to have all of our experts and technology monitoring the weather and warning us when tornadoes or other dangers are coming our way. It is amazing to discover the different tools wildlife have for knowing what is coming too. It is also important for readers to understand that these birds apparently sensed the storm at a great distance, and there is a logical scientific explanation for how they did it; they did not magically detect the storm long before it existed like many media outlets have suggested.”

The report, “Tornadic Storm Avoidance Behavior in Breeding Songbirds,” was completed by Henry M. Streby, Gunnar R. Kramer, Sean M. Peterson, Justin A. Lehman, David A. Buehler, and David E. Andersen, and was published in the online Current Biology.

By Sid Douglas