The study was led by Prof. Jeff Hausdorff from the Department of Physical Therapy at the Faculty of Medical & Health Sciences and the Sagol School of Neuroscience at Tel Aviv University, and the Center for the Study of Movement, Cognition, and Mobility at the Tel Aviv Medical Center, together with Amit Salomon and Eran Gazit from the Tel Aviv Medical Center. Other investigators included researchers from Belgium, France, and Harvard University. The paper was published in Nature Communications and featured in the Editors’ Highlights.

Prof. Hausdorff, an expert in the fields of gait, aging, and Parkinson's disease, explains: "FOG is a debilitating and so far unexplained phenomenon, affecting 38-65% of Parkinson's sufferers. A FOG episode can last from a few seconds to more than a minute, during which the patient's feet are suddenly 'glued' to the floor, and the person cannot begin or continue walking. FOG can seriously impair the mobility, independence, and quality of life of people with Parkinson’s disease, causing great frustration, and frequently leading to falls and injuries".

Amit Salomon adds: "Today the diagnosis and tracking of FOG are usually based on self-report questionnaires and visual observation by clinicians, as well as frame-by-frame analysis of videos of patients in motion. This last method, currently the prevailing gold standard, is reliable and accurate. Still, it has some serious drawbacks: it is time-consuming, requires the involvement of at least two experts, and is impracticable for long-term monitoring in the home and daily living environment. Researchers worldwide are trying to use wearable sensors to track and quantify patients' daily functioning. So far, however, successful trials have all relied on a very small number of subjects".

TAU's AI Challenge Advances FOG Tracking

In the current study, the researchers collected data from several existing studies, relating to over 100 patients and about 5,000 FOG episodes. All data were uploaded to the Kaggle platform, a Google company that conducts international machine learning competitions. Members of the worldwide machine learning community were invited to develop models that would be incorporated into wearable sensors to quantify various FOG parameters (e.g. duration, frequency, and severity of episodes). A prize of $100,000, funded by Kaggle and the Michael J. Fox Foundation for Parkinson's Research, was offered for the best solutions. 1,379 groups from 83 countries rose to the challenge, ultimately submitting a total of 24,862 solutions. The results of the best models were very close to those obtained through the video analysis method, and significantly better than previous experiments relying on a single wearable sensor.

Moreover, the models led to a discovery: an interesting relationship between FOG frequency and the time of day. Co-author Eran Gazit notes: "We observed, for the first time, a recurring daily pattern, with peaks of FOG episodes at certain hours of the day, that may be associated with clinical phenomena such as fatigue, or effects of medications. These findings are significant for both clinical treatment and continued research about FOG".

Prof. Hausdorff: "Wearable sensors supported by machine learning models can continuously monitor and quantify FOG episodes, as well as the patient's general functioning in daily life. This gives the clinician an accurate picture of the patient's condition at all times: has the illness improved or deteriorated? Does it respond to prescribed drugs? The informed clinician can respond promptly, while data collected through this technology can support the development of new treatments. In addition, our study demonstrates the power of machine learning contests in advancing medical research. The contest we initiated brought together capable, dynamic teams all over the world, who enjoyed a friendly atmosphere of learning and competition for a good cause. Rapid improvement was gained in the effective and precise quantification of FOG data. Moreover, the study laid the foundations for the next stage: long-term 24/7 FOG monitoring in the patient's home and real-world environment".

The research was conducted under the leadership of Prof. Yasmine Meroz from the School of Plant Sciences and Food Security at the Wise Faculty of Life Sciences at Tel Aviv University, in collaboration with Prof. Orit Peleg from the University of Colorado Boulder in the USA. The research team included Dr. Chantal Nguyen (Boulder), Roni Kempinski and Imri Dromi (TAU). The research was published in the prestigious journal Physical Review X.

Do flowers have a sense of direction?

Prof. Meroz explains: "Previous studies have shown that if sunflowers are densely planted in a field where they shade each other they grow in a zigzag pattern - one forward and one back - so as not to be in each other's shadow. This way they grow side by side to maximize illumination from the sun, therefore photosynthesis, on a collective level. Plants know how to distinguish between the shadow of a building and the green shadow of a leaf. If they sense the shadow of a building - they usually don’t change their growth direction, because they 'know' that will have no effect. But if they sense the shadow of a plant, they will grow in a direction away from the shadow".

According to the researchers, Darwin was the first to recognize that all plants grow while exhibiting a kind of cyclical movement known as "circumnutation", which is observed in both stems and roots. However, until today—except for a few cases, such as climbing plants that grow in large circular movements to find something to grab onto—it was unclear whether this was an artifact or a critical feature of growth. Why would a plant invest energy to grow in random directions?

In the current study, the researchers examined how sunflowers "know" to grow optimally—maximizing sunlight capture for the collective—and analyzed the growth dynamics of sunflowers in the laboratory, where they exhibit a zigzag pattern. Prof. Meroz and her team grew sunflowers in a high-density environment and photographed them during growth, taking pictures every few minutes. The photographs were then combined to create a time-lapse movie. By tracking the movement of each sunflower, the researchers observed that the flowers were "dancing" a lot.

Shake your Tail Petal

Prof. Meroz stated, "As part of our research, we conducted a physical analysis that captured the behavior of each sunflower within the collective, revealing that the sunflowers 'dance' to find the optimal angle, ensuring that each flower does not block the sunlight of its neighbor. We quantified this movement statistically and demonstrated through computer simulations that these random movements are used collectively to minimize shadowing. It was also surprising to find that the distribution of the sunflowers' 'steps' was very wide, ranging over three orders of magnitude, from nearly zero displacements to movements of up to two centimeters every few minutes in various directions".

In conclusion, Prof. Meroz adds: "The sunflower plant takes advantage of its ability to use both small, slow steps and large, fast ones to find the optimal arrangement for the collective. If the range of steps were smaller or larger, the arrangement would result in more mutual shading and less photosynthesis. It's somewhat like a crowded dance party, where individuals move around to create more space: if they move too much, they'll interfere with the other dancers, but if they move too little, the crowding problem won't be solved, leaving one corner of the square overcrowded and the other empty. Sunflowers exhibit a similar communication dynamic—a combination of responding to the shade of neighboring plants and making random movements regardless of external stimuli".

A new study conducted at Tel Aviv University’s School of Zoology, Wise Faculty of Life Sciences and Steinhardt Museum of Natural History reveals that the Israel-Hamas war has had a severe impact on animals. The study, which focused on geckos, found that the sound of explosions from fired rockets induces stress and anxiety in these creatures, leading to a sharp increase in their metabolic rates — an energy cost that, if chronic, may be life-threatening. The researchers hypothesize that these stress responses characterize many other animals, especially those who live in the conflict zones in northern and southern Israel.

The study was led by a team of researchers from TAU’s School of Zoology and Steinhardt Museum of Natural History — Shahar Dubiner, Prof. Shai Meiri, and Prof. Eran Levin — in collaboration with Dr. Reut Vardi of the University of Oxford. The study was published in the journal Ecology.

Energy Changes in Wildlife

Prof. Shai Meiri explains: "The most tragic aspect of war is the loss of human life, among both soldiers and civilians. However, animals are also severely affected, both directly and indirectly, in ways that may threaten their survival. A few weeks before October 7, we began working on a long-term study to measure the rate of energy consumption of small ground geckos of the species Stenodactylus sthenodactylus. We obviously did not foresee the outbreak of the war, but unintentionally, we recorded the energy consumption of five geckos during the rocket barrages launched into Tel Aviv in the first month of the war".

The study’s findings showed that at the sound of the bombings, the geckos’ metabolic rate jumped to double what it was when they were at rest. Their breathing became faster, and they clearly exhibited signs of stress. The experiment lasted up to four hours after the barrages, yet even within this timeframe the geckos did not calm down and return to their resting levels. Moreover, even after a month of continuous fighting, the geckos did not acclimate to the sound of the explosions — their stress response remained unchanged.

Left to right: Prof. Shai Meiri and Prof. Eran Levin.

Prof. Levin: "A state of stress is detrimental to both humans and animals. To compensate for the increase in oxygen consumption and depletion of energy reserves, animals need to eat more. Even if they manage to find food, in the process they expose themselves to predators and lose opportunities to reproduce. In a situation of ongoing conflict, such as the current reality in Gaza, the Gaza Envelope, and along the Israeli-Lebanese border, the metabolic cost can be significant and have a real impact on the energy reserves and activity periods of reptiles and other animals. This can exacerbate their conservation status, especially for species that are already endangered".

The researchers note that the findings of this study are consistent with another experiment conducted during Operation Guardian of the Walls, in which they also observed a stress response in a small snake of the species Xerotyphlops syriacus.

Shahar Dubiner concludes: "Our research was conducted in a laboratory at Tel Aviv University and pertained to the reverberations of explosions from interceptions in the Tel Aviv area. However, given the unequivocal results showing symptoms of stress, we can infer that animals that are in the immediate conflict zones in the south and north of the country, where the intensity and frequency of fire are much higher, suffer from significantly more severe stress and anxiety symptoms that may endanger their lives".