Individualized Alpha-Wave Matched Entrainment Improves Visual Learning in Adults

Alpha Waves credit: Wikipedia

Alpha waves are produced in the brain when a person is wakeful and at rest; not working or concentrating particularly hard. Alpha waves in the occipital lobes are associated with visual perception. Researchers at the University of Cambridge recently completed a study on the effect of flickering stimulus on visual learning.

BrainCap credit: BrainVision

The researchers recruited 100 volunteers aged 18 to 35, 90 of whom were able to participate in the study. Participants wore BrainCaps from BrainVision to measure brain waves. Once their wave patterns were characterized, they were shown images of concentric and radial dot patterns, and then asked to classify partially randomized patterns as radial or concentric. The images were shown for 200 milliseconds. Between images the participants were shown a square flicker in the center of the screen. It was set to match either peaks or troughs in Alpha wave patterns, or was slightly offset from the peak or trough. The flicker was shown for 15 cycles. The experiment was broken into two sessions. In the second session no flicker or EEG was used.

The groups given Alpha wave matched flickers learned to identify the patterns more accurately over the course of the experiment, though their accuracy started out lower than the non-matched group. The non-matched group showed no improvement.

More interesting is that the participants who were given trough-matched flickers learned more than three times faster than the peak-matched group. That learning was sustained the next day when participants were tested a second time. Previous studies using flickering stimulus showed inconsistent results in learning patterns. This study shows that individualized stimulus is effective in improving visual learning in willing adult participants.

(A) The image on the right is from the study, and credit is given to the researchers. At the top left are the ideal forms of the images, and on the right are the partially randomized versions.

(B) Visual representation of the visual flicker

(C) Representation of the peak, trough, and non-Matched groups

The bottom image shows the learning curves of the peak-matched, trough-matched, and non-matched participants

London Doctors Pioneer Treatment of Hypertension-Causing Adrenal Adenomas

Aldosterone Structure
Aldosterone Structure credit: Wikipedia

Aldosterone is a steroid hormone produced in the adrenal glands. It regulates potassium and sodium exchange in cells, so it can have a drastic long-term effect on blood pressure. Studies have found that between 5% and 20% of cases of high blood pressure is caused by high aldosterone levels caused by benign growths on the adrenal glands. These growths can be classified as adrenal adenomas or bilateral hyperplasias. Other conditions can be caused by these growths, including Cushing’s syndrome and hyperandrogenism.

credit: Wikipedia

Hyperaldosteronism has been diagnosed historically by Adrenal Venous Sampling. It’s accomplished by running a catheter through the femoral vein up to each of the adrenal veins and sampling blood as it leaves the adrenal tissue. The amount and proportions of cortisol and aldosterone are compared. The method carries a risk of producing venal thrombosis and misdiagnosis is possible. If a diagnosis is made adenomas can be removed by laproscopic surgery. Bilateral hyperplasias can’t be removed surgically and need to be treated by medication and lifestyle. The CT images at the bottom of this post show the difference between the two, and demonstrate how difficult visual diagnosis can be.

In a paper published a few days ago in the Journal of Hypertension 25 patients were recruited for an experimental procedure to locate and remove adrenal adenomas from patients suffering from primary aldosteronism. Doctors used a Carbon-11 Metomidate radioactive tracer to mark adenomas for PET-CT identification. Where a diagnosis couldn’t be made via the PET scan, venous sampling was used as a second-line test. The PET process achieved 80% diagnostic accuracy, venous sampling achieved 75% accuracy, and the two combined were 100% accurate.

Twenty of the patients were able to be surgically treated. All of these patients saw their blood aldosterone levels return to normal. For five of them their blood pressure went down to normal levels. Ten others experienced some improvement, and five had no clinical improvement their blood pressure, giving an overall efficacy of 75%. None of the patients reported long term side effects. The surgical procedure itself was took about 10 minutes to carry out.

The study only involved a few patients so further studies are needed, but appears very promising for patients suffering high blood pressure. Patients with Cushing’s syndrome, hyperandrogenism, or hyperfeminization could also potentially benefit.

Black arrow indicates adenoma
Black arrows indicate bilateral hyperplasia

Study of Grey Wolf Packs Examines Pack Stability

A study published in Frontiers of Ecology examined grey wolf pack stability over 33 years from five National Parks in the United States. The parks were located in Alaska, Wyoming, and Minnesota. Many different population management methods have been used throughout American history, ranging from complete eradication to full protection under the Endangered Species Act. The study examined the survival of packs based on mortality levels of pack members.

Grey Wolf
Image Credit: Yellowstone Wolf Project

The largest average pack sizes were found in Yellowstone and Grand Teton National Parks, where sizes ranged from 6 to 8 in the early spring, to 10 to 12 in the fall. The smallest were found in Voyageurs National park, with a range of 4 to 5 members.

The authors found that human caused deaths tended to have much more drastic effects than natural deaths among pack members. Human caused deaths are more likely to involve pack leaders, breeding females, or other healthy members of the pack. When breeding females were lost, the pack was very unlikely to produce pups the next spring. Most human caused deaths were from legal hunting or illegal poaching. Most accidental deaths were caused by vehicle collisions. Packs that experienced no human caused deaths had an 80% or greater chance of persisting into the next year. Human caused deaths reduced that chance to as low as 60%.

The authors noted that the dissolution or collapse of a pack doesn’t necessarily imply the death of all the pack members. Pack dissolution and formation are a natural part of the lives of grey wolves. Overall populations tend to persist even when packs come apart.

Voyageurs National Park Wolf Project

History of Wolves at Yellowstone Video

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