Here's a tidbit I feel like sharing: Yesterday, I was flying from LA to SF - the last leg of a excruciating 22-hour journey back home from Israel. During that 15 minute window before landing, when my kindle had to be turned off just in case its electric presence flummoxed my Southwest airplane, I flipped through the inflight magazine.
And found this gem of sort-of neuroscience: a Brain Quiz (aka an advert for something in a pill bottle called "AlphaBrain". The website for AlphaBrain is so full of dubious neuro-technobabble that I'm categorically refusing to provide a link.)
With a befuddlement mostly provided by substantial amounts of jetlag (still feeling it. woohoo), I stared longest at question 3:
Ready for the answers? Curious which one of the rightmost boxes could possibly be the "most accurate association" with GABA (the major inhibitory neurotransmitter that is involved in just about everything)?
Here it goes.
Mental speed, focus, memory. Commentary: Uh, I guess so. But maybe also muscle movements, seeing as how acetylcholine is THE transmitter at the neuromuscular junction. And I'm not too sure how what "mental speed" means, but acetylcholine is involved in attention, which I guess could work with the focus thing. And screwing with acetylcholine does affect learning/memory/plasticity, so I guess that's fine. Whatever.
Positive mood. Commentary: Did you know that the vast majority of serotonin release is in the gastrointestinal tract, where it regulates intestinal movements? Mis-regulated intestinal movements sure leaves me in a bad mood. But sure, in the brain, release of serotonin does regulate mood. Drugs that increase serotonin levels in the brain are prescribed as antidepressants (e.g. selective serotonin re-uptake inhibitors, SSRI's), or used (and abused) as psychedelics (e.g. LSD, mescaline, MDMA).
Coordination, pleasure, mental drive. Commentary: Pleasure? Ugh. Try "reward-driven learning". Does the coordination come from the loss of movement accompanying the death of dopaminergic neurons in Parkinson's disease? Not really a loss of coordination, so much as a categorical degeneration of motor control. "Mental drive" likely refers to the deficits in mental acuity, attention, and memory that accompany dopaminergic cell loss in Parkinson's. Also, reduced dopamine concentrations have been associated with ADHD, which could be characterized by less "mental drive". I guess. Maybe.
Relaxation, sense of calm. Commentary: GABA, aka gamma-aminobutyric acid, aka the main inhibitory neurotransmitter in the CNS. It's diverse roles, reduced to the fact that many potent anesthetics are either GABA receptor agonists or positive modulators (e.g. alcohol, valium). Oh well. Note: for those interested in the differences in GABAergic inhibition between awake and anesthetized states, I direct you to a great recent publication by Michael Hausser and Matteo Carandini. First author Bilal Halder shows that in the mouse visual system, synaptic inhibition was substantially stronger in awake animals, when compared with anesthetized animals. A fun finding, given the (radically oversimplified) hypothesis that anesthetics work by increasing inhibition within the CNS. Insert spirited discussion about the difference between general changes in GABAergic tone (produced by anesthetics) and temporally/spatially/neuron specific synaptic inhibition (observed in awake conditions, likely disrupted by anesthetics).
Citation: Halder, Hausser and Carandini (2013). "Inhibition dominates sensory responses in the awake cortex." Nature 492, 97-100. Link.