Exam 8: Motor and Regulatory Systems

A fly decides to go on vacation, gets in an airplane, and travels from the west coast of the USA to the east coast of the USA. When the fly gets to the east coast, it experiences jetlag. What is the molecular mechanism by which the fly's circadian clock is shifted?

If you are studying for an exam and only get 3 hours of sleep one night, based on sleep homeostasis, what will happen to you the following day?

In Figure Q8-23, a single neuron in the motor cortex was recorded from while the animal moved its fingers (fingers 1-5). What does this experiment tell you about how individual motor neurons are tuned? Figure Q8-23

The hypothalamus is important for homeostasis in the body. What if your heart rate became too slow? What is general concept of how the hypothalamus detects a low heart rate and what output signal would increase the heart rate? How Is Eating Regulated?

What is one piece of evidence that circadian rhythms can run in constant darkness?

Which areas contribute to cerebral control over the autonomic nervous system?

Knowing the synaptic connections between neurons will tell you how the circuit works. Explain your answer.

The primary motor cortex contains a somatotopic map. What does that mean?

Put the following events in order of their occurrence for muscle contraction. A. ATP hydrolysis B) Release of Ca²⁺ from sarcoplasmic reticulum C) An action potential in the motor neuron D) Power stroke E) Activation of the nicotinic acetylcholine receptor F) ADP-myosin binds actin G) Release of acetylcholine H) Flow of K⁺ and Na⁺ ions through their receptor I) Movement of troponin/tropomyosin

What do you predict would happen if the activity of hypocretin neurons in the hypothalamus were genetically silenced?

What is the input nucleus of the basal ganglia?

The data in Figure Q8-34 are from a set of experiments that provide evidence that leptin is a feedback signal to control food intake. The mice used were Ob/Ob mice. Figure Q8-34 A. Figure Q8-34A is a Northern blot that shows staining to leptin mRNA. What can be concluded from this experiment? B. What happened to the mice in Figure Q8-34B and what can be concluded? C. Why is the buffer injection necessary for both experiments shown in Figure Q8-34B?

The basal ganglia are needed to initiate very fast eye movements called saccades. Based on the basal ganglia circuitry, what would the action potential activity be to allow a saccade? The superior colliculus is the premotor area that drives eye movement. Draw the basic action potential response next to the name of the nucleus listed below. The arrow demarks the start of the saccade.

You specifically lesion the arcuate nucleus of the hypothalamus in one mouse and the lesion mouse was joined parabiotically to a non-lesioned mouse (Figure Q8-33). Figure Q8-33 A. What do you predict would happen to the lesioned mouse and non-lesioned mouse? Circle the predicted outcome. B. Justify your answer. Why would the lesioned mouse lose or gain weight and why would the joined mouse lose or gain weight?

SCN neurons are the 'pacemaker cells' for the circadian rhythm. Circadian rhythms can be altered by the time of day, for example when you travel and go to a new time zone your clock has to reset. How do neurons in your SCN receive information about daylight?

Based on the idea in Weber's Law in which the just-noticeable difference in a stimulus is proportional to the magnitude of the stimulus, what is an advantage of having motor units of different sizes recruited in an orderly manner? If there were a small weight, for example, then small motor units would be recruited.

If a human has a mutation in the MC4R gene, what are the potential pathways that would lead to weight gain? Include the nuclei involved and disrupted feedback systems.

Although central pattern generating circuits are located in the spinal cord, the direct initiation of these circuits is located in which part of the brain?

Huntington's disease is a result of the selective loss of striatal neurons in the indirect pathway. One of the many symptoms of the disease is involuntary and continuous movement, called choreiform movement (chorea is derived from a Greek word for 'dance'). Based on the circuitry of the basal ganglia, why would selective loss of these neurons result in excess movement?

Wakefulness is maintained by the ascending arousal system with several pathways. Sleep is regulated by sleep-active neurons. An animal should not be both asleep and awake and your textbook compares this alternation between sleep and wake to central pattern generating circuits that control locomotion. Draw a basic circuit, from the perspective of pattern-generating circuits, and outline how sleep and wake regulate each other's activity, including the neurotransmitters they use.