CHAPTER TWONeuroscience as a Basis for Adult

Development and Aging

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Neuroscience Tools…

…allow for the study of age related pathologies:

• Alzheimer’s• Parkinson’s

• Magnetic resonance imaging (MRI) – provides static snapshots of

the brain

Neuroscience Tools

• Functional magnetic resonance imaging (fMRI) – fMRI monitors blood flow

in the brain concurrent with behavioral performance.

The Nervous System

• Neurons: cells that send and receive messages– Dendrites receive messages– Cell body keeps the cell alive and decides when to send

message– Axon sends message– Terminal buttons release chemical messengers into gap– Neurotransmitters are the chemical messengers that allow

neurons to communicate– Synapse is the space between neurons

Healthy Neurons & Unhealthy neurons

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Structural Changes in Neurons• Plasticity

– Neurofibrillary tangles– Amyloid plaques

• Both considered characteristics of Alzheimer’s disease

Changes in communication between the neurons

• Parkinson’s disease

The Nervous System

Methodological Perspectives

Neuropsychological Perspective

• Compares healthy older adults with those with pathological disorders of the brain

Methodological Perspectives

Correlational Perspective• Links measures of cognitive performance to measures of

brain structure or functioning

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Methodological Perspectives

Activation imaging• Links functional brain

activity with cognitive behavior data

Anatomy of the Human Brain

• Executive functions– Ability to make and carry out plans– Switch between tasks– Maintain attention and focus

• Brain structures involved:– Prefrontal cortex– Hippocampus– Cerebellum

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Age-Related Changes in the Structure of the Brain

Thinning and shrinkage in volume and density are linked to:

– Lower cognitive test scores– Poor performance of executive

function– Memory decline– Decline in speed of processing

• White matter hyperintensities (WMH)– Indicate myelin loss or neural

atrophy

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Age-Related Changes in Neurochemical Properties

The dopaminergic system is associated with:

• higher–level cognitive functioning • Inhibiting thoughts• Attention• Planning

• a decline in functioning as one ages normally

• Research has found a decline in cognitive tasks that involve more effort:• Episodic memory• Speed tasks• working memory

Functional Consequences of Brain Deterioration

• Anterior cingulate cortex (ACC) • Affiliated with the prefrontal cortex and is also

involved in executive control• As one ages, this area tends to deteriorate,

affecting tasks involving working memory

Compensation and Prefrontal Bilaterality

When presented with similar tasks:• younger adults exhibit

unilateral activity in left prefrontal region

• older adults exhibit bilateral activity (both left and right prefrontal areas)– Perhaps the aging brain

makes compensatory changes

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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 an increase in number of newly generated neurons after sessions in complicated mazes.

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Neuroscience and Cognitive Aging

• 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).

Emotional Processing and the Brain

Information with high emotional significanceis 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 to.

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Aging and Emotional Processing

Younger and older adults process positive and negative information differently.• Positivity Effect: Older adults are more motivated

to derive emotional meaning from life and to maintain a positive affect.

• As a result, older adults pay more attention to and remember positive information.

• Younger adults tend to pay more attention to and remember negative information.