Unlocking a major secret of the brain

McGill researchers uncover crucial link between hippocampus and prefrontal cortex

A clue to understanding certain cognitive and mental disorders may involve two parts of the brain which were previously thought to have independent functions, according to a McGill University team of researchers led by Prof. Yogita Chudasama, of the Laboratory of Brain and Behavior, Department of Psychology. The McGill team discovered a critical interaction between two prominent brain areas: the hippocampus, a well-known memory structure made famous by Dr. Brenda Milner’s patient H.M., and the prefrontal cortex, which is involved in decision-making and inhibiting inappropriate behaviours.

“We had always thought that the hippocampus and the prefrontal cortex functioned independently,” says Prof. Chudasama. “Our latest study provides the first indication that that is not the case.”

The team’s finding, just published in the Journal of Neuroscience, reveals a critical interaction between these two brain areas and the control of behavior, and may advance the treatment of some cognitive and mental disorders including schizophrenia, and depression. The interaction between the hippocampus and the prefrontal cortex shows that brain circuits function not just as specific parts of the brain, but are linked together and work as a system.

“Although the prefrontal cortex has long been known to be the driving force that steers our behavior, pushing us to make good decisions and withhold improper actions, it turns out that it can’t do this unless it interacts with the hippocampus,” added Prof. Chudasama.  “We found that when we prevented these two structures from communicating with each other, like humans with compulsive disorders, rats persisted with behaviours that were not good for them; they didn’t correct their errant behaviours and could not control their natural urges.

The ability to control impulsive urges or inhibit our actions allows us to interact normally in personal or social situations, and this type of behaviour depends on the normal interaction of the hippocampus and the prefrontal cortex. This result provides a means for understanding the neural basis for social and cognitive deficits in disorders of brain and behaviour, such as those with frontotemporal dementia”, concludes Prof. Chudasama.

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Goodbye, IQ Tests: Brain Imaging Can Reveal Intelligence Levels

Research from Washington University in St. Louis has identified variations in brain scans that they believe identify portions of the brain that are responsible for intelligence.

As suspected (and as explained by cartoons) brain size does play a small role; they said that brain size accounts for 6.7 percent of variance in intelligence. Recent research has placed the brain’s prefrontal cortex, a region just behind the forehead, as providing for 5 percent of the variation in intelligence between people.

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What is it like to experience the frightening auditory and visual hallucinations characteristic of schizophrenia? Yellowlees and Cook (2006) developed a virtual reality program in Second Life based on interviews with schizophrenic patients. The researchers used this as a tool to educate the general public about schizophrenia, in order to increase understanding and reduce stigma. A video sample of the program can be viewed below.


As you can see, these hallucinations are straight out of a horror movie or a terrible nightmare, except they reflect the reality of living with schizophrenia:
  • Multiple voices, occasionally overlapping, criticizing the user
  • A newspaper in which the word “death” would stand out in a headline
  • A floor that would fall away, leaving the user walking on stepping stones above a bank of clouds
  • A television that would play a political speech, but then criticize the user and encourage suicide
  • A gun that would appear under a cone of light and pulse, with associated voices telling the user to take the gun and commit suicide
  • A mirror in which a person’s reflection would appear to die, becoming gaunt with bleeding eyes
The authors also provide information about accessing the Virtual Hallucination environment directly.

Persons with other psychiatric disorders may be plagued by voices saying they’re worthless and directing them to commit suicide, but the voice is a self-deprecating internal monologue and clearly identified as their own (as in nonpsychotic unipolar and bipolar depression). The issue in schizophrenia is one of reality monitoring, so that internal thoughts and impulses are interpreted as external to the self.

The most common type of hallucination is hearing voices. To determine which brain regions are implicated, a number of neuroimaging studies have scanned participants with schizophrenia while they are actively experiencing auditory hallucinations, compared to the non-hallucinating state (Allen et al., 2008;Kompus et al., 2011;Jardri et al., 2011). A common finding is increased activation of auditory cortex in the absence of external stimulation, along with greater activity in Broca’s area(speech production) and the medial temporal lobe (memory). One interpretation of this pattern is that memory retrieval triggers aberrant auditory perceptual experiences. Another is that inner speech is attributed to external sources due to defective self-monitoring.

A new study by Kim and colleagues (2012) took a different approach. They constructed a virtual reality environment in the scanner to produce the illusion of burning flames, and compared the neural responses of schizophrenic and control participants. The experimental setup is shown below.

Fig. 1A (adapted from Kim et al., 2012). The virtual flame illusion.A participant could see his/her body through a head-mounted display (HMD) during the “flame off” block and watched a superimposed, animated image of a virtual flame on the right or left index finger during the “flame on” block.

The participants were 16 schizophrenic patients with mild to moderately severe symptoms and 17 controls. They were instructed that the purpose of the experiment was to examine the brain’s response to “observing the body.” However, they werenotinformed about the potentially frightening illusion:
Participants were not told about the virtual flame and were instructed to observe their body without closing their eyes. As shown in Fig. 1, the experiment used a blocked paradigm and consisted of two conditions: 1) a ‘flame off’ block (30 s), during which only a real-time body image was presented, and 2) a ‘flame on’ block (16 s), during which the virtual flame was generated by a computer in real-time and superimposed on the participant’s index finger. The blocks were alternatively repeated 8 times, and the presentation of the flame on the left or the right finger was counterbalanced.

Fig. 1B (adapted from Kim et al., 2012). fMRI task sequence. The experiment used a blocked design and alternated between ‘flame off’ blocks (30 s) and ‘flame on’ blocks (16 s).

Lest you think this situation skirts the boundaries of unethical (as I did), the study was approved by the local institutional review board and subjects signed[semi-]informed consent statements.

After the fMRI session was over, the participants filled out a questionnaire which indicated (A) the strength of their reactions from 1 (“not at all”) to 7 (“extremely strong”), and (B) how much their feelings changed when the blocks were repeated, rated from 1 (“severely attenuated”) to 7 (“severely augmented”):
After scanning, most participants reported that they initially felt the ‘flame on their finger,’ but then the feeling disappeared after realizing that the flame was not real… . …both patient and control groups showed similar subjective responses to the task stimuli: moderate strength in feeling the flame (4.6 ± 1.9 and 3.8 ± 1.8, respectively) and slight attenuation in flame strength over time (3.3 ± 1.8 and 2.6 ± 1.3, respectively).[The group differences were not statistically significant.]

The data analysis strategy went beyond the standard boxcar comparison between “flame on” and “flame off.” Instead, the authors…
…considered that the process of virtual flame-specific learning (i.e., gaining insight into the reality of a visual image) might be reflected as a linear or quadratic function of fMRI signal changes. A linear function could reflect repetition enhancement, sensitization/repetition attenuation, or habituation to the stimulus. A quadratic function could reflect transitions between repetition enhancement and repetition attenuation.
The brain activation differences between groups were not all that spectacular, once you discard all the p<.001 uncorrected regions that were reported in Table 2. What was left?
…only five areas including the left anterior prefrontal cortex, left occipito-temporal junction, left occipital gyrus, right amygdala, and left cerebellum were included. As depicted inFig. 2,the control group demonstrated transitions from repetition enhancement to attenuation in these five brain regions, in contrast to the lack of enhancement and attenuation in the patient group [i.e., a flat response].

Fig. 2 (Kim et al., 2012). Changing patterns of brain activity related to the virtual flame across time in patients with schizophrenia and in healthy controls. The selected regions were significant in the two-sample tests with the quadratic repetition-variant response at p < 0.05, FDR-corrected: the anterior prefrontal cortex (APFC), occipito-temporal junction (OTJ), occipital cortex (OC), amygdala (AMG), and cerebellum (CER). Rt., right; and Lt., left

Have we come away with a better understanding of the neural processes involved in gaining insight into unreality? Becoming aware of the fact that an unexpected and alarming visual illusion isn’t real differs from internally generated hallucinations, of course, but the authors suggest that:
Patients with schizophrenia may use a salience-related region1 instead of reality monitoring-related regions[anterior medial PFC]to react to the unusual stimuli, and this peculiarity of the neural processes may be related to vulnerability to psychosis.

1 The salience-related region (anterior cingulate cortex) did not survive FDR correction for multiple comparisons.

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Artificial jellyfish built from rat cells

Bioengineers have made an artificial jellyfish using silicone and muscle cells from a rat’s heart. The synthetic creature, dubbed a medusoid, looks like a flower with eight petals. When placed in an electric field, it pulses and swims exactly like its living counterpart.

“Morphologically, we’ve built a jellyfish. Functionally, we’ve built a jellyfish. Genetically, this thing is a rat,” says Kit Parker, a biophysicist at Harvard University in Cambridge, Massachusetts, who led the work.

When an electric field is applied across the structure, the muscle contracts rapidly, compressing the medusoid and mimicking a jellyfish’s power stroke. The elastic silicone then pulls the medusoid back to its original flat shape, ready for the next stroke. 

When placed between two electrodes in water, the medusoid swam like the real thing. It even produced water currents similar to those that wash food particles into jellyfish’s mouths. “We thought if we’re really good at this, we’re going to recreate that vortex, and we did,” says Parker. “We took a rat apart and rebuilt it as a jellyfish.”

The team now plans to build a medusoid using human heart cells. The researchers have filed a patent to use their design, or something similar, as a platform for testing drugs.

Read full article here

Extract from

Gif made from this Youtube video: Parker et al/ Nature Biotechnology

There’s one gif. Where’s my gifset?

Squeek Squeek Glub Glub

Da fuq.


Dark Matter and the Phantom Filaments

Sounds like a good band name, eh?

Simulations of how we think the universe is organized, astrophysically speaking, show patterns resembling nodes of clustered galaxies connected by filaments of dense matter. We’ve found plenty of the galaxy clusters, but the filaments have been harder to actually observe. That’s because they are likely made of dark matter, which neither emits or absorbs light (and is therefore invisible to we mere humans).

But scientists may have witnessed the effect of one of these filaments recently, marking the first time that dark matter has been observed connecting galaxy clusters. As Matthew Francis reports:

The researchers used archival data from the 8.2 meter Subaru telescope in Hawaii, which includes visible and infrared observations of the supercluster. These were scanned to look for subtle changes in the light from objects behind the clusters. These can be signs of weak gravitational lensing, which would reveal the distribution of dark matter near the clusters.

Gravitational lensing basically means that something invisible with mass, like dark matter, is bending the light from the cluster of galaxies. So although we can’t see the dark matter, we can see it affecting the light’s path and take a pretty good guess it is there.

I bet these guys wish they hadn’t announced this in the same week as the Higgs boson, but hey … can’t win ‘em all. It gives support to the idea that our universe could be built on enormous webs of dark matter, and where these filaments and strands intersect, there is where gravity pulls galaxies together to form the clusters of stars and visible matter that we see every time we look up at night.

( Ars Technica)

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If you keep going around the universe, will you end up where you started?

Is the universe flat or spherical or saddle-shaped, and what do any of these things really mean? Do we live in a Pac-Man universe, or an infinite one?

 [ …  

 Why should our universe be curved at all? For the same reason that any sort of space-time gets curved in our crazy universe: there’s stuff in it. In case you’ve forgotten, one of the major predictions of Einstein’s theory of general relativity is that mass and energy curve space and time.

The same is true for the universe — our human 3-d universe — as a whole. If there’s too little stuff the universe is saddle-shaped. Put in too much, and the universe is spherical. But put in just the right amount (and this seems to be the case for us) and the universe will be flat. As we used to rather cheesily put it, “Density is destiny.”

 [ …  

ask a physicist!

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when elephants come across the carcass of another dead elephant they do this ritual, where they gather around the bones and proceed to touch their hind legs to them. Scientists believe this is how they grieve and mourn the loss of one of their kind. 

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String Theory says that all the notes on a vibrating string correspond to a particle. That to an electron is actually a rubber band; a very tiny rubber band. but if you twang this rubber band and the rubber band vibrates at a different frequency, it turns into a quark. And you twang it again and it turns into a neutrino. So, how many musical notes are there? An infinite. How many musical notes are there on a string? An infinite number. And that may explain why we have so many subatomic particles. They are nothing but musical notes.

So, physics are nothing but the laws of harmonies on a string. Chemistry is nothing but the melodies you can play on vibrating strings. And the mind of God, the mind of God that Einstein worked on for the last 30 years of his life, the mind of God would be cosmic music. Cosmic music resonating through 11 dimensional hyperspace.

Micho Kaku, Theoretical Physicist (via randomglory)

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UNDER the intense stare of the Kepler space telescope, more and more planets similar to our own are revealing themselves to us. We haven’t found one exactly like Earth yet, but so many are being discovered that it appears the galaxy must be teeming with habitable planets. These discoveries are bringing an old paradox back into focus. As physicist Enrico Fermi asked in 1950, if there are many suitable homes for life out there and alien life forms are common, where are they all? More than half a century of searching for extraterrestrial intelligence has so far come up empty-handed. Of course, the universe is a very big place. Even Frank Drake’s famously optimistic “equation” for life’s probability suggests that we will be lucky to stumble across intelligent aliens: they may be out there, but we’ll never know it. That answer satisfies no one, however. There are deeper explanations. Perhaps alien civilisations appear and disappear in a galactic blink of an eye, destroying themselves long before they become capable of colonising new planets. Or maybe life very rarely gets started even when conditions are perfect.

Life: is it inevitable or just a fluke? - life - 25 June 2012 - New Scientist (via wildcat2030)

OR Intelligent civilizations have technology that has evolved beyond human comprehension, so much that our own technology would have trouble detecting it.

(via ikenbot)

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