Complex sentence: Testosterone is "associated with approach-related behavior, reward sensitivity, and fear reduction", and injecting testosterone "shift (s) the balance from punishment to reward sensitivity", decreases fearfulness, and increases "responding to angry faces".
Split into simpler sentences: Testosterone is "associated with approach-related behavior, reward sensitivity, and fear reduction". Injecting testosterone "shift (s) the balance from punishment to reward sensitivity", decreases fearfulness, and increases "responding to angry faces".