Rod: A sensory neuron located in the periphery of the retina. It is sensitive to light of low intensity and specialized for nighttime vision.
S
Second Messengers: Recently recognized substances that trigger communications between different parts of a neuron. These chemicals are thought to play a role in the manufacture and release of neurotransmitters, intracellular movements, carbohydrate metabolism and, possibly, even processes of growth and development. Their direct effects on the genetic material of cells may lead to long-term alterations of behavior, such as memory.
Sensitization: A change in behavior or biological response by an organism that is produced by delivering a strong, generally noxious, stimulus.
Serotonin: A monoamine neurotransmitter believed to play many roles including, but not limited to, temperature regulation, sensory perception and the onset of sleep. Neurons using serotonin as a transmitter are found in the brain and in the gut. A number of antidepressant drugs are targeted to brain serotonin systems.
Short-Term Memory: A phase of memory in which a limited amount of information may be held for several seconds to minutes.
Stimulus: An environmental event capable of being detected by sensory receptors.
Stroke: The third largest cause of death in America, stroke is an impeded blood supply to the brain. It can be caused by a blood clot forming in a blood vessel, a rupture of the blood vessel wall, an obstruction of flow caused by a clot or other material, or by pressure on a blood vessel (as by a tumor). Deprived of oxygen, which is carried by blood, nerve cells in the affected area cannot function and die. Thus, the part of the body controlled by those cells, cannot function either. Stroke can result in loss of consciousness and brain function, and death.
Sympathetic Nervous System: A branch of the autonomic nervous system responsible for mobilizing the body's energy and resources during times of stress and arousal.
Synesthaesia: A condition in which a person quite literally tastes a shape or sees a colour in a sound. This is not just a way of describing experiences as a poet might use metaphors. Synaesthetes actually experience the sensations.
Synapse: A gap between two neurons that functions as the site of information transfer from one neuron to another.
T
Temporal Lobe: One of the four major subdivisions of each hemisphere of the cerebral cortex. It functions in auditory perception, speech and complex visual perceptions.
Temporal lobe epilepsy: A condition which may produce a heightened sense of self and has been linked to religious or spiritual experiences. Some people may undergo striking personality changes and may also become obsessed with abstract thoughts. One possible explanation is that repeated seizures may cause a strengthening of the connections between two areas of the brain - the temporal cortex and the amygdala. Patients have been observed to have a tendency to ascribe deep significance to everything around them (including themselves!).
Thalamus: A structure consisting of two egg-shaped masses of nerve tissue, each about the size of a walnut, deep within the brain. It is the key relay station for sensory information flowing into the brain, filtering out only information of particular importance from the mass of signals entering the brain.
U
V
Ventricles: Of the four ventricles, comparatively large spaces filled with cerebrospinal fluid, three are located in the brain and one in the brainstem. The lateral ventricles, the two largest, are symmetrically placed above the brainstem, one in each hemisphere.
W
Wernicke's Area: A brain region responsible for the comprehension of language and the production of meaningful speech.
Try out some of the experiments referred to by Professor Ramachandran.
Blindspot Experiments
Each eye has a blindspot. It's caused by the fact that the small area of the retina where the optic nerve is connected to the eyeball is not sensitive to light.
The following experiments prove the existence of the blindspot and demonstrate how the brain can fill in the missing information. They provide important hints about how the neural machinery of the brain works in practice.
All experiments are taken from V.S. Ramachandran's book, Phantoms In The Brain, published by Fourth Estate.
Try blindspot experiment number 1 (one of five)
Cover or shut your right eye and look at the black dot on the right with your left eye.
Move your head towards and away from the monitor.
At a critical distance the white disc on the left will disappear.
Notice that when the disc disappears you don't see a dark void or hole in its place.
The region is "filled in" with the same light blue colour as the background.
Below are some useful links to sites of interest.
About Professor Ramachandran
Professor Ramachandran's website
Find out more about Professor Ramachandran
Background to the lectures
The background to these lectures was a series of articles by Professor Ramachandran for the Journal of Consciousness Studies. The Journal has kindly made these articles available.
Synapses and the Self
The Artful Brain
Purple Numbers and Sharp Cheese
Other BBC sites of interest
Interactive brain (from BBCi Science)
How does the brain work? Find out where your cerebellum is and what your medulla oblongata does.
The Human Body (the brain and the spinal chord) (from BBCi Science)
A brief introduction to all aspects of the brain.
Intelligence (from BBCi Science)
An overview of issues relating to the brain and intelligence.
The Brain (from The Life of Mammals, BBCi Nature)
Another introduction to all aspects of the brain.
The Brain (from BBCi World Service)
Another introduction to all aspects of the brain.
God on the Brain (from Horizon)
Is a part of the brain closely connected with the sensations of belief?
About the Brain
The Open University - Introduction to the Brain
A comprehensive introduction to the human brain and nervous system.
The Whole Brain Atlas
A collection of images of brain scans showing all aspects of the brain.
Brain Awareness Week
Aims to elevate the public awareness of brain and nervous system research.
Brain Briefings (from the Society for Neuroscience)
A series of two-page newsletters explaining how basic neuroscience discoveries lead to clinical applications.
Brain Facts (from the Society for Neuroscience)
A 52-page primer on the brain and nervous system, published by the Society for Neuroscience.
Journal of Consciousness Studies
A peer-reviewed monthly which examines issues of the brain in plain English.
Mind-Brain.com
An internet site dealing with consciousness, transcendence, and the brain, not to mention poetry, art, and music.
Mind/ Brain Behaviour (from Harvard University)
An interfaculty initiative exploring issures of conciousness and behaviour.
The Mind/Brain Institute (from John Hopkins University)
The institute is dedicated to the study of the neural mechanisms of higher brain functions using modern neurophysiological, anatomical, and computational techniques.
Mind and Body: René Descartes to William James (from Serendip)
An overview of the debates around mind/body dualism.