Which of the following neurotransmitters affects neurons involved in sleep, appetite, sensory perception, temperature regulation, pain suppression, and mood?

At what age do children engage in cooing?

a) 2 months b) 4 months c) 6 months d) 8 months

At what age would we expect to hear the pattern called intonation in young children?

a) 2 - 3 months b) 6 - 7 months c) 8 - 11 months d) 20 - 24 months