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Caffeine and memory

What's your memory like on caffeine? Caffeine, the central nervous system stimulant, is the energy boost of choice for millions, except if you have adverse reactions, such as panic or anxiety feelings or a faster pulse, after consuming caffeinated foods or beverages. Ideas and at least one patent for caffeinated objects that go in the mouth where caffeine is absorbed without swallowing exist.

Caffeine and memory.
Anne Hart, photography.

For example, there's a patent filed for making caffeinated toothbrushes, according to a May 17, 2013 article, "Toothbrush With Caffeine? Patent Filed For Device That Delivers Chemicals While You Brush," Colgate-Palmolive filed a patent application for a toothbrush capable of delivering a dose of chemicals to the user with every brush. While a number of medicines could conceivably be distributed, the idea appears to have taken off in a singular direction: a toothbrush with caffeine, notes that Huffington Post article.

If you have an over-aroused nervous system compared to an under-aroused nervous system, it makes a different how you feel after drinking a caffeinated beverage or food. You may wish to check out the abstract of a new study published online today, "Post-study caffeine administration enhances memory consolidation in humans," published online January 12, 2014, in the journal Nature Neuroscience.

Memory enhancer: Caffeine?

Now, however, researchers have found another use for the stimulant: memory enhancer, according to the new study funded by the NIH/National Institute on Aging National Science Foundation, and Johns Hopkins University. But caffeine as a stimulant for memory enhancement is no substitute for visualizing and studying the subject you want to remember.

For some, it's the tradition of steeping tealeaves to brew the perfect cup of tea. For others, it's the morning shuffle to a coffee maker for a hot jolt of java. Then there are those who like their wake up with the kind of snap and a fizz usually found in a carbonated beverage, explains a January 12, 2014 news release, "It's all coming back to me now: Researchers find caffeine enhances memory."

Regardless of the routine, the consumption of caffeine is the energy boost of choice for millions to wake up or stay up. Now, however, researchers at the Johns Hopkins University have found another use for the stimulant: memory enhancer.

Michael Yassa, assistant professor of psychological and brain sciences in the Krieger School of Arts and Sciences at Johns Hopkins, and his team of scientists found that caffeine has a positive effect on long-term memory in humans. Their research, published by the journal Nature Neuroscience, shows that caffeine enhances certain memories at least up to 24 hours after it is consumed.

Caffeine enhances only certain memories at least up to 24 hours after it's consumed

"We've always known that caffeine has cognitive-enhancing effects, but its particular effects on strengthening memories and making them resistant to forgetting has never been examined in detail in humans," said Yassa, senior author of the paper, according to the news release. "We report for the first time a specific effect of caffeine on reducing forgetting over 24 hours."

The Johns Hopkins researchers conducted a double-blind trial; which participants who did not regularly eat or drink caffeinated products received either a placebo or a 200-milligram caffeine tablet five minutes after studying a series of images. Salivary samples were taken from the participants before they took the tablets to measure their caffeine levels. Samples were taken again one, three and 24 hours afterwards.

Ability to recognize images

The next day, both groups were tested on their ability to recognize images from the previous day's study session. On the test, some of the visuals were the same as from the day before, some were new additions and some were similar but not the same as the items previously viewed. More members of the caffeine group were able to correctly identify the new images as "similar" to previously viewed images versus erroneously citing them as the same.

The brain's ability to recognize the difference between two similar but not identical items, called pattern separation, reflects a deeper level of memory retention, the researchers said.

"If we used a standard recognition memory task without these tricky similar items, we would have found no effect of caffeine," Yassa said, according to the news release. "However, using these items requires the brain to make a more difficult discrimination -- what we call pattern separation, which seems to be the process that is enhanced by caffeine in our case."

The brain has to make a difficult discrimination using pattern separation, which may be enhanced by caffeine

The memory center in the human brain is the hippocampus, a seahorse-shaped area in the medial temporal lobe of the brain. The hippocampus is the switchbox for all short-term and long-term memories. Most research done on memory -- the effects of concussions in athletics to war-related head injuries to dementia in the aging population -- are focused on this area of the brain.

Until now, caffeine's effects on long-term memory had not been examined in detail. Of the few studies done, the general consensus was that caffeine has little or no effect on long-term memory retention.

The research is different from prior experiments because the subjects took the caffeine tablets only after they had viewed and attempted to memorize the images

"Almost all prior studies administered caffeine before the study session, so if there is an enhancement, it's not clear if it's due to caffeine's effects on attention, vigilance, focus or other factors. By administering caffeine after the experiment, we rule out all of these effects and make sure that if there is an enhancement, it's due to memory and nothing else," said Yassa in the news release.

According to the U.S. Food and Drug Administration, 90 percent of people worldwide consume caffeine in one form or another. In the United States, 80 percent of adults consume caffeine every day. The average adult has an intake of about 200 milligrams -- the same amount used in the Yassa study -- or roughly one strong cup of coffee or two small cups of coffee per day.

Yassa's team completed the research at Johns Hopkins before his lab moved to the University of California-Irvine at the start of this year

"The next step for us is to figure out the brain mechanisms underlying this enhancement," he said. "We can use brain-imaging techniques to address these questions. We also know that caffeine is associated with healthy longevity and may have some protective effects from cognitive decline like Alzheimer's disease. These are certainly important questions for the future."

The lead author of the paper is Daniel Borota, an undergraduate student in Yassa's lab who received an undergraduate research award from Johns Hopkins to conduct the study. Additional authors, all from Johns Hopkins, are: Elizabeth Murray, a research program coordinator in the Department of Psychological and Brain Sciences; John Toscano, professor in the Department of Chemistry; Gizem Kecili, a graduate student also in the Chemistry Department and Allen Chang, Maria Ly and Joseph Watabe, all undergraduates in the Department of Psychological and Brain Sciences.

This research was supported by grants number P50 AG05146 and R01 AG034613 from the National Institute on Aging as well as CHE-1213438 from the National Science Foundation.

The memory consolidation hypothesis proposed 100 years ago by Müller and Pilzecker continues to guide memory research.

The hypothesis that new memories consolidate slowly over time has stimulated studies revealing the hormonal and neural influences regulating memory consolidation, as well as molecular and cellular mechanisms, says the abstract of another study. Scientists examine the progress made over the century in understanding the time-dependent processes that create our lasting memories.

It's of value to researchers that so many older people suddenly have memories or visual imagery of scenes that happened when they were three or four years old that made an impact on them at the time. You also may wish to check out the abstract of an older study from 2000, "Memory--a century of consolidation."

Ultrasound's effects on boosting the brain's tactile sensory inputs

William "Jamie " Tyler, an assistant professor at the Virginia Tech Carilion Research Institute, studied the effects of ultrasound on the region of the brain responsible for processing tactile sensory inputs. Ultrasound directed to the human brain can boost sensory performance, says a new study, "Transcranial focused ultrasound modulates the activity of primary somatosensory cortex in humans," published online Jan. 12, 2014 in the journal Nature Neuroscience.

This new research provides the first demonstration that low-intensity, transcranial-focused ultrasound can modulate human brain activity to enhance perception. Virginia Tech's Carilion Research Institute scientists say ultrasound ranks with leading neuromodulation techniques in achieving spatial resolution.

Whales, bats, and even praying mantises use ultrasound as a sensory guidance system — and now a new study has found that ultrasound can modulate brain activity to heighten sensory perception in humans. Virginia Tech Carilion Research Institute scientists have demonstrated that ultrasound directed to a specific region of the brain can boost performance in sensory discrimination.

"Ultrasound has great potential for bringing unprecedented resolution to the growing trend of mapping the human brain's connectivity," said William "Jamie" Tyler, according to a January 12, 2014 news release, "Ultrasound directed to the human brain can boost sensory performance." Tyler, an assistant professor at the Virginia Tech Carilion Research Institute, led the study. "So we decided to look at the effects of ultrasound on the region of the brain responsible for processing tactile sensory inputs," he explained in the news release.

The scientists delivered focused ultrasound to an area of the cerebral cortex that processes sensory information received from the hand. To stimulate the median nerve — a major nerve that runs down the arm and the only one that passes through the carpal tunnel — they placed a small electrode on the wrist of human volunteers and recorded their brain responses using electroencephalography, or EEG. Then, just before stimulating the nerve, they began delivering ultrasound to the targeted brain region.

The scientists found that the ultrasound both decreased the EEG signal and weakened the brain waves responsible for encoding tactile stimulation

The scientists then administered two classic neurological tests: the two-point discrimination test, which measures a subject's ability to distinguish whether two nearby objects touching the skin are truly two distinct points, rather than one; and the frequency discrimination task, a test that measures sensitivity to the frequency of a chain of air puffs.

What the scientists found was unexpected. The subjects receiving ultrasound showed significant improvements in their ability to distinguish pins at closer distances and to discriminate small frequency differences between successive air puffs.

"Our observations surprised us," said Tyler, according to the news release. "Even though the brain waves associated with the tactile stimulation had weakened, people actually got better at detecting differences in sensations."

Why would suppression of brain responses to sensory stimulation heighten perception?

Tyler speculates that the ultrasound affected an important neurological balance. "It seems paradoxical, but we suspect that the particular ultrasound waveform we used in the study alters the balance of synaptic inhibition and excitation between neighboring neurons within the cerebral cortex," Tyler said in the news release. "We believe focused ultrasound changed the balance of ongoing excitation and inhibition processing sensory stimuli in the brain region targeted and that this shift prevented the spatial spread of excitation in response to stimuli resulting in a functional improvement in perception."

To understand how well they could pinpoint the effect, the research team moved the acoustic beam one centimeter in either direction of the original site of brain stimulation – and the effect disappeared. "That means we can use ultrasound to target an area of the brain as small as the size of an M&M," Tyler explained in the news release. "This finding represents a new way of noninvasively modulating human brain activity with a better spatial resolution than anything currently available."

Ultrasound has a greater spatial resolution than some other noninvasive brain stimulation technologies

Based on the findings of the current study and an earlier one, the researchers concluded that ultrasound has a greater spatial resolution than two other leading noninvasive brain stimulation technologies — transcranial magnetic stimulation, which uses magnets to activate the brain, and transcranial direct current stimulation, which uses weak electrical currents delivered directly to the brain through electrodes placed on the head.

"Gaining a better understanding of how pulsed ultrasound affects the balance of synaptic inhibition and excitation in targeted brain regions — as well as how it influences the activity of local circuits versus long-range connections — will help us make more precise maps of the richly interconnected synaptic circuits in the human brain," said Wynn Legon, in the news release. Legon is the study's first author and a postdoctoral scholar at the Virginia Tech Carilion Research Institute. "We hope to continue to extend the capabilities of ultrasound for noninvasively tweaking brain circuits to help us understand how the human brain works."

"The work by Jamie Tyler and his colleagues is at the forefront of the coming tsunami of developing new safe yet effective noninvasive ways to modulate the flow of information in cellular circuits within the living human brain," said Michael Friedlander, in the news release. Friedlander is the executive director of the Virginia Tech Carilion Research Institute and a neuroscientist who specializes in brain plasticity.

"This approach is providing the technology and proof of principle for precise activation of neural circuits for a range of important uses, including potential treatments for neurodegenerative disorders, psychiatric diseases, and behavioral disorders," explained Friedlander, according to the news release. "Moreover, it arms the neuroscientific community with a powerful new tool to explore the function of the healthy human brain, helping us understand cognition, decision-making, and thought. This is just the type of breakthrough called for in President Obama's BRAIN Initiative to enable dramatic new approaches for exploring the functional circuitry of the living human brain and for treating Alzheimer's disease and other disorders."

A team of Virginia Tech Carilion Research Institute scientists — including Tomokazu Sato, Alexander Opitz, Aaron Barbour, and Amanda Williams, along with Virginia Tech graduate student Jerel Mueller of Raleigh, N.C. — joined Tyler and Legon in conducting the research. In addition to his position at the institute, Tyler is an assistant professor of biomedical engineering and sciences at the Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences. In 2012, he shared a Technological Innovation Award from the McKnight Endowment for Neuroscience to work on developing ultrasound as a noninvasive tool for modulating brain activity.

"In neuroscience, it's easy to disrupt things," said Tyler, according to the news release. "We can distract you, make you feel numb, trick you with optical illusions. It's easy to make things worse, but it's hard to make them better. These findings make us believe we're on the right path."