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PSY213 LEC 3 NOTES.docx

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Giampaolo Moraglia

Thursday January 24, 2013 LECTURE 3: SENSORY AGING Today: Many topics not mentioned in textbooks Sensory process change over time plays a fundamental role in our later years and decades Any perceptional experience always arises from an encounter from sources of environmental stimulation Specialized sensory systems occur due to stimulus (acoustic energy enters our ears stimulating receptors) -Mechanical pressure, for touch… -In general most of us will experience some loss of sensitivity as we age No other age related loss is as universal as sensory loss GENERAL ASPECTS OF SENSORY FUNCTIONING  Each sensory system responds to specific forms of energy (and to the information carried by this energy) present in the environment  Energy levels are picked up by specialized receptors and recoded into nerve impulses (‘sensory transduction’)  These nerve impulses are carried by sensory nerves to the brain….  Where they are analyzed and interpreted within specialized sensory areas There are many obvious differences in sensory differences At the fundamental level all sensory systems share basic features Sensitive to some sort of energy in the environment Energy has to be picked up by special receptor cells located in sensory organs and converted into electrical nerve signals (SENSORY TRANSDUCTION) These nerve signals are carried by sensory nerves to specialize in the centers of the brain where the info they contain will be analyzed and interpreted AGE RELATED CHANGES OCCUR AT AL LEVELS OF A SENSORY SYSTEM  Sensory organs and receptors  Sensory nerves  Sensory areas within brain -Loses that come with aging may occur at different levels in the sensory systems -Sensory loss may be causes by: 1. Deteriorationsomething goes wrong in our sensory organs 2. Degeneration in our nerve fibers that connect our sensory nerves, which connect to the brain 3. Directly in the brain itself -Sensory decline may also be caused or sped up by disease, abuse, or disabuse 2 VISION & HEARING ARE THE ‘DOMINANT’ SENSES IN HUMANS  Significant impairments in the functioning of these sensory systems seriously impair people’s ability to negotiate the environment Any sensory loss interferes with the world -Isolation of a person with loss to any dominate senses -Severe hearing loss may find it tiring to keep up, and may result in social isolation and may lead to mental health -Disturbing effect in college students -EXPERIMENT: Students had to deal with sensory loss that many older adults have to live with, where they had plugs inserted into their ears and wear glasses and asked to shop at the super market)  Disorientation; fumbling Significant problems in the environment BASIC FEATURES OF THE HUMAN EYE  Size of a ping pong ball and nearly spherical  3 layers: 1. Sclerotic coat: Withstands atmospheric pressure and becomes transparent towards the front when it becomes the cornea 2. Choroid carries nutrients, become visible in the central portion and is called the aqueous humor and the iris  At the centre of the iris is the hole, which is the pupil, which will constrict or dilate with the amount of light in the environment  Dark pupil will open up to allow as much light in as possible  Changes with emotional arousal of an individual (size of the pupil because pupil responds to emotional arousal) 3. Retina contains several millions of cells and receptors which is specialized to capture particles of light, lead to generation of nerve signals 3  2chambers: 1. Aqueous humor chamber: filled with fluid 2. Largest portion of the eye is the vitreous humor, which contains a jelly like substance  Lens can change curvature (refractor/bending) -If the eye is looking at a far away object (5-6metres away or beyond) lens is perfectly flat -Lens will refract or bend light rays in order to focus (retina) -Shift gaze to something closer, if the lens remained flat the image will be unfocused in the retina -Changing the refractory of the lens, muscles will contract increasing the curvature of the lens, and the ability of lens to bend will increase in the amount sufficient for the image to be projected in the retina, so the image will be sharp but only to a point  Near point: can still see an object clearly, but if continues lens can no longer bend to compensate and image will be blurred SOME ‘NORMAL’ AGE RELATED CHANGES WITHIN THE EYE  Vitreous humor loses some transparency  Senile miosis (reduction in maximum size attainable by the pupil)  Pupil size changes more slowly  The lens loses some transparency, thickens, hardens (hence losing flexibility), and turns yellowish  Vitreous humor chambers: become more opaque, loses some of its transparency and limits amount of light allowed in -Not continuously regenerated: waste product of the metabolicity of the eye, and settle at the bottom of the eye -Shower: out of nowhere you see a shower of tiny sparks, which is a sign that your retina is at risk of being detached (report immediately) Pupil: (small opening at the centre of the iris) the iris gets smaller with age further limiting the amount of light that can enter the eye, and leads to the decreasing size of a pupil; amount of light that reaches the retina may be reduced by 60-65% by the age of 60 As we get older the pupil responds more slowly, its widening and constricting abilities to accommodate changes in the ambient illumination (sudden) due to the weakening of the muscles that control the pupil Lens: when we are born, the lens is quite tiny and grows throughout one’s life and adds layers over time and gets thicker The older cells over time lose most of the water they come up with and shrivel and harden Due to this the lens becomes less transparent reducing the amount of light allowed in which leads to pupil being unable to open up Around 35, the lens begins to turn yellow. Discriminate to green, blue, and violet ray in the short end of the spectrum 4 As the lens thickens becomes less flexible; since it hardens it becomes more diff to change its shape to focus as your approach objects in shorter distances; can’t properly accommodate its curvature Weakening of the muscles that control the lens; increasing inability to accommodate its shape as you approach closer objects is referred to PRESBYOPIA PRESBYOPIA  Everyone who lives long enough will experience presbyopia, a severely diminished ability to bring very close objects into focus due to the hardening of the lens, which limits its ability to change shape to focus properly (accommodate), especially at short distances  Presbyopia also lengthens the time required to change gaze from near to distant objects and vice versa  A convex lens, often in the bottom of bifocals, helps the presbyopic eye to focus on nearby objects -Most notice when they have to hold a news paper at arms length --Increase distance from eye; begins around age 40, women exp. 3-4 years earlier than men --Keeps worsening towards age 70 until they cannot accommodate at all --The ability to focus on objects near to the eye decreases and the distance to focus increases --Fortunately this is a condition that can be corrected with convex lenses -As we get older the speed of accommodation (adjustment) slows down (switching gaze from back to front of room) because muscles get less functional WITH PRESBYOPIA, THE NEAR POINT, THE CLOSESTS DISTANCE AT WHICH A TARGET CAN BE SEEN CLEARLY, INCREASES WITH AGE Most of the age related changes in the eye discussed above contribute to the decline in VISUAL ACUITY  Changes taking place within the neural parts of the visual system also play a role 5 -Smallest detail you can perceive decreases with age -If we combine all eye related factors that factor into acuity we still cannot account for all the large loses of acuity meaning neurological factors must account for the reduction in visual acuity which is unexplained by the changes in the eye alone -This alone cannot predict the reduction of acuity -Death of visual cells and a number of other factors -X and Y-axis: charts at optometrist of letters -- Normal vision: 20/20 vision --When young, should exceed 20/20 vision --Pretty stable until 30 --Quite a significant decline in acuity when you age --By age 80, acuity is 20% of what it was when you were 20years old -Canadian study: Male in late 60s and had 50 yrs of shooting at targets Response time and performance and acuity: acuity could have been kept in good shape with target practice and genetics could play a role -Another type of acuity is Age related changes with the eye and other parts of the visual system have a number of other consequences aside from declining visual acuity… AGE RELATED CHANGES WITHIN THE EYE AND OTHER PARTS OF THE VISUAL SYSTEM HAVE A NUMBER OF OTHER CONSEQUENCES ASIDE FROM DECLINING VISUAL ACUITY  Reduced dynamic visual acuity  Reduced size of the visual field  Reduced depth perception  Slower processing of visual information REDUCED DYNAMIC VISUAL ACUITY -Ability to read a definition of a banner on a bus/subway towards or away from you, and declines more dramatically with stable objects REDUCED SIZE OF THE VISUAL FIELD -Another change in the size of the visual field (how much of the room you can process at once) As we get older it shrinks and by age 70 it has shrunk to 140 degrees from 170; visual world shrinks, as we get older REDUCED DEPTH PERCPETION Distance btw one object from another Declines btw age 40-50 and picks up speed Loss of depth, can be caused by binocular cells from the two eyes SLOWER PROCESSING OF VISUAL INFORMATION 6 SPEED OF VISUAL PROCESSING -People process visual info once slowly than they once did When visual acuity decreases it will take longer to process due to slower speed that nervous system slows down to as we age *ALL PREDICTABLE CHANGES VISUAL DISORDERS  All of the previously discussed changes are normal age related changes in visual functioning  The following disorders are not due to age per se, although they tend to occur more frequently as we get older Disorders not due to age per say but do occur more frequently as we get older -They develop slowly and painlessly for the most part May be far advanced when it is finally detected  Glaucoma  Cataracts  Macular Degeneration (‘dry’ and ‘wet’)  Diabetic Retinopathy  Retinal Detachment  Corneal Disease GLAUCOMA Most often (not always) due to steady increase in pressure within the anterior chamber of the eye (Aqueous humor) --Aqueous helps maintain shape and carry nutrients and waste products- --In the healthy eye, rate of new humor being created and how much old humor is being drained --When too much humor is being produced or improper drainage; pressure will build within the eye and access amount of humor --This increased pressure constrained the neighboring blood vessels, which provide nutrients that make up the optic nerve --If you deprive any cell of oxygen and nutrients will begin to whither and die --Don’t receive to remain healthy and degenerate --Vision is destroyed in the periphery of the field and leads to tunnel vision then leads to blindness --Kills cells that provide vision in the periphery (center of the visual field) --Typically appears past the age of 40, greater incidents in elder adults --6% has mild cases 65yrs+ --Genetic factors play a role in this disease --If a family member has had this disease your chance is increased by a factor of 3 if you are diabetic: HIGH RISK (monitor eye regularly) --Note: when you go to the optometrist key symptoms… 7 By products of other disease and other injuries --Eye drops prevent further destruction of cells --Surgery helps drain the fluid and reestablish appropriate Level of pressure CATARACTS --The lens becomes increasingly opaque --Become increasingly common with age ¾ people are people who are passed their retirement age --Cause unknown but those who develop it have high levels of sugar in blood and increased exposure to radiation (ultra violet) --Can be treated and can surgically remove lens and replace with other lens --Partial vision is restored --Disappointment, artificial lens will have less ability to accommodate to change its shape to preserve its image --Limit to how well you can make due to it --Diet rich in vitamin A lower the risk MACULAR DEGENERATION --Central portion of the retina (use to do advanced visual acuity) deteriorates -Rich in vitamin may help prevent onset of disease --Essential to tasks of visual abilities such as reading --When a person passes the age of 80yrs, white women are especially affected --Secondary effect of diseases or can be produced by some prescription drugs --Photoreceptor cells that capture light and degeneration of nerve signal --Manifests: blurred and jagged image --No surgical can reduce “dry” --Less common form of WET MD –breaking up of blood vessels just beneath the retina, and treated with drugs or surgery targeted to destroy these blood vessels --Does not touch the periphery field --Can still move around in a familiar environment and does not lead to complete loss of vision DIABETIC RETINOPATHY… Blood vessel that nourishes the retina which either leak fluid causing serious loss of vision -Laser surgery is used with some benefit RETINAL DETACHMENT -Break apart and can often be reattached but time is of the essence CORNEAL DISEASE -Transparent and outer most part of the Eye -Misshapen and loses transparency due to injury or genetic factors and leads to blurred or distorted vision 8 CHANGES IN VISUAL FUNCTIONING HAVE A SIGNIFICANT IMPACT ON DAILY LIFE… Many older adults will find it increasingly harder to read, recognize faces, recognize important features of the environment, and see with low levels of light -Those who escape serious visual disorders and only exp normal declines -Perception: fall down stairs -Response: feel insecure and avoid unfamiliar setting and reduce physical activity and less social interaction -Many older adults live independently and access to work places and community services is important to them -Driving helps access these activities DRIVING AND AGE  Widespread concerns about aging drivers: how justified are they?  Factors to be considered: - Sensory - Psychomotor - Attentional - Useful Field of View (UFOV) - Medications - Medical Disorders  Some data suggests that age per se is a poor predictor of ability to drive safely among 25-75 age group  Drivers age 65-74 have a safety record as good as that of drivers age 25- 54  Past age 75-80, drivers are twice as likely to have accidents as younger drivers (some data does not confirm this)  Some data suggests that among the 75+ drivers, it is unhealthy drivers who are the primary reason for high accident rate  The most accident prone drivers are the under 24 year old drivers  Older drivers as a group are safe drivers despite their limitations because… - Some of them are unaffected by these limitations - Those who are affected tend to drive less and more defensively -Those in rural areas drive more than those who live in the city -How serious is the problem of the aging driver -Lets consider the various limitations that the aging driver has to --Increased sensitivity to glare, smaller visual field, slow to respond to stimulation etc. --Hearing can become an issue to certain driving conditions --Other factors: Reaction time to sudden changing information (green to yellow) 9 Changes in attention: know from research our attentional resources decline, as we get older. “Never noticed the other car” research has demonstrated that the efficiency declines if we decreases our demand of attentional resources (talking and driving) --Individual tasks --Older people are more affected by this than younger people since their resources are more limited --As the complexity of task that we have to carry on increases  uFOV --Extent of visual field available to a person at a brief glance --More than the sheer size of the visual field (varies with attention, how much we can process at a glance) --Amount of visual space available to us shrinks as we age --Useful size of visual field is determined by our att. Span --Research shows the UFOV decreases competes with attentional demand --Not unique to all drivers --Effect is particularly severe in older adults --Restricted field of view --Visual acuity test: can predict the risk of accidents --Useful field of few: can predict 13% of accidents ---This notion of field of view is more predictive of accidents in older adults Tend to use more prescription medications --Have many side effects --Impair reaction time processes (true in all adults but especially true for elders) Btw the ages of 25-75 (over 5 decades) is a poor predictor of being able to drive safely --Drivers between the ages 60-74 safety record better or as good as those of 20-25 --Age doesn’t look to be a issue --75-80+ become twice as likely to be in an accident as a young driver ---Often leads to call for restriction --Seniors involved in accidents are the most likely to die from injuries --Not all data conquers with the latter fact ---Concerning this 70+ pop: cruel observation  refocus on medically at risk drivers Not age per say but health of driver --Cataracts: 3 times more likely than seniors without --75-80: early stages of dementia (passed age 80; or Alzheimer’s of other types) --Rather the presence of medical conditio
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