Rho inserts a small electrode into a cat’s brain and connects the electrode to a lever that administers a small electric shock to the brain every time it is pressed. dr rho notices that after the cat presses the lever the first time, she purrs and rubs up against the lever as she presses it over and over again. what part of the brain is the electrode most likely stimulating?

The part of the brain the electrode is most likely to be stimulating is the reward pathway of the brain.

Explanation:

The reward pathway of the brain is the area of the brain that senses pleasure.  The pathway covers the region starting from the  Ventral Tegmental Area (VTA), through to the amygdala, the nucleus accumbens, the pre-frontal cortex and finally to the hippocampus.

The amygdala deals with emotions and some other things, the nucleus accumbens controls the motor functions of the body, the pre-frontal cortex helps with attention and planning while the hippocampus  is responsible for the formation of memories.

Dr. Rho's experimental cat purred and rubbed up against the lever that administers electric shock to the brain each time it is pressed signals that the animal is deriving pleasure sensation from the electric shock. When the reward pathway of the brain becomes stimulated, neurons in the VTA release dopamine, a neurotransmitter often referred to as the pleasure hormone.

The released dopamine then travels to the other parts of the reward pathway making the body to feel pleasure and the need for more of the pleasure. This made Dr. Rho's cat to keep pressing the lever over and over again.