Intro to Synaesthesia

Musicians painting scenes, hearing unidentifiable colours, chefs feeling flavors and artists experiencing colours. These are not the effects of LSD, but symptoms of a nonthreatening neurological condition called Synaesthesia. Meaning "The combining of the senses", individuals with synaesthesia experience consistent confusion of sensory input. Why and how can this happen? Is this a muddling of sensory input, or the awareness of nonvisual information passing through the eyes? A person with Synasthesia may associate every number they see with a different colour, experience 'seeing' sound or tasting shapes. Cases of synaesthesia have been reported in psychology and medicine for over a hundred years yet little is understood about why the sensation may occur and apart from inheritance, how someone may be physiologically vulnerable to it. Also, to what extent are most of us synaestheic( do you understand what is meant bysharp cheese, a blue day or any popular metaphor??) Until recently scientists were unsure synaesthesics existed as the symptoms are largely subjective and there had been no scientific evidence or means to acquire data for a comprehensive study. The little understanding of synathesia leads to fewer possible means to investigate; most people who have symptoms of graphene synaesthesia,the most interesting to study colour-associated form, have held symptoms from a young age or denveloped them as an adolescent. In both cases they may learn early on that most adults wont believe them or they assume everyone has a similar experience with senses. As a result, many people will keep symptoms and their subsequent effect on perception to themselves. Now, neuroscientists recognize specific stimuli can induce it leading scientists to ideas for experimental methods to investigate this strange mingling of the senses. To describe this strange sensation, particularly the more common visual part of it, we will first have to explore the visual system in more detail.

Senses and your brain

Apart from the somatosensory "feel" map, there are other highly specialised functional areas of the brain for sensory input and output. The Wernicke (language) and Broca (hearing) areas are of particular historical and anatomical significance. In 1874, Carl Wernicke hypothesized a link between the left posterior section of the superior temporal gyrus and reflexive mimicking,

associated with sensory and motor images. Wernicke notices that patients with damage to this area had trouble forming words, called aphasia. Like most structures in the brain, Wernicke's and Broca's area have symmetry and are contained on both sides of the brain, The dominant hemisphere processes dominant word meanings such as "barista given, coffee." The non-dominant side has a role in processing subordinate meanings of ambiguous words when presented in a context, like coffee given the ambiguous word -shop- when "coffee shop" is mentioned.

Motor Somatosensory Maps

As we talked about on Sunday, the parietal lobe of the brain contains a particularly interesting region known as the somatosensory map. These sensory maps are unique for every person and each has body parts placed onto a region of the cortex that represents it, with size proportional to cortical representation and sensitivity through sense input. If you do something that requires quick and complex figer movements touching something, like playing instruments or working with your hands, your homunculus will have larger hand representational areas, leading to the opportunity for more connection between that region and different parts of the brain (even other regions on the same map) This map is one of 8 and counting homunculi contained in the brain. The other important and closely nested map is part of the motor cortex which has a similar map but codes for the movement of different parts of the body.

What would your Motorsensory maps look like? Think about it as you do your normal routine... What parts of your body do you use the most? What parts of the body feel and sense things the most?

Diffusion Tensor Imaging

The brain has more than 100billion neurons communicating via axons creating complex and vast neuro networks. Connectivity patterns between regions of the brain, or connectomes can be shown by Diffusion Tensor Imaging, DTI. DTI works with the environment established by MRI, by measuring the restricted diffusion of water in tissue (while in the established MRI magnetic field), producing neural tract images that trace the pathways connecting areas of the brain that are in communication. Slicing and staining brains for observation post-partum is not very helpful towards understanding how the brain works and interacts with itself on the whole. DTI is the newest and only minimally invasive technique that can show the tracts of the brain.

Following fiber bundles have been shown in images: [1] Corpus Callosum (CC) and its subdivisions, [2] Tapetum (TP), [3] Inferior Longitudinal Fasciculus (ILF), [4] Uncinate Fasciculus (UNC), [5] Inferior fronto-occipital fasciculus (IFO), [6] Optic Pathways (OP), [7] Superior Longitudinal Fasciculus (SLF), [8] Arcuate Fasciculus (AF), [9] Fornix (FX), [10] Cingulum (CG), [11] Anterior Thalamic Radiation (ATR), [(12] Superior Thalamic Radiation (STR), [13] Posterior Thalamic Radiation (PTR), [14] Corticospinal/Corticopontine Tract (CST/CPT), [15] Medial Lemniscus (ML), [16] Superior Cerebellar Peduncle (SCP), [17] Middle Cerebellar Peduncle (MCP), and [18] Inferior Cerebellar Peduncle (ICP). [From Advanced Digital Imaginc Solutions Laboratory] If you are interested or a particular image catches your eye, google scholar or image search for any of the fiber bundles listed.

Reading CTs

If you have a CT scan that you have never been able to make sense of, check out this site...CT Scan Page You can get to know your own brain anatomy by identifying structures and understanding what functions they are responsible for.
For example, roll the curser over "Amygdala" and identify the same structure on your own scan.. this is the region responsible for emotional coding particularly when related to survival (fear, anger and pleasure) and deciding what aspect should be stored as memory and where.

And another really helpful neuroanatomy site MedWayne Diagradiology Great for getting a feel of what you are looking at on brain scans and orientating yourself around brain anatomy using sulci and gyrus, (the folds and valleys that look very dark on the scans)

fMRI Activation map and Subtraction

Activation maps — FMRIB Centre, University of Oxford
This Oxford webpage guides you through a simple fMRI experiment

To highlight a particular region's activation scientifically, a subtraction technique between a simulated and a control run of the experiment is frequently used. This minimises risk of misinterpreting activation from another area, a region that is not of significant interest to the experiment or study.

fMRI, the basics

fMRI or functional MRI is technique that can map brain areas activated by a task or sensory input. fMRI can be used for clinical or research purposes and like most of the devices I am mentioning, is non invasive, though uncomfortable. fMRI like most neuroimaging uses an understanding of principles of electromagnetism to infer the brain's activity. Taking advantage of the known orientation of atoms and a constant magnetic field in the MRI scanner allows scientists to see changes in blood flow associated with brain activity, then infer the activations that must be the source. The intensity of an MRI signal is determined by the level of magnetic resonance, specifically what is called the BOLD effect (blood oxygenation level dependent). All materials have some effect on magnetic fields depending on it's susceptibility or "magnetic moment". Blood that is oxygen rich differs in how it effects a magnetic field from deoxygenated blood. Oxygenated blood is diamagnetic, it tends to take a position at right angles to lines of magnetic force. Deoxygenated hemoglobin (blood) takes a position parallel and proportional to the the intensity of whaever local magnetic field is present. The MRI, with its created and constant field is able to set up an environment where a difference in as little of 3% change in oxygen levels of the blood is detected and imaged.
Typically a high resolution MRI is done to be used as a backdrop before redoing the MRI with BOLD scans at lower resolutions and the participant engaging in an activity. A person in the MRI can wear special goggles or glasses to show the images of their brain. Images are made slice by slice, combined in the computer to form 3-D pictures of the brain. Final images will show the areas of activity during the experiment.

MRI

MRI is brilliant for imaging our bodies, it does so non-invasively meaning theres no injections or cutting. You do however, have to stay extremely still in a very uncomfortable environment. It is well worth the discomfort when you get to see your body, inside-out.

Radiofrequency, RF waves are a form of electromagnetic energy and can excite the protons in living tissue. The protons get excited to a higher energy level, then a photon (light), is released as the proton 'relaxes' back to it's resting energy level. Protons act like tiny magnets with their own associated field which can cancel out. This along with all the noise generated by protons in areas that are not the focus, make the information the photons are sending out very difficult to pick up and interpret. An analogy is a room full of people talking at the same time, each person is saying something meaningful, but the room from a distance sounds like a meaningless cloud of noise. By setting up an external magnetic field, an environment is set up in which protons will line up either upward or downward, parallel to the field. A net magnetic field is then created by the protons with a strength that is proportionate to the strength of the magnet. The stronger the magnet, the more protons align, the less noise from "other voices".
RF pulses help each proton to rotate and move in unison at 90degrees to the magnetic field. Aligning to 90degrees from the field, reexcites the protons to higher energy states which takes to steps to return to a resting state from.

10% of your brain

Why do people (which people??) say that humans only use 10% of the brain? This has become a modern myth with no discernable origin. It is completely and utterly untrue. WE USE ALL OF OUR BRAINs and there is nothing scientific to back up the widely pronounced claim. I am a fan of science fiction but not of fiction posing as science!! Corporations have used this claim as a marketing strategy (american airlines and this ad for satellite tv, for example). Its a bit surprising that no one in any of the companies that represented this "information" or any of the individuals that have said the statement flippantly (likely to make a point in an argument) had the thought to find a source or any reasonable proof. Why do we as humans like to consider ourselves stunted, physically unable to fulfill our potential?
I have a few guesses at the distant origins of this statement, perhaps it is a made up statistic originally used to demonstrate the difference between how much of the brain lights up when consciously attending to something when not consciously attending. The running, accepted theory is it is a misinterpretation of Pierre Flourens, the french physiologist who was the first to notice that lobotomies didnt affect all the functions of bird and rat brains in the 1800s. This led to the understanding of localised brain activity from structures in the brain evolved for specialised activity.Why would our brains evolve to this size if, it isn't all used?
George Orwell said, "Myths which are believed in tend to become true..." and if our brains at their current size of about 3lbs had 90% of it removed.. we would have a brain that is equivalent in size and weight to a sheep's brain. Don't be a sheep, keep using 100% just like you already do.

Explicit versus Implicit control

Implicit control over brain activation is learned through the normal development and acquisition of new skills. Unaware, we implicitly control brain activation with every voluntary action performed. Every perspective a mind takes activates particular brain mechanisms.

Explicit control over brain activity is that which must be deliberately controlled. A subject must be conscious and take charge over brain activation through deliberate choices. An example given by Christopher DeCharms (2008) is the case whereby one can learn to control activation (pain in DeCharms study) in a region of their brain by exerting exactly the type of thought that will maximize or minimize its activation. It will be interesting to observe to what extent people can learn greater explicit control over their brain activation in an area of their brain by training and the consequences of such training. Charms noted that real-time functional MRI has the potential to bring normally non-conscious brain processes into our conscious awareness. This will transform implicit control of brain activation into explicit control.
Click here for DeCharms full pdf article of the pain study

Critical Reasoning for Neuroscience

Okay, so the brain is incredible. Its vast, and can hold more information in better ways than the best computer. That may change soon click and read.. "When will computer hardware match the human brain?" for more thoughts along those lines. What extent are the nuances of our behaviour and emotional responses governed by functionally

specific parts of the brain? What behaviours and environmental or chemical influences give rise to disorder, or shut down a specific functionality?

I highly recommend reading this blog entry on some tips for critical neuroscience reasoning. Ketyov reminds us some important things to keep in mind when researching or listening to anything related to neuroscience. Over estimating the specificity of language for one, leads to many problems.

Its important to keep in mind that metaphor and similar forms of descriptive language are not caused by a specific "metaphor" region of the brain but are meaningful and effectively descriptive because they activate networks of activity across the brain, for eg, from different sense operators like sensation of sun on the skin to the face recognition region (fusiform gyrus) when thinking of "Juliet as the Sun".

Electromagnetism

H.C. Orsted observed in 1820 that an electric current in a wire generates a surrounding magnetic field. In the brain, impulses are generated by electric currents which in turn produce local magnetic fields associated with each current. Although the resistive skull blocks us from seeing the electric activity directly, the magnetic fields (the ones which dont cancel each other out) produced by the electric currents in the brain pass through the skull with no interference. The magnetic fields do get exponentially weaker at a distance, but can be detected without contact with the scalp or or body with highly sensitive detection devices (SQUID).

The electromagnetic signals in the brain are due to the net effect of ionic currents flowing through the dendrites of neurons that are actively transmitting ions across their synapses. Although action potentials are moving charges, the fields associated with them cancel out so the only externally detectable activity will be due to these major cortical neurons or groups of neurons firing at the same time, a form of resonance.

Unfortunately MEG doesn't on its own offer a perfect view of all the activity. The orientation of the neuron makes a difference to its detectability. The SQUID detectors are detecting changes in magnetic flux which can only be measured across a specific two dimensional area. It is therefore only going to detect the tangential components of brain activity, this reduces the brain imaged by MEG to that of the Sulci. But what MEG does detect it can localise and model with extremely high accuracy offering an exceptional (though arguably incomplete) view of the brain.

MEG, Babies and Moral judgement

One of the many incredible opportunities MEG (Magnetoencephalography) provides, is the ability to look silently into the brain of a baby, without affecting any of the activity/development. We can then see what goes on in the developing brain as the baby does different activities and even map changes from visit to visit. Mothers can potentially correlate growth spurts of different structural areas with different environmental, social or educational influences. Scientists are finding more and more locations that can be clearly seen to develop in parallel with what we casually refer to as maturity.
Studies by researchers like Patricia Kuhl translate what the brain of a baby hears and understands. Kuhl is developing a statistical model of early learning as a result of her MEG research with babies, this is shedding light on why early language learning is so important and why it gets so much harder to learn a language as we mature.


Also, check out this video presentation of the research of Rebecca Saxe at MIT. Saxe has pinned down an anatomical region, the temporoparietal junction which develops over our childhood and adolescence and is responsible for how we consider other peoples thoughts and decisions. The story of two cheese sandwich loving pirates brilliantly demonstrates the correlation between the TPJ and understanding the root of ethics and why people in general can assume other people have brains and are similarly responsible, thinking rational creatures without actually seeing their brain in action.

Ancient History of Neuroscience

Only as recently as the past few decades, technology and collaboration with different fields of science has developed to the point of today's effective brain mapping technologies. Where did brain science start, and what are the limitations of our technological adolescence?
Aristotle, during 4BC deemed the brain to be the AirConditioner of the body, its principle function he assumed, was to prevent the body from overheating due to the heart's activity. He famously said "There is nothing in the intellect that is not in the Senses" he assumed all the sense "spirits", (what we may call information) must come together in a sensus communis.

A Roman Physician, called Galen in 1AD was the first to see and describe what we now know as the purpose of the brain. Based on the observations done himself and by other early Alexandrian anatomists, Galen noted that the brain must be the space of mental activity, (not the heart as Aristotle had thought and taught.) Galen noticed a correlation between brain injuries and abnormal behaviour states leading him to the conclusion that the brain is the seat of the animal soul, that which governs our animal-like behaviour. Galen also described two other souls he believed were contained in the body.

Over the Middle ages and Renaissance, anatomy and study of the human body got better and more ofthe body was understood by the physicians and anatomists. The brain however was less understood, more structures and processes were seen and defined, yet still the supernatural ideas of animal soul and spirits that take up space dominated study of the brain.

It wasn't until the 1600s that skeptism over the concept of an animal soul and sense spirits began. English Physician Thomas Willis and Danish anatomist Nicolaus Steno both published works on the anatomy of the brain with critiques of previous conclusions on the nature of the mind and brain. About sensus communis Steno said, " That beautifully arched cavity does not exist" and further, that that brain was not formed as a God's design for the purpose of containing spirits, but the structure must have formed "accidently from the complication of the brain". (this is still a sound theory)

Mind became synonymous with Soul and the Brain was (and still is by many) thought to contain the immaterial spiritual soul.. the stuff that makes us conscious and human.

By the 1800s the problem of other minds was brought up as an epistemological(theory of knowledge) critique by philosophers like Mills and Bertrand Russell. The thought is that I can never know for sure that other people have minds (like I know I have a mind) based by observing other's behaviour alone. The concept of zombies, the fact that in our imaginations it is not so far fetched to imagine mindless creatures, looking and acting like a human but clearly not alive, only responding to an urge to devour and destroy. Mindless. How can we say for sure

anyone around us really has a brain? How can we really tell we aren't living in the matrix. From the Stanford Philosophy Dictionary, “There is general agreement among philosophers that the problem of other minds is concerned with the fundamental issue of what entitles us to our basic belief that other human beings do have inner lives rather than whether we are able in specific cases to be sure what is happening in those inner lives.”
There are many examples in Neuroscience that shed light on this famous problem. For one, Mirror Neurons are those that are activated in response to watching someone else do something. These specialized cells are activated empathetically and do not illicit motor responses.. ie they don’t actively force the body to move an arm when we see someone else do it. We do however have some sort of experience of what it is like mentally to raise an arm as another does. This is evolutionarily advantageous as it allows us to learn without doing…. By watching and experiencing the actions of someone else. Doing this, assumes an intelligent inner world that
We also see things in nature and engineering that we assume must have brains or at least complex microchips driving them, their behaviour is so lifelike., on closer examinations like in Theo Jensen's sculptures, we can see how intelligent engineering; with only geometry, curved feet and the wind can give an illusion of some sort of intelligence, or a mind contained within. Jensen considers his kinetic sculptures, creatures of a sort and has basic binary navigation system on some of them. This creates even more of an illusion of intellect or reasoning.

From Philosophy to Brain Science

Throughout history there have been two quintessential points of view on how to view ourselves in the world. The monist view supposes that since we are all made up of essentially the same kind of thing, there can be only one fundamental material in the universe. In terms of Monism, everything can be reduced; either to God, to a near infinitely small material dot or string of substance which can also be argued to be a form of Energy. Whatever reduction is done, the assumptions are the same. The dualists think other wise, that there is a distinction between the soul stuff and the body stuff, that there must be at least 2 types of things in reality, spiritual and material. One is as mortal as our body, the other immortal consciousness. According to dualists Soul/Mind and Matter must be distinct and immeasurable by eachother.
Many Scientists and Philosophers have held both points of view but it should understood that the objective of physical sciences is to understand the material, that which is detectable by our senses and material body. To study the brain or the mind with tools from sciences we must accept if only for a purpose of inquiry that the brain, mind and soul are synonymous and exist and act under the same physical laws as everything else in the known universe. Making such an assumption opens the mind to a frontier of exploration, self awareness and technology. Descartes once said that "Introspection is the only way to access the mind", that is no longer true and and I am interested in exploring what can, person-person be done and what ethically, should be done with this newly realised access.

Magnetoencephalography and Physics

The most enthralling development in Neuroscience to me, is that of using an understanding of

electromagnetism to engineer a device which, when coupled with a powerful computer can non-invasively and comfortably show a simulation of the brain in action, in real time.

The skull is a resistive plate, protecting the electrically active brain from the elements, accidents and electrical interference. Resistors like bone and plastic don't allow electrons to pass freely through them. This makes it difficult to detect the electrical activity in the brain, or "see the brain" non-invasively. Techniques like Magnetoencephalography, MEGs have been built and developed by engineers and physicists. MEG allows us to look inside the brain based on an understanding of the fundamental relationship between electric and magnetic fields, which are produced by currents of moving charges. Consider the neuron like a circuit and if you are interested look up the Hodgkins Huxley model of the cell, and more on that later.

Superconductive materials give no resistance to moving charges at a cost, they must be cooled to extremely low temperatures, an expensive and space consuming process. (Responsible for the bulk of the device.) In MEGs Helium is used to cool the superconducting quantum interference devices, SQUIDs to extremely cold temperatures allowing changes detected near the head to be sent to the computer faster than any detector has ever done before. The brain’s electrical activity can be visualized from the magnetic dipole activity created by "Big Boy" Cortical neurons. the resistive skull plate does not interrupt or change the magnetic fields as opposed to Electric fields which can only be directly measured by EEG through tiny gaps in the skull. Source of electromagnetic activity can be localized accurately and quickly, allowing new experimental methods in cognitive science to be developed with real time imaging capability.

Welcome

This blog will act as a course page for the Free University SF class on the Physics of Brains and Neuroimaging. I will post relevant and interesting links to essays, tutorials and videos that can be helpful to gain insight and information for better understanding our brains in context of current technology and theoretical research. FUSF Classes Sundays, 12- 26th of June at Viracocha 998 Valencia st SF 12-1.45pm..