Amélie Doesn’t Have A Boyfriend. She Tried Once Or Twice, But The Results Were A Let-down. Instead,

How to Beam ➝ Noemi Makra Style

Fricken heartbreaking.

It’s about time we put that perfectly good food to use rather than let it go to waste (x) | follow @the-future-now

David Silverman ‏@tubatron

1st appearance of Milhouse in 1st Butterfinger storyboard 11/18/1988 (missed the anni thing by a few weeks – )

There is a time when it is necessary to abandon the used clothes, which already have the shape of our body and to forget our paths, which takes us always to the same places. This is the time to cross the river: and if we don’t dare to do it, we will have stayed, forever beneath ourselves

Fernando Pessoa (via paizleyrayz)

Whistler, Canada

Finding Your Way Around in an Uncertain World

Suppose you woke up in your bedroom with the lights off and wanted to get out. While heading toward the door with your arms out, you would predict the distance to the door based on your memory of your bedroom and the steps you have already made. If you touch a wall or furniture, you would refine the prediction. This is an example of how important it is to supplement limited sensory input with your own actions to grasp the situation. How the brain comprehends such a complex cognitive function is an important topic of neuroscience.

Dealing with limited sensory input is also a ubiquitous issue in engineering. A car navigation system, for example, can predict the current position of the car based on the rotation of the wheels even when a GPS signal is missing or distorted in a tunnel or under skyscrapers. As soon as the clean GPS signal becomes available, the navigation system refines and updates its position estimate. Such iteration of prediction and update is described by a theory called “dynamic Bayesian inference.”

In a collaboration of the Neural Computation Unit and the Optical Neuroimaging Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), Dr. Akihiro Funamizu, Prof. Bernd Kuhn, and Prof. Kenji Doya analyzed the brain activity of mice approaching a target under interrupted sensory inputs. This research is supported by the MEXT Kakenhi Project on “Prediction and Decision Making” and the results were published online in Nature Neuroscience on September 19th, 2016.

The team performed surgeries in which a small hole was made in the skulls of mice and a glass cover slip was implanted onto each of their brains over the parietal cortex. Additionally, a small metal headplate was attached in order to keep the head still under a microscope. The cover slip acted as a window through which researchers could record the activities of hundreds of neurons using a calcium-sensitive fluorescent protein that was specifically expressed in neurons in the cerebral cortex. Upon excitation of a neuron, calcium flows into the cell, which causes a change in fluorescence of the protein. The team used a method called two-photon microscopy to monitor the change in fluorescence from the neurons at different depths of the cortical circuit (Figure 1).

(Figure 1: Parietal Cortex. A depiction of the location of the parietal cortex in a mouse brain can be seen on the left. On the right, neurons in the parietal cortex are imaged using two-photon microscopy)

The research team built a virtual reality system in which a mouse can be made to believe it was walking around freely, but in reality, it was fixed under a microscope. This system included an air-floated Styrofoam ball on which the mouse can walk and a sound system that can emit sounds to simulate movement towards or past a sound source (Figure 2).

(Figure 2: Acoustic Virtual Reality System. Twelve speakers are placed around the mouse. The speakers generate sound based on the movement of the mouse running on the spherical treadmill (left). When the mouse reaches the virtual sound source it will get a droplet of sugar water as a reward)

An experimental trial starts with a sound source simulating a distance from 67 to 134 cm in front of and 25 cm to the left of the mouse. As the mouse steps forward and rotates the ball, the sound is adjusted to mimic the mouse approaching the source by increasing the volume and shifting in direction. When the mouse reaches just by the side of the sound source, drops of sugar water come out from a tube in front of the mouse as a reward for reaching the goal. After the mice learn that they will be rewarded at the goal position, they increase licking the tube as they come closer to the goal position, in expectation of the sugar water.

The team then tested what happens if the sound is removed for certain simulated distances in segments of about 20 cm. Even when the sound is not given, the mice increase licking as they came closer to the goal position in anticipation of the reward (Figure 3). This means that the mice predicted the goal distance based on their own movement, just like the dynamic Bayesian filter of a car navigation system predicts a car’s location by rotation of tires in a tunnel. Many neurons changed their activities depending on the distance to the target, and interestingly, many of them maintained their activities even when the sound was turned off. Additionally, when the team injects a drug that suppresses neural activities in a region of the mice’s brains, called the parietal cortex they find that the mice did not increase licking when the sound is omitted. This suggests that the parietal cortex plays a role in predicting the goal position.

(Figure 3: Estimation of the goal distance without sound. Mice are eager to find the virtual sound source to get the sugar water reward. When the mice get closer to the goal, they increase licking in expectation of the sugar water reward. They increased licking when the sound is on but also when the sound is omitted. This result suggests that mice estimate the goal distance by taking their own movement into account)

In order to further explore what the activity of these neurons represents, the team applied a probabilistic neural decoding method. Each neuron is observed for over 150 trials of the experiment and its probability of becoming active at different distances to the goal could be identified. This method allowed the team to estimate each mouse’s distance to the goal from the recorded activities of about 50 neurons at each moment. Remarkably, the neurons in the parietal cortex predict the change in the goal distance due to the mouse’s movement even in the segments where sound feedback was omitted (Figure 4). When the sound was given, the predicted distance from the sound became more accurate. These results show that the parietal cortex predicts the distance to the goal due to the mouse’s own movements even when sensory inputs are missing and updates the prediction when sensory inputs are available, in the same form as dynamic Bayesian inference.

(Figure 4: Distance estimation in the parietal cortex utilizes dynamic Bayesian inference. Probabilistic neural decoding allows for the estimation of the goal distance from neuronal activity imaged from the parietal cortex. Neurons could predict the goal distance even during sound omissions. The prediction became more accurate when sound was given. These results suggest that the parietal cortex predicts the goal distance from movement and updates the prediction with sensory inputs, in the same way as dynamic Bayesian inference)

The hypothesis that the neural circuit of the cerebral cortex realizes dynamic Bayesian inference has been proposed before, but this is the first experimental evidence showing that a region of the cerebral cortex realizes dynamic Bayesian inference using action information. In dynamic Bayesian inference, the brain predicts the present state of the world based on past sensory inputs and motor actions. “This may be the basic form of mental simulation,” Prof. Doya says. Mental simulation is the fundamental process for action planning, decision making, thought and language. Prof. Doya’s team has also shown that a neural circuit including the parietal cortex was activated when human subjects performed mental simulation in a functional MRI scanner. The research team aims to further analyze those data to obtain the whole picture of the mechanism of mental simulation.

Understanding the neural mechanism of mental simulation gives an answer to the fundamental question of “How are thoughts formed?” It should also contribute to our understanding of the causes of psychiatric disorders caused by flawed mental simulation, such as schizophrenia, depression, and autism. Moreover, by understanding the computational mechanisms of the brain, it may become possible to design robots and programs that think like the brain does. This research contributes to the overall understanding of how the brain allows us to function.

Researchers identify method of creating long-lasting memories

Imagine if playing a new video game or riding a rollercoaster could help you prepare for an exam or remember other critical information.

A new study in mice shows this link may be possible.

Attention-grabbing experiences trigger the release of memory-enhancing chemicals. Those chemicals can etch memories into the brain that occur just before or soon after the experience, regardless of whether they were related to the event, according to researchers at UT Southwestern Medical Center’s Peter O’Donnell Jr. Brain Institute.

The findings, published in Nature, hold intriguing implications for methods of learning in classrooms as well as an array of potential uses in the workplace and personal life, researchers said.

The trick to creating long-lasting memories is to find something interesting enough to activate the release of dopamine from the brain’s locus coeruleus (LC) region.

“Activation of the locus coeruleus increases our memory of events that happen at the time of activation and may also increase the recall of those memories at a later time,” said Dr. Robert Greene, the study’s co-senior author and a Professor of Psychiatry and Neurosciences with the O’Donnell Brain Institute.

The study explains at the molecular level why people tend to remember certain events in their lives with particular clarity as well as unrelated details surrounding those events: for instance, what they were doing in the hours before the Sept. 11, 2001, terrorist attacks; or where they were when John F. Kennedy was assassinated.

“The degree to which these memories are enhanced probably has to do with the degree of activation of the LC,” said Dr. Greene, holder of the Sherry Gold Knopf Crasilneck Distinguished Chair in Psychiatry, in Honor of Mollie and Murray Gold, and the Sherry Knopf Crasilneck Distinguished Chair in Psychiatry, in Honor of Albert Knopf. “When the New York World Trade Center came down on 9/11, that was high activation.”

But life-changing events aren’t the only way to trigger the release of dopamine in this part of the brain. It could be as simple as a student playing a new video game during a quick break while studying for a crucial exam, or a company executive playing tennis right after trying to memorize a big speech.

“In general, anything that will grab your attention in a persistent kind of way can lead to activation,” Dr. Greene said.

Scientists have known dopamine plays a large role in memory enhancement, though where the chemical originates and how it’s triggered have been points of study over the years.

Dr. Greene led a study published in 2012 that identified the locus coeruleus as a third key source for dopamine in the brain, besides the ventral tegmental area and the substantia nigra. That research demonstrated the drug amphetamine could pharmacologically trigger the brain’s release of dopamine from the LC.

The latest study builds upon those findings, establishing that dopamine in this area of the brain can be naturally activated through behavioral actions and that these actions enhance memory retention.

The new study suggests that drugs targeting neurons in the locus coeruleus may affect learning and memory as well. The LC is located in the brain stem and has a range of functions that affect a person’s emotions, anxiety levels, sleep patterns, memory and other aspects of behavior.

The study tested 120 mice to establish a link between locus coeruleus neurons and neuronal circuits of the hippocampus – the region of the brain responsible for recording memories – that receive dopamine from the LC.

One part of the research involved putting the mice in an arena to search for food hidden in sand that changed location each day. The study found that mice that were given a “novel experience” – exploring an unfamiliar floor surface 30 minutes after being trained to remember the food location – did better in remembering where to find the food the next day.

Researchers correlated this memory enhancement to a molecular process in the brain by injecting the mice with a genetically encoded light-sensitive activator called channelrhodopsin. This sensor allowed them to selectively activate dopamine-carrying neurons of the locus coeruleus that go to the hippocampus and to see first-hand which neurons were responsible for the memory enhancement.

They found that selectively activating the channelrhodopsin-labeled neurons with blue light (a technique called optogenetics) could substitute for the novelty experience as a memory enhancer in mice. They also found that this activation could cause a direct, long-lasting synaptic strengthening – an enhancement of memory-relevant communication occurring at the junctions between neurons in the hippocampus. This process can mediate improvement of learning and memory.

Some next steps include investigating how big an impact this finding can have on human learning, whether it can eventually lead to an understanding of how patients can develop failing memories, and how to better target effective therapies for these patients, said Dr. Greene.

Depositing books due at the library, the grad student takes a humiliating whirlwind tour of everything his past self had planned to read.

Zillertal Alps // Tom Klocker