Teach Effectively!

Mainstream news sources are abuzz with the story that Stanford University neurobiologist Craig Garner and his colleagues compared the effects of pentylenetetrazole (PTZ) to picrotoxin and bilobalide on object recognition and maze learning of mice bred to have an analog of Down Syndrome. As they report in Nature Neuroscience, after a couple of weeks of receiving the drug, Professor Garner and his team found that the mice receiving PTZ not only did better than mice receiving the other compounds, but they performed as well as unimpaired mice on the learning tests. In addition, they found that the effects of the treatment lasted up to two months after treatment ended.

PTZ, which causes convulsions and has been used in shock therapy, is clearly a dangerous substance. It should not be administered to humans except with close medical supervision.

Ts65Dn mice, a model for Down syndrome, have excessive inhibition in the dentate gyrus, a condition that could compromise synaptic plasticity and mnemonic processing. We show that chronic systemic treatment of these mice with GABAA antagonists at non-epileptic doses causes a persistent post-drug recovery of cognition and long-term potentiation. These results suggest that over-inhibition contributes to intellectual disabilities associated with Down syndrome and that GABAA antagonists may be useful therapeutic agents for this disorder.

Pharmacotherapy for cognitive impairment in a mouse model of Down syndrome
Fabian Fernandez, Wade Morishita, Elizabeth Zuniga, James Nguyen, Martina Blank, Robert C Malenka & Craig C Garner, Published online: 25 February 2007 | doi:10.1038/nn1860

The drug is presumed to affect learning because it interferes with GABA_A receptors in neurons. Activated GABA_A receptors inhibit cells from forming new synapses with neighboring cells. That is, as I understand it, PTZ inhibits some inhibitors. (Anyone who knows this stuff better than I, please comment and explain it better.)

Even if clinical trials, which the Garner team reportedly is considering, reveal benefits for humans, there will still be a need for systematic, explicit instruction. It would be too bad to give some learners a drug just so that they could be subjected to the junky instruction from which only some unimpaired learners can benefit.

Link to info about Professor Garner and to his lab’s Web site. Link to Google news listing of stories.