What causes a twitch?
A: Involuntary muscle twitching, also known as muscle fasciculation, involves small contractions of a single muscle group that is controlled by a single nerve.
There are three main types of muscles in your body: cardiac muscle in the heart, smooth muscle that lines the hollow organs and blood vessels of the body, and skeletal muscle that is attached to the skeleton. Typically only skeletal muscle is under voluntary control. These muscles are made up of many cylindrical muscle fibres, running along the length of the muscle, which exert force by contracting.
The contraction of a muscle is initiated by electrical signals sent from the brain via conductive cells called motor neurons. Signals are sent along neurons, also called nerve cells, by the flow of charged ions, particularly potassium and sodium. The signals stimulate calcium ions to be released from inside the muscle cells, which then trigger an interaction two proteins found in the muscle cell, called myosin and actin. These proteins change shape, pulling and sliding past each other in small increments in a ratchet-like motion that shortens the entire muscle.
Basically, any imbalance or abnormal activity at any stage of this process can cause spontaneous muscle contraction. Being stressed out, tired, anxious, or not eating properly can lead to irregular activity in the brain and nervous system and trigger twitching. A dietary imbalance may lead to abnormal levels of potassium, sodium, or calcium-all essential in nerve and muscle activity-and cause twitching.
Certain diseases can also cause twitching, particularly if there is damage to the nervous system. Spinal muscular atrophy, Lou Gehrig’s Disease, muscular dystrophy, and myopathy are a few such examples. Drug overdose and drug side effects are also known to cause twitching.
-Qing Hua Wang
How does the Nintendo Duck Hunt work?
A: The Nintendo Zapper Gun, also remembered fondly as the Duck Hunt gun, isn’t really a gun, it’s a photoelectric sensor that detects the light given off by the TV. When you pull the trigger on the gun, the Nintendo system tells the TV to momentarily replace the ducks with white rectangles. If you go back and play the game again, you’ll notice that the screen flashes momentarily when you pull the trigger. If the gun happened to be pointing at a duck at that specific moment, the sensor in the gun transmits to the NES that it had a white rectangle in its field of view, which the game registers as a hit. In the oldest models of the gun, you could simply point the gun at a light bulb and make a direct hit every time. Later versions of the gun corrected the problem by having the screen flash completely black, then with white triangles, then black again. The gun was programmed to recognize “black, white, black” as a direct hit. This system used by the Zapper, which is known as a light gun, was also used in arcade games.
-Zoe Cormier, with files from Sarosh Jamal
