How do these four drugs work on individual nerve cells?
marijuana, cocaine, meth, and ecstasy.

Marijuana - One such part of the brain, the hippocampus, manages short-term memory, meaning that marijuana use can impede recollection of recent events. Additional regions of the brain that are impacted include the cerebellum and basal ganglia, which help to control coordination and involuntary muscle movements respectively. When someone abuses marijuana, impaired motor skills, mood alterations, distorted time and sensory perception, decreased memory, and trouble thinking clearly and solving problems are all common short-term side effects.

Cocaine and Meth - they speed up the central nervous system, increasing heart rate, body temperature, and blood pressure while increasing energy levels, focus, attention, alertness, and wakefulness. They also suppress appetite. They create high dopamine levels but then crash creating irritation and short tempers.

Ecstasy - Ecstasy stimulates a sense of emotional closeness and warmth, while enhancing and distorting the senses, heightening energy levels, decreasing anxiety, and increasing feelings of pleasure. Heart rate, body temperature, and blood pressure are also elevated by ecstasy use. Hyperthermia, high blood pressure, panic attacks, faintness, involuntary teeth clenching, blurred vision, nausea, sweating, chills, arrhythmia, heart failure, kidney failure, dehydration, loss of consciousness, and seizures are possible side effects of ecstasy abuse and/or overdose.

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature