FMRI's.

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Published on 16 Apr 2013
School
McGill University
Department
Psychology
Course
PSYC 180
Professor
Page:
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FMRI and Neuorealism
The fMRI concept builds on the earlier MRI scanning technology and the discovery of
properties of oxygen-rich blood. MRI brain scans use a strong, permanent, static
magnetic field to align nuclei in the brain region being studied. Another magnetic field,
the gradient field, is then applied to kick the nuclei to higher magnetization levels, with
the effect depending on where they are located. When the gradient field is removed, the
nuclei go slowly back to their original states, and the energy they emit is measured with a
coil to recreate the positions of the nuclei. MRI thus provides a static structural view of
brain matter. The central thrust behind fMRI was to extend MRI to capture functional
changes in the brain caused by neuronal activity. Differences in magnetic properties
between arterial (oxygen-rich) and venous (oxygen-poor) blood provided this link.
Since the 1890s it has been known that changes in blood flow and blood
oxygenation in the brain (collectively known as hemodynamics) are closely linked to
neural activity. When neurons become active, local blood flow to those brain regions
increases, and oxygen-rich (oxygenated) blood displaces oxygen-depleted
(deoxygenated) blood around 2 seconds later. This rises to a peak over 46 seconds,
before falling back to the original level (and typically undershooting slightly). Oxygen is
carried by the hemoglobin molecule in red blood cells. Deoxygenated hemoglobin (dHb)
is more magnetic (paramagnetic) than oxygenated hemoglobin (Hb), which is virtually
resistant to magnetism (diamagnetic). This difference leads to an improved MR signal
since the diamagnetic blood interferes with the magnetic MR signal less. This
improvement can be mapped to show which neurons are active at a time.
Neurorealism (Neuro-Ethics) - The ethics of neuroscience comprises the bulk of work
in neuroethics. It concerns the ethical, legal and social impact of neuroscience, including
the ways in which neurotechnology can be used to predict or alter human behavior and
"the implications of our mechanistic understanding of brain function for society...
integrating neuroscientific knowledge with ethical and social thought".
Some neuroethics problems are not fundamentally different from those encountered
in bioethics. Others are unique to neuroethics because the brain, as the organ of the mind,
has implications for broader philosophical problems, such as the nature of free will,
moral responsibility, self-deception, and personal identity.[2] Examples of neuroethics
topics are given later in this article ("Key issues in neuroethics").
Neuroethics encompasses the myriad ways in which developments in basic and clinical
neuroscience intersect with social and ethical issues. The field is so young that any
attempt to define its scope and limits now will undoubtedly be proved wrong in the
future, as neuroscience develops and its implications continue to be revealed. At present,
however, we can discern two general categories of neuroethical issue: those emerging
from what we can do and those emerging from what we know.
In the first category are the ethical problems raised by advances in
functional neuroimaging, psychopharmacology, brain implants and brain-machine
interfaces. In the second category are the ethical problems raised by our growing
understanding of the neural bases of behavior, personality, consciousness, and states of
spiritual transcendence.
First of all, researchers are fully aware that their results rarely (if ever) prove or disprove
anything. We are encouraged to say that the evidence found from a piece of research
supports a hypothesis and in fact lose marks for writing that any of our experiments prove
or disprove a hypothesis. All confounding variables are taken into account and in fact are
included in all (good) papers. Funnily enough it is the media who take scientific research
out of context and it is the media who make the claims, not the scientists. I Media often
portray scientific research in the wrong light. Secondly, the rather negative view of
research that has been undertaken is unwelcome. Nearly all-scientific research increases
our knowledge and provides us with further insight into ourselves and the world around
us. Science is often reductionist in nature however this piece of media in particular is not
taking into account that scientists openly hold their hands up to this.
And in regards to whether scientists believe something is real or not based on physiology
- psychologists are scientists and are also well aware of the discrepancy between what a
person feels or experiences and physiological changes (phantom pain in amputated limbs
for example). That said, trying to understand how these phenomenons occur through
analysis of physiology is of undeniably great importance. I think it is thus necessary to
consider the difference between what scientists say about what they have found and how
the media reports it.