Introduction <ul><li>Some of the most critical brain changes during the lifespan happen during infant development & becoming elderly. </li></ul><ul><li>Similarities include development or degeneration of sensory function (sight, hearing, touch), motor skills, sleep cycles, and problem solving. </li></ul><ul><li>We will look at each of those aspects in further depth. </li></ul>
Infants are born with all the tools they need to see, but it takes about six months for them to see objects & colors efficiently. Adult vision usually takes until ages 4-7 to develop. Newborns see in shades of gray, and are born very near-sighted. They can see clearly about 8-15 inches away and have a particular affinity for faces and dark objects (like eyes), which is one way they bond with their mother.
The elderly can suffer from a number of eye diseases, including glaucoma, cataracts (left), & a lifetime of wear-and-tear on the eyes. Many senior citizens can still function normally, and compensate for decreased visual function by wearing corrective lenses or having eye surgery.
However, as noted in the 2005 study by the University of Texas, there may be a link between age-related vision loss & decline in other mental function. This could be due to many factors. Poor quality of vision can make it difficult to engage in other brain-strengthening activities. Also it can place disappointing limitations on daily & social activities, health & self care, and driving. * * Impact of Low Vision on Daily Life by Donia E. Nolan
Auditory development begins in the womb, and by the 20th week of fetal development, a healthy baby has a functioning inner ear. During the first 6 months of life, a baby is able to hear & recognize sounds but has not yet developed other skills needed to respond to them (like turning the head in recognition or imitating sound). Hearing Development in Infants by Rose Welton
According to the National Institute of Health, 30 percent of adults 65-74 years old, and 47 percent of adults 75 years old or older have a hearing impairment. Much of the hearing loss can be due to noises that a person was exposed to during his or her lifetime. Hearing receptor cells are able to regenerate, but not fast enough to keep up with the rate at which they are lost. Equilibrium is also conducted in the inner ear, meaning that elderly people who begin to lose auditory function may be more prone to losing their balance and having a fall.
The elderly who do suffer from hearing loss have options as to dealing with it: hearing aids, cochlear implants, and amplifiers are ways to improve hearing. Some people also learn to lip-read or learn sign language in order to communicate with hearing loss.
Touch, the first sense developed, is one of the most crucial factors in an infant ’ s development. Not only does it create permanent emotional bonds & encourage secure psychological attachment, but touch is also a way for the infant brain to make sense of its surroundings.
Coming into contact with an object sends signals to the infant cortex, causing it to map its surroundings & learn sensations. This information will become the basis for a baby ’ s perception of its environment.
But as the elderly age, they begin to lose some of their touch receptors. Their skin can become thin, and they become less able to recognize some touch sensations. However, touch is still a valid need for an older person ’ s health and well-being.
This loss of touch reception has the potential to be dangerous, both for elderly people or for anyone suffering from a receptor disorder. They become less able to identify specific sensations, as well as temperature shifts. This can be detrimental, as pain receptors indicate danger. The elderly in particular can be at risk for hypo- or hyperthermia for this reason.
The movement of a newborn is mostly limited to reflexes. The basic movements of kicking the legs or turning the head to look for milk are the infant stages of developing neural connections for movement, and strengthening the muscles needed to control these movements voluntarily. As an infant develops, it becomes more & more able to control its motor skills, progressing to grabbing objects, reaching cross-laterally, and walking.
As infants learn new stages of movement, they are in a constant state of re-learning. When they learn to sit up, they must develop their center of gravity & know their limits; when they move to crawling, these behaviors must be learned again rather than building on what is already known.
For each new stage of movement, the infant develops a new set of perspectives & limitations. This gives him or her a broad & verifiable grasp of the environment & the physics within it.
Whereas babies & toddlers increase their capacity for & speed of movement, the elderly begin to slow down as they age.
According to our text, muscle proteins begin to degrade at a rapid pace, and even as early as age 30, the body can no longer keep up. Muscle mass is decreased by 50% as a person enters his or her mid-70 ’ s. This causes older people to lose weight and begin to look frail.
Sometimes older people begin to “ shrink ” -- this is due to loss of bone mass in the spine, and can make an older person look shorter or hunched over.
Newborns sleep up to 16 hours a day, and this is crucial for their development, both physically & mentally. Though they may not appear active during rest, their brains are the most active while they sleep. Proceedings of the National Academy of Sciences, 2007
As noted by the same study, particularly active areas during infant sleep are the visual, auditory, & processing centers (similar to adult sleep studies). This confirms the maternal desire to rock & sing or talk to a baby while putting it to sleep; these are the regions that the infant ’ s brain is working on.
Babies need a lot of sleep in order to grow, but as adults grow old, they tend to need less sleep, and the quality of sleep they get may not be as good because they are prone to respond to external stimuli (noises, movement, etc.). Sleep disturbances can be partially responsible for some of the decline in memory or concentration that the elderly experience, because they may be chronically fatigued. Brain: The Complete Mind (p. 285)
Plasticity refers to the brain ’ s innate & subconscious ability to strengthen useful neural connections while pruning away the unnecessary ones. Our brains are constantly changing and adapting, but the most significant period of plasticity occurs in the early years.
Babies regard faces of varying ethnicities & even species with the same interest. As a baby grows older, the brain learns to identify more strongly with face types that the infant is exposed to & disregards some of the ability to differentiate other face types. Plasticity of face-processing in infancy (PNAS)
Similarly, the PBS documentary “ The Science of Babies ” discusses that babies are born with the capacity to understand & speak the different word dialects, but as they grow they become adapted to the speech patterns of their own culture, and lose the ability to pronounce other sounds. Later in life, a person could gain these skills back again, but beyond this period of plasticity, the skills are harder to acquire.
Until recently, many scientists believed that the brain had a limited number of neurons, & that they were unregenerate. Now, scientists agree that the brain continues to reform itself, even in old age.
In fact, as our text discusses in chapter 9, this explains why some older people seem happier than ever: their neurons have adapted to their aging body & brain. Often they display better language skills & vocabulary, not to mention a lifetime of experience. Also, they may have better focus; since memories can be more difficult to access, the elderly may have a higher capacity to concentrate & process information.
The elderly continue to be able to absorb & process new information as they age, pruning unneeded information & enhancing new neural connections. Our brain ’ s commitment to plasticity continues until we die.
Conclusion : . Many of the ways in which we develop as infants become the ways by which we grow old as seniors, but our brain never stops compensating & adapting to our situation.
There is a marked crossover between the young & old generations: each is on its way back to where the other came from, and then the cycle begins anew.
Bibliography Bryner, Jeanna. “Sleeping babies’ brains are buzzing.” MSNBC. Sept. 17, 2007. Web. Feb. 20, 2012. This news article describes the sleep study done on healthy infants which proved that their brains remain active while they sleep. It also contained pictures on the brain images that resulted. Carey, Susan E. “Plasticity of face processing in infancy.” Proceedings of the National Academy of Sciences in the United States. Feb. 10, 2005. Web. Feb. 20, 2012. A summary of the studies done on infants and facial recognition. Includes the process and method of their studies as well as the findings. “ Neuroplasticity.” Science department, SCSU. Web. Feb. 20, 2012. This article, used as literature for their psychology program, details the science behind neuroplasticity and the changing brain, both in early infancy throughout the lifespan. Nolan, Diona E. “ Normal Age-Related Vision Lossand Related Services for the Elderly”. Austin State University. Web. Feb. 20, 2012. This article details the causes and recommendations for vision loss in elderly subjects. It discusses potential harms of vision loss as well as solutions for those affected.
Bibliography , continued “ The Science of Babies.” PBS. Movie. Jan. 21, 2012. Documentary chronicling the first year of a baby’s life and the physical and neurological developments made. Of particular interest were the studies on infant movement and language development. The Secret Life of the Brain: The Baby’s Brain. PBS. Web. Feb. 20, 2012. This site highlights important aspects of brain development through the lifespan. Of particular interest for this presentation was their information on infant visual perception. Welton, Rose. “Hearing Development in Infants.” Aug. 18, 2010. Web. Feb. 20, 2012. This is a concise parenting article about what to expect during different stages of a baby’s development with regards to their auditory skills.