2 HUS 133 Neuroscience


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2 HUS 133 Neuroscience

  1. 1. Neuroscienceas a Basis for Adult Development 1 of 26
  2. 2. The Neuroscience Approach 2 of 26
  3. 3. The Neuroscience Approach Learning Objectives • How do the basic developmental forces benefit from the neuroscience approach? • What is the major focus of the neuropsychological approach to neuroscience? • Describe the difference between the correlational approach and the activation imaging approach to studying neuroscience. • What is the difference between MRI and fMRI scanning? 3 of 26
  4. 4. The Neuroscience Approach Implications of the Developmental Forces • Age is not the best predictor of behavior. • Behavior is determined by multiple forces. • Cognitive - Social – Emotional • Structural changes in brain volume and density • Functional changes in brain areas • Brain plasticity • Environmental interventions on structure and activation of the brain • Social, biological, and psychological interventions to influence positive changes 4 of 26
  5. 5. The Neuroscience Approach Neuroscience Tools • Magnetic resonance imaging (MRI) • Functional magnetic resonance imaging (fMRI) • MRI provides static snapshots of the brain • fMRI monitors dynamic activities of the brain concurrent with behavioral performance • Allows study of age related pathologies • Alzheimer’s • Parkinson’s 5 of 26
  6. 6. The Neuroscience Approach Neuroscience Perspective • Methodological Perspectives • Neuropsychological • Compares healthy older adults with those with pathological disorders of the brain • Correlational • Links measures of cognitive performance to measures of brain structure or functioning • Activation imaging • Links functional brain activity with cognitive behavior data 6 of 26
  7. 7. Neuroscience & Cognitive Aging 7 of 26
  8. 8. Neuroscience and Cognitive Aging Learning Objectives • What are the basic structural changes in the brain as we age? • What cognitive functions are associated with volume shrinkage in the aging brain? • How do decreases in the dopaminergic system relate to changes in cognitive functioning as we grow older? • What happens to brain activation as we age? • What are the cultural implications of neuroimaging? • How does bilateral activation serve a functional role in older adults’ cognitive functioning? • What are the major differences between the HAROLD and STAC models of brain activation and aging? 8 of 26
  9. 9. Neuroscience and Cognitive Aging Structure of the Brain • Anatomy of the human brain • Executive functions • Ability to make and carry out plans • Switch between tasks • Maintain attention and focus • Age-Related Changes in the Structure of the Brain • Thinning and shrinkage in volume and density • White matter hyperintensities (WMH) • Indicates myelin loss or neural atrophy • Diffusion tensor imaging (DTI) • Index of density or structural health of the white matter 9 of 26
  10. 10. Neuroscience and Cognitive Aging Structure of the Brain • How deteriorating structural changes relate to cognitive function • Less efficient information processing • Speed of processing • Executive functions • Declarative long-term memory • Volume shrinkage in the brain linked to: • Lower cognitive test scores • Poor performance of executive function which is also linked to: • Decreased volume of prefrontal cortex • Memory decline • Frontal volume as predictor of cognitive function has yielded inconsistent findings. 10 of 26
  11. 11. Neuroscience and Cognitive Aging Structure of the Brain • Studies in structural changes in the aging brain and cognitive functions has overall produced inconsistent findings. • However, inconsistencies can be attributed to: • Sample composition • Whether cross-sectional differences or longitudinal changes are being examined • Whether different subregions are under investigation • Whether different cognitive test are used • Regardless, when longitudinal converge with cross-sectional studies, it is clear that increases in WMH are associated with reduced performance on executive functioning tasks. 11 of 26
  12. 12. Neuroscience and Cognitive Aging Age-Related Changes in Neurochemical Properties • The dopaminergic system is associated with: • Higher–level cognitive functioning • Inhibiting thoughts • Attention • Planning • Declines in dopamine system are related to declines in: • Episodic memory • Speed tasks • Age-related deficits in working memory • Declines in memory 12 of 26
  13. 13. Neuroscience and Cognitive Aging Age-Related Changes in Brain Activity • Functional imaging (fMRI) examines how: • Changes in brain activity are related to: • Changes in task demands • Type of cognitive functioning under investigation • Do older adults compared to younger adults use different areas of the brain in order to perform cognitive tasks more effectively? • Is this a method of adaptive accommodation by the brain in order to assist older adults to adjust to neurological impairment brought about by increasing age? 13 of 26
  14. 14. Neuroscience and Cognitive Aging Functional Consequences of Brain Deterioration • Anterior cingulate cortex (ACC) • Affiliated with the prefrontal cortex and is also involved in executive control • Reduced working memory performance is related to decreased activation of the ACC in older adults. • Reduced brain activation (under-recruitment) of the prefrontal cortex occurs during intentional cognitive processing. • Reduced frontal recruitment in aging is context-dependent. • Other studies show equal frontal activity in older and younger adults in memory retrieval. 14 of 26
  15. 15. Neuroscience and Cognitive Aging Culture, Neuroimaging, and Aging • Examining cultural differences in neurobiological aging • Older adults in from Western cultures show significantly greater object-processing adaptation in the lateral occipital complex, relating visual processing, than older East Asians. • Overall, however, age-related changes seem to be more profound than cultural effects. • Different regions of the brain do not deteriorate evenly. • Prefrontal area is more prone to decay than, for example, the amygdala (involved in emotional processing). 15 of 26
  16. 16. Neuroscience and Cognitive Aging Compensation and Prefrontal Bilaterality • Studies show that, when presented with similar tasks, younger adults exhibit focal, unilateral activity in left prefrontal region and older adults exhibit bilateral activity (both left and right prefrontal areas). • Why? Is it compensation for deterioration in older brains or is it inefficient inhibitory mechanisms? • Growing body of evidence supports the theory that bilateral activation in older adults plays a supportive role in their cognitive function. (see fig, 2.2) 16 of 26
  17. 17. Neuroscience and Cognitive Aging Compensation and Prefrontal Bilaterality • STAC (scaffolding theory of cognitive age) • Default network theory holds that when the cognitive demands are made on the brain the default network is suppressed. - Increased demand scaffolds increase areas of the brain. • HAROLD (hemispheric asymmetry reduction in older adults. • Suggests bilaterality is compensatory in older adult with reduced cognitive ability • CRUNCH (compensation-related utilization of neural circuits hypothesis) • This hypothesis is similar to HAROLD but suggests additional mechanisms at work of aging brains over-utilizing other regions in the left hemisphere on demanding tasks before going to the right hemisphere. 17 of 26
  18. 18. Neural Plasticity & the Aging Brain 18 of 26
  19. 19. Neural Plasticity and the Aging Brain Learning Objectives • How do animal models contribute to our understanding of neural plasticity and aging? • What evidence is there for neural plasticity and aging? • How does aerobic exercise influence cognitive aging? 19 of 26
  20. 20. Neural Plasticity and the Aging Brain• Plasticity involves the interaction between the brain and the environment and is mostly used to describe the effects of experience on the structures and function of the neural system.• Neural stem cells (which give rise to new neurons) persist in adult brains and can generate new cells throughout adulthood.• Environmental enrichment – Experiments with aging mice showed the increased number of newly generated neurons after sessions on complicated mazes. 20 of 26
  21. 21. Neuroscience & Socio-Emotional Aging 21 of 26
  22. 22. Neuroscience and Socio-Emotional Aging Learning Objectives • Are there differences in the brain for cognitive versus socio-emotional functioning? • What is the neural circuitry responsible for enhanced memory for emotional information? • What are the neural underpinnings of the positivity effect found in older adults? 22 of 26
  23. 23. Neuroscience and Socio-Emotional Aging Emotional Processing and the Brain • Information with high emotional significance is more likely to be remembered than information that is emotionally neutral for both older and young adults. • Negative high-arousal information is: – automatic in nature – linked to activation of the amygdala interacting with the hippocampus • Negative low-arousal information: – more activation of the prefrontal cortex-hippocampus network is necessary • If the amygdala is damaged, arousing stimuli are not attended. 23 of 26
  24. 24. Neuroscience and Socio-Emotional Aging Aging and Emotional Processing • Younger and older adults process positive and negative information differently. – Older adults are more motivated to derive emotional meaning from life and to maintain a positive affect. – As a result, older adults pay attention and remember positive more than negative information. – Younger adults tend to pay attention and remember negative more that positive information. 24 of 26
  25. 25. Neuroscience and Socio-Emotional Aging Neurological Recruitment Underlying the Positive Effect in Memory • Core emotional memory network consists of the: – amygdala – hippocampus – lateral orbitofrontal cortex • In older adults, these areas are relatively well preserved in emotional memory and correspond to memory performance in both positive and negative items. • In both older and younger adults, the occipito-temporal regions (specifically the fusiform gyrus) are used for successful encoding of negative information. • Positive information activates the anterior prefrontal regions. • Older adults show activation of the medial prefrontal cortex and regions of the cingulate gyrus when responding to positive information whereas younger adults do not. 25 of 26
  26. 26. Neuroscience and Socio-Emotional Aging Neurological Recruitment Underlying the Positive Effect in Memory • The positivity effect should be seen only when an individual has a high degree of cognitive control resources. – Older adults who are low in cognitive resources show no positivity effect. • Young and old adults show different brain activation when viewing faces with negative emotional expressions. – Young adults show increased activity in the amygdala when viewing negative emotional expressions compared to older adults. – Older adults do show increased activity in the anterior cingulate gyrus when viewing negative emotional expressions. • Research reveals the core emotional memory networks is preserved with aging. Age differences are found in encoding positive and negative information. 26 of 26
  27. 27. The End 27 of 26