Neurobiology: The motivational speaker

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Neurobiology: The motivational speaker
Neurobiology: The motivational speaker

The Motivational Speaker

Rewards usually lead to better memory performance - even if you only expect the desired reward. The reason for this stimulation lies in the interaction of several brain regions.


Sometimes everything just goes wrong: A memory lapse in the middle of a university presentation, forgetting your mother-in-law's birthday, and the name of the person sitting next to you in the canteen doesn't come to mind either. First signs of mental rusting? Possible. Or maybe the forgotten information just wasn't appealing enough to motivate the brain to remember effectively.

Motivation is not only considered an important key element of successful learning in today's pedagogy. Unlike the acquisition of important data based on a stimulus or repetitive feedback, which strengthens the association between stimulus and information and thus loops it into the brain - especially related to detention à la "Thou sh alt not lie" - motivation can also be generated from within the learning individual. Consider the humanistic ideal of intellectual gratification.

Mostly, however, external and rather mundane factors are decisive for the emergence of the significant learning prerequisite: a good grade in the school presentation, the paycheck at the end of the month or simply the appreciative or envious look of dear colleagues. Rewards, it seems, are still the best motivator. A study by neuroscientist Alison Adcock and her colleagues at the University of California and Stanford University in San Francisco has now uncovered the reason for this somewhat selfish human quirk.

The researchers asked twelve subjects to solve two different memory tasks in return for a reward. Meanwhile, they registered the brain activity of their participants using functional magnetic resonance imaging. This determines the blood flow to the different areas of the brain and can thus provide information about which areas were used in the respective cognitive processes.

The participants' first task was to press a specific key when a white rectangle flashed on a monitor. Before each attempt, different symbols were used to indicate how high the respective reward would be if they reacted quickly enough. The aim of this test was to use tomography to identify those areas of the brain that are particularly active when a reward is expected.

The scientists found what they were looking for in the mesolimbic system, specifically in the area ventralis tegmentalis (AVT) and in the nucleus accumbens. The AVT is a group of cells located in the midbrain whose neurons produce the transmitter dopamine and have therefore long been implicated by brain researchers in reward-dependent responses. Both areas were particularly active when the five-dollar reward was very high, and only slightly active when there was no reward.

The subjects' second task was to memorize certain scenes and select them from a series of different images the following day. Here, too, a symbol was displayed before each image sequence, which indicated how much money could be won if the memorization was successful.

As the researchers had expected, the next day, participants were more likely to recall scenes worth five dollars than ones that fetched a stingy ten cents. However, the results of the magnetic resonance imaging were even more significant: If the reward-dependent brain areas AVT and nucleus accumbens were particularly active during the test phase, in which the respective money value was displayed, then the associated image was better remembered later. Scenes later forgotten, however, saw little reward center activity in their vanguard. Likewise, the promise of small amounts of money only lured a few corresponding nerve cells into the active state.

Parts of the hippocampus, whose activity is related to memory performance, were also active before the actual learning task. And here, too, the higher the activity of this brain region was during the reward signal, the greater the probability that the later scene was actually remembered. A specific comparison of the respective tomography results of the individual participants also revealed a clear correlation between activated AVT and activated hippocampal areas.

All three areas of the brain were activated even before information was successfully stored. However, since only the hippocampus was heavily supplied with blood during the actual memory performance, the memorization of the scene, Adcock and her colleagues suspect that the other two areas are not involved in learning itself, but only serve to stimulate the storage process: the mesolimbic system - the motivational speaker of the hippocampus.

Possibly, according to the researchers, a release of dopamine by the AVT is responsible for the rapid and successful pre-activation of the learning center. However, this cannot be determined with functional magnetic resonance imaging alone and therefore requires further studies.

One thing at least seems clear: the image of the brain as a neutral data processor is becoming more and more unstable. Not only the external influences, but also the internal expectations contribute significantly to the handling of external information. However, it remains to be clarified whether, in addition to the capitalist principle of remuneration examined, other forms of recognition are also able to positively influence memory performance.

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