Posts Tagged ‘brain’

Are IQ tests fundamentally flawed?

December 20, 2012

The issue is not measurement – for measurements made properly do not lie.

But the interpretation of what they measure and how they may be related to what we choose to call “intelligence” is controversial. The uncertainty is exacerbated by the varying definitions of what “intelligence” is. Where is the boundary between native intelligence and that dependent upon some measure of knowledge? Is there intelligence without memory or artificial intelligence without data storage? Is intelligence just processing power or is it processing with purpose? Does judgement matter? Or the speed of learning? Can there be wisdom without intelligence?

Nevertheless “well-constructed IQ tests are generally accepted as an accurate measure of intelligence by the scientific community”.

IQ scores are used as predictors of educational achievement, special needs, job performance and income. They are also used to study IQ distributions in populations and the correlations between IQ and other variables. The average IQ scores for many populations have been rising at an average rate of three points per decade since the early 20th century, a phenomenon called the Flynn effect. It is disputed whether these changes in scores reflect real changes in intellectual abilities.

Science Daily reports on a new paper : “After conducting the largest online intelligence study on record, a Western University-led research team has concluded that the notion of measuring one’s intelligence quotient or IQ by a singular, standardized test is highly misleading.”

Fractionating Human Intelligence by Adam Hampshire, Roger R. Highfield, Beth L. Parkin and Adrian M. Owen, http://dx.doi.org/10.1016/j.neuron.2012.06.022

(A pdf version of the paper is available here).

Summary

What makes one person more intellectually able than another? Can the entire distribution of human intelligence be accounted for by just one general factor? Is intelligence supported by a single neural system? Here, we provide a perspective on human intelligence that takes into account how general abilities or “factors” reflect the functional organization of the brain. By comparing factor models of individual differences in performance with factor models of brain functional organization, we demonstrate that different components of intelligence have their analogs in distinct brain networks. Using simulations based on neuroimaging data, we show that the higher-order factor “g” is accounted for by cognitive tasks corecruiting multiple networks. Finally, we confirm the independence of these components of intelligence by dissociating them using questionnaire variables. We propose that intelligence is an emergent property of anatomically distinct cognitive systems, each of which has its own capacity. 

Highlights

  •  We propose that human intelligence is composed of multiple independent components
  •  Each behavioral component is associated with a distinct functional brain network
  •  The higher-order “g” factor is an artifact of tasks recruiting multiple networks
  •  The components of intelligence dissociate when correlated with demographic variables
While this paper adds weight to the view that the standard IQ test is much too simplistic, I tend to accept that IQ tests do measure some diffuse thing which is connected to whatever can be said to constitute intelligence. But in over 30 years of recruiting I have never found it particularly decisive as a selection criterion. While it has been sometimes helpful in screening a large number of applicants, I cannot recall a single instance where an IQ score has been the deciding factor for my making a selection.
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The art of neurogenesis

November 21, 2010

http://thebeautifulbrain.com/2010/11/gallery-the-art-of-neuroscience-vol-iii/

Neurogenesis– the creation of new neurons in the brain– was conventionally believed to only occur in the growing brains of infants and children.  In the 1960s, data started appearing that showed the birth of new neurons in adult, fully formed brains.  Now, 40 years later, adult neurogenesis is one of the more robust fields of study in the neurosciences.

Jason Snyder studies adult neurogenesis in Heather Cameron’s lab at the National Institute of Mental Health in Bethesda, MD.  Snyder’s research focuses on neurogenesis in the hippocampus, highlighting the role of these new neurons in such fundamental behaviors as memory formation and learning.

Here are some of Snyder’s images made using electrophysiological techniques for studying the brain.

Further images can be enjoyed at The Beautiful Brain:

GFAP and TK staining around the ventral portion of the 3rd ventricle: image Jason Snyder

Tissue stained for doublecortin and NeuN: image Jason Snyder

The Keepers of Memory

July 28, 2010

Yesterday I met someone after 35 years.

The memories that were triggered were sharp and clear but we each remembered different episodes with differing degrees of clarity. Many memories that surged to the surface were matters that I had not consciously thought of during the 35 year interval.

Why then are some memories stored in the brain with – apparently – no deterioration and a mass or surrounding detail and others are only vague recollections or even non-existent?

Perhaps the answer lies in the protein kinase PKMzeta. In The Beautiful Brain PodcastTodd Sacktor, Professor of Physiology and Pharmacology at SUNY talks about his research regarding the mechanisms of long-term memory storage—and deletion— in the brain.

image: http://www.cerebromente.org.br/n14/mente/chaos.html

Sacktor’s research investigates the activity of a class of proteins which are very active around synapses— the protein kinases –  and they come in several varieties in the brain. They catalyze chemical reactions at the synapse, allowing a neuron to become more or less responsive to the electrical firing of its neighbor by aiding reactions that reshuffle neurotransmitter receptors.

Sacktor has identified one kinase in particular—called PKMzeta—which seems to be directly responsible for the maintenance of memory in the brain. When PKMzeta is found at a synapse, the memory encoded there is OK—it’s being maintained. When PKMzeta stops working at a synapse, the memory floats into the abyss of the brain, disassembled into its consituent cellular parts and extinguished from our recollection. In this edition of the podcast, Sacktor discusses his research and its implications on the way we understand memory storage in the brain.

Cajal’s Butterflies of the Soul

June 12, 2010

Santiago Ramón y Cajal, the father of modern neuroscience, was born on May 1, 1852 in Navarre, Spain. His drawings of what he saw in his light microscope slides are the inspiration for Cajal’s Butterflies of the Soul (2010) by Javier DeFelipe, Oxford University Press. The book contains two-hundred and eighty-two exquisite images of the brain.

Exquisite Data: a Review of Cajal’s Butterflies of the Soul




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