Are bigger brains better?

January 16, 2020

EAST LANSING, Mich. - When it comes to certain parts of the brain, bigger doesn't necessarily equate to better memory. According to a new study led by Michigan State University, a larger hippocampus, a curved, seahorse-shaped structure embedded deep in the brain, does not always reliably predict learning and memory abilities in older adults.

It's normal for the hippocampus to shrink as we age, but it's much more pronounced in people with mild cognitive impairment or Alzheimer's disease. Scientists long believed that a bigger hippocampus meant a better memory until a 2004 study showed that its size does not always matter for memory in older adults. But scientists are only now starting to understand why.

This latest study published online in the journal Cerebral Cortex shows the size or volume of the hippocampus is only a meaningful marker of learning for older people with more intact limbic white matter - the neural circuitry that connects the hippocampus to the rest of the brain.

"Our findings highlight the need to measure not just the size of the hippocampus but also how well it's connected to the rest of the brain when we look for physical markers of memory decline in older adults," said Andrew Bender, lead author on the study and assistant professor of epidemiology and biostatistics, and neurology and ophthalmology at MSU's College of Human Medicine.

The study has potential implications for earlier diagnosis of aging-related memory disorders such as Alzheimer's disease. Some older adults whose brain scans show a larger hippocampus - perhaps due to high levels of education, physical activity, or social and cognitive engagement - could have their cognitive decline overlooked or mischaracterized if physicians do not also consider their white matter connectivity.

Bender, and colleagues at Harvard University, the Hungarian Academy of Sciences and the Max Planck Institute for Human Development, analyzed two different types of MRI brain scans: one that evaluated hippocampal size and another that evaluated the white matter circuitry that connects the hippocampus with other brain regions involved in learning. The scans came from more than 330 older adults who are part of the Berlin Aging Study-II, or BASE-II, a large, population-based investigation of aging in Germany.

The BASE-II participants also took learning and memory tests in which they heard a list of 15 words and then had to record as many words as they could remember. Each participant repeated the exact same test five times to gauge how they learn through repetition.

Bender and colleagues then analyzed the relationships between how quickly the participants learned and the size of their hippocampus and white matter structure. They reported that faster learning was found only in older adults who had both a larger hippocampus and more uniform white matter circuitry connecting it to other parts of the brain.

"Our findings reinforce a growing perspective that studying age-related changes in learning and memory from a systems perspective appears far more informative in understanding different patterns of brain and cognitive declines than focusing on any single brain region," Bender said.

Next, he and his colleagues plan to analyze new data from BASE-II ¬- participants who returned for a second round of brain scans and memory recall tests two to three years after their first visits.

"By following people over time," Bender said, "we can see if there is actually change in older adults' brain structure and whether that is linked with observable declines in learning and memory."
-end-
(Note for media: Please include a link to the original paper in online coverage: https://www.nature.com/articles/s41467-019-12962-4)

Michigan State University has been working to advance the common good in uncommon ways for 160 years. One of the top research universities in the world, MSU focuses its vast resources on creating solutions to some of the world's most pressing challenges, while providing life-changing opportunities to a diverse and inclusive academic community through more than 200 programs of study in 17 degree-granting colleges.

For MSU news on the Web, go to MSUToday. Follow MSU News on Twitter at twitter.com/MSUnews.

Michigan State University

Related Memory Articles from Brightsurf:

Memory of the Venus flytrap
In a study to be published in Nature Plants, a graduate student Mr.

Memory protein
When UC Santa Barbara materials scientist Omar Saleh and graduate student Ian Morgan sought to understand the mechanical behaviors of disordered proteins in the lab, they expected that after being stretched, one particular model protein would snap back instantaneously, like a rubber band.

Previously claimed memory boosting font 'Sans Forgetica' does not actually boost memory
It was previously claimed that the font Sans Forgetica could enhance people's memory for information, however researchers from the University of Warwick and the University of Waikato, New Zealand, have found after carrying out numerous experiments that the font does not enhance memory.

Memory boost with just one look
HRL Laboratories, LLC, researchers have published results showing that targeted transcranial electrical stimulation during slow-wave sleep can improve metamemories of specific episodes by 20% after only one viewing of the episode, compared to controls.

VR is not suited to visual memory?!
Toyohashi university of technology researcher and a research team at Tokyo Denki University have found that virtual reality (VR) may interfere with visual memory.

The genetic signature of memory
Despite their importance in memory, the human cortex and subcortex display a distinct collection of 'gene signatures.' The work recently published in eNeuro increases our understanding of how the brain creates memories and identifies potential genes for further investigation.

How long does memory last? For shape memory alloys, the longer the better
Scientists captured live action details of the phase transitions of shape memory alloys, giving them a better idea how to improve their properties for applications.

A NEAT discovery about memory
UAB researchers say over expression of NEAT1, an noncoding RNA, appears to diminish the ability of older brains to form memories.

Molecular memory can be used to increase the memory capacity of hard disks
Researchers at the University of Jyväskylä have taken part in an international British-Finnish-Chinese collaboration where the first molecule capable of remembering the direction of a magnetic above liquid nitrogen temperatures has been prepared and characterized.

Memory transferred between snails
Memories can be transferred between organisms by extracting ribonucleic acid (RNA) from a trained animal and injecting it into an untrained animal, as demonstrated in a study of sea snails published in eNeuro.

Read More: Memory News and Memory Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.