Final answer:
Neurons in the aging brain fire more slowly and there is a reduction in synaptic connections as people reach middle adulthood.
Step-by-step explanation:
With age, neurons in the brain fire more slowly. Additionally, by middle adulthood, there are fewer synaptic connections. This is evidenced by research comparing elderly participants to younger ones, where older participants demonstrated slower responses and increased errors due to degeneration of corticostriatal connections.
The aging process in the brain is complex and involves the loss of neurons, as well as synaptic pruning, where unused pathways are eliminated. However, some neural development continues into adulthood through neurogenesis, which is the birth of new neurons, particularly noted in the hippocampus - a region critical for learning and memory.