Explain how genetic mutations that cause neurodegenerative disorders such as Huntington disease and Alzheimer disease can also cause abnormal behavior

Question

What will be an ideal response?

Answer 1

Because the nervous system receives and processes stimuli and generates behavioral responses, it is the focus of behavior genetics. The central nervous system (CNS) includes the brain and spinal cord; the peripheral nervous system (PNS) includes the nerves that radiate from the CNS and the sense organs. This emphasis is reinforced by the finding that many disorders with a behavioral phenotype—including Huntington disease, Alzheimer disease, and Charcot-Marie-Tooth disease—alter the structure and/or function of the brain and the nervous system.

When a nerve impulse travels to the axon of one cell (neuron A), it must cross the synapse to neuron B in order to continue its journey. Axon tips contain membrane-bound vesicles enclosing packets of chemicals called neurotransmitters. These chemicals are an important component of human behavior. When a nerve impulse arrives at the axon, neurotransmitters are released into the synaptic cleft. These chemical signals diffuse across the cleft and bind to receptors on the membrane of the postsynaptic neuron. Neurotransmitter binding triggers a new nerve impulse in the postsynaptic cell. Changes in the timing or duration of neurotransmitter action can affect someone's behavior. In addition to mediating behavior, neurotransmitters can affect our mood, memory, and our sense of well-being. Endorphins are one type of neurotransmitter. When endorphins are released, often during exercise, stress, or excitement, we feel a rush of exhilaration. Many drugs, such as cocaine, that change our moods also bind to endorphin receptors and mimic the effect of our own neurotransmitters, creating a similar feeling.