Neuroimaging and Ocular Changes in Aging

1. Today Neuroimaging Dementia in aging—get some charts from her lecture Ocular changes with aging—learn hyperopia

2. Working Memoryis the ability to maintain and manipulate information over short periods of time necessary to guide behavior

3. 1000 800 20s-30s 50s-60s Mean Reaction Time (msec) 600 70s-80s 400 200 ALONE COUNTING DIGIT SPAN Task Condition

4. Structural brain changes with aging changes in brain volume young old

5. STRUCTURAL FUNCTIONAL Magnetic Resonance Imaging Positron Emission Tomography

6. YOUNG OLD

8. YOUNG ELDERLY UNDERRECRUITMENT NON-SELECTIVE RECRUITMENT OVER RECRUITMENT YOUNG OLD

10. 1500 1250 1000 750 500 Old Young Reaction Time (msec) 2 6 2 6 Memory Load

11. FASTEST SLOWEST YOUNG OLD

13. Summary • Age-related decline in selective cognitive processes • Functional MRI is a powerful method with excellent spatial and temporal resolution to study the physiological basis of cognitive decline in normal aging • Evidence for selective prefrontal cortical dysfunction (I.e. under-recruitment) with normal aging • Possible neural as well as behavioral compensation

14. Questions • What is fMRI? What is it used for and how does it work? • What area of the brain has been shown to have change in older people?

15. AGING OF THE NERVOUS SYSTEM—FUNCTIONAL CHANGESAgain, in the normal aging brain the changes are relatively few. However impaired function and increased pathology do occur. Major functional deficits/ pathologies involve: Motility (e.g. Parkinson’s Disease) Senses and communication Cognition (e.g. dementias) Affect and mood (e.g. depression) Blood circulation (stroke, multi-infarct dementia) Parkinson’s Disease: Chapter 8, pp. 110-113 Dementias: Chapter 8, pp. 130-136

16. Dementia • Dementia: global deterioration of intellectual and cognitive function characterized by 5 major mental functions: • Orientation • Memory • Intellect • Judgment • affect • (But clear consciousness)

17. Dementia (cont.) • There are two types of dementia: • Reversible • Irreversible

22. Amyloid Connections • In Alzheimer’s, amyloids are made and accumulate in brain tissues and cause disturbances. • Maybe these could be a point of intervention to prevent progression of alzheimers.

23. Characteristics of Multi Infarct Dementia (table 8.9) • Transient ischemic attack or stroke • Hypertension, arrythmia • Focal neurological signs • Stepwise deterioration

24. Questions • What are the causes of reversible dementia? • What are the characteristics of multi-infarct dementia? • What are the major functional deficits/pathologies in aging?

25. Aging of the Visual System

26. Definitions • To look at a near source, the lens has to accommodate (become more round); to look at a far source it doesn’t have to accommodate. • Myopia: nearsightedness because eyeball is too long or lens is too strong. Corrected with concave lens. • Hyperopia: farsightedness due to eye too short or lens is not strong enough. Corrected with convex lens • Presbyopia: loss of focusing power of lens because it has stiffened—results in difficulty seeing objects close up which necessitates lens to accommodate.

27. Structural Changes (See handout given in class) Tear Film: Dry eyes or tearing Sclera: Fat deposits – yellowing Thinning – blueing Cornea Diameter does not change after age 1 Shape changes Retina Photoreceptor density decreases; other layers become disordered (rod density decreases with age, cone density remains) Illuminance decreases with age Lens Increased size and thickness Becomes more yellow Aging of the Visual System

28. Aging of the Visual System • Function • Corneal and Lens • Decreased accommodation power (loss of presbyopia: loss of focusing power of lens because it has stiffened—results in difficulty seeing objects close up.) • Increased accommodation reflex latency • Refractive error becomes more hyperopic with age • Corneal sensitivity decreases • Scatter increases • Pupil • Size decreases with age, particularly for dim light conditions.

29. Aging of the Visual System • Retinal (MANY changes due to decreased amt of light reaching retina) • Decreased critical flicker frequency • Visual acuity declines • Visual Field decreases • Color vision changes • Darkness adaptation is slowed • Increased glare problems, longer time to recover from glare • Decreased light reaches retina • Visual acuity declines most with age when tested in low contrast with dim light. The difference as compared to young people is very significant in this case. (not as significant if tested with high contrast, bright light) • Attentional visual field size decrease • Stereopsis (close-up depth perception) shows large loss with age due to difference in function of 2 eyes. • Face recognition impaired

30. Other changes • Words per minute decrease in reading • Increased hyperopia: (farsightedness because eye is short) • Increased astigmatism (cornea of eye is asymmetrically curved causing out of focus vision)

31. Graph from handout—summary of some main points • Most change with age in: • acuity in glare 18x worse with aging • Next: glare recovery 15x • Next: attentional field 12x • Etc…

32. Aging of the Visual System • Recommendation to Accommodate Problems: (she didn’t discuss in too much detail, but good to know) • Wear appropriate optical correction • Increase ambient light • Make lighting even and reduce glare • Improve contrast in critical areas • Avoid rapid changes in light level • Avoid Pastel • Allow more time