New study reveals where memories of familiar places are stored in the brain

As we move through the world, what we see is seamlessly integrated with our memory of the broader spatial environment. How does the brain accomplish this feat? A new study from Dartmouth College reveals that three regions of the brain in the posterior cerebral cortex, which the researchers call "place-memory areas," form a link between the brain's perceptual and memory systems. The findings are published in Nature Communications.

"As we navigate our surroundings, information enters the visual cortex and somehow ends up as knowledge of where we are -- the question is where this transformation into spatial knowledge occurs. We think that the place-memory areas might be where this happens," explains lead author Adam Steel, a Neukom Fellow with the department of psychology and brain sciences in the Robertson Lab at Dartmouth. "When you look at the location of the brain areas that process visual scenes and those that process spatial memories, these place-memory areas literally form a bridge between the two systems. Each of the brain areas involved in visual processing are paired with a place-memory counterpart."

For the study, an innovative methodology was employed. Participants were asked to perceive and recall places that they had been to in the real world during functional magnetic resonance imaging (fMRI), which produced high-resolution, subject specific maps of brain activity. Past studies on scene perception and memory have often used stimuli that participants knew of but had never visited, like famous landmarks, and have pooled data across many subjects. By mapping the brain activity of individual participants using real-world places that they had been to, researchers were able to untangle the brain's fine-grained organization.

In one experiment, 14 participants provided a list of people that they knew personally and places that they have visited in real-life (e.g., their father or their childhood home). Then, while in the fMRI scanner, the participants imagined that they were seeing those people or visiting those places. Comparing the brain activity between people and places revealed the place-memory areas. Importantly, when the researchers compared these newly identified regions to the brain areas that process visual scenes, the new regions were overlapping but distinct.

"We were surprised," says Steel, "because the classic understanding is that the brain areas that perceive should be the same areas that are engaged during memory recall."

In another experiment, the team investigated whether the place-memory areas were involved in recognition of familiar places. During fMRI scanning, participants were presented with panning images of familiar and unfamiliar real-world locations downloaded from Google Street View. When the researchers looked at the neural activity, they found that the place-memory areas were more active when images of familiar places were shown. The scene-perception areas did not show the same enhancement when viewing familiar places. This suggests that the place-memory areas play an important role in recognizing familiar locations.

"Our findings help explain how a generic image of a clock tower becomes one that we recognize, such as Baker-Berry Library's tower here on Dartmouth's campus," says Steel.

"It's thrilling to discover a new set of brain areas," says senior author Caroline Robertson, an assistant professor of psychological and brain sciences at Dartmouth. "Learning how the mind is organized is at the heart of the quest of understanding what makes us human."

"The place-memory network provides a new framework for understanding the neural processes that drive memory-guided visual behaviors, including navigation," explains Robertson.

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Charting the expansion history of the universe with supernovae

An international research team analyzed a database of more than 1000 supernova explosions and found that models for the expansion of the Universe best match the data when a new time dependent variation is introduced. If proven correct with future, higher-quality data from the Subaru Telescope and other observatories, these results could indicate still unknown physics working on the cosmic scale.

Edwin Hubble's observations over 90 years ago showing the expansion of the Universe remain a cornerstone of modern astrophysics. But when you get into the details of calculating how fast the Universe was expanding at different times in its history, scientists have difficulty getting theoretical models to match observations.

To solve this problem, a team led by Maria Dainotti (Assistant Professor at the National Astronomical Observatory of Japan and the Graduate University for Advanced Studies, SOKENDAI in Japan and an affiliated scientist at the Space Science Institute in the U.S.A.) analyzed a catalog of 1048 supernovae which exploded at different times in the history of the Universe. The team found that the theoretical models can be made to match the observations if one of the constants used in the equations, appropriately called the Hubble constant, is allowed to vary with time.

There are several possible explanations for this apparent change in the Hubble constant. A likely but boring possibility is that observational biases exist in the data sample. To help correct for potential biases, astronomers are using Hyper Suprime-Cam on the Subaru Telescope to observe fainter supernovae over a wide area. Data from this instrument will increase the sample of observed supernovae in the early Universe and reduce the uncertainty in the data.

But if the current results hold-up under further investigation, if the Hubble constant is in fact changing, that opens the question of what is driving the change. Answering that question could require a new, or at least modified, version of astrophysics.

From Science Daily

Hidden processes at work in the hearts of large stars revealed

Astronomers commonly refer to massive stars as the chemical factories of the Universe. They generally end their lives in spectacular supernovae, events that forge many of the elements on the periodic table. How elemental nuclei mix within these enormous stars has a major impact on our understanding of their evolution prior to their explosion. It also represents the largest uncertainty for scientists studying their structure and evolution.

A team of astronomers led by May Gade Pedersen, a postdoctoral scholar at UC Santa Barbara's Kavli Institute for Theoretical Physics, have now measured the internal mixing within an ensemble of these stars using observations of waves from their deep interiors. While scientists have used this technique before, this paper marks the first time this has been accomplished for such a large group of stars at once. The results, published in Nature Astronomy, show that the internal mixing is very diverse, with no clear dependence on a star's mass or age.

Stars spend the majority of their lives fusing hydrogen into helium deep in their cores. However, the fusion in particularly massive stars is so concentrated at the center that it leads to a turbulent convective core similar to a pot of boiling water. Convection, along with other processes like rotation, effectively removes helium ash from the core and replaces it with hydrogen from the envelope. This enables the stars to live much longer than otherwise predicted.

Astronomers believe this mixing arises from various physical phenomena, like internal rotation and internal seismic waves in the plasma excited by the convecting core. However, the theory has remained largely unconstrained by observations as it occurs so deep within the star. That said, there is an indirect method of peering into stars: asteroseismology, the study and interpretation of stellar oscillations. The technique has parallels to how seismologists use earthquakes to probe the interior of the Earth.

"The study of stellar oscillations challenges our understanding of stellar structure and evolution," Pedersen said. "They allow us to directly probe the stellar interiors and make comparisons to the predictions from our stellar models."

Pedersen and her collaborators from KU Leuven, the University of Hasselt, and the University of Newcastle have been able to derive the internal mixing for an ensemble of such stars using asteroseismology. This is the first time such a feat has been achieved, and was possible thanks only to a new sample of 26 slowly pulsating B-type stars with identified stellar oscillations from NASA's Kepler mission.

Slowly pulsating B-type stars are between three and eight times more massive than the Sun. They expand and contract on time scales of the order of 12 hours to 5 days, and can change in brightness by up to 5%. Their oscillation modes are particularly sensitive to the conditions near the core, Pedersen explained.

"The internal mixing inside stars has now been measured observationally and turns out to be diverse in our sample, with some stars having almost no mixing while others reveal levels a million times higher," Pedersen said. The diversity turns out to be unrelated to the mass or age of the star. Rather, it's primarily influenced by the internal rotation, though that is not the only factor at play.

"These asteroseismic results finally allow astronomers to improve the theory of internal mixing of massive stars, which has so far remained uncalibrated by observations coming straight from their deep interiors," she added.

The precision at which astronomers can measure stellar oscillations depends directly on how long a star is observed. Increasing the time from one night to one year results in a thousand-fold increase in the measured precision of oscillation frequencies.

"May and her collaborators have really shown the value of asteroseismic observations as probes of the deep interiors of stars in a new and profound way," said KITP Director Lars Bildsten, the Gluck Professor of Theoretical Physics. "I am excited to see what she finds next."

The best data currently available for this comes from the Kepler space mission, which observed the same patch of the sky for four continuous years. The slowly pulsating B-type stars were the highest mass pulsating stars that the telescope observed. While most of these are slightly too small to go supernova, they do share the same internal structure as the more massive stellar chemical factories. Pedersen hopes insights gleaned from studying the B type stars will shed light on the inner workings of their higher mass, O type counterparts.

She plans to use data from NASA's Transiting Exoplanet Survey Satellite (TESS) to study groups of oscillating high-mass stars in OB associations. These groups comprise 10 to more than 100 massive stars between 3 and 120 solar masses. Stars in OB associations are born from the same molecular cloud and share similar ages, she explained. The large sample of stars, and constraint from their common ages, provides exciting new opportunities to study the internal mixing properties of high-mass stars.

In addition to unveiling the processes hidden within stellar interiors, research on stellar oscillations can also provide information on other properties of the stars.

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Solar wind from the center of the Earth

High-precision noble gas analyses indicate that solar wind particles from our primordial Sun were encased in the Earth's core over 4.5 billion years ago. Researchers from the Institute of Earth Sciences at Heidelberg University have concluded that the particles made their way into the overlying rock mantle over millions of years. The scientists found solar noble gases in an iron meteorite they studied. Because of their chemical composition, such meteorites are often used as natural models for the Earth's metallic core.

The rare class of iron meteorites make up only five percent of all known meteorite finds on Earth. Most are fragments from inside larger asteroids that formed metallic cores in the first one to two million years of our Solar System. The Washington County iron meteorite now being studied at the Klaus Tschira Laboratory for Cosmochemistry at the Institute of Earth Sciences was found nearly 100 years ago. Its name comes from the location in Colorado (USA) where it was discovered. It resembles a metal discus, is six cm thick, and weighs approx. 5.7 kilograms, according to Prof. Dr Mario Trieloff, head of the Geo- and Cosmochemistry research group.

The researchers were finally able to definitively prove the presence of a solar component in the iron meteorite. Using a noble gas mass spectrometer, they determined that the samples from the Washington County meteorite contain noble gases whose isotopic ratios of helium and neon are typical for the solar wind. According to Dr Manfred Vogt, a member of the Trieloff team, "the measurements had to be extraordinarily accurate and precise to differentiate the solar signatures from the dominant cosmogenic noble gases and atmospheric contamination." The team postulates that solar wind particles in the primordial Solar System were trapped by the precursor materials of the Washington County parent asteroid. The noble gases captured along with the particles were dissolved into the liquid metal from which the asteroid's core formed.

The results of their measurements allowed the Heidelberg researchers to draw a conclusion by analogy that the core of the planet Earth might also contain such noble gas components. Yet another scientific observation supports this assumption. Prof. Trieloff's research group has long been measuring solar noble gas isotopes of helium and neon in igneous rock of oceanic islands like Hawaii and Réunion. These magmatites derive from a special form of volcanism sourced by mantle plumes rising from thousands of kilometres deep in the Earth's mantle. Their particularly high solar gas content makes them fundamentally different from the shallow mantle as represented by volcanic activity of submarine mid-ocean mountain ridges. "We always wondered why such different gas signatures could exist at all in a slowly albeit constantly convecting mantle," states the Heidelberg researcher.

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New research optimizes body's own immune system to fight cancer

A groundbreaking study led by engineering and medical researchers at the University of Minnesota Twin Cities shows how engineered immune cells used in new cancer therapies can overcome physical barriers to allow a patient's own immune system to fight tumors. The research could improve cancer therapies in the future for millions of people worldwide.

The research is published in Nature Communications, a peer-reviewed, open access, scientific journal published by Nature Research.

Instead of using chemicals or radiation, immunotherapy is a type of cancer treatment that helps the patient's immune system fight cancer. T cells are a type of white blood cell that are of key importance to the immune system. Cytotoxic T cells are like soldiers who search out and destroy the targeted invader cells.

While there has been success in using immunotherapy for some types of cancer in the blood or blood-producing organs, a T cell's job is much more difficult in solid tumors.

"The tumor is sort of like an obstacle course, and the T cell has to run the gauntlet to reach the cancer cells," said Paolo Provenzano, the senior author of the study and a biomedical engineering associate professor in the University of Minnesota College of Science and Engineering. "These T cells get into tumors, but they just can't move around well, and they can't go where they need to go before they run out of gas and are exhausted."

In this first-of-its-kind study, the researchers are working to engineer the T cells and develop engineering design criteria to mechanically optimize the cells or make them more "fit" to overcome the barriers. If these immune cells can recognize and get to the cancer cells, then they can destroy the tumor.

In a fibrous mass of a tumor, the stiffness of the tumor causes immune cells to slow down about two-fold -- almost like they are running in quicksand.

"This study is our first publication where we have identified some structural and signaling elements where we can tune these T cells to make them more effective cancer fighters," said Provenzano, a researcher in the University of Minnesota Masonic Cancer Center. "Every 'obstacle course' within a tumor is slightly different, but there are some similarities. After engineering these immune cells, we found that they moved through the tumor almost twice as fast no matter what obstacles were in their way."

To engineer cytotoxic T cells, the authors used advanced gene editing technologies (also called genome editing) to change the DNA of the T cells so they are better able to overcome the tumor's barriers. The ultimate goal is to slow down the cancer cells and speed up the engineered immune cells. The researchers are working to create cells that are good at overcoming different kinds of barriers. When these cells are mixed together, the goal is for groups of immune cells to overcome all the different types of barriers to reach the cancer cells.

Provenzano said the next steps are to continue studying the mechanical properties of the cells to better understand how the immune cells and cancer cells interact. The researchers are currently studying engineered immune cells in rodents and in the future are planning clinical trials in humans.

While initial research has been focused on pancreatic cancer, Provenzano said the techniques they are developing could be used on many types of cancers.

"Using a cell engineering approach to fight cancer is a relatively new field," Provenzano said. "It allows for a very personalized approach with applications for a wide array of cancers. We feel we are expanding a new line of research to look at how our own bodies can fight cancer. This could have a big impact in the future."

In addition to Provenzano, the study's authors included current and former University of Minnesota Department of Biomedical Engineering researchers Erdem D. Tabdanov (co-author), Nelson J. Rodríguez-Merced (co-author), Vikram V. Puram, Mackenzie K. Callaway, and Ethan A. Ensminger; University of Minnesota Masonic Cancer Center and Medical School Department of Pediatrics researchers Emily J. Pomeroy, Kenta Yamamoto, Walker S. Lahr, Beau R. Webber, Branden S. Moriarity; National Institute of Biomedical Imaging and Bioengineering researcher Alexander X. Cartagena-Rivera; and National Heart, Lung, and Blood Institute researcher Alexander S. Zhovmer, who is now at the Center for Biologic Evaluation and Research.

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New ebolavirus vaccine design seeks to drive stronger antibody defense

Scientists at Scripps Research have unveiled a new Ebola virus vaccine design, which they say has several advantages over standard vaccine approaches for Ebola and related viruses that continue to threaten global health.

In the new design, described in a paper in Nature Communications, copies of the Ebola virus outer spike protein, known as the glycoprotein, are tethered to the surface of a spherical carrier particle. The resulting structure resembles the spherical appearance of common RNA viruses that infect humans -- and is starkly different from the snake-like shape of the Ebola virus.

The scientists say the design is intended to stimulate a better protective immune response than standard vaccine approaches, which often expose the immune system to individual glycoproteins rather than realistic-looking virus particles.

In designing the vaccine, the researchers also modified the outer spike protein to be more stable than the normal, "wild-type" version found in actual Ebola virus. In tests in mice and rabbits, they showed that this stabilized version elicited virus-neutralizing antibodies more strongly than the wild-type glycoprotein used in prior Ebola vaccine approaches.

"Here, we did a step-by-step investigation of glycoprotein stability and how that affects the vaccine's ability to elicit antibodies," says Jiang Zhu, PhD, associate professor in the Department of Integrative Structural and Computational Biology at Scripps Research and inventor of the vaccine. "In the end, we were able to develop a really promising vaccine design."

Continued viral threat

Ebola virus is endemic in various African bat species and can jump to humans, causing outbreaks of hemorrhagic fever with high mortality rates. The largest known outbreak of occurred in West Africa during 2013-2016, killing more than 11,000 people.

About two decades ago, Canadian researchers developed a vaccine against Zaire ebolavirus, more commonly known as Ebola virus. The vaccine, which was later licensed to a major pharma company and is called rVSV-ZEBOV, uses a live virus -- vesicular stomatitis virus -- which has been modified to include the gene for the Ebola virus glycoprotein.

When injected, the rVSV-ZEBOV vaccine infects cells and produces copies of the glycoprotein, eliciting an immune response to protect against future exposure to Ebola virus. Tests in Africa amid the aforementioned outbreak suggested it worked well and it was approved by the Food and Drug Administration in late 2019. However, those tests lacked placebo groups and other standard features of typical large-scale phase-III trials. Thus, questions remain on true efficacy.

In developing their new ebolavirus vaccine design, Zhu and his team focused on the relative instability of the glycoprotein structure as a potential factor in vaccine effectiveness. They investigated the molecular sources of this instability in detail, and eventually came up with a set of modifications that greatly stabilize the glycoprotein. In mice and rabbits, their modified glycoprotein elicited a more potent neutralizing antibody response against two different ebolaviruses -- the Makona strain of Ebola virus and the Uganda strain of Bundibugyo ebolavirus -- and compared those with the wild-type glycoprotein.

The team's design also included special protein segments that self-assemble tightly into a ball-shaped "nanoparticle" that support multiple glycoproteins on their surface. This nanoparticle-based structure presents the glycoproteins to the immune system similar to common human viruses, and thus the body has learned to recognize the spherical particles.

"Think of our nanoparticle as your sport vehicle, with a roof rack that carries a mountain bike and a trunk where you stow your clothes, gears and food," Zhu explains. "The only difference here is that the Ebola virus spike is your mountain bike, and the locking domains and T-cell epitopes are your stuff in the trunk. We call that a multilayered design."

A new approach

This nanoparticle design is distinctively different from other nanoparticle platforms. Zhu explains that in his team's design, the genetic codes of the optimized glycoprotein, the nanoparticle-forming unit, the locking domain and the T-cell epitope are all contained in a single piece of DNA. In cells, this DNA generates a single protein chain that can self-assemble, forming the right structure and associating with other identical chains to create a virus-like protein ball with multiple layers.

"The idea is that the all-in-one design simplifies the manufacturing process and drives the vaccine cost lower," Zhu says.

His team already has used the nanoparticle platform to create a COVID-19 vaccine candidate, which has shown in animal models that it can induce a powerful antibody response to both SARS-CoV-1 and SARS-CoV-2. It also has shown to be effective against variants.

For Ebola virus, the nanoparticle-based vaccines showed far better results in mouse and rabbit virus-neutralization tests that tests that used only glycoproteins to stimulate immune response. Inoculating animals with the Ebola wild-type glycoprotein, which tends to fall apart, led to signs suggesting a vaccine phenomenon known as antibody-dependent enhancement -- in which a vaccine elicits not only virus-neutralizing antibodies, but also antibodies that paradoxically increase the virus's ability to infect cells. The researchers found that their best nanoparticle-based designs only minimally elicit these bad antibodies.

"There are a lot of things in the Ebola virus vaccine field that still need to be examined carefully, but in this study, we ended up with two nanoparticle-based designs that seem very suitable for further optimization and testing," Zhu says.

He says the vaccine approach can be extended to other members of the same virus family, such as Marburg virus, which is also a major threat. Ebolaviruses and marburgvirus both belong to a group of viruses, known as filoviruses, that have a bizarre thread-like shape when seen under a microscope.

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Organic meat less likely to be contaminated with multidrug-resistant bacteria

Meat that is certified organic by the U.S. Department of Agriculture is less likely to be contaminated with bacteria that can sicken people, including dangerous, multidrug-resistant organisms, compared to conventionally produced meat, according to a study from researchers at the Johns Hopkins Bloomberg School of Public Health.

The findings highlight the risk for consumers to contract foodborne illness -- contaminated animal products and produce sicken tens of millions of people in the U.S. each year -- and the prevalence of multidrug-resistant organisms that, when they lead to illness, can complicate treatment.

The researchers found that, compared to conventionally processed meats, organic-certified meats were 56 percent less likely to be contaminated with multidrug-resistant bacteria. The study was based on nationwide testing of meats from 2012 to 2017 as part of the U.S. National Antimicrobial Resistance Monitoring System (NARMS).

In order for meat to be certified organic by the USDA, animals can never have been administered antibiotics or hormones, and animal feed and forage such as grass and hay must be 100 percent organic. A longstanding concern about antibiotic use in livestock and livestock feed is the increased prevalence of antibiotic-resistant pathogens. To monitor this trend, in 1996 the federal government developed NARMS to track antibiotic resistance in bacteria isolated from retail meats, farmed animals, and patients with foodborne illness in the U.S.

For their study, the Bloomberg School research team analyzed U.S. Food and Drug Administration-NARMS data from randomly sampled chicken breast, ground beef, ground turkey, and pork for any contamination and for contamination by multidrug-resistant organisms. The analysis covers four types of bacteria: Salmonella, Campylobacter, Enterococcus, and Escherichia coli.

The study covered a total of 39,348 meat samples, of which 1,422 were found to be contaminated with at least one multidrug-resistant organism. The rate of contamination was 4 percent in the conventionally produced meat samples and just under 1 percent in those that were produced organically.

The study was published May 12 in Environmental Health Perspectives.

"The presence of pathogenic bacteria is worrisome in and of itself, considering the possible increased risk of contracting foodborne illness," says senior author Meghan Davis, DVM, PhD, associate professor in the Department of Environmental Health and Engineering at the Bloomberg School. "If infections turn out to be multidrug resistant, they can be more deadly and more costly to treat."

The analysis also suggested that the type of processing facility may influence the likelihood of meat contamination. Meat processors fall into three categories: exclusively organic, exclusively conventional, or those that handle both organic and conventional meats -- so-called "split" processors. The study found that among conventional meats, those processed at facilities that exclusively handled conventional meats were contaminated with bacteria one-third of the time, while those handled at facilities that processed both conventional and organic meats were contaminated one-quarter of the time. The prevalence of multidrug-resistant bacteria was roughly the same in these two meat processor categories.

"The required disinfection of equipment between processing batches of organic and conventional meats may explain our findings of reduced bacterial contamination on products from facilities that process both types of meats," says Davis.

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How smartphones can help detect ecological change

Leipzig/Jena/Ilmenau. Mobile apps like Flora Incognita that allow automated identification of wild plants cannot only identify plant species, but also uncover large scale ecological patterns. These patterns are surprisingly similar to the ones derived from long-term inventory data of the German flora, even though they have been acquired over much shorter time periods and are influenced by user behaviour. This opens up new perspectives for rapid detection of biodiversity changes. These are the key results of a study led by a team of researchers from Central Germany, which has recently been published in Ecography.

With the help of Artificial Intelligence, plant species today can be classified with high accuracy. Smartphone applications leverage this technology to enable users to easily identify plant species in the field, giving laypersons access to biodiversity at their fingertips. Against the backdrop of climate change, habitat loss and land-use change, these applications may serve another use: by gathering information on the locations of identified plant species, valuable datasets are created, potentially providing researchers with information on changing environmental conditions.

But is this information reliable -- as reliable as the information provided by data collected over long time periods? A team of researchers from the German Centre for Integrative Biodiversity Research (iDiv), the Remote Sensing Centre for Earth System Research (RSC4Earth) of Leipzig University (UL) and Helmholtz Centre for Environmental Research (UFZ), the Max Planck Institute for Biogeochemistry (MPI-BGC) and Technical University Ilmenau wanted to find an answer to this question. The researchers analysed data collected with the mobile app Flora Incognita between 2018 and 2019 in Germany and compared it to the FlorKart database of the German Federal Agency for Nature Conservation (BfN). This database contains long-term inventory data collected by over 5,000 floristic experts over a period of more than 70 years.

Mobile app uncovers macroecological patterns in Germany

The researchers report that the Flora Incognita data, collected over only two years, allowed them to uncover macroecological patterns in Germany similar to those derived from long-term inventory data of German flora. The data was therefore also a reflection of the effects of several environmental drivers on the distribution of different plant species.

However, directly comparing the two datasets revealed major differences between the Flora Incognita data and the long-term inventory data in regions with a low human population density. "Of course, how much data is collected in a region strongly depends on the number of smartphone users in that region," said last author Dr. Jana Wäldchen from MPI-BGC, one of the developers of the mobile app. Deviations in the data were therefore more pronounces in rural areas, except for well-known tourist destinations such as the Zugspitze, Germany's highest mountain, or Amrum, an island on the North Sea coast.

User behaviour also influences which plant species are recorded by the mobile app. "The plant observations carried out with the app reflect what users see and what they are interested in," said Jana Wäldchen. Common and conspicuous species were recorded more often than rare and inconspicuous species. Nonetheless, the large quantity of plant observations still allows a reconstruction of familiar biogeographical patterns. For their study, the researchers had access to more than 900,000 data entries created within the first two years after the app had been launched.

Automated species recognition bears great potential

The study shows the potential of this kind of data collection for biodiversity and environmental research, which could soon be integrated in strategies for long-term inventories. "We are convinced that automated species recognition bears much greater potential than previously thought and that it can contribute to a rapid detection of biodiversity changes," said first author Miguel Mahecha, professor at UL and iDiv Member. In the future, a growing number of users of apps like Flora Incognita could help detect and analyse ecosystem changes worldwide in real time.

The Flora Incognita mobile app was developed jointly by the research groups of Dr. Jana Wäldchen at MPI-BGC and the group of Professor Patrick Mäder at TU Ilmenau. It is the first plant identification app in Germany using deep neural networks (deep learning) in this context. Fed by thousands of plant images, that have been identified by experts, it can already identify over 4,800 plant species.

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Study shows how our brains sync hearing with vision

Every high-school physics student learns that sound and light travel at very different speeds. If the brain did not account for this difference, it would be much harder for us to tell where sounds came from, and how they are related to what we see.

Instead, the brain allows us to make better sense of our world by playing tricks, so that a visual and a sound created at the same time are perceived as synchronous, even though they reach the brain and are processed by neural circuits at different speeds.

One of the brain's tricks is temporal recalibration: altering our sense of time to synchronize our joint perception of sound and vision. A new study finds that recalibration depends on brain signals constantly adapting to our environment to sample, order and associate competing sensory inputs together.

Scientists at The Neuro (Montreal Neurological Institute-Hospital) of McGill university recruited volunteers to view short flashes of light paired with sounds with a variety of delays and asked them to report whether they thought both happened at the same time. The participants performed this task inside a magnetoencephalography (MEG) machine, which recorded and imaged their brain waves with millisecond precision. The audio-visual pairs of stimuli changed each time, with sounds and visual objects presented closer or farther apart in time, and with random orders of presentation.

The researchers found that the volunteers' perception of simultaneity between the audio and visual stimuli in a pair was strongly affected by the perceived simultaneity of the stimulus pair before it. For example, if presented with a sound followed by a visual milliseconds apart and perceived as asynchronous, one is much more likely to report the next audio-visual stimulus pair as synchronous, even when it's not. This form of active temporal recalibration is one of the tools used by the brain to avoid a distorted or disconnected perception of reality, and help establish causal relations between the images and sounds we perceive, despite different physical velocities and neural processing speeds.

The MEG signals revealed that this brain feat was enabled by a unique interaction between fast and slow brain waves in auditory and visual brain regions. Slower brain rhythms pace the temporal fluctuations of excitability in brain circuits. The higher the excitability, the easier an external input is registered and processed by receiving neural networks.

Based on this, the researchers propose a new model for understanding recalibration, whereby faster oscillations riding on top of slower fluctuations create discrete and ordered time slots to register the order of sensory inputs. For example, when an audio signal reaches the first available time slot in the auditory cortex and so does a visual input, the pair is perceived as simultaneous. For this to happen, the brain needs to position the visual time slots a bit later than the auditory ones to account for the slower physiological transduction of visual signals. The researchers found that this relative delay between neural auditory and visual time slots is a dynamic process that constantly adapts to each participant's recent exposure to audiovisual perception.

Their data confirmed the new dynamic integration model by showing how these subtle tens-of-millisecond delays of fast brain oscillations can be measured in every individual and explain their respective judgments of perceived simultaneity.

In autism and speech disorders, the processing of the senses, especially hearing, is altered. In schizophrenia as well, patients can be affected by perceived distortions of sensory inputs. The neurophysiological mechanisms of temporal recalibration described in this study may be altered in these disorders, and their discovery may reveal new research goals to improve these deficits.

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What does your voice say about you?

Everyone has at some point been charmed by the sound of a person's voice: but can we believe our ears? What can a voice really reveal about our character? Now an international research team led by the University of Göttingen has shown that people seem to express at least some aspects of their personality with their voice. The researchers discovered that a lower pitched voice is associated with individuals who are more dominant, extrovert and higher in sociosexuality (more interested in casual sex). The findings were true for women as well as for men. The results were published in the Journal of Research in Personality.

The researchers analysed data from over 2,000 participants and included information from four different countries. Participants filled in questionnaires about themselves to measure personality and provided recordings of their voice so that the pitch could be measured using a computer programme. This is the first time that an objective digital measure of voice pitch has been used in a study of this kind, rather than subjective ratings of how "high" or "deep" a voice might sound. The researchers measured "sociosexuality" by collecting responses about sexual behaviour, attitude and desire. They also collected data to provide ratings of dominance and other character traits such as neuroticism, extraversion, openness to experience, agreeableness and conscientiousness. The number of participants helps to confirm the robustness of the findings: the study involves the largest number to date compared to similar research in this theme.

The researchers found that people with lower pitched voices were more dominant, extroverted and higher in sociosexuality (eg were more interested in sex outside a relationship). However, the relationship between voice pitch and other personality traits (such as agreeableness, neuroticism, conscientiousness or openness) seems less clear. It is possible that these traits are not expressed in the pitch of voices. The researchers found no difference between men and women.

"People's voices can make a huge and immediate impression on us," explains Dr Julia Stern, at the University of Göttingen's Biological Personality Psychology Group. "Even if we just hear someone's voice without any visual clues -- for instance on the phone -- we know pretty soon whether we're talking to a man, a woman, a child or an older person. We can pick up on whether the person sounds interested, friendly, sad, nervous, or whether they have an attractive voice. We also start to make assumptions about trust and dominance." This led Stern to question whether these assumptions were justified. "The first step was to investigate whether voices are, indeed, related to people's personality. And our results suggest that people do seem to express some aspects of their personality with their voice."

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