Archive for October, 2010

Right and Left Brain

October 26, 2010 Leave a comment

The brain is divided physically into a left and right half is not a new discovery. The Egyptians knew that the left side of the brain controlled and received sensations from the right side of the body and vice versa.

It is only in the last two dozen years, however, that the true implication of the left/right split has gradually become apparent, through the work of a number of researchers. The most famous are probably Dr. Roger Sperry and Dr. Robert Ornstein of the California Institute of Technology. Their work has won them a Nobel prize.

Sperry and Ornstein noted that the left and the rig hemispheres are connected by an incredibly complex network of up to 300 million nerve fibres called the Corpus callosum. They were also able to show that the two halves of the brain tend to have different functions.

They (and other researchers) indicate that the left brain primarily appears to deal with language and mathematical processes and logical thought, sequences, analysis and what we generally label academic pursuits. The right brain principally deals with music, and visual impressions, pictures, spatial patterns, and colour recognition. They also ascribe to the right brain the ability to deal with certain kinds of conceptual thought – intangible ‘ideas’ such as love, loyalty, beauty.

The specialization of the two halves of the brain can result in some bizarre behaviour. Patients who, for medical reasons, have had their Corpus callosum severed, have effectively two semi-independent brains: two minds in one head.

If a ball is shown to the left visual field of such a person, i.e. registered to their right brain hemisphere, the speaking half of the brain, which is in the other, (left) brain will claim to have seen nothing. If, however, the patient is asked to feel in a bag of assorted shapes he will correctly pull out a ball. If he is asked what he has done he will say ‘nothing’. The ball has only been seen with the right brain, and felt with the right brain. The speech centre, which is located in the left brain, has registered nothing.

Even more delicate experiments have been performed on surgically split-brained patients. The word SINBAD was projected to such a patient while his eyes were focused on the precise spot between N and B. The first 3 letters went to his right brain, the last three to his left hemisphere. When asked to saywhat he had seen, he replied BAD. When asked to point with his left hand to what he had seen he pointed to the word SIN.

The specialisation of the two brains has also been demonstrated by measuring the electrical activity of the brain during various activities.

When the brain is relaxed in a state of rest, it tends predominantly to show an alpha brain wave rhythm – i.e. 8-12Hz waves. Ornstein found that a subject tackling a mathematical problem showed an increase in alpha in the right hemisphere. This indicated that the right side was relaxing whilst the left was active and, therefore, in a beta brain wave pattern. In contrast, when a subject was matching coloured patterns, the left showed alpha (i.e. was resting) and the right showed beta (i.e. was active).

The brain scans, show the varying levels of electrical brain activity in a subject listening to music, words and singing. The first activity (music) involved the right brain. The second (listening to words only) involved the left brain, but singing (words and music together) involved the whole brain.

The left brain is now thought to be the half that specialises in serial, sequential thought, i.e. analysing information in sequence in a ”logical” step by step approach. The left rationalises. The right brain seems to take in several bits of information ”at a glance” and process them into one overall thought. The right synthesises.

When you meet someone it seems to be the right brain that takes all the elements at once and synthesises the pattern into a whole to recognise the person instantaneously. If you were using your left brain only you would probably scan first the hair, then the forehead, then the eyes, nose, mouth and chin in sequence to ”build up” a picture. The right brain, however, recognises the pattern immediately.

It is the left brain that is dominant in, for example, mathematical calculations. It is the right brain that processes non-verbal signals.

We have come as a society to stress, and value more highly, the functions of the left brain. The analytical thinking of the physicist is usually valued higher (in money terms) than the artistic and intuitive ability of the musician or artist. Most schools relegate right brain dominant activities to two or three periods a week. Yet those schools who have tried increasing the proportion of arts subjects, have found that levels of all scholastic performance improved. Because, although the two halves of the brain may indeed be specialised, they are far from being isolated. Each compliments and improves the performance of the other.

Education that emphasises only analytical thinking is literally ”single minded”. As one psychologist put it »Such people’s brains are being systematically damaged. In many ways they are being de-educated.«


Brain Waves

October 25, 2010 Leave a comment

The brain generates tiny electrical pulses as thoughts traverse the labyrinth of the mind. The physical conduits of these thoughts are the millions of nerve cells or neurons in the brain. Just as radio signals, in order to make a comprehensible message, are beamed out on radio waves, a band of signals within a defined frequency, so the brain’s activity also occurs in waves. Brain waves can be measured on an electro-encephalograph machine (which is normally abbreviated to EEG Machine). By attaching sensitive electrodes to the scalp, it is possible to measure accurately the type of brain wave that a subject is producing. These waves are usually expressed in the number of cycles per second (CPS) or with their frequency (Hz).

Brain waves

The brain produces four main waves with specific frequencies:

Beta level brain waves – range 12-16 Hz (also 13-25 Hz)

Alpha level brain waves – range 8-12 Hz

Theta level brain waves – range 4-7 Hz

Delta level brain waves – range 0.5-3 Hz

The following chart relates each type of brain wave to its principal function. We must remember however, that when we speak of someone being ‘in alpha’ we mean that this is their characteristic and predominant brain wave. Other brain waves will also be present, but in smaller quantities than usual.

Brain activities

The linking of left and right brain activities is important in producing a shift from learning to accelerated learning. Yet our society is very ‘beta orientated’. We are busy thinking about the problem in hand, but don’t leave ourselves sufficiently open to  other influences, which would help us memorize faster and make the sort of less expected connections that we call creative thinking.

Beta brain

In beta you don’t see the wood for concentrating on the trees. But learn to relax, increase the proportion of the alpha and ideally theta brain waves, and you have created the conditions where you may begin to see the whole picture.

Alpha brain

‘Alpha’ is a natural and receptive state of mind, that we can all attain through the techniques of relaxation. They principally involve simple and pleasant relaxation exercises and listening to certain types of music.

Theta brain

The theta brain wave pattern is especially interesting. It occurs spontaneously to most of us in the twilight state between being fully awake and falling asleep. Arthur Koestler called it ‘reverie’. This drowsy stage is associated with fleeting semi-hallucinatory images. Thousands of artistic and literary inspirations and scientific inventions have been credited to this state, a sort of freeform thinking that puts you in touch with your subconscious.

Brain waves interpretation

Many psychologists would agree it is a reasonable hypothesis that, when left/right brain symbiosis takes place, conscious and subconscious are also united. The proportion of theta brain waves becomes much higher than normal. This is the moment when logical left brain activity declines. The left brain, which normally acts as a filter or censor to the subconscious, drops its guard, and allows the more intuitive, emotional and creative depths of the right brain to become increasingly influential.

If the hypothesis is true, then do women, popularly characterised as more intuitive, reach a walking theta state more often than men; and can this be associated with the fact that their left/right brain link, the Corpus callosum, is larger and richer in connective capabilities than men’s? We do not yet know, but it is a fascinating area for future research.

At the University of Colorado Medical Centre and at the Biofeedback Centre in Denver, Dr. Thomas Budzyski has found that, when people were trained to achieve and maintain theta brain waves using biofeedback techniques, they did indeed learn much faster. Moreover, many emotional and attitudinal problems were solved at the same time.

For example, in a theta state, suggestions that racial prejudice is wrong were well accepted. Suggestions to overweight people to follow a sensible eating pattern were accepted and subsequently complied with, and insomnia and drinking problems were successfuly tackled.

Some time ago a New York advertising agency was asked to produce a TV commercial to combat racial prejudice. They produced two. The first used a carefully built up rational argument. The second was a highly emotional film featuring attractive young black children and using many subconscious but positive appeals for fairness.

The logical TV commercial actually intensified the degree of racial prejudice. The subjects felt themselves threatened as they realized they could not give an equally dispassionate and rational counter argument. Consequently the only possible response was an aggressive defence involving an increased emotional commitment to their original attitude.

The second commercial however, worked. Emotion laden appeals went beyond the conscious, the intellectual objections, and created a new positive image at the subconscious level that changed the subject’s entire personal response, so no conflict or threat was aroused. Can intelligence be increased?

Whilst it is certainly an oversimplification to relate intelligence to brain capacity it is, however, interesting to relate three statements:

The average IQ is 100.

The genius-level is 160.

The average human probably uses 4% of his potential brain power.

If that average human could learn to use not 4% of his brain but a still minimal 7% of his brain, could he attain genius level? This article is about techniques that probably improve the human memory, that increase creativity and that provide access to unused brain power. The indications are that the same techniques can measurably improve intelligence.


Specific Brain Areas for Sex, Money

October 18, 2010 Leave a comment


This image illustrates the dissociation between primary and secondary rewards in the orbitofrontal cortex, a frontal region of the brain that is known to play a role in the evaluation of gratification. The more primitive region (in the back, shown in yellow) represents the value of erotic images shown to the participants, while the most recent region (in the front, in blue) represents the value of monetary prizes won by the volunteers in the experiment. Credit: © Sescousse / Dreher


A team of French researchers headed by Jean-Claude Dreher of the Centre de Neuroscience Cognitive in Lyon, France, has provided the first evidence that the orbitofrontal cortex (located in the anterior ventral part of the brain) contains distinct regions that respond to secondary rewards like money as well as more primary gratifications like erotic images. These findings, published in The Journal of Neuroscience, open new perspectives in the understanding of certain pathologies, such as gambling addiction, and the study of the neural networks involved in motivation and learning.

In our everyday lives, we often encounter various types of “rewards”: a 20-euro bill, a chocolate bar, a glass of good wine… Moreover, we must often choose between them, or trade one for another. To do this, we must be able to compare their relative value on a single consistent scale, which suggests that all types of rewards are assessed in the same brain areas. At the same time it is possible that, due to their individual characteristics, different rewards may activate distinct cerebral regions. In particular, there could be a dissociation between so-called “primary” gratifications such as food or sex, which satisfy basic vital needs and have an innate value, and more “secondary” rewards such as money or power, which are not essential for survival and whose value is assessed by association with primary gratifications.

To verify these hypotheses, Jean-Claude Dreher and Guillaume Sescousse conducted an original experiment in the form of a game that rewarded 18 volunteers with money or erotic images, while their cerebral activity was monitored using an FMRI (functional magnetic resonance imaging) scanner.

The experiment showed that the rewards are indeed evaluated in partially shared cerebral regions, namely the ventral striatum, insula, mesencephalon and anterior cingulate cortex. The researchers have also confirmed that there is a dissociation between primary and secondary rewards in the orbitofrontal cortex. Its posterior region (more primitive) is specifically stimulated by erotic images (a primary reward), while its anterior region (which is more recent in man) is activated by monetary gain (a secondary reward). The more abstract and complex the reward, the more its representation stimulates the anterior regions of the orbitofrontal cortex.



The volunteers in the experiment played a game in which they could win money or view erotic images, while their cerebral activity was recorded using an FMRI scanner. Credit: © CERMEP – Imagerie du Vivant



These results provide the first evidence of a dissociation in the brain between two types of reward, suggesting the existence of distinct regions corresponding to various gratifications. Dreher and Sescousse’s research could lead to a better understanding of certain psychiatric disorders, including gambling addiction.

More information: G. Sescousse, J. Redouté, J-C Dreher (2010) The architecture of reward value coding in the orbitofrontal cortex. J Neurosci, 30 (39)

Provided by CNRS

Journal Reference:

G. Sescousse, J. Redoute, J.-C. Dreher. The Architecture of Reward Value Coding in the Human Orbitofrontal Cortex. Journal of Neuroscience, 2010; 30 (39): 13095 DOI: 10.1523/JNEUROSCI.3501-10.2010

The Neural Basis of Synesthesia

October 18, 2010 Leave a comment

Wikipedia has a page on the neural basis of synesthesia, but not yet described there is a new study in press by Vilayanur S. Ramachandran’s group that provides interesting insights.

Synesthesia is a neurological condition in which affected individuals experience one sense (e.g. hearing) as another sense (e.g. visual colours). Ramachandran’s latest study investigated grapheme-colour synesthetes who experience specific colours when they view specific graphemes (i.e., letters and numbers). The results demonstrate that two brain areas – for grapheme and colour representation respectively – are activated at virtually the same time in the brains of synesthetes who are viewing letters and numbers. On the other hand, normal controls viewing the same thing exhibit activity in the grapheme region but not the colour region.

This is the first study of synesthesia to demonstrate simultaneous activation of the two brain areas, known as the posterior temporal grapheme area (PTGA) and colour area V4 (pictured below in the brain of a representative synesthete). The finding was made possible because the researchers used a neuroimaging technique called magnetoencephalography (MEG) to measure weak magnetic fields emitted by specific areas of the brain while the subjects viewed graphemes. Compared to other neuroimaging techniques, such as fMRI and EEG, MEG offers the best combination of temporal and spatial precision in measuring brain activation.

If you read the Wikipedia page, you know that there are two main theories that attempt to explain how synesthesia occurs in the brain: the cross-activation theory and the disinhibited feedback theory. Let’s call them Theory 1 and Theory 2 for simplicity. Theory 1 posits that the grapheme and colour brain areas are ‘hyper-connected’ such that activity in the grapheme area evoked by viewing a letter or number immediately leads to activity in the colour area and conscious perception of colour. Theory 2 maintains that there are ‘executive’ brain areas that control the communication between the grapheme and  colour areas, and in synesthetes this control is disrupted. To reiterate, Theory 1 says that normal brains are anatomically different than synesthete brains, whereas Theory 2 says that normal brains are the same as synesthete brains but the two brains act differently.
The results of Ramachandran’s group support Theory 1, the cross-activation theory, since this model predicts that the colour and grapheme areas should be activated at roughly the same time in synesthetes looking at graphemes.
This is perhaps the strongest evidence for the cross-activation theory of synesthesia to date. But to complicate things, Ramachandran’s group proposed a new theory called ‘cascaded cross-tuning model,’ which is essentially a refinement of the cross-activation model (let’s call it Theory 1.1).

According to Theory 1.1, when a synesthete views a number, a series of simultaneous activations lead to perception of a colour. First, a subcomponent of the grapheme area responds to features of the number (e.g. the “o” that makes up the top of the number 9). This leads to activity in other subcomponents of the grapheme area representing possible numbers that the feature is part of (e.g. the “o” could be a component of the numbers 6, 8, or 9) as well as the colour area V4. At this point however, colour is not consciously perceived. Next, when the grapheme area identifies the number 6 (based on monitoring by other brain areas), activity in V4 is triggered, leading to conscious perception of the colour associated with the number 6.

Cool theory? Cool theory.

Note, however, that it only applies to ‘projector’ synesthetes who see colours in the outside world when they see numbers, but not ‘associator’ synesthetes who perceive the colours in the “mind’s eye.” Also, it doesn’t yet apply to other forms of synesthesia, such as acquired synesthesias (e.g. synesthesia for pain).

Yeah, it’s only a matter of time before Theory 1.2 takes over.

Brang D, Hubbard EM, Coulson S, Huang M, & Ramachandran VS (2010). Magnetoencephalography reveals early activation of V4 in grapheme-color synesthesia. NeuroImage PMID: 20547226