Jamie Hale

Jamie Hale

Thursday, September 10, 2020

So Many Brain Myths

Discussions on the brain are ubiquitous. Magazines, books and T.V. are saturated with  information related to the brain. Lots, if not most of it is wrong.

How Many Neurons Are in the Human Brain?

When I was an undergraduate in graduate school, I learned the human brain consists of 100 billion neurons (Kolb and Whishaw 2009). This number was reported in scholarly journals, textbooks, and in college lectures. It was accepted as fact. I never saw a citation of an original source to support the claim, nor did I ever hear anyone question whether or not there was evidence to support it. I just assumed it was common knowledge and must be supported by a large body of data. Even the general public knew that the human brain consists of 100 billion neurons. In addition to academia’s dissemination of the supposed fact, popular media embraced and promoted the 100 billion neuron idea...

  

The Allure of Brain Science

The media have become fascinated with brain images—and the use of those images to explain almost everything. Neuroscience (the scientific study of the nervous system, in many cases focusing only on the brain) has made a mark in mainstream media and everyday conversation. You have probably seen headlines such as “This Is Your Brain on Sugar,” “The Brain’s Evil Spot,” or “Brain Based Learning.” These phrases, and the stories associated with them, generally hold some truth but at the same time are misrepresented and often fuel false beliefs and misconceptions. As an example, consider the implications of the so-called “Sugar Brain.” Proponents claim that consumption of sugar can activate the same brain reward mechanisms (dopamine pathway referred to as mesolimbic dopamine system) as those activated when consuming addictive drugs. Some of the same brain areas are activated (varying in strength and intensity) when consuming sugar and drugs, but other stimuli also activate the mesolimbic dopamine system. The mesolimbic dopamine system is rich in dopaminergic neurons. Dopamine cell bodies (parts of brain cells where dopamine is synthesized) are located in the brainstem...

 

The Truth About Nootropic Supplements

Nootropic substances—from the Greek words meaning “mind-bending” –are ingestible chemicals often promoted for their cognitive enhancing properties (Jasanoff 2018). According to companies selling nootropic products, benefits of using the products include prevention of cognitive decline, enhanced memory, increased learning, improved concentration, and rapid cognition. Nootropic drugs include stimulants like amphetamine and methylphenidate, marketed under the names Adderall and Ritalin, as well as sleep suppressants like Modafinil. Nootropics also include a range of dietary supplements...

 

 

 

  

Monday, August 17, 2020

Replication Studies in Science

Ideally, scientific research should be replicable (reproducible). The research should use processes that can be used by others wanting to conduct a similar or the same study. When referring to the replication crisis it is often understood that what is meant is lack of replicating statistically significant findings. It would be more precise to say there is a "statistically significant replication crisis." It is possible that original studies that fail to show significance may demonstrate a type 2 error- missing an effect. This could occur do to a number of methodological or statistical issues. As an example, when I conducted a study on expectations influence on food liking the finding was insignificant; when I ran a statistical power analysis it revealed I needed a larger sample, considering effect size and p-value to find significance. Statistically significant and insignificant finding should be replicated, and they should involve different type of replications using samples with varying characteristics.

What are some different types of replication studies?

There are least 3 general types of replication studies- direct replication, conceptual replication and replication-plus-extension. In direct replication, researchers attempt to conduct research using methods that are as close as they can to those used by original researchers. The more transparent the original research the easier it will generally be to directly replicate. In conceptual replication researchers address same topics, questions, but use different methods. Variables are manipulated and measured using different strategies, but conceptualization remains intact. In a replication-plus-extension study, researchers replicate original studies, but also add variables, that may include different operationalizations.

What are the implications of replication studies?

Extra weight is often given to studies that are replicated (also find significance) outside of the original lab, or when conducted by researchers other than the ones making the original findings. A red flag is indicated if only a specific group or lab is able to make a finding. Why is it others can't make the finding? It is essential that researchers are transparent with their methods and all relevant research materials. Strong evidence is the result of various studies; not a single study, or series of studies that can only be found by one research group. To reiterate, scientific progress is cumulative; it develops as a product of the work, of sometimes many people. In some cases it is necessary to repeat studies that didn't find significance. The original study might be flawed. The Apex of evidence is converging evidence. Various research methods, stats, models and inferential strategies have limitations- it is the preponderance of evidence from various lines of inquiry that converge to produce the highest level of evidence.

For further discussion on issues with scientific methods refer to -   In Evidence We Trust 2nd Edition  

Various articles on replication from Andrew Gelman's site