Cognitive Enhancement (Nicotine, Caffeine, Cocaine, Amphetamine) and General Anesthesia

Cognitive enhancers or psychostimulants are pleasurable and invigorating molecules claimed to alter the state of the human mind by stimulating cognitive functions, memory, creativity or motivation, without causing major hallucinations. They include nicotine caffeine, cocaine, amphetamines... In contrast, general anesthetics (GAs) causes a decreased awareness to painful stimuli and a loss of consciousness. They include propofol, etomidate, isoflurane, benzodiazepines, and barbiturates.

Nicotine is used by Aboriginal groups to excite their courage, particularly in warfare. Andean workers use cocaine to reduce fatigue, improve mood, and even enhance sexual vigor. Most cognitive enhancers are structural homologs of brain neurotransmitters and target the chemical synapse. Nicotine and caffeine bind to the active site of neurotransmitter receptors: the nicotinic acetylcholine receptor for nicotine and the adenosine receptor for caffeine. On the other hand, cocaine and amphetamines block presynaptic transport and cause accumulation of excitatory neurotransmitters like dopamine at the synapse. In contrast, GAs act as allosteric modulators mainly of inhibitory GABA_A receptors and enhance cortical inhibition.

The connectomic architectures engaged in cognitive enhancement and anesthesia are accounted for the Global Neuronal Workspace (GNW) theory of conscious access. These architectures are grounded on a reciprocal network of pyramidal neurons with long range axons which globally and reciprocally broadcast signals to (and from) multiple brain areas. Enhancers would cause a global activation of the GNW and GAs its down regulation. A causal link would then be established between the molecular targets of the drugs and the altered states of the human mind.