Neuroscience is the scientific study of the
nervous system. Such studies span the
structure,
function,
evolutionary history,
development,
genetics,
biochemistry,
physiology,
pharmacology,
informatics,
computational neuroscience and
pathology of the nervous system.
The
International Brain Research Organization was founded in 1960,
the
European Brain and Behaviour Society in 1968,
and the
Society for Neuroscience in 1969, but the study of the
brain dates at least to
ancient Egypt. Traditionally, neuroscience has been seen as a branch of the
biological sciences. Recently, however, there has been a surge of interest from many allied disciplines, including
cognitive and
neuro-psychology,
computer science,
statistics,
physics,
philosophy, and
medicine. The scope of neuroscience has now broadened to include any systematic, scientific, experimental or theoretical investigation of the central and
peripheral nervous system of biological organisms. The empirical methodologies employed by
neuroscientists have been enormously expanded, from biochemical and genetic analyses of the dynamics of individual
nerve cells and their molecular constituents to
imaging of perceptual and motor tasks in the brain. Recent theoretical advances in neuroscience have been aided by the use of computational modeling.
Overview
The
scientific study of the
nervous systems underwent a significant increase in the second half of the twentieth century, principally due to revolutions in
molecular biology,
electrophysiology, and
computational neuroscience. It has become possible to understand, in much detail, the complex processes occurring within a single
neuron. However, how networks of neurons produce intellectual behavior, cognition, emotion, and physiological responses is still poorly understood.
Stained neuron
The nervous system is composed of a network of
neurons and other supportive cells (such as
glial cells). Neurons form functional circuits, each responsible for specific tasks to the behaviors at the organism level. Thus, neuroscience can be studied at many different levels, ranging from molecular level to cellular level to systems level to cognitive level.
At the molecular level, the basic questions addressed in
molecular neuroscience include the mechanisms by which neurons express and respond to molecular signals and how
axons form complex connectivity patterns. At this level, tools from
molecular biology and
genetics are used to understand how neurons develop and die, and how genetic changes affect biological functions. The
morphology, molecular identity and physiological characteristics of neurons and how they relate to different types of behavior are also of considerable interest. (The ways in which neurons and their connections are modified by experience are addressed at the physiological and cognitive levels.)
At the cellular level, the fundamental questions addressed in
cellular neuroscience are the mechanisms of how neurons process signals physiologically and electrochemically. They address how signals are processed by the
dendrites,
somas and
axons, and how
neurotransmitters and electrical signals are used to process signals in a neuron. Another major area of neuroscience is directed at investigations of the development of the nervous system. These questions of
neural development include the
patterning and regionalization of the nervous system, neural
stem cells,
differentiation of neurons and glia,
neuronal migration, axonal and dendritic development,
trophic interactions, and
synapse formation.
At the systems level, the questions addressed in
systems neuroscience include how the circuits are formed and used anatomically and physiologically to produce the physiological functions, such as
reflexes,
sensory integration,
motor coordination,
circadian rhythms,
emotional responses,
learning and
memory. In other words, they address how these neural circuits function and the mechanisms through which behaviors are generated. For example, systems level analysis addresses questions concerning specific sensory and motor modalities: how does
vision work? How do
songbirds learn new songs and
bats localize with
ultrasound? How does the
somatosensory system process tactile information? The related field of
neuroethology, in particular, addresses the complex question of how neural substrates underlies specific
animal behavior.
Para-sagittal MRI of the head in a patient with benign familial
macrocephalyAt the cognitive level,
cognitive neuroscience addresses the questions of how psychological/cognitive functions are produced by the neural circuitry. The emergence of powerful new measurement techniques such as
neuroimaging (e. g.,
fMRI,
PET,
SPECT),
electrophysiology and
human genetic analysis combined with sophisticated
experimental techniques from cognitive psychology allows neuroscientists and psychologists to address abstract questions such as how
human cognition and emotion are mapped to specific neural circuitries.
Neuroscience Education engages students from pre-Kindergarten through College in the study of neuroscience and provides training for Graduate students and Post-Doctoral fellows. Research in this area tests hypotheses pertaining to best practices in teaching and learning neuroscience concepts and can be funded through RO1 and R25 mechanism from NIH, major grants from NSF, and other federal and private granting mechanisms.
Neuroscience Literacy includes efforts to raise knowledge and awareness about the nervous system and behavior among the general public, as well as public officials, policy makers, and legislators. Major world wide efforts in both Neuroscience Education and Neuroscience Literacy include
Brain Awareness Week cosponsored by the
Society for Neuroscience and
Dana Alliance for Brain Initiatives, as well as the
International Brain Bee which is an academic competition.
Neuroscience Core Concepts for K-12 teachers and students have been developed by members of the public education and communications committee of the Society for Neuroscience. Brain Facts, a downloadable primer on human brain anatomy and function is currently being translated into Spanish and other world languages.
Neuroscience is also beginning to become allied with
social sciences, and burgeoning interdisciplinary fields of
neuroeconomics,
decision theory,
social neuroscience are starting to address some of the most complex questions involving interactions of brain with environment.
Neuroscience generally includes all scientific studies involving the nervous system.
Psychology, as the scientific study of mental processes, is closely related to neuroscience, although the two disciplines are distinct, with such subjects as
behaviorism and traditional
cognitive psychology studied independently of the underlying neural processes. In
Principles of Neural Science,
Nobel laureate Eric Kandel contends that cognitive psychology is one of the pillar disciplines for understanding the brain in neuroscience. The term neurobiology is usually used interchangeably with neuroscience, although the former refers specifically to the
biology of the
nervous system, whereas the latter refers to the entire
science of the nervous system.
Neurology,
psychiatry, and
neuropathology are medical specialties that specifically address the diseases of the nervous system. These terms also refer to clinical disciplines involving diagnosis and treatment of these diseases. Neurology deals with diseases of the central and peripheral nervous systems such as
amyotrophic lateral sclerosis (ALS) and
stroke, while psychiatry focuses on behavioural, cognitive, and emotional disorders. Neuropathology focuses upon the classification and underlying pathogenic mechanisms of central and peripheral nervous system and muscle diseases, with an emphasis on morphologic, microscopic and chemically observable alterations. The boundaries between these specialties have been blurring recently, and they are all influenced by
basic research in neuroscience.
Integrative neuroscience makes connections across these specialized areas of focus.
History
Evidence of
trepanation, the surgical practice of either drilling or scraping a hole into the skull with the aim of curing headaches or
mental disorders or relieving cranial pressure, being performed on patients dates back to
Neolithic times and has been found in various cultures throughout the world. Manuscripts dating back to 5000BC indicated that the
Egyptians had some knowledge about symptoms of brain damage.
Early views on the function of the brain regarded it to be a "cranial stuffing" of sorts. In Egypt, from the late
Middle Kingdom onwards, the brain was regularly removed in preparation for
mummification. It was believed at the time that the
heart was the seat of intelligence. According to
Herodotus, during the first step of mummification: "The most perfect practice is to extract as much of the brain as possible with an iron hook, and what the hook cannot reach is mixed with drugs".
The view that the heart was the source of consciousness was not challenged until the time of
Hippocrates. He believed that the brain was not only involved with sensation, since most specialized organs (e.g., eyes, ears, tongue) are located in the head near the brain, but was also the seat of intelligence.
Aristotle, however, believed that the heart was the center of intelligence and that the brain served to cool the blood. This view was generally accepted until the Roman physician
Galen, a follower of Hippocrates and physician to
Roman gladiators, observed that his patients lost their mental faculties when they had sustained damage to their brains.
In
al-Andalus,
Abulcasis, the father of modern
surgery, developed material and technical designs which are still used in
neurosurgery.
Averroes suggested the existence of
Parkinson's disease and attributed
photoreceptor properties to the
retina.
Avenzoar described
meningitis, intracranial
thrombophlebitis,
mediastinal tumours and made contributions to modern
neuropharmacology.
Maimonides wrote about
neuropsychiatric disorders and described
rabies and
belladonna intoxication. Elsewhere in
medieval Europe,
Vesalius (1514-1564) and
René Descartes (1596-1650) also made several contributions to neuroscience.
Studies of the brain became more sophisticated after the invention of the
microscope and the development of a staining procedure by
Camillo Golgi during the late 1890s that used a
silver chromate salt to reveal the intricate structures of single neurons. His technique was used by
Santiago Ramón y Cajal and led to the formation of the
neuron doctrine, the hypothesis that the functional unit of the brain is the neuron. Golgi and Ramón y Cajal shared the
Nobel Prize in Physiology or Medicine in 1906 for their extensive observations, descriptions and categorizations of neurons throughout the brain. The hypotheses of the neuron doctrine were supported by experiments following
Galvani's pioneering work in the electrical excitability of muscles and neurons. In the late 19th century,
DuBois-Reymond,
Müller, and
von Helmholtz showed neurons were electrically excitable and that their activity predictably affected the electrical state of adjacent neurons.
In parallel with this research, work with brain-damaged patients by
Paul Broca suggested that certain regions of the brain were responsible for certain functions. At the time Broca's findings were seen as a confirmation of
Franz Joseph Gall's theory that language was localized and certain psychological functions were localized in the
cerebral cortex.
[Greenblatt, SH., (1995) ", " Neurosurgery 37 790-805.][Bear, M. F.; B. W. Connors, and M. A. Paradiso (2001). Neuroscience: Exploring the Brain. Baltimore: Lippincott. ISBN 0-7817-3944-6.] The localization of function hypothesis was supported by observations of
epileptic patients conducted by
John Hughlings Jackson, who correctly deduced the organization of
motor cortex by watching the progression of seizures through the body.
Wernicke further developed the theory of the specialization of specific brain structures in language comprehension and production. Modern research still uses the
Brodmann cytoarchitectonic (referring to study of
cell structure) anatomical definitions from this era in continuing to show that distinct areas of the cortex are activated in the execution of specific tasks.
Major branches
Current neuroscience education and research activities can be very roughly categorized into the following major branches, based on the subject and scale of the system in examination as well as distinct experimental or curricular approaches. Individual neuroscientists, however, often work on questions that span several distinct subfields.
Note: In 1990s, neuroscientist
Jaak Panksepp coined the term "affective neuroscience" to emphasize that emotion research should be a branch of neurosciences, distinguishable from the nearby fields like cognitive neuroscience or behavioral neuroscience. More recently, the social aspect of the emotional brain has been integrated in what is called "social-affective neuroscience" or simply social neuroscience.
There has also been some research published arguing that some of fair play and the
Golden Rule may be stated and rooted in terms of neuroscientific and
neuroethical principles.
Major themes of research
Neuroscience research from different areas can also be seen as focusing on a set of specific themes and questions. (Some of these are taken from http://www.northwestern.edu/nuin/fac/index.htm)
- Behavior/Cognition/Language
- Neurobiology of the neuron
- Autonomic systems and homeostasis
- Genetics of the nervous system
- Injury of the nervous systems
Allied and overlapping fields
Neuroscience, by its very interdisciplinary nature, overlaps with and encompasses many different subjects. Below is a list of related subjects and fields.
Future directions
See also
