Lecture 3

Vocabulary terms and definitions covering structural, functional, and systemic biological changes associated with aging, including neural changes, neurotransmitter systems, and neuroplasticity.

Gyri

The outward folds or bulges of the brain that shrink as a consequence of aging, contributing to a less convoluted cerebral surface.

Sulci

The inner folds or grooves of the brain that widen as brain volume decreases with age.

Prefrontal Cortex

A brain region located behind the eyes, accounting for about $10\%$ of the brain, that undergoes age-related shrinkage and governs executive functions such as attention, decision making, problem solving, and social inhibition.

Hippocampus

A brain structure spanning the midbrain to the temporal lobe that is vulnerable to age-related shrinkage, plays key roles in memory, pattern recognition, and spatial location, and retains the capacity to generate new neurons in older adulthood.

Cerebellum

A primitive brain region, sometimes called the 'little brain,' containing more neurons than the rest of the brain combined; it supports balance, muscle tone, gait, sensory integration, and motor coordination.

Gray Matter

Neural tissue composed of post-mitotic neurons, dendrites, and synapses that begins deteriorating in young adulthood.

Post-mitotic Cells

Cells, such as neurons, that do not divide or reproduce, meaning that once they die, they are permanently lost.

White Matter

Brain tissue consisting of myelin sheaths that insulate axons to accelerate neural transmission; its deterioration begins during midlife.

Cerebrospinal Fluid

Fluid held within the brain's four ventricles and spinal column that cushions the brain (reducing the felt weight by $97\%$), eliminates metabolic waste, and delivers nutrients.

Microglial Cells

Support cells comprising $10\%$ to $15\%$ of nervous system cells that perform phagocytosis and release chemicals to trigger immune responses against infection and injury.

Phagocytosis

The immune process by which microglial cells engulf and break down unwanted biological products, such as abnormal proteins and cellular debris from dying cells.

Covert Brain Diseases

Diseases of the brain that emerge clinically only after the formal conclusion of a research study, which can distort normative aging findings if participants are not reassessed and excluded.

Dopamine

A neurotransmitter synthesized from dietary phenylalanine that regulates attention, short-term memory, motor control, and reinforcement or reward processing.

Substantia Nigra

A midbrain structure where dopamine is produced specifically to regulate motor movement; deficits here are linked to Parkinson's disease.

Ventral Tegmental Area

A midbrain dopaminergic nucleus primarily linked to the psychological sensations of reinforcement, euphoria, and reward.

Transporters (Neurotransmitter)

Proteins located on the presynaptic neuron responsible for the reuptake of released neurotransmitters from the synaptic cleft.

Serotonin

A neurotransmitter that regulates mood, eating behavior, sleep (by acting as a precursor to melatonin), and sexual function.

Raphe Nuclei

Clusters of nuclei in the brainstem where serotonergic neurons originate and send diffuse projections throughout higher and lower brain areas.

Neuroplasticity

The brain's lifelong capability to adaptively modify its structure and functional connections in response to experiences, behavior, and environmental opportunities.

Olfactory Bulb

A sensory brain structure that exhibits ongoing adult neurogenesis, allowing individuals to form new olfactory memories across the lifespan.

Andropause

The gradual age-related decline of testosterone in males, typically characterized by an approximate reduction of $1\%$ per year during older adulthood.

Hypothyroidism

An endocrine disorder affecting roughly $6\%$ of older adults (predominantly women) where the thyroid fails to produce sufficient thyroxine, leading to impaired metabolic rate.

Osteopenia

An age-related reduction in bone mineral density that precedes osteoporosis, occurring more severely in women due to the postmenopausal cessation of estrogen.

Ligaments

Fibrous connective tissues that attach bones to other bones, becoming progressively more rigid with advancing age.

Tendons

Fibrous connective tissues that link bones to muscles, which stiffen with age and contribute to reduced physical mobility.