brain factoids dr. diane cepela [email protected] 815.258.5251
TRANSCRIPT
Abused Children Have Smaller Brains Parts of the brain of a severely abused and neglected child can be substantially smaller than that of a healthy child.
Babies Lose Half their Neurons at Birth
It is estimated that a baby loses about half their neurons before
they are born. This process is sometimes referred to as pruning and may eliminate neurons that do not receive sufficient input
from other neurons.
Baby Talk Increases Vocabulary A study showed that when mothers
frequently spoke to their infants, their children learned about 300 more words by age two than did children whose mothers rarely
spoke to them.
Birdsong and human speech have similar characteristics. Birds, like
humans, learn their complex vocalizations early in life and imitate their adult counterparts to acquire
these skills. These two species have evolved a complex hierarchy of
specialized forebrain areas where motor and auditory areas interact continuously in order to produce
detailed vocalizations.
The optic nerve exits the retina as a single bundle. The exit point within the
retina has no receptor cells. This location forms a blind spot in each eye. We rarely notice these spots because they do not overlap within the image
formed by the two eyes. Your ophthalmologist can only detect your
blind spots by having you close the eye not being tested.
The effects of a stroke depend on the affected blood vessel and the area of brain that it supplies with nutrients. For instance,
if the middle cerebral artery is occluded, motor areas in the frontal cortex can be
damaged resulting in the loss of voluntary muscle movements on the contralateral, or
opposite, side of the body from the damaged side of the brain. This condition is
known as hemiplegia.
Strokes or "brain attacks" are the 3rd leading cause of death in the United
States. A stroke occurs when the blood flow to the brain is disrupted.
Disruption takes place either when a brain artery is blocked or when an artery explodes. Recently, exciting medical breakthroughs have been
announced with respect to treating stroke.
Electroencephalogram, or EEG, is a non-invasive technique used to record small
changes of electrical activity in the brain with surface electrodes on the scalp. Scientists
who study sleep find EEG especially useful. The tiny fluctuations detected with EEG are
clear indicators of whether a person is asleep, aroused, or somewhere in between.
Approximately 20% of the blood flowing from the heart is pumped to the brain. The brain needs constant blood flow in
order to keep up with the heavy metabolic demands of the neurons. Brain
imaging techniques such as functional magnetic resonance imaging (fMRI) rely
on this relationship between neural activity and blood flow to produce images of deduced brain activity.
Although the brain accounts for only 2% of
the whole body's mass, it uses 20% of all the oxygen we breathe. A continuous
supply of oxygen is necessary for survival. A
loss of oxygen for 10 minutes can result in
significant neural damage.
Measures of brain activity show that during the second half of a child's first year, the prefrontal cortex, the seat of forethought and logic, forms synapses at such a rate that it consumes twice
as much energy as an adult brain. That furious pace continues for the child's
first decade of life.
Commisurotomy, the transection of the corpus callosum, is one possible treatment for patients with severe epilepsy. This procedure causes a complete split between the two hemispheres of the brain. As a result of this split, words presented to the patient's far left visual field cannot be read (alexia), and hidden objects placed into the left hand cannot be named (anomia). This is significant evidence for hemispheric specialization.
During the first month of life, the number of connections or synapses,
dramatically increases from 50 trillion to 1 quadrillion. If an infant's body grew at
a comparable rate, his weight would increase from 8.5 pounds at birth to 170
pounds at one month old.
Did you know that healthy ears actually emit sounds? These sounds are usually very soft, but can occasionally be heard by others. Surprisingly, the sounds are
rarely heard by the person whose ear is emitting the sounds! The cause of these
sounds is still under debate, but is thought by some to be due to input from
the central nervous system.
Nearsightedness (myopia) is the most common visual problem we
experience. It is the result of an overly elongated eye, which has become
specialized for seeing near objects extremely well.
Yawning is an age-old activity that occurs in reptiles, birds
and, of course, mammals. This behavior is controlled by
chemicals in the brain called neurotransmitters.
Neurotransmitters, such as nitric oxide and dopamine, act in the hypothalamus to induce
and control yawning.
The light-detecting receptor cells within the retina, called rods and cones, are
actually at the back of the retina under several layers of cells. The neurons and support cells within the retina are fairly
translucent, so light is able to pass through them and reach the receptors.
Because receptors (rods and cones) are at the back of the retina, an image
actually passes through the retina three times: as light to the receptor cells
(back); as neural signals through the initial visual processing of the retina
(forward); as neural signals via the optic nerve to the brain (back again).
The human cerebellum, or "little brain", weighs about 150 grams. Located at the lower back of the brain, the cerebellum is key to
maintaining posture, walking, and performing coordinated
movements. It is also thought to play a role in olfaction or smell.
Nearsighted people can often read the lettering on
distant signs by looking through a small hole with one eye. The hole focuses the light entering the eye and replaces the function
of the eye's own lens
There are one hundred billion neurons in the brain. A stack of one
hundred billion pieces of paper would be about 5000 miles high, the distance from San
Francisco to London.
Olfactory receptor cells, the neurons in our nose that allow us to smell, are
neurons that can regenerate throughout life. Although these cells are continually being born and dying, they maintain the same connections as their ancestors. The
result is that once we learn a smell, it always smells the same to us -- despite
the fact that there are always new neurons smelling it!
Children as young as four days old can distinguish the vowel sounds of the language in their natural environment from those
of a foreign language.
The octopus has a single layer of cells in the back of its eye. These receptor cells
project directly back to the brain via the optic nerve. Because the optic nerve forms behind the receptors
rather than passing through them, the octopus has no blind spot.
There is no sense of pain within the brain itself. This fact allows
neurosurgeons to probe areas of the brain while the patient is awake. Feedback from the patient during
these probes is useful for identifying important regions, such as those for speech, that are spared if possible.
At night, our peripheral vision is better than our foveal (straight on)
vision. Hikers at night do better when they look slightly above the trail, and airplane pilots are taught to look for traffic out of the sides of their eyes.
This is because our rod cells, photoreceptors that respond best to dim light, are located mostly in the
periphery of the retina.
The pupillary light reflex results when light is shined into either eye causing
both pupils to constrict. Doctors use this reflex to determine if the reflex
pathway through the midbrain has in any way been disrupted. If the reflex fails to produce a response in one or both eyes, the doctor can deduce the location of the malfunction based on
which of the eyes failed to respond and which eye was stimulated.
Reading aloud to children helps stimulate brain
development, yet only 50% of infants and
toddlers are routinely read to by their parents.
Research shows brain growth contains its own
rhythm. Certain skills come into preeminence for a period of intensive
networking. At three months, the visual cortex
dominates synapse formation.
A child's ability to learn can increase or decrease by 25 percent or more,
depending on whether he or she grows up in a
stimulating environment.
The expression "crying crocodile tears" means expressing insincere
grief and it arose because crocodiles appear to weep while they are happily munching on prey. A
neurological disorder called crocodile tears results from damage to the fifth
cranial nerve, which controls the mucous membranes of the face.
When the patient is eating, signals that should stimulate salivation
instead stimulate lacrimation -- crying crocodile tears.
Receptor cells in the eye are thought to be capable of detecting single photons, the smallest units of light. Nocturnal animals take advantage of this sensitivity by having large eyes with large apertures to let in as many photons as possible allowing them to see remarkably well at night.
Scratching an itch is a puzzling biological response, because it seems to hinder rather than help a wound's healing. One theory of
why we itch suggests that scratching stimulates the release of endorphins,
naturally occurring opiates which block pain sensation. Because scratching injures our
skin a little more, we release a flood of endorphins to block the pain of the initial
injury more effectively.
It's no accident that telephone numbers in the United States are seven digits long. Our working memory, a very short-term form of memory which stores ideas just long enough for us to understand them,
can hold on average a maximum of seven digits. This allows you to look up a phone
number and remember it just long enough to dial.
