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Brain waves guide us in spotlighting surprises -- ScienceDaily
By measuring thousands of neurons along the surface, or cortex, of the brain in animals as they reacted to predictable and surprising images, the researchers observed that low frequency alpha and beta brain waves, or rhythms, originating in the brain's frontal cognitive regions tamped down neural activity associated with predictable stimuli. That paved the way for neurons in sensory regions in the back of the brain to push forward information associated with unexpected stimuli via higher-frequency gamma waves. The backflow of alpha/beta carrying inhibitory predictions typically channeled through deeper layers of the cortex, while the forward flow of excitatory gamma carrying novel stimuli propagated across superficial layers.
Could consciousness all come down to the way things vibrate?
The central thesis of our approach is this: the particular linkages that allow for large-scale consciousness – like those humans and other mammals enjoy – result from a shared resonance among many smaller constituents. The speed of the resonant waves that are present is the limiting factor that determines the size of each conscious entity in each moment.
As a particular shared resonance expands to more and more constituents, the new conscious entity that results from this resonance and combination grows larger and more complex. So the shared resonance in a human brain that achieves gamma synchrony, for example, includes a far larger number of neurons and neuronal connections than is the case for beta or theta rhythms alone.
What about larger inter-organism resonance like the cloud of fireflies with their little lights flashing in sync? Researchers think their bioluminescent resonance arises due to internal biological oscillators that automatically result in each firefly syncing up with its neighbors.
Could consciousness all come down to the way things vibrate?
Gamma waves are associated with large-scale coordinated activities like perception, meditation or focused consciousness; beta with maximum brain activity or arousal; and theta with relaxation or daydreaming. These three wave types work together to produce, or at least facilitate, various types of human consciousness, according to Fries. But the exact relationship between electrical brain waves and consciousness is still very much up for debate.
Fries calls his concept “communication through coherence.” For him, it’s all about neuronal synchronization. Synchronization, in terms of shared electrical oscillation rates, allows for smooth communication between neurons and groups of neurons. Without this kind of synchronized coherence, inputs arrive at random phases of the neuron excitability cycle and are ineffective, or at least much less effective, in communication.
An Amygdala-Hippocampus Subnetwork that Encodes Variation in Human Mood: Cell
The most common subnetwork, found in 13 of 21 subjects, was characterized by β-frequency coherence (13-30 Hz) between the amygdala and hippocampus. Increased variability of this subnetwork correlated with worsening mood across these 13 subjects. Moreover, these subjects had significantly higher trait anxiety than the 8 of 21 for whom this amygdala-hippocampus subnetwork was absent.
Neurons get the beat and keep it going in drumrolls -- ScienceDaily
The researchers recorded the activities of individual neurons in the hippocampus, which is located in the lower center of the brain, with a robotic device called a patch clamp. It's a hollow glass needle one micron in diameter that latches onto a single neuron via suction and measures its electrical activity.
The researchers observed electrical rumblings, symbolized here by a drumroll. And they observed spikes, symbolized here by a cymbal crash.
Though the pattern of rumblings wasn't uniform, it rose and fell like a drumroll undulating between softer and louder volumes. Spikes occurred much more rarely than drumbeats, but with notable timing.
"The spikes repeated in the same spots with high precision, so they weren't just random," Singer said. "They came around the peaks of rumblings, not always right on top of a peak but within a hair of it."
It would be like a cymbal crash hitting not every time, but every few times the undulating drumroll topped a volume peak. And the drumroll-cymbal-crash patterns sustained themselves for surprisingly long periods.
"The time periods of activity that was structured like this were much longer than we expected," Singer said. "People have shown sustained periods of signaling like this for 100 to 300 milliseconds before, but this appears to be the first time it's been seen for 900 milliseconds (nearly a full second), and it may go on even longer."
The brain's spontaneous activity and its psychopathological symptoms - "Spatiotemporal binding and integration". - PubMed - NCBI
I here suggest to conceive the brain's spontaneous activity in spatiotemporal terms that is, by various mechanisms that are based on its spatial, i.e., functional connectivity, and temporal, i.e., fluctuations in different frequencies, features. I here point out two such spatiotemporal mechanisms, i.e., "spatiotemporal binding and integration". Alterations in the resting state's spatial and temporal features lead to abnormal "spatiotemporal binding and integration" which results in abnormal contents in cognition as in the various psychopathological symptoms. This, together with concrete empirical evidence, is demonstrated in depression and schizophrenia.
Details of information processing in the brain revealed: New research shows that, when focused, we process information continuously, rather in waves as previously thought -- ScienceDaily
Our brains oscillate at many different frequencies, explains Mathewson, and each frequency has a different role.
"This study examined 12 hertz alpha oscillations, a mechanisms used to inhibit, or ignore, a certain stimulus thereby allowing us to focus on a particular time or space that we are experiencing, while ignoring others," says Mathewson.
For example, if there is a repetitive stimulus in the world, such as the sound of someone's voice in a lecture theatre, the alpha waves lock onto the timing of that stimulus, and the brain becomes better at processing things that occur in time with that stimulus. The new findings show, surprisingly, that this happens more in places we are ignoring.
"We are bombarded with so much information and stimulation that we can't possibly process it all at once. Whether it be commuting, engaging in our work, studying for a class, or working out, our brains select the useful information and ignore the rest, so that we can focus on a single or a few items in order to make appropriate responses in the world. This research helps explain how," says Mathewson.
Portions of the brain fall asleep and wake back up all the time, Stanford researchers find | EurekAlert! Science News
The team used what amounts to sets of very sensitive pins that can record activity from a column of neurons in the brain. In the past, people had known that individual neurons go through phases of being more or less active, but with this probe they saw for the first time that all the neurons in a given column cycled together between firing very rapidly then firing at a much slower rate, similar to coordinated cycles in sleep.
"During an on state the neurons all start firing rapidly," said Kwabena Boahen, a professor of bioengineering and electrical engineering at Stanford and a senior author on the paper. "Then all of a sudden they just switch to a low firing rate. This on and off switching is happening all the time, as if the neurons are flipping a coin to decide if they are going to be on or off."
Those cycles, which occur on the order of seconds or fractions of seconds, weren't as visible when awake because the wave doesn't propagate much beyond that column, unlike in sleep when the wave spreads across almost the entire brain and is easy to detect.
Kelly Clancy on the Logic Behind the Myth That We Only Use 10 Percent of Our Brains
Over the past 15 years scientists have begun to amass evidence that these brain waves play an active role in information processing, shunting some neural inputs while enhancing others, for example, or altering the timing of spikes. This suggests that spikes are not the sole information-carrying signal in the brain, and that, in turn, the “inactive” neurons are doing much more than it seems.
Fluid immortality, a poem by Robert Krulwich
When the storm passes, you'd think the water would calm, settle and return to a quiet equilibrium, but the energy, oddly, doesn't dissipate. The storm has become a wave that now lives in a patch of sea, moving along with no need for a push from above. It is, says Pretor-Pinney, what scientists call a "free wave," no longer driven by wind (those are "forced waves"). Now it is a moving bit of history, an old sea storm moving on, free to roam. It has become a "swell."
