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Radiology and intelligence
Elīna Romanovska
18.03.2017., Rīga
Mentors:
Gaida Krūmiņa MD.PhD.
Professor, Head Department of Radiology
Nauris Zdanovskis
Doctor - resident
Riga Stradins University
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Intelligence:
» Measuring intelligence;
Networks for human intelligence:
» Connectome;
Intelligence and:
» Cerebral glucose metabolism;
» Brain biochemistry.
Take home message
Presentation content
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Derives from Latin verb Intelligere – ability to think;
“..a capacity for logic abstract thought, understanding, self-
awareness, communication, learning, emotional knowledge,
memory, planning, creativity, problem solving.”
Intelligence
Acquire knowledge Apply knowledge
Engage in abstract reasoning
1 http://bcr2016.org/files/event_sessions_lections/50eee4ee7dc7fe63c80a90bc9ecd03af.pdf
2 http://www.dictionary.com/browse/intelligence
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Historically – by observing
people behavior in daily life;
First attempt to measure
human intelligence:
»The Binet –Simon Scale
(1905)
Measuring intelligence
"Which of these two faces is the prettier?"
1 http://open.lib.umn.edu/intropsyc/chapter/9-1-defining-and-measuring-intelligence/
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Nowadays, the most commonly used
individual IQ test:
»Wechsler Adult Intelligence Scale
(WAIS – IV),
»Wechsler Intelligence Scale for
Children.
Other tests:
»Stanford– Binet,
»Woodstock – Johnson test,
»Cognitive Assessment System,
»Differential Ability scales,
»Kaufman Assessment Battery for
Children.
Measuring intelligence
1 http://open.lib.umn.edu/intropsyc/chapter/9-1-defining-and-measuring-intelligence/
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WAIS - IV
Which 3 of these pieces go together to
make this puzzle?
Which one of these goes here to
balance the scale?
1 http://images.pearsonclinical.com/images/assets/WAIS-IV/WAISIV2_6_08.pdf
2 http://www.talentissimo.eu/giftedness/
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Scanning the connectome - I
Mapping structure
DTI MR
Mapping function
Resting-state fMRI
1 http://www.dynamic-connectome.org
2 http://www.meduniwien.ac.at/fmri/research/functional-mri/
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Based on diffusion of water molecules in the brain;
»Water diffusion in white matter fibers is anisotropic faster in the
direction of the fibers.
MR DTI
1 http://emedicine.medscape.com/article/345561-overview#a6
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Data on structure and function can be
combined and analyzed by Graph
(network) theory;
Neural fiber pathways connecting
grey matter can now be represented
as a network, a set of nodes and
edges
» Nodes
» Edges
» Hubs
» “Rich club”
Scanning the connectome - II
1 http://www.jneurosci.org/content/29/23/7619.long
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Hubs, cores and ”rich club” play important
role in global communication, by:
» Creating short (efficient) paths;
» Supporting integration of information
across diverse brain systems.
“Rich-club” members:
» Superior parietal cortex;
» Superior frontal cortex;
» Precuneus;
» Putamen;
» Hippocampus;
» Thalamus.
Scanning the connectome - II
1 http://www.jneurosci.org/content/29/23/7619.long
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“Rich club” regions and connections
Almost all regions of the brain
have at least one link directly
to the “rich club”!
1 http://www.jneurosci.org/content/29/23/7619.long
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Most prominent effects between IQ and the level of global connectivity efficiency
were found in the:
» Medial prefrontal cortex (yellow box),
» Bilateral inferior parietal cortex (red box),
» Precuneus/posterior cingulate regions (orange box) of the functional brain network.
1 http://www.jneurosci.org/content/29/23/7619.long
Correlations between IQ and resting-state fMRI:
The brain areas that were activated as an efficient network during resting periods (with less
activity in more intelligent individuals) matched the frontal and parietal regions that
were found to be activated in intelligent subjects under high cognitive demand!
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Brain energy metabolism
The brain has high energy
requirement:
» 20% oxygen,
» 25% of the glucose.
The main processes contributing
to the high brain energy needs:
1 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900881/figure/F1/
2 https://issuu.com/gfbertini/docs/brain_imaging_studies_of_intelligence_and_creativi/8
Maintenance and
restoration of ion
gradients
Uptake and recycling
of
neurotransmitters
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The most frequently-used methods of brain metabolic
imaging are the detection of 18F-FDG by positron
emission tomography (PET);
Brain energy metabolism
1 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900881/figure/F1/
2 https://issuu.com/gfbertini/docs/brain_imaging_studies_of_intelligence_and_creativi/8
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Intelligence and cerebral glucose metabolism –
at rest
Higher IQ
Increased brain activity
Glucose metabolism
is lower;
Downgraded IQ
Glucose metabolism is higher
Slower mind works less
economically.
1 http://bcr2016.org/files/event_sessions_lections/50eee4ee7dc7fe63c80a90bc9ecd03af.pdf
2 https://issuu.com/gfbertini/docs/brain_imaging_studies_of_intelligence_and_creativi/8
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Intelligence and cerebral glucose metabolism –
performing tasks
Normal distribution of FDG uptake in the brain.
Higher IQ
Accomplished the
task with a lower
consumption of
energy
Downgraded IQ
Used more glucose
(non effective) to
solve tasks
1 http://bcr2016.org/files/event_sessions_lections/50eee4ee7dc7fe63c80a90bc9ecd03af.pdf
2 https://issuu.com/gfbertini/docs/brain_imaging_studies_of_intelligence_and_creativi/8
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Intelligence and cerebral glucose metabolism –
performing highly complicated tasks
Glucose
consumption in
gifted people is
vastly higher than
in control groups
Outstanding
individuals have
higher neuronal
reserve and higher
brain plasticity.
1 http://bcr2016.org/files/event_sessions_lections/50eee4ee7dc7fe63c80a90bc9ecd03af.pdf
2 https://issuu.com/gfbertini/docs/brain_imaging_studies_of_intelligence_and_creativi/8
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Investigates brain biochemistry in vivo;
The basic principle of MRS:
»Uses signals from hydrogen protons:
- MRI uses the information to create 2D
images of the brain,
- MRS uses 1H signals to determine the
relative concentrations of target brain
metabolites.
MR spectroscopy
1 http://www.medscape.com/viewarticle/430195
2 http://www.ajnr.org/content/27/10/2210/F1.expansion.html
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Each metabolite appears at a specific ppm, and each one
reflects specific cellular and biochemical processes:
» N-acetyl Aspartate (NAA)
» Choline (Cho)
» Creatine (Cr)
» Lipids/lactate (L)
» Glutamate (Glu)
» Myoinositol (Myo)
MR spectroscopy
1 http://www.medscape.com/viewarticle/430195
2 http://www.ajnr.org/content/27/10/2210/F1.expansion.html
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Positive correlations between intelligence and concentrations of:
» Elevated N-acetyl aspartate
- A metabolite of the oligodendrocytes that form the myelin sheath
around nerve fibers
Human intelligence and brain
biochemistry
Indicates neuronal
and axonal
integrity
↓
Healthy, vital
neurons, high
intellect;
1 http://bcr2016.org/files/event_sessions_lections/50eee4ee7dc7fe63c80a90bc9ecd03af.pdf
2 http://www.ajnr.org/content/27/10/2210/F1.expansion.html
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Positive correlations between intelligence and concentrations of:
» Elevated Creatine
- Tissue energetics, tissue energy store for brain,
- Increased mental performance;
Human intelligence and brain
biochemistry
Outstanding
mind
abilities
1 http://bcr2016.org/files/event_sessions_lections/50eee4ee7dc7fe63c80a90bc9ecd03af.pdf
2 http://www.ajnr.org/content/27/10/2210/F1.expansion.html
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Positive correlations between intelligence and concentrations of:
» Lowered Choline
- A precursor of acetylcholine (ACH), a component of cell membranes
associated with membrane turnover, or increase in cell division.
Human intelligence and brain
biochemistry
Excellent
myelin
membranes
condition
Fast
transmission
1 http://bcr2016.org/files/event_sessions_lections/50eee4ee7dc7fe63c80a90bc9ecd03af.pdf
2 http://www.ajnr.org/content/27/10/2210/F1.expansion.html
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Intelligence is determined besides genetic and
environmental factors, by structure and
neurochemistry of the brain;
Brain is on big always active neural network –
connectome;
Structural and functional connectivity, especially in
frontal and parietal regions higher IQ;
Outstanding individuals have higher neuronal reserve
and higher brain plasticity;
Economical approach.
Take home message
What is that defines us? Is it our visual appearance, character or places where we choose to live?
One of the most gratests things that can define and differ human beings is – intelligence!
Intelligence derives from the Latin verb intelligere = ability to think;
There are many definitions of intelligence Some of them suggest defining intelligence as a capacity for logic abstract thought, understanding, self-awareness, communication, learning, emotional knowledge, memory, planning, creativity, problem solving.
More precisely Intelligence is a person’s capacity to:
acquire knowledge (i.e. learn and understand),
apply knowledge (solve problems),
and engage in abstract reasoning.
What is the first thing that comes in to your mind when you think about measuring intelligence?
Well for me, it was IQ or intelligence quotient test.
Historically, even before IQ tests were invented, there were many attempts to classify people into intelligence categories by observing their behavior in daily life.
The first attempt to measure human intelligence had begun in the 19th century, when Alfred Binet (Binei) in collaboration with Theodore Simon developed the first intelligence test known as The Binet-Simon Scale (contained 30 items)
Attēls: Here you can see one of the original questions of the first IQ test!
Nowadays, there are a variety of IQ tests. The most commonly used individual IQ test is the Wechsler Adult Intelligence Scale for adults and the Wechsler Intelligence Scale for Children.
And here are mentioned other commonly used tests:
Frequency distribution of IQ scores in population
It all looks quite nice - solving puzzles, answering questions -, but there is one huge problem with all these tests – they only give us number, measured intelligence’s number! But what actually happens in such a beautiful and powerful/minds? How does intelligent mind work?
This is the moment when radiology (neuroimaging) steps in and let us look inside secrets of human intelligence!
To better understand how brain network works, we should start from the tiniest element of the brain – neuron.
When we look at neurons we see that they are not individual, alone floating elements of brain they primary property (as we can see in this picture) is that they want to connect with other neurons.
Millions of neurons form local networks, that together is connected by short range connections, but besides these short-range connections, some neurons have very long connections, projecting information to other side of brain As a result – brain is on big always active neural network and a complete neuronal interaction of this network is called connectome = a detailed road map of all connections of the brain.
First of all, when we speak about connectome it’s important to understand how we can build connectome.
There are 3 main points of building connectome:
Scanning structural brain network;
Scanning functional brain network’
And analysing information of these scans.
For mapping (other words) scanning structure we can use diffusion tensor MRI
As the name already says in front of us DT MRI is based on diffusion of water molecules in the brain;
Water diffusion in white matter fibers is anisotropic faster in the direction of the fibers.
By measuring water diffusion in many directions the orientation of white matter bundles can be retrieved at each brain location.
In different word, this technique provides information about size, orientation and geometry of myelinated axonal bundles.
And all together it gives information about structural connectivity of brain network.
In different word, this technique provides information about size, orientation and geometry of myelinated axonal bundles.
And all together it gives information about structural connectivity of brain network.
For mapping function – resting-state fMRI is used:
Resting-state fMRI measures brain spontaneous activity by detecting changes associated with blood flow Blood oxygen level dependent (BOLD) contrast.
Blood flow in the brain is highly locally controlled in response to O2 and CO2 (carbon dioxide) tension of cortical tissue:
When a specific region of the cortex increases its activity in response to a task the extraction fraction of oxygen from the local capillaries leads to an initial drop in oxygenated Hb and an increase in local CO2 and deoxygenated Hb.
After 2-6 seconds, cerebral blood flow increases, delivering a surplus of oxygenated Hb, washing away deoxygenated Hb The reason fMRI is able to detect this change is due to a fundamental difference in the paramagnetic properties of oxyHb and deoxyHb.
While arterial blood is similar in its magnetic properties to tissue, deoxygenated blood is paramagnetic
fcMRI maps and gradients are sensitive to the task used to acquire the data. An extreme example is displayed. Functional connectivity is displayed for a seed region (black circle) for data acquired during rest (left) and during the continuous, self-paced performance of a semantic classification task (right). The asterisk demarcates a region of prefrontal cortex that changes its coupling pattern. Whereas many results of fcMRI analyses are stable across rest and task states, other features and estimated network configurations change.
Resting-state networks. A number of group resting-state studies have consistently reported the formation of functionally linked resting-state networks during rest. These studies, although all using different groups of subjects, different methods (e.g. seed, ICA or clustering) (Beckmann et al., 2005, Biswal et al., 1995, Damoiseaux et al., 2006, De Luca et al., 2006 and Salvador et al., 2005a; Van den Heuvel et al., 2008a) and different types of MR acquisition protocols, show large overlap between their results, indicating the robust formation of functionally linked resting-state networks in the brain during rest. This figure shows the most consistent reported resting-state networks across these studies, including the primary sensorimotor network, the primary visual and extra-striate visual network, a network consisting of bilateral temporal/insular and anterior cingulate cortex regions, left and right lateralized networks consisting of superior parietal and superior frontal regions (*reported as one single network) and the so-called default mode network consisting of precuneus, medial frontal, inferior parietal cortical regions and medial temporal lobe.
Attēls un informācija: http://www.sciencedirect.com/science/article/pii/S0924977X10000684
Moving forward, we have finally reached the final part of building connectomics:
Nodes = brain areas, individual neuronal units;
Edges = physical connectivity between nodes;
Hubs = highly connected and highly central nodes;
Central hubs have a tendency to be highly connected to each other “Rich club” organization.
To better understand importance of rich club, I want to show you an example of airline traffic (air traffic map attēls):
“Areas in the brain are like airports of different sizes You have small airports like Pretoria (SA), intermediate airports like Rio de Janeiro, and big, wealthy hubs like JFK (NY) or Heathrow.
When there’s a problem at a small airport, it will have a limited impact on the rest of the traffic. But when there’s a problem at a hub, there will be consequences for the whole network. (It’s the same in the brain; some diseases affect hubs, others intermediate or small areas, and the effects on the organism will differ accordingly,”).
There are lots of studies that uses connectome not only to better understand how pathologies affects brain network, but to better understand brain functioning.
One of that kind of study was searching for associations between Efficiency of functional brain networks and intellectual performance (PĒTĪJUMS):
It seems that brains with higher IQ is in a energy saving mode while at rest so they can use maximum energy for functional efficiency when they are under high cognitive demand.
In a way, we can compare brain to the city:
In the big city, there are millions of people how life and work in hoses, shops and moles. There are hundreds of roads that keeps these buildings connective, providing people the opportunity to go from one place to another it is this flow that provides character to the city. It is not one property that define New York as NY, our Paris as Paris. It is this flow that gives a city it’s personality.
In the same way works our brain it’s not individual neuron our individual connections that makes our brain rather the functional state, flow of information in our connectome is that makes us how we are.
In a way, we can compare brain to the city:
In the big city, there are millions of people how life and work in hoses, shops and moles. There are hundreds of roads that keeps these buildings connective, providing people the opportunity to go from one place to another it is this flow that provides character to the city. It is not one property that define New York as NY, our Paris as Paris. It is this flow that gives a city it’s personality.
In the same way works our brain it’s not individual neuron our individual connections that makes our brain rather the functional state, flow of information in our connectome is that makes us how we are.
This is not the end of presentation, because connectome is not the only way how we can look to human intelligence throughout radiology.
Another way how we can look to INTELLIGENCE is by brain GLUCOSE METABOLISM:
The brain has high energy requirements:
About 20% of the oxygen and 25% of the glucose consumed by the human body are dedicated to cerebral functions, yet the brain represents only 2% of the total body mass.
The main processes contributing to the high brain energy needs:
Maintenance and restoration of ion gradients dissipated by signalling processes such as postsynaptic and action potentials,
As well as uptake and recycling of neurotransmitters.
The most frequently-used methods of brain metabolic imaging are the detection of radiolabeled glucose (FDG) by positron emission tomography (PET)
PET scan studies provide compelling evidence that:
at rest, when subjects can engage in any mental acitivity they wish
Individuals with higher IQ demonstrate increased brain activity Glucose metabolism is lower;
Individuals with downgraded IQ glucose metabolism is higher Slower mind works less economically.
Performing tasks:
Individuals with higher IQ accomplished the task with a lower consumption of energy;
Individuals with downgraded IQ used more glucose (non effective) to solve tasks.
Performing highly complicated tasks:
Glucose consumption in gifted people is vastly higher than in control groups Thereby outstanding individuals have higher neuronal reserve and higher brain plasticity.
Just like MRI MRS uses signals from hydrogen protons (1H)
Studies across a range of age groups have applied MR spectroscopy to examine white matter integrity in relation to intelligence, and they showed:
elevated Cr – outstanding mind abilities; lowered Ch - excellent myelin membranes condition, fast transmission - careful, politic, extravert individuals
found in metabolically active tissues (brain, muscle, heart) where it is important in storage and transfer of energy. It tends to be maintained at a relatively constant level, and is predominantly used as a convenient internal standard
Lowered Choline
A precursor of acetylcholine (ACH), a component of cell membranes associated with membrane turnover, or increase in cell division.
Excellent myelin membranes condition, fast transmission.
