Mechanism of nicotine's learning effects explored

April 4, 2007

While nicotine is highly addictive, researchers have also shown the drug to enhance learning and memory—a property that has launched efforts to develop nicotine-like drugs to treat cognitive deficits in Alzheimer’s and Parkinson’s diseases, schizophrenia, and attention-deficit/hyperactivity disorder.

A key problem in designing such drugs has been that little was known about the detailed mechanism by which nicotine exerts its learning-enhancing effects.

Now, researchers have discovered important details of how nicotine adjusts the signaling properties of neuronal wiring to enhance memory. Such signaling properties include the strength of the connections by which one neuron triggers another. Huibert Mansvelder and colleagues reported their findings in the April 5, 2007, issue of the journal Neuron, published by Cell Press.

The researchers made their discoveries by analyzing the electrophysiological properties of neurons in slices of mouse brain, as they treated the slices with nicotine or with drugs that prevent nicotine’s action. Specifically, the researchers studied the neurons of the prefrontal cortex, which contain centers for learning and memory.

Researchers had known that nicotine enhances learning by activating receptors for the neurotransmitter acetylcholine. Such neurotransmitters are the chemical signals that one neuron launches at another to trigger a nerve impulse in the receiving neuron.

In their studies, Mansvelder and colleagues found that by activating acetylcholine receptors, nicotine affects a process called “spike-timing-dependent potentiation” that governs changes in strength of signaling connections among neurons. What’s more, the researchers traced this effect to nicotine’s action on specific kinds of neurons, called GABAergic neurons, in the learning centers. In turn, the effects on GABAergic neurons affected signaling between neurons mediated by the key substance calcium.

The researchers also discovered key details of the mechanisms by which nicotine excites different kinds of “interneurons” in the prefrontal cortex. Interneurons are the way-stations for neuronal impulses, passing neuronal signals from one neuron to another.

Source: Cell Press

Explore further: Nicotine triggers the same brain reward circuitry as opiates

Related Stories

Nicotine triggers the same brain reward circuitry as opiates

June 15, 2005

In experiments with mice, researchers have found that nicotine triggers the same neural pathways that give opiates such as heroin their addictively rewarding properties--including associating an environment with the drug's ...

Two Nicotine Addiction Puzzles Explained

August 2, 2007

The stranglehold of nicotine addiction leads to more than four million smoking-related deaths each year. Scientists at the California Institute of Technology have now explained two roots of that addiction. The discoveries ...

Dissecting the machinery of nicotine's reward

June 14, 2006

Understanding what makes people crave the high of nicotine is a key to developing treatment for this highly addictive drug. And that understanding involves tracing the neural machinery by which nicotine switches on the brain's ...

Researchers find link between nicotine addiction and autism

November 17, 2008

Scientists have identified a relationship between two proteins in the brain that has links to both nicotine addiction and autism. The finding has led to speculation that existing drugs used to curb nicotine addiction might ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

( -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.