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First read this abstract of scientific research:
http://www.sciencemag.org/content/341/6150/1123.abstract
Topographic Representation of Numerosity in the Human Parietal Cortex
Abstract:
Numerosity, the set size of a group of items, is processed by the association cortex, but certain aspects mirror the properties of primary senses. Sensory cortices contain topographic maps reflecting the structure of sensory organs. Are the cortical representation and processing of numerosity organized topographically, even though no sensory organ has a numerical structure? Using high-field functional magnetic resonance imaging (at a field strength of 7 teslas), we described neural populations tuned to small numerosities in the human parietal cortex. They are organized topographically, forming a numerosity map that is robust to changes in low-level stimulus features. The cortical surface area devoted to specific numerosities decreases with increasing numerosity, and the tuning width increases with preferred numerosity. These organizational properties extend topographic principles to the representation of higher-order abstract features in the association cortex.
Now see for yourself how it was spinned:
http://kuow.org/post/scientists-put-sixth-sense-numbers-brain-map
Scientists Put A 'Sixth Sense' For Numbers On Brain Map
A sixth sense? A small patch of neurons on either side of the brain recognizes how many dots are on a screen. As more dots appear, active neurons shift to the right.
Scientists have found a region of the brain that quickly senses quantities. It's a small patch of neurons just above each ear that allows us to say at a glance.
Some scientists think of this ability as a kind of sixth sense, something like a number sense. One reason is that the skill appears to originate in specific parts of the brain much like our sense of touch and sight, a team of scientists said Thursday in the journal Science.
Listen to this podcast where the scientist Ben Harvey discusses the new evidence for a numerosity map in the brain here:
http://www.sciencemag.org/content/341/6150/1123/suppl/DC2
Nowhere had I come across the word sixth sense in the paper or the podcast. But the journalist gave a twist to the research either to suit his beliefs or to make the story more sensational!! This is bad science journalism!

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Hit them on the head!

238

When Science Becomes News, The Facts Can Go Up In Smoke
At dinner the other night with an experimental psychologist, we turned to the topic of science in the popular media. She bemoaned the fact that it's hard to get newspapers to get the facts right; even when you help reporters describe results correctly, she said, there is a tendency for headlines to bypass the subtlety and go for sensation. If it were up to her, she said, she'd simply refuse to return calls from science journalists and stick to taking care of business inside the lab.

A case in point: Last month news outlets around the country reported new findings on the damaging effects of pot smoking. A sample of the headlines (taken from at MedpageToday):

"" (Boston Globe)

"" (USA Today)

"" (Washington Post)

"" (Time)

The striking thing was that the study supported no such interpretation of the facts.

What was actually reported was that there were observed differences in the brains of 20 casual pot users as compared to 20 nonusers. In particular, it was found that there were some differences in grey matter densities in the nucleus accumbens of users and differences in shape in the right amygdala and the left nucleus accumbens.

But, crucially, it was not demonstrated that the relevant differences were caused by marijuana use. It would have been impossible to show that, given the study's design, since the study looked at a cross-section of people at a given moment in time and did not look for changes in individual brains after smoking.

Nor, crucially, was any evidence adduced to support the claim that any of the reported differences were associated with any harm. In fact, it was not shown that the differences made a difference.

What's going on here? Why were the findings misreported in this way?

The first thing I did, when I heard reports about the new findings, was to convey them to my 12-year-old son. It's now been proved, I warned him, that even casual pot use hurts the brain!

I was embarrassed to learn that no such thing had been proved at all!

This state of affairs prompted by Jacob Sellum with the hysterical title: "Study of Pot Smoker's Brains Shows that MRIs Cause Bad Science Reporting."

Humor aside, I think we need to look deeper to understand the misreporting.

My anxious delivery of the finding to my kid is a clue to what's really going on. We look at science, and its findings, not in the isolation of the laboratory, but rather, in the setting of our concerns and, indeed, our anxieties.

Lots of people smoke pot. They do so, presumably, because it affects their brains, and not despite that fact. It would be astonishing and inexplicable to find that getting high didn't bring about changes in the brain. But are those changes lasting? Are they permanent? We don't know and we'd like to know. As a culture, I think it's fair to say, we're worried about this, especially in light of the fact that across the country there is a move to legalize pot use and that pot continues to have a pretty positive representation in youth-oriented media.

The handling of the results in the media — and even in discussions of the findings by the scientists behind the study themselves — expresses this anxiety. Reports got the results wrong. But they got the results wrong for the very reason that the study is interesting and important in the first place. We care about whether pot smoking is harmful.

So back to my friend at the dinner table. No, don't retreat to the lab. What we need, rather, are better, broader, more open discussions, in public, of the meaning of scientific results. That, after all, is why we have labs in the first place.

I'm left with a question: should I sit my son down and explain to him that, as a matter of fact, the press got it wrong, that it has not been proved that smoking pot is bad for the brain?

http://www.npr.org/blogs/13.7/2014/05/04/308926616/when-science-bec...

--

  • Marijuana News: Casual Pot Use Impacts Brains of Young Adults, Researchers Find (The Oregonian)
  • Study Finds Brain Changes in Young Marijuana Users (Boston Globe)
  • Casual Marijuana Use Linked to Brain Changes (USA Today)
  • Even Casually Smoking Marijuana Can Change Your Brain, Study Says (Washington Post)
  • Study Finds Changes in Pot Smokers' Brains (Denver Post)
  • Recreational Pot Use Harmful to Young People's Brains (TIME)

Striking a Nerve: Bungling the Cannabis Story
http://www.medpagetoday.com/Neurology/GeneralNeurology/45290
Correlation does not equal causation, and a single exam cannot show a trend over time. Basic stuff, right?

But judging by coverage of a study just out in the Journal of Neuroscience, these are apparently foreign concepts for many folks in the media.

In the study, researchers at Boston's Massachusetts General Hospital and Northwestern University in Chicago performed MRI brain scans on 20 young adult "casual" marijuana users and 20 age- and sex-matched nonusers. They found that, in the users, gray matter densities in the nucleus accumbens were higher than in controls, and the right amygdala and left nucleus accumbens were shaped differently.

Interesting, but remember that these findings only reflected differences between the marijuana users and controls at a single point in time. The researchers did not, could not, demonstrate that the differences resulted from marijuana smoking or even that the "abnormalities" relative to controls reflected changes from some earlier state.

You wouldn't know that from the media coverage. Here's a sampling of headlines:

Marijuana News: Casual Pot Use Impacts Brains of Young Adults, Researchers Find (The Oregonian)
Study Finds Brain Changes in Young Marijuana Users (Boston Globe)
Casual Marijuana Use Linked to Brain Changes (USA Today)
Even Casually Smoking Marijuana Can Change Your Brain, Study Says (Washington Post)
Study Finds Changes in Pot Smokers' Brains (Denver Post)
Recreational Pot Use Harmful to Young People's Brains (TIME)

Sad to say, the Society for Neuroscience (SfN), which publishes the Journal of Neuroscience, may have driven these dramatic overinterpretations by promoting the study in a press release headlined "Brain changes are associated with casual marijuana use in young adults."

Also note that the study did not identify any cognitive or behavioral abnormalities in the cannabis users versus controls -- it was strictly an MRI study.

That, however, didn't stop senior author Hans Breiter, MD, of Northwestern from opining in the SfN press release that the study "raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences."

Um, no, it doesn't -- not without before-and-after MRI scans showing brain structure changes in users that differ from nonusers and documentation of functional impairments associated with those changes.

To their credit, the study team's actual paper stuck fairly close to their data, concluding that the users showed "structural abnormalities." They only strayed into overinterpretation when they wrote that "the left nucleus accumbens was consistently affected by cannabis use." Nope, it was still just an association, no cause-and-effect shown -- as Breiter and colleagues acknowledged later in their paper.

It might also have been a stretch to call their subjects "casual users." The mean intakes were 3.83 days of use and 11.2 joints per week, and 1.8 smoking occasions per day of use. To me -- and I lived in Ann Arbor in the 1970s -- this sounds more like the profile of a just-short-of-heavy regular user.

I don't want to minimize the paper's genuine importance. The differences in brain structure from controls could well have functional consequences, and could well reflect the effects of marijuana use. Certainly these findings deserve follow-up.

But until we get it, everyone, please dial back the Reefer Madness hype.

Striking a Nerve is a blog by John Gever for readers interested in neurology and psychiatry.

This week a study of cannabis consumers published by The Journal of Neuroscience provided powerful evidence that MRI scans cause shoddy science reporting. Researchers at Northwestern University and Massachusetts General Hospital used MRIs to compare the brains of 20 young adults who reported smoking pot at least once a week and 20 controls who had used marijuana no more than five times in their lives and had not consumed it at all in the previous year. The pot smokers had higher gray-matter densities in the left nucleus accumbens, and there were "significant shape differences" between subjects and controls in that area and in the right amygdala. The differences were more pronounced in subjects who reported smoking marijuana more frequently. "Because this is a cross-sectional study," the authors noted, "causation cannot be determined." In other words, it is not clear whether the brain differences were caused by marijuana. It also is not clear how long the differences last or whether they have any functional significance.

Those nuances generally were lost in press coverage of the study, which presented the MRI scans as evidence that smoking pot causes brain damage. News outlets claimed the study found that "marijuana re-shapes brains of users" (NBC News), that "even casually smoking marijuana can change your brain" (The Washington Post), that "casual pot use impacts brains of young adults" (The Oregonian), that "recreational pot use" is "harmful to young people's brains" (Time), that "casual marijuana use" is "bad for young adults" (The Times of India), and that "even 'casual' marijuana use can knacker bits of your brain" (Gizmodo UK). A Medical News Today headline quoted the researchers as saying "casual marijuana use changes the brain," although that statement does not appear in the article under the headline, in the study itself, or in press releases about the study issued by Northwestern University, Massachusetts General, and the Society for Neuroscience, which publishes The Journal of Neuroscience. Similarly, an MSN NZ headline had the study claiming that "cannabis use 'alters brain regions,'" another phrase that is absent from the study and the press releases.

Although they seem to have been misquoted in some cases, the researchers themselves are partly responsible for the misrepresentation of their findings. As John Gever points out in a coolheaded MedPage Today analysis, the study says "the left nucleus accumbens was consistently affected by cannabis use," even though the authors acknowledge elsewhere that their data cannot prove causation. One of the study's authors, Northwestern University psychiatrist Hans Breiter, goes even further in the Society for Neuroscience press release, saying, "This study raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences." Gever responds: "Um, no, it doesn't—not without before-and-after MRI scans showing brain structure changes in users that differ from nonusers and documentation of functional impairments associated with those changes."

Yet Breiter goes further still in the Northwestern press release. "People think a little recreational use shouldn't cause a problem, if someone is doing OK with work or school," he says. "Our data directly [say] this is not the case." No, they don't, as the study itself concedes. In the Massachusetts General press release, Breiter claims the study, which was supported by the National Institute on Drug Abuse, has policy implications: "Our findings—which need to be followed up with longer-terms studies—raise serious concerns about efforts to legalize recreational marijuana use, particularly for young adults."

What is the nature of the "bad consequences" and "problem[s]" that Breiter fears? "These two brain regions have been broadly implicated in processes underlying addiction," he says, "so it's a real problem that people claiming their marijuana use does not negatively impact their lives show significant changes in these structures." Harvard psychologist Jodie Gilman, the study's lead author, offers similar comments in the Northwestern press release. "It may be that we're seeing a type of drug learning in the brain," she says. "We think when people are in the process of becoming addicted, their brains form these new connections." It is not clear what the practical significance of "these new connections" might be, since Gilman et al. emphasize that their subjects "were not dependent" on marijuana.

Presumably Gilman and Breiter are not suggesting that anyone who smokes pot once a week is destined for addiction, which seems inconsistent with research on patterns of cannabis consumption. Data from the National Comorbidity Survey indicate that 9 percent of cannabis consumers experience "dependence" at some point in their lives. According to the National Survey on Drug Use and Health, about 18 million Americans have used marijuana in the last month, while about 3 million qualify as "dependent" at some point during a given year.

While the researchers were not always careful in explaining the significance of their findings, the misunderstandings reflected in the press coverage got a strong boost from the publicity departments at Northwestern and Massachusetts General, which picked headlines for their press releases that encouraged reporters to conflate correlation with causation and differences with damage:

Casual Marijuana Use Changes Brain Structures Involved in Reward, Emotion and Motivation: Mass. General, Northwestern Study First to Find Changes in Brains of Recreational Users

Casual Marijuana Use Linked to Brain Abnormalities: First Study to Show Effects of Small Time Use; More 'Joints' Equal More Damage

Those summaries are actually more misleading than a lot of the headlines in the general press, which is saying something.

Addendum: Pete Guither notes a scathing assessment of Gilman et al.'s study by U.C.-Berkeley computational biologist Lior Pachter, who calls it "quite possibly the worst paper I've read all year."

Study of Pot Smokers' Brains Shows That MRIs Cause Bad Science Reporting
http://reason.com/blog/2014/04/18/study-of-pot-smokers-brains-shows...

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