**Core Concept**
Barbiturates are a class of central nervous system depressants that exert their effects by enhancing the activity of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABA_A receptor, a ligand-gated chloride channel. This results in neuronal hyperpolarization and decreased neuronal excitability.

**Why the Correct Answer is Right**
The correct answer is that barbiturates are used in the treatment of epilepsy. Barbiturates, such as phenobarbital, are effective in controlling seizures due to their ability to increase the activity of GABA, which has an inhibitory effect on neuronal activity. By enhancing GABAergic transmission, barbiturates can reduce the excitability of neurons and prevent the spread of seizure activity.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because barbiturates are not primarily used as anxiolytics; benzodiazepines are more commonly used for this purpose.
**Option B:** This option is incorrect because barbiturates do not primarily act as stimulants; they are actually central nervous system depressants.
**Option C:** This option is incorrect because barbiturates do not primarily act as sedatives; while they can cause sedation, this is not their primary mechanism of action.

**Clinical Pearl / High-Yield Fact**
Barbiturates can be used as an antidote for strychnine poisoning, as the increased GABAergic activity can counteract the excitatory effects of strychnine.

**Correct Answer:** D.