ApertureData, a company at the forefront of multimodal AI data management, has raised $8.25 million in an oversubscribed seed round to drive the development and expansion of its groundbreaking platform, ApertureDB. The round was led by TQ Ventures with participation from Westwave Capital, Interwoven Ventures, and…
The way sensory prediction changes under anesthesia tells us how conscious cognition works
Our brains constantly work to make predictions about what’s going on around us to ensure that we can attend to and consider the unexpected, for instance. A new study examines how this works during consciousness and also breaks down under general anesthesia. The results add evidence to the idea that conscious thought requires synchronized communication — mediated by brain rhythms in specific frequency bands — between basic sensory and higher-order cognitive regions of the brain.
Previously, members of the research team in The Picower Institute for Learning and Memory at MIT and at Vanderbilt University had described how brain rhythms enable the brain to remain prepared to attend to surprises. Cognition-oriented brain regions (generally at the front of the brain) use relatively low-frequency alpha and beta rhythms to suppress processing by sensory regions (generally toward the back of the brain) of stimuli that have become familiar and mundane in the environment (e.g., your co-worker’s music). When sensory regions detect a surprise (e.g., the office fire alarm), they use faster-frequency gamma rhythms to tell the higher regions about it, and the higher regions process that at gamma frequencies to decide what to do (e.g., exit the building).
The new results, published Oct. 7 in the Proceedings of the National Academy of Sciences, show that when animals were under propofol-induced general anesthesia, a sensory region retained the capacity to detect simple surprises but communication with a higher cognitive region toward the front of the brain was lost, making that region unable to engage in its “top-down” regulation of the activity of the sensory region and keeping it oblivious to simple and more complex surprises alike.
What we’ve got here is failure to communicate
“What we are doing here speaks to the nature of consciousness,” says co-senior author Earl K. Miller, Picower Professor in The Picower Institute for Learning and Memory and MIT’s Department of Brain and Cognitive Sciences. “Propofol general anesthesia deactivates the top-down processes that that underlie cognition. It essentially disconnects communication between the front and back halves of the brain.”
Co-senior author Andre Bastos, an assistant professor in the psychology department at Vanderbilt and a former member of Miller’s MIT lab, adds that the study results highlight the key role of frontal areas in consciousness.
“These results are particularly important given the newfound scientific interest in the mechanisms of consciousness, and how consciousness relates to the ability of the brain to form predictions,” Bastos says.
The brain’s ability to predict is dramatically altered during anesthesia. It was interesting that the front of the brain, areas associated with cognition, were more strongly diminished in their predictive abilities than sensory areas. This suggests that prefrontal areas help to spark an “ignition” event that allows sensory information to become conscious. Sensory cortex activation by itself does not lead to conscious perception. These observations help us narrow down possible models for the mechanisms of consciousness.
Yihan Sophy Xiong, a graduate student in Bastos’ lab who led the study, says the anesthetic reduces the times in which inter-regional communication within the cortex can occur.
“In the awake brain, brain waves give short windows of opportunity for neurons to fire optimally — the ‘refresh rate’ of the brain, so to speak,” Xiong says. “This refresh rate helps organize different brain areas to communicate effectively. Anesthesia both slows down the refresh rate, which narrows these time windows for brain areas to talk to each other and makes the refresh rate less effective, so that neurons become more disorganized about when they can fire. When the refresh rate no longer works as intended, our ability to make predictions is weakened.”
Learning from oddballs
To conduct the research, the neuroscientists measured the electrical signals, “or spiking,” of hundreds of individual neurons and the coordinated rhythms of their aggregated activity (at alpha/beta and gamma frequencies), in two areas on the surface, or cortex, of the brain of two animals as they listened to sequences of tones. Sometimes the sequences would all be the same note (e.g., AAAAA). Sometimes there’d be a simple surprise that the researchers called a “local oddball” (e.g., AAAAB). But sometimes the surprise would be more complicated, or a “global oddball.” For example, after seeing a series of AAAABs, there’d all of a sudden be AAAAA, which violates the global but not the local pattern.
Prior work has suggested that a sensory region (in this case the temporoparietal area, or Tpt) can spot local oddballs on its own, Miller says. Detecting the more complicated global oddball requires the participation of a higher order region (in this case the frontal eye fields, or FEF).
The animals heard the tone sequences both while awake and while under propofol anesthesia. There were no surprises about the waking state. The researchers reaffirmed that top-down alpha/beta rhythms from FEF carried predictions to the Tpt and that Tpt would increase gamma rhythms when an oddball came up, causing FEF (and the prefrontal cortex) to respond with upticks of gamma activity as well.
But by several measures and analyses, the scientists could see these dynamics break down after the animals lost consciousness.
Under propofol, for instance, spiking activity declined overall but when a local oddball came along, Tpt spiking still increased notably but now spiking in FEF didn’t follow suit as it does during wakefulness.
Meanwhile, when a global oddball was presented during wakefulness, the researchers could use software to “decode” representation of that among neurons in FEF and the prefrontal cortex (another cognition-oriented region). They could also decode local oddballs in the Tpt. But under anesthesia the decoder could no longer reliably detect representation of local or global oddballs in FEF or the prefrontal cortex.
Moreover, when they compared rhythms in the regions amid wakeful versus unconscious states they found stark differences. When the animals were awake, oddballs increased gamma activity in both Tpt and FEF and alpha/beta rhythms decreased. Regular, non-oddball stimulation increased alpha/beta rhythms. But when the animals lost consciousness the increase in gamma rhythms from a local oddball was even greater in Tpt than when the animal was awake.
“Under propofol-mediated loss of consciousness, the inhibitory function of alpha/beta became diminished and/or eliminated, leading to disinhibition of oddballs in sensory cortex,” the authors wrote.
Other analyses of inter-region connectivity and synchrony revealed that the regions lost the ability to communicate during anesthesia.
In all, the study’s evidence suggests that conscious thought requires coordination across the cortex, from front to back, the researchers wrote.
“Our results therefore suggest an important role for prefrontal cortex activation, in addition to sensory cortex activation, for conscious perception,” the researchers wrote.
In addition to Xiong, Miller, and Bastos, the paper’s other authors are Jacob Donoghue, Mikael Lundqvist, Meredith Mahnke, Alex Major, and Emery N. Brown.
The National Institutes of Health, The JPB Foundation, and The Picower Institute for Learning and Memory funded the study.
Mixing joy and resolve, event celebrates women in science and addresses persistent inequalities
For two days at The Picower Institute for Learning and Memory at MIT, participants in the Kuggie Vallee Distinguished Lectures and Workshops celebrated the success of women in science and shared strategies to persist through, or better yet dissipate, the stiff headwinds women still face in the field.
“Everyone is here to celebrate and to inspire and advance the accomplishments of all women in science,” said host Li-Huei Tsai, Picower Professor in the Department of Brain and Cognitive Sciences and director of the Picower Institute, as she welcomed an audience that included scores of students, postdocs, and other research trainees. “It is a great feeling to have the opportunity to showcase examples of our successes and to help lift up the next generation.”
Tsai earned the honor of hosting the event after she was named a Vallee Visiting Professor in 2022 by the Vallee Foundation. Foundation president Peter Howley, a professor of pathological anatomy at Harvard University, said the global series of lectureships and workshops were created to honor Kuggie Vallee, a former Lesley College professor who worked to advance the careers of women.
During the program Sept. 24-25, speakers and audience members alike made it clear that helping women succeed requires both recognizing their achievements and resolving to change social structures in which they face marginalization.
Inspiring achievements
Lectures on the first day featured two brain scientists who have each led acclaimed discoveries that have been transforming their fields.
Michelle Monje, a pediatric neuro-oncologist at Stanford University whose recognitions include a MacArthur Fellowship, described her lab’s studies of brain cancers in children, which emerge at specific times in development as young brains adapt to their world by wiring up new circuits and insulating neurons with a fatty sheathing called myelin. Monje has discovered that when the precursors to myelinating cells, called oligodendrocyte precursor cells, harbor cancerous mutations, the tumors that arise — called gliomas — can hijack those cellular and molecular mechanisms. To promote their own growth, gliomas tap directly into the electrical activity of neural circuits by forging functional neuron-to-cancer connections, akin to the “synapse” junctions healthy neurons make with each other. Years of her lab’s studies, often led by female trainees, have not only revealed this insidious behavior (and linked aberrant myelination to many other diseases as well), but also revealed specific molecular factors involved. Those findings, Monje said, present completely novel potential avenues for therapeutic intervention.
“This cancer is an electrically active tissue and that is not how we have been approaching understanding it,” she said.
Photo: David Orenstein/Picower Institute
Previous item
Erin Schuman, who directs the Max Planck Institute for Brain Research in Frankfurt, Germany, and has won honors including the Brain Prize, described her groundbreaking discoveries related to how neurons form and edit synapses along the very long branches — axons and dendrites — that give the cells their exotic shapes. Synapses form very far from the cell body where scientists had long thought all proteins, including those needed for synapse structure and activity, must be made. In the mid-1990s, Schuman showed that the protein-making process can occur at the synapse and that neurons stage the needed infrastructure — mRNA and ribosomes — near those sites. Her lab has continued to develop innovative tools to build on that insight, cataloging the stunning array of thousands of mRNAs involved, including about 800 that are primarily translated at the synapse, studying the diversity of synapses that arise from that collection, and imaging individual ribosomes such that her lab can detect when they are actively making proteins in synaptic neighborhoods.
Persistent headwinds
While the first day’s lectures showcased examples of women’s success, the second day’s workshops turned the spotlight on the social and systemic hindrances that continue to make such achievements an uphill climb. Speakers and audience members engaged in frank dialogues aimed at calling out those barriers, overcoming them, and dismantling them.
Susan Silbey, the Leon and Anne Goldberg Professor of Humanities, Sociology and Anthropology at MIT and professor of behavioral and policy sciences in the MIT Sloan School of Management, told the group that as bad as sexual harassment and assault in the workplace are, the more pervasive, damaging, and persistent headwinds for women across a variety of professions are “deeply sedimented cultural habits” that marginalize their expertise and contributions in workplaces, rendering them invisible to male counterparts, even when they are in powerful positions. High-ranking women in Silicon Valley who answered the “Elephant in the Valley” survey, for instance, reported high rates of many demeaning comments and demeanor, as well as exclusion from social circles. Even U.S. Supreme Court justices are not immune, she noted, citing research showing that for decades female justices have been interrupted with disproportionate frequency during oral arguments at the court. Silbey’s research has shown that young women entering the engineering workforce often become discouraged by a system that appears meritocratic, but in which they are often excluded from opportunities to demonstrate or be credited for that merit and are paid significantly less.
“Women’s occupational inequality is a consequence of being ignored, having contributions overlooked or appropriated, of being assigned to lower-status roles, while men are pushed ahead, honored and celebrated, often on the basis of women’s work,” Silbey said.
Often relatively small in numbers, women in such workplaces become tokens — visible as different, but still treated as outsiders, Silbey said. Women tend to internalize this status, becoming very cautious about their work while some men surge ahead in more cavalier fashion. Silbey and speakers who followed illustrated the effect this can have on women’s careers in science. Kara McKinley, an assistant professor of stem cell and regenerative biology at Harvard, noted that while the scientific career “pipeline” in some areas of science is full of female graduate students and postdocs, only about 20 percent of natural sciences faculty positions are held by women. Strikingly, women are already significantly depleted in the applicant pools for assistant professor positions, she said. Those who do apply tend to wait until they are more qualified than the men they are competing against.
McKinley and Silbey each noted that women scientists submit fewer papers to prestigious journals, with Silbey explaining that it’s often because women are more likely to worry that their studies need to tie up every loose end. Yet, said Stacie Weninger, a venture capitalist and president of the F-Prime Biomedical Research Initiative and a former editor at Cell Press, women were also less likely than men to rebut rejections from journal editors, thereby accepting the rejection even though rebuttals sometimes work.
Photo: David Orenstein/Picower Institute
Previous item
Several speakers, including Weninger and Silbey, said pedagogy must change to help women overcome a social tendency to couch their assertions in caveats when many men speak with confidence and are therefore perceived as more knowledgeable.
At lunch, trainees sat in small groups with the speakers. They shared sometimes harrowing personal stories of gender-related difficulties in their young careers and sought advice on how to persist and remain resilient. Schuman advised the trainees to report mistreatment, even if they aren’t confident that university officials will be able to effect change, to at least make sure patterns of mistreatment get on the record. Reflecting on discouraging comments she experienced early in her career, Monje advised students to build up and maintain an inner voice of confidence and draw upon it when criticism is unfair.
“It feels terrible in the moment, but cream rises,” Monje said. “Believe in yourself. It will be OK in the end.”
Lifting each other up
Speakers at the conference shared many ideas to help overcome inequalities. McKinley described a program she launched in 2020 to ensure that a diversity of well-qualified women and non-binary postdocs are recruited for, and apply for, life sciences faculty jobs: the Leading Edge Symposium. The program identifies and names fellows — 200 so far — and provides career mentoring advice, a supportive community, and a platform to ensure they are visible to recruiters. Since the program began, 99 of the fellows have gone on to accept faculty positions at various institutions.
In a talk tracing the arc of her career, Weninger, who trained as a neuroscientist at Harvard, said she left bench work for a job as an editor because she wanted to enjoy the breadth of science, but also noted that her postdoc salary didn’t even cover the cost of child care. She left Cell Press in 2005 to help lead a task force on women in science that Harvard formed in the wake of comments by then-president Lawrence Summers widely understood as suggesting that women lacked “natural ability” in science and engineering. Working feverishly for months, the task force recommended steps to increase the number of senior women in science, including providing financial support for researchers who were also caregivers at home so they’d have the money to hire a technician. That extra set of hands would afford them the flexibility to keep research running even as they also attended to their families. Notably, Monje said she does this for the postdocs in her lab.
Photo: David Orenstein/Picower Institute
Previous item
A graduate student asked Silbey at the end of her talk how to change a culture in which traditionally male-oriented norms marginalize women. Silbey said it starts with calling out those norms and recognizing that they are the issue, rather than increasing women’s representation in, or asking them to adapt to, existing systems.
“To make change, it requires that you do recognize the differences of the experiences and not try to make women exactly like men, or continue the past practices and think, ‘Oh, we just have to add women into it’,” she said.
Silbey also praised the Kuggie Vallee event at MIT for assembling a new community around these issues. Women in science need more social networks where they can exchange information and resources, she said.
“This is where an organ, an event like this, is an example of making just that kind of change: women making new networks for women,” she said.
Using JPEG Compression to Improve Neural Network Training
A new research paper from Canada has proposed a framework that deliberately introduces JPEG compression into the training scheme of a neural network, and manages to obtain better results – and better resistance to adversarial attacks. This is a fairly radical idea, since the current general…
Competition Law as a tool for promoting AI innovation in the USA
USA leads in AI with the National AI Initiative Act and AI Bill of Rights, ensuring secure and ethical development….
China Telecom trains AI model with 1 trillion parameters on domestic chips
China Telecom, one of the country’s state-owned telecom giants, has created two LLMs that were trained solely on domestically-produced chips. This breakthrough represents a significant step in China’s ongoing efforts to become self-reliant in AI technology, especially in light of escalating US limitations on access to…
Many organisations unprepared for AI cybersecurity threats
While AI improves the detection of cybersecurity threats, it simultaneously ushers in more advanced challenges. Research from Keeper Security finds that, despite the implementation of AI-related policies, many organisations remain inadequately prepared for AI-powered threats. 84% of IT and security leaders find AI-enhanced tools have exacerbated…
10 Best AI Cover Letter Generators (October 2024)
Artificial Intelligence is being integrated throughout the job application process, and cover letters are no exception. As these documents remain crucial for showcasing personality and fit, AI-powered generators are emerging as valuable tools. These tools leverage advanced algorithms to create personalized, ATS-friendly cover letters in minutes,…
New 3D printing technique creates unique objects quickly and with less waste
Multimaterial 3D printing enables makers to fabricate customized devices with multiple colors and varied textures. But the process can be time-consuming and wasteful because existing 3D printers must switch between multiple nozzles, often discarding one material before they can start depositing another.
Researchers from MIT and Delft University of Technology have now introduced a more efficient, less wasteful, and higher-precision technique that leverages heat-responsive materials to print objects that have multiple colors, shades, and textures in one step.
Their method, called speed-modulated ironing, utilizes a dual-nozzle 3D printer. The first nozzle deposits a heat-responsive filament and the second nozzle passes over the printed material to activate certain responses, such as changes in opacity or coarseness, using heat.
By controlling the speed of the second nozzle, the researchers can heat the material to specific temperatures, finely tuning the color, shade, and roughness of the heat-responsive filaments. Importantly, this method does not require any hardware modifications.
The researchers developed a model that predicts the amount of heat the “ironing” nozzle will transfer to the material based on its speed. They used this model as the foundation for a user interface that automatically generates printing instructions which achieve color, shade, and texture specifications.
One could use speed-modulated ironing to create artistic effects by varying the color on a printed object. The technique could also produce textured handles that would be easier to grasp for individuals with weakness in their hands.
“Today, we have desktop printers that use a smart combination of a few inks to generate a range of shades and textures. We want to be able to do the same thing with a 3D printer — use a limited set of materials to create a much more diverse set of characteristics for 3D-printed objects,” says Mustafa Doğa Doğan PhD ’24, co-author of a paper on speed-modulated ironing.
This project is a collaboration between the research groups of Zjenja Doubrovski, assistant professor at TU Delft, and Stefanie Mueller, the TIBCO Career Development Professor in the Department of Electrical Engineering and Computer Science (EECS) at MIT and a member of the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL). Doğan worked closely with lead author Mehmet Ozdemir of TU Delft; Marwa AlAlawi, a mechanical engineering graduate student at MIT; and Jose Martinez Castro of TU Delft. The research will be presented at the ACM Symposium on User Interface Software and Technology.
Modulating speed to control temperature
The researchers launched the project to explore better ways to achieve multiproperty 3D printing with a single material. The use of heat-responsive filaments was promising, but most existing methods use a single nozzle to do printing and heating. The printer always needs to first heat the nozzle to the desired target temperature before depositing the material.
However, heating and cooling the nozzle takes a long time, and there is a danger that the filament in the nozzle might degrade as it reaches higher temperatures.
To prevent these problems, the team developed an ironing technique where material is printed using one nozzle, then activated by a second, empty nozzle which only reheats it. Instead of adjusting the temperature to trigger the material response, the researchers keep the temperature of the second nozzle constant and vary the speed at which it moves over the printed material, slightly touching the top of the layer.
“As we modulate the speed, that allows the printed layer we are ironing to reach different temperatures. It is similar to what happens if you move your finger over a flame. If you move it quickly, you might not be burned, but if you drag it across the flame slowly, your finger will reach a higher temperature,” AlAlawi says.
The MIT team collaborated with the TU Delft researchers to develop the theoretical model that predicts how fast the second nozzle must move to heat the material to a specific temperature.
The model correlates a material’s output temperature with its heat-responsive properties to determine the exact nozzle speed which will achieve certain colors, shades, or textures in the printed object.
“There are a lot of inputs that can affect the results we get. We are modeling something that is very complicated, but we also want to make sure the results are fine-grained,” AlAlawi says.
The team dug into scientific literature to determine proper heat transfer coefficients for a set of unique materials, which they built into their model. They also had to contend with an array of unpredictable variables, such as heat that may be dissipated by fans and the air temperature in the room where the object is being printed.
They incorporated the model into a user-friendly interface that simplifies the scientific process, automatically translating the pixels in a maker’s 3D model into a set of machine instructions that control the speed at which the object is printed and ironed by the dual nozzles.
Faster, finer fabrication
They tested their approach with three heat-responsive filaments. The first, a foaming polymer with particles that expand as they are heated, yields different shades, translucencies, and textures. They also experimented with a filament filled with wood fibers and one with cork fibers, both of which can be charred to produce increasingly darker shades.
The researchers demonstrated how their method could produce objects like water bottles that are partially translucent. To make the water bottles, they ironed the foaming polymer at low speeds to create opaque regions and higher speeds to create translucent ones. They also utilized the foaming polymer to fabricate a bike handle with varied roughness to improve a rider’s grip.
Trying to produce similar objects using traditional multimaterial 3D printing took far more time, sometimes adding hours to the printing process, and consumed more energy and material. In addition, speed-modulated ironing could produce fine-grained shade and texture gradients that other methods could not achieve.
In the future, the researchers want to experiment with other thermally responsive materials, such as plastics. They also hope to explore the use of speed-modulated ironing to modify the mechanical and acoustic properties of certain materials.