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Jun 25, 2024
Neuronal representation of visual working memory content in the primate primary visual cortex
Posted by Dan Breeden in categories: materials, neuroscience
To capture a broader understanding of memory encoding, we expanded our experiments to include two other stimulus types: colors and face pictures (see Materials and Methods). Both monkeys demonstrated high accuracy in memorizing grating orientations in the “orientation DMTS” task, colors in the “color DMTS” task, and face pictures in the “face DMTS” task [DP: ~94% and DQ: ~87% versus 50%, all P < 0.01 (one-sample t test)] (fig. S1), indicating that they had been well trained.
We implanted a Utah array in each monkey’s V1 area (see Materials and Methods; Fig. 1B) and presented the stimuli onto the receptive field (RF) centers of the recorded neurons (fig. S2, A and D). This enabled simultaneous monitoring of neuronal activity in our experiments. Our analyses focused primarily on neuronal activity before probe stimulus onset.
Representative neuronal responses for two of the VWM content conditions in the orientation DMTS task at a selected electrode are shown in Fig. 1C. During the stimulus period (0 to 200 ms after cue onset), neurons displayed distinct firing patterns between the two content conditions (90° or 180° orientation). An off-response emerged following the cue offset, and activity gradually diminished. During the delay period, defined as 700 to 1,700 ms after cue onset (the thick gray line in Fig. 1C), neurons also exhibited a significant difference in firing rate between the two content conditions (N = 1,810 trials for 90°; N = 1,865 trials for 180°; all marked positions P < 0.01) without any behavioral performance bias (N = 16 sessions, P = 0.94; right panel in Fig. 1C). The difference in response between these two content conditions during the delay period at the same electrode was less prominent in incorrect-response trials and in the fixation task (Fig. 1D).
Jun 25, 2024
Is there a second arrow of time? New research says yes
Posted by Paul Battista in category: futurism
“We could be wrong. But if we are right, it’s profoundly important.” Leading mineralogist Dr. Robert Hazen on the missing law of nature that could explain why life emerges.
Jun 25, 2024
The Universe’s Biggest Explosions made Elements we are Composed of, but there’s Another Mystery Source out there
Posted by Natalie Chan in categories: chemistry, cosmology, nuclear energy, particle physics
After its “birth” in the Big Bang, the universe consisted mainly of hydrogen and a few helium atoms. These are the lightest elements in the periodic table. More-or-less all elements heavier than helium were produced in the 13.8 billion years between the Big Bang and the present day.
Stars have produced many of these heavier elements through the process of nuclear fusion. However, this only makes elements as heavy as iron. The creation of any heavier elements would consume energy instead of releasing it.
In order to explain the presence of these heavier elements today, it’s necessary to find phenomena that can produce them. One type of event that fits the bill is a gamma-ray burst (GRB)—the most powerful class of explosion in the universe. These can erupt with a quintillion (10 followed by 18 zeros) times the luminosity of our sun, and are thought to be caused by several types of event.
Jun 25, 2024
| Proceedings of the National Academy of Sciences
Posted by Dan Breeden in categories: biological, climatology, physics, robotics/AI, sustainability
Physics meets machine learning.
The Progress and Promise for Science in Indonesia Regional Special Feature focuses on biodiversity and climate change, highlighting research based on the unique geology and biology of a nation comprising more than 17,600 islands, containing about 10 percent of the world’s remaining tropical forests, and home to over 300,000 species of wildlife.
Jun 25, 2024
A mature quasar at cosmic dawn revealed by JWST rest-frame infrared spectroscopy
Posted by Dan Breeden in category: cosmology
A JWST/MIRI spectrum of an early quasar in the mid-infrared indicates that J1120+0641 had a mature feeding structure 760 Myr after the Big Bang. This finding suggests that supermassive black holes and their torii build up surprisingly quickly.
Jun 25, 2024
Skin-inspired soft bioelectronic materials, devices and systems
Posted by Dan Breeden in categories: biotech/medical, wearables
Soft bioelectronic devices are made from polymer-based and hybrid electronic materials that form natural interfaces with the human body. In this Review, the authors present recent developments in soft bioelectronic sensors and actuators, and discuss system-level integration for wearable and implantable medical applications.
Jun 25, 2024
Engineering brain-on-a-chip platforms
Posted by Dan Breeden in categories: engineering, neuroscience
Brain-on-a-chip models, mimicking brain physiology, hold promise for developing treatments for neurological disorders. This Review discusses the engineering challenges and opportunities for these devices, including the integration of 3D cell cultures and electrodes and scaffold engineering strategies.
Heat facilitates electrical resistance switching in Mott insulators and can synergistically enhance neuromorphic computing.
Jun 25, 2024
A high-performance deep reservoir computer experimentally demonstrated with ion-gating reservoirs
Posted by Dan Breeden in categories: computing, neuroscience
Daiki Nishioka and colleagues show a nanodevice implementation of deep reservoir computing using an ion-gating reservoir, achieving record-low error rates on a complex computational task. This device is more efficient and scalable for brain-like computing systems exploiting physical systems.