Zapping the brain with tiny magnetic pulses improves memory

October 6, 2014 by Elizabeth Maratos, The Conversation
Who doesn’t want more brain power? Credit: James Steidl

The practice of physically stimulating the brain in order to alleviate symptoms of illness and injury has been around since the early 20th century. For example, electroconvulsive therapy (ECT) is still used to alleviate symptoms of depression.

However, perhaps in part due to negative connotations associated with ECT, in modern medicine treatment of psychological disorders have tended to use other forms of intervention. These now mostly involve drugs or therapy. However, a recent study, published in the journal Science, sees a return to this idea of stimulating brain regions to improve brain function.

Researchers at Northwestern University have shown that targeted stimulation of regions of the brain involved in the functioning of memory can enhance our ability to memorise. The method they used was not ECT, but transcranial magnetic stimulation (TMS).

In TMS, electromagnetic pulses are applied to the outside of the head over the part of the brain that is to be stimulated. The magnetic stimulation then induces electrical activity – that is, impulses – in those parts. Importantly, whereas ECT has to be used with anaesthetics and muscle relaxants and has side effects, TMS is a less invasive procedure. In TMS the patient is able to remain fully conscious and may only experience mild physical symptoms such as a small tapping sensation to the head.

In neuropsychology, the region of the brain predominantly associated with memory is the hippocampus. However, the hippocampus is located deep within the brain and its direct stimulation is difficult. Instead, the researchers used magnetic resonance imaging (MRI) techniques to identify regions located closer to the skull that connect with the hippocampus. They then targeted these cortical-hippocampal memory networks and tested the effects of this manipulation on memory.

Sixteen people were recruited for the study. Half of these people received 20 minutes of TMS stimulation to the memory networks for five consecutive days. The other half received a "sham" application of TMS to the same networks. All people were also required to take a memory test both preceding the TMS stimulation – which was treated as the baseline – and after the five days of stimulation.

The memory test consisted of a study phase whereby pictures of faces were paired with common words – and a subsequent test phase where people were again shown the faces and were required to recall the matching word. In addition, after the five days of TMS stimulation a second MRI scan was conducted in order to see if the "zapped" neural networks had changed.

The researchers found that memory in the people that had received the TMS application was improved relative to those that had received the sham TMS application. However, what caused this improvement? Did it improve specific brain networks work or just help the brain overall?

By conducting tests, such as stimulating regions of the motor cortex (making thumbs twitch for example) and also testing other cognitive abilities, the possibility that it was only the TMS stimulation "per se" on brain activity and function that produced the improved memory was eliminated. Also, MRI scans revealed increased connectivity in the brain networks targeted.

The authors of the study note that this procedure is not a cure for memory disorders following neurological illnesses or brain injury. Rather the application offers insight into the possibility of an alternative form of intervention than drugs for illnesses such as Alzheimer's.

The problem with pharmacological intervention – that is, the use of drugs – is that it is hard to target specific regions of the brain – and due to this non-selectiveness many drugs have unwanted side effects. It is the recognition of the ability of TMS to target specific regions of the brain that offers the promise of a new approach to recovery of brain function following brain injury and illness.

Incidentally, if you are also envisaging some kind of futuristic alternative to smart drugs – such as that found in the movies Limitless or Lucy – you are probably not the only one. For now, however, the research focus is firmly clinical with the view to improving the lives of those with debilitating memory disorders.

Explore further: Transcranial Magnetic Stimulation of brain boosts memory

Related Stories

Transcranial Magnetic Stimulation of brain boosts memory

August 28, 2014
Stimulating a particular region in the brain via non-invasive delivery of electrical current using magnetic pulses, called Transcranial Magnetic Stimulation, improves memory, reports a new Northwestern Medicine study.

Selectively rewiring the brain's circuitry to treat depression

September 30, 2014
On Star Trek, it is easy to take for granted the incredible ability of futuristic doctors to wave small devices over the heads of both humans and aliens, diagnose their problems through evaluating changes in brain activity ...

Visualising plastic changes to the brain

September 4, 2014
Tinnitus, migraine, epilepsy, depression, schizophrenia, Alzheimer's: all these are examples of diseases with neurological causes, the treatment and study of which is more and more frequently being carried out by means of ...

Low strength brain stimulation may be effective for depression

July 22, 2014
Brain stimulation treatments, like electroconvulsive therapy (ECT) and transcranial magnetic stimulation (TMS), are often effective for the treatment of depression. Like antidepressant medications, however, they typically ...

Study reveals new clues to help understand brain stimulation

September 29, 2014
Over the past several decades, brain stimulation has become an increasingly important treatment option for a number of psychiatric and neurological conditions.

Early brain stimulation may help stroke survivors recover language function

June 27, 2013
Non-invasive brain stimulation may help stroke survivors recover speech and language function, according to new research in the American Heart Association journal Stroke.

Recommended for you

New technique helps uncover changes in ALS neurons

June 22, 2018
Northwestern Medicine scientists have discovered that some neurons affected by amyotrophic lateral sclerosis (ALS) display hypo-excitability, using a new method to measure electrical activity in cells, according to a study ...

Broken shuttle may interfere with learning in major brain disorders

June 22, 2018
Unable to carry signals based on sights and sounds to the genes that record memories, a broken shuttle protein may hinder learning in patients with intellectual disability, schizophrenia, and autism.

Watching stem cells repair spinal cord in real time

June 22, 2018
Monash University researchers have restored movement and regenerated nerves using stem cells in zebra fish where the spinal cord is severely damaged.

Scientists discover fundamental rule of brain plasticity

June 21, 2018
Our brains are famously flexible, or "plastic," because neurons can do new things by forging new or stronger connections with other neurons. But if some connections strengthen, neuroscientists have reasoned, neurons must ...

Waking up is hard to do: Prefrontal cortex implicated in consciousness

June 21, 2018
Philosophers have pondered the nature of consciousness for thousands of years. In the 21st century, the debate over how the brain gives rise to our everyday experience continues to puzzle scientists. To help, researchers ...

Researchers find mechanism behind choosing alcohol over healthy rewards

June 21, 2018
A new study links molecular changes in the brain to behaviours that are central in addiction, such as choosing a drug over alternative rewards. The researchers have developed a method in which rats learn to get an alcohol ...

0 comments

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.