transcript of episode 2: ELECTROCOMPULSIVE THERAPY, 29th January 2021

[🎶 INTRO: "Spring Swing" by Dee Yan-Kee 🎶]

welcome to the error bar: where neural artifice is annihilated

in this episode: how electrocuting the face & brain reduces obsessive behaviour, how nose-pumping helps with sleep hygiene, & the monkeys who'll swap your iphone for food

here is the brain news on the 29th January 2021:



both Scientific American and The Daily Mail picked up on a remarkable report of an apparent treatment for obsessive-compulsive-disorder. while the Mail focused on the potential to cure problem gamblers, shopaholics, and compulsive eaters, Scientific American stuck a little closer to the actual story.

the study was in two parts. first, three groups of 20 healthy young people were given one of three kinds of electrical brain stimulation over the orbitofrontal cortex - an important part of the brain. two kinds of stimulation were expected to do nothing, and the third was expected to interfere with the volunteers' decision-making skills. their task was to choose one of two random characters on screen, learning which to choose by trial and error. sometimes they would be rewarded with $10, other times they would lose $10.

the brain stimulation worked amazingly well - the placebo and the lower-frequency stimulation didn't seem to affect people's decisions, but the higher-frequency stimulation really impaired their ability to learn from rewards.

second, 64 people were split into two groups of 32. they reported their obsessive-compulsive symptoms in a questionnaire at the start of the study, then had brain stimulation for 5 days, then repeated the questionnaire immediately afterwards, and again 1, 2, and 3 months later.

the results were equally impressive - very large reductions in obsessive-compulsive behaviours were reported for the higher-frequency stimulation group.


does brain stimulation really cure ocd?

despite the Mail's headline, this study involved no-one actually being treated for - let alone CURED of - OCD. and in the first half of the study, they also didn't measure any OCD behaviours. let's take the two halves of the study separately.

the first half reported data showing extremely large and strong effects of the brain stimulation - within the first few minutes of the experiment, effects are already clear and the error bars are tiny - the volunteers just can't seem to learn from rewards (receiving $10), whereas they can learn totally fine from punishments (losing $10). for the rewards, half of the group were performing individually at chance, and half better than chance.

if true, this result would be an enormous and very specific effect of brain stimulation on behaviour. and that's the only reason i have for not really believing it - it's just too strong to be true - such a massive effect, changing a group of people's decision-making behaviour so strongly and so specifically. it needs to be replicated.

the headline-grabbing part 2 of the study was about how the same kind of brain stimulation reduces obsessive behaviours. and just like the first part, the effect-sizes are very large, with participants consistently reporting reductions in obsessive behaviours over as long as 3 months.

but some things are gnawing at me.

first, the authors do a classic 'double dip' - by showing a strong relationship between the scores at baseline, and changes in those scores from baseline to afterwards. this is a topic for a later episode, but it's a common statistical mistake.

second, there are some minor errors in their calculations. they kindly provide all the raw data, but the data don't quite match up with their graphs. not a big problem, but a worry.

third, the group who received brain stimulation continued decreasing their obsessive behaviours months after treatment - there seemed to be no wearing-off. that just seems a bit odd.

fourth, the treatment group showed a very large increases in variability after treatment. why would obsessive variability increase - it could be that some people had indeed been 'cured' but some were unaffected or made worse.

fifth, colleagues have suggested that this form of stimulation could be quite uncomfortable, and would likely produce flashes of light in the eyes, although this was ruled out in the paper.

sixth, along with this increased variability for the treatment group, the relationships between the untreated participants' scores seemed a bit too good. perfect every time.

this skepticism may just be effect-size jealousy, but there's just something too good to be true in these data. two massive, perfect effects in one paper? hmmmm.


electrical brain stimulation seems to have massive and highly-specific effects on people learning about monetary rewards but not punishments, and on obsessive-compulsive behaviours. replication required


the science was by Grover et al. in Nature Medicine; reported in The Daily Mail by @shivalibest on 18/Jan/21, & Scientific American by @DianaMKwon on 25/Jan/21



the Daily Mail informs us that a good night's sleep helps to clear your mind from toxic proteins. they helpfully point out that the NHS recommends 6 to 9 hours' sleep a night.

the study found that deep sleep is associated with decreased brain activity, high arousal, rhythmic movement and the removal of toxic waste. the study authors from northwestern university, illinois proposed that waste clearance is an ancient function of deep sleep


does a good night's sleep clear the mind?

yes. if you're a fly.

and that's the only problem with this story - that it's about fruit flies, and the way they clear their brain of toxins is by repeatedly pumping their proboscis back and forth every 3 seconds, which moves the waste along their guts and out onto the bedsheets.

just like humans, the flies were harder to wake up during their deep sleep, and they could be drugged into getting to sleep quicker, but that's where the similarities end.


sleep is good for your brain, but we recommend against repeated snout-pumping and waste clearance as that may adversely affect your bed partner's sleep quality


the science was by van Alphen et al. in Science Advances; reported in The Daily Mail by @shivalibest on 21/Jan/21


MICHAEL LAND (1942-2020)

Daniel Osorio, Professor of Neuroscience at Sussex University, writes of the death of Michael Land in December 2020, Emeritus Professor of Neuroscience at Sussex.

"The Marco Polo of vision science" - he explored the many ways animals use light; for example prawns use lots of mirrored boxes for eyes. A PhD on scallops, a post-doc on jumping spiders, and a fellowship on venomous snakes and butterflies, he later studied where humans look during everyday tasks like making tea, steering, and playing the piano. A musical, mathematical, nature-loving Fellow of the Royal Society.


rest in peace


reported in The Guardian by Daniel Osorio on 19/Jan/21

and the brain in brief...



around 350 long-tailed macaques live near the Uluwatu Temple in Bali; the temple staff feed them fruit and vegetables daily, but they also steal from and trade with the 1.5 million visiting tourists each year.

for nearly a year, the macaques were videod by two researchers, starting recoding when the monkey looked at and approached a tourist holding or wearing an inedible object likely to be stolen - glasses, flipflops, cell phones. these would soon be traded back for food with the temple staff.

juvenile monkeys got 40% of their targets, increasing to 70% in experienced adults. the items stolen did not correlate with their local availability, suggesting the monkeys were being choosy. they got increasingly-choosy with age, rejecting more of the lower-value items as they reached adulthood.


do monkeys know the cost of everything?

this is a simple story of primate versus primate.

the graphs and the numbers don't quite match, and they don't say where the error bars come from - tut tut - but otherwise this is a straightforward report - monkeys seem to learn much from tourists. i suspect that the temple staff are in on the game too.


hold my banana


the science was by Leca et al. in Philosophical Transactions of the Royal Society of London, B: Biological Sciences; reported in The Independent by @SamuelOsborne93 on 26/Jan/21



the Telegraph and Mail both report on physicists knocking eggs about to discover how the yolk is displaced inside.

the tenuous neuroscience link here is that the head is a bit like an egg, and the brain its yolk.


how do your like your brain omelette?

the error bar does not comment on physics papers




the science was by Lang et al. in Physics of Fluids; reported in The Daily Mail by @shivalibest on 19/Jan/21, & The Telegraph by @DominicPenna on 20/Jan/21

[🎶 OUTRO: "Cosmopolitan - Margarita - Bellini" by Dee Yan-Kee 🎶]

it's closing time at the error bar, but do drop in next time for more brain news, fact-checking & neuro-opinions. take care.

the error bar was devised & produced by Dr Nick Holmes from the University of Nottingham. the music by Dee Yan-Kee is available from the free music archive. find us at the error bar dot com, on twitter at bar error, or email talk at the error bar dot com