How brain imaging redefine intelligence

High-tech scans of the resting human brain can provide a new way to define and interpret the brain's actual mental capacity, new research suggests. NYU School of Medicine researchers used a specialized imaging technology to measure patients' brains for entropy , the variety of nerve circuits used to interpret the surrounding world.

Part of theories on human consciousness, the concept of entropy has become a greater research focus with recent improvements in the ability of functional magnetic resonance imaging (fMRI) to track chemical activity patterns in the brain.

By analyzing fMRI images in every region of the brains in 892 American men and women, the study authors linked greater entropy to more versatile processing of information. This is considered a key aspect of intelligence, researchers say, because of the large volume of sensory information coming into the brain from its environment.

Functional MRI scans of brain entropy are a new means to understanding human intelligence," says study lead investigator Glenn Saxe, MD, a professor in child and adolescent psychiatry at NYU School of Medicine and a member of NYU Langone Health's Neuroscience Institute.

Human intelligence is so meaningful because it is about the capacity to understand whatever may come, when there is no way beforehand to know what may come. An intelligent brain has to be flexible in the number of possible ways its nerve cells, or neurons, may be rearranged.

Functional MRI scans use magnetic fields and radio waves to measure subtle changes in blood flow to detect which brain cells and circuits are active or inactive. As part of the study, people were tested when their brains and minds were resting (not unengaged in a particular task) to get a base reading. Study participants had their brains imaged as they enrolled in the Harvard-based Brain Genomics Superstruct study over the last decade, with the stored images forming the foundation of the NYU team's analysis.

Researchers compared hundreds of fMRI scans taken milliseconds apart. The scans revealed the number of possible combinations of electrically active brain cells available to interact with each other in specific regions of the brain. The research team then used mathematical models validated by past studies to arrive at reliable, statistical entropy scores based on how well one set of active nerve-cell combinations captured by one image predicted those in the next image. Experts say the activity level of the estimated 100 billion neurons in the brain depends on how much sensory information is being processed at any instant, with many often inactive.

Scientists next compared their statistical measures of relatively higher or lower entropy with participants' scores on two standard IQ tests: the Shipley-Hartford test, which gauges verbal skills, and the Wechsler test, which assesses problem-solving abilities. If brain entropy could offer useful insight into intelligence, then it should track closely with IQ scores.

People with average intelligence have an IQ score of about 100, with current study participants having an above-average IQ, at 108. Study participants ' entropy scores were strongly tied to IQ. Using standard statistical techniques that were performed two different ways to ensure accuracy, the researchers found that higher entropy was significantly related to the brain regions where previous research has shown it matters most.

 Entropy scores closely matched IQ scores from the Shipley-Hartford test for the left side of the middle brain (the left inferior temporal lobe), which is tied to learning speech. Similarly, entropy scores tracked closely with those from the Wechsler test for the front region of the brain (bilateral anterior frontal lobes), a known center for organization, planning, and emotional control.
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Memory depends on subtle brain signals

The fragrance of hot pumpkin pie can bring back pleasant memories of holidays past, while the scent of an antiseptic hospital room may cause a shudder. The power of odors to activate memories both pleasing and aversive exists in many animals. The intricate biochemical mechanism for storing scent-associated memories differs slightly from a less-understood mechanism for erasing unnecessary memories.

Understanding how brains actively erase memories may open new understanding of memory loss and aging, and open the possibility of new treatments for neurodegenerative disease. In multiple ways, the processes of forgetting and remembering are alike. In fruit fly models of odor-associated learning, both the saving and erasure of memories involves
dopamine activation of the brain cells. This clue in flies is important for understanding the human brain.

The olfactory systems of flies and humans are actually quite similar in terms of neuron types and their connections.activation of the neurons causes them to make an identical messenger molecule,  Tcyclic AMP, leading to a cascade of activity within the cell, either building or breaking down memory storage.

The research team discovered one G protein, called G alpha S, that latched on to a neural dopamine receptor called dDA1, associated with memory formation. They found a different G protein, called G alpha Q, linked up with a nearby dopamine receptor called Damb, associated with the machinery of forgetting. The next question was whether those two different G proteins could be controllers of the fly brain's memory machinery.

To find out, the researchers silenced genes involved in the production of the G alpha Q protein in the flies. The flies with the protein silenced were exposed to odors in aversive situations and sent through mazes to see how well they remembered to turn away in the presence of the scent. It appears in flies that some level of forgetting is a constant, healthy process.

There is a slow process that whittles away memories, and it continues whittling them away unless another part of the brain signals the memory is important and overrides it.It may be that the process of acquiring and forgetting memories ebbs and flows in a state of balance. Important memories like the taste of mom's pumpkin pie might be forever retained, but trivialities like what you wore ten years ago can fade into oblivion without consequence.
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Emotional reaction to odors

An alexithymic individual has difficulty, to a greater or lesser degree, in relating to sensations associated with emotion.
There is a partial overlap between the areas in human brain that deal with olfactory perception and those that process emotions.

Scientists divided study participants into three groups according to the severity of alexithymia (high, medium and low). They underwent a series of olfactory tests in order to investigate their reaction to different types of stimulation.

The scientists found that alexithymic individuals differ from others in their reaction to smells. What specifically distinguishes them are physiological parameters such as heart rate and electrical conductivity of their skin, which was found to be accelerated.

The tests also showed that there are differences in reactions between subjects characterised by affective alexithymia, in which the sphere of sensations, imagination and creativity is restricted, and those with cognitive alexithymia, which compromises the ability to identify, express and distinguish emotions.

The results obtained show that one of the characteristics of alexithymia is the altered physiological response to olfactory stimuli. Contrary to what one might expect, this study shows that the physiological reactions of alexithymic individuals to emotions induced by smells are not lower, but rather more intense. It is as if these subjects find themselves in a situation of perpetual, extreme activation in relation to their emotions, which appears to make them insensitive to emotional changes.
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How sleep helps the brain

Sleep contributes to the brain's ability to change and reorganise itself and this can help people with learning and memory disorders. Researchers used cutting edge techniques to record activity in the dendrites. Dendrite is parts of brain cells that is responsible for keeping new information.

They discovered that activity in dendrites increases when we sleep, and that this increase is linked to specific brain waves that are seen to be key to how we form memories.

Human brain have the ability to change and adapt based on our different experiences, sleep is very important for the changes. A large proportion of these changes may occur during very short and repetitive brain waves known as spindles.

Sleep spindles have been associated with memory formation in humans. During spindles, specific pathways are activated in dendrites, allowing memories to be reinforced during sleep.
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Long term use of electronics gadgets hinders brain development

According to neuroscientists, long term use of smartphones can hinders brain development, the use of technology is reducing hard work and accumulation of knowledge.

Human brain has a ‘use it or lose it policy’, the ability to store facts may become diminished through lack of regular practice to recall information without checking the internet.

Time spent in a screen-based world displaced time spent ‘learning, playing and socialising in the real world’.
Outsource thinking to smartphones and other digital devices will leads to loss of brain muscles.

 Technological dependence on internet for information could have profound effects on how we routinely make sense of complex arguments, logical reasoning and creativity.

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Use of marijuana is associated with psychosis

 Psychosis is a severe mental disorder that affects thought and emotions which leads to impaired contact with external reality.

Ingredients in marijuana have opposite effects on human brain, tetrahydrocannabinol THC, increases the brain processes that can lead to symptoms of psychosis.

Marijuana users may experience psychosis because THC interferes with the brain's ability to distinguish between stimuli that are important, and those that are not.

Psychotic symptoms have been linked to abnormal salience attribution, meaning that the brain has difficulty telling the difference between stimuli that are important and those that are not.

Functional magnetic resonance imaging (fMRI) scans was used to observe participants brains after they took pills containing THC. The images showed changes in the areas of the brain that linked to symptoms of psychosis.

Taking THC increased the activity in the prefrontal cortex, but lower activity in the striatum because THC alters the brain's levels of the neurotransmitter dopamine.
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