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Smells connect to memories more than other senses
"The smell of fresh chopped parsley may evoke a grandmother's cooking, or a whiff of a cigar may evoke a grandfather's presence," says author.
It's called the Proust effect after a story in the author's "Remembrance of Things Past: Swann's Way." When a character dipped a madeleine, a sweet, buttery French cake, into some lime-blossom tea, the scent suddenly transported him back in time to the moment his aunt had served him that same combination:
"Immediately the old grey house upon the street, where her room was, rose up like the scenery of a theatre to attach itself to the little pavilion, opening on to the garden, which had been built out behind it for my parents… and with the house the town, from morning to night and in all weathers, the Square where I was sent before luncheon, the streets along which I used to run errands, the country roads we took when it was fine."
Nothing conjures up a memory so viscerally as the scent with which you associate it. While it's been understood for some time that our olfactory system has a unique ability to vividly summon memories, the mechanism behind the phenomenon has net been well-understood. Now a study by researchers from Northwestern University's Feinberg School of Medicine may have solved the puzzle. The olfactory system has an unusually direct connection to the brain's hippocampus, believed to play an important role in memory.
The study's published in the journal Progress in Neurobiology.
A lasting connection
Credit: schankz/Adobe Stock
Previous neuroimaging and intracranial electrophysiology investigations have revealed that our senses are functionally connected to the hippocampus, if not directly. However, the new research, for which the principle investigator is Christina Zelano, is the first rigorous comparison of the strength of those connections.
It turns out that our primary olfactory cortex is a sense that's still directly connected to the hippocampus.
"This has been an enduring mystery of human experience," Zelano tells Medical Xpress. "Nearly everyone has been transported by a whiff of an odor to another time and place, an experience that sights or sounds rarely evoke. Yet, we haven't known why. The study found the olfactory parts of the brain connect more strongly to the memory parts than other senses. This is a major piece of the puzzle, a striking finding in humans. We believe our results will help future research solve this mystery."
It's believed that during evolution, the hippocampus' role shifted away from its original strong relationship to the sensory cortexes and toward connections with higher association cortexes. (In rodents, for example, the hippocampus maintains a powerful connection to all sensory cortexes.) It now appears that as this occurred, the olfactory cortex alone continued to be directly wired to the hippocampus.
"Humans experienced a profound expansion of the neocortex that re-organized access to memory networks," explains Zelano. "Vision, hearing and touch all re-routed in the brain as the neocortex expanded, connecting with the hippocampus through an intermediary-association cortex-rather than directly. Our data suggests olfaction did not undergo this re-routing, and instead retained direct access to the hippocampus."
The importance of smell
It's known that people who experience a loss of smell, or "anosmia," often develop depression. "Loss of the sense of smell is underestimated in its impact," says Zelano. "It has profound negative effects of quality of life, and many people underestimate that until they experience it. Smell loss is highly correlated with depression and poor quality of life."
Anosmia is also associated with COVID-19. "The COVID-19 epidemic," says Zelano, "has brought a renewed focus and urgency to olfactory research." Lead author Guangyu Zhou agrees: "There is an urgent need to better understand the olfactory system in order to better understand the reason for COVID-related smell loss, diagnose the severity of the loss and to develop treatments."
"Most people who lose their smell to COVID regain it," notes Zelano, "but the time frame varies widely, and some have had what appears to be permanent loss. Understanding smell loss, in turn, requires research into the basic neural operations of this under-studied sensory system."
She notes that, "While our study doesn't address COVID smell loss directly, it does speak to an important aspect of why olfaction is important to our lives: Smells are a profound part of memory, and odors connect us to especially important memories in our lives, often connected to loved ones."
- The Evolutionary Paradox of Our Sense of Smell - Big Think ›
- A new AI algorithm is learning how to smell - Big Think ›
- Scientists link sense of smell and sense of direction - Big Think ›
Thanks to modern technology, we can reexamine our assumptions about ancient warriors.
- The 2600-year-old remains of a young Scythian warrior are now known to be female.
- The young warrior appears to have been around 13 years old when she died.
- The findings shed light on the Scythian culture.
Throughout the literature of the ancient world, tales of great bands of warrior women captivated listeners' imaginations. From China to Greece, stories of their exploits filled hearts with fear and awe. Recently, historians have begun to accept that the Amazons were real, in a way; they were slightly embellished versions of Scythian warriors.
While we've known for some time that many of the warrior graves their culture left behind were the burial sites of women, modern DNA analysis allows us to review if every skeleton previously thought to be male really is. One such review of a mummy found in 1988 proves that one young warrior was actually a 13-year-old girl.
Joan of Scythia?
The 2600-year-old remains were discovered at Saryg-Bulun in Central Tuva in 1988 when the region was still part of the USSR. Contained in a tightly sealed coffin made of larch trunk, the remains were mummified and well preserved. One report states that a wart on the child's face was still evident. The coffin also contained a battle-ax, a quiver with arrows, a headdress, coat, and various bronze ornaments.
As the young warrior was presumed to be male, the researchers were surprised when they analyzed her genome and discovered the remains belonged to a young woman. Despite how common it is to see the remains of female warriors, this coffin did not contain items typically given to deceased women, such as beads or mirrors.
Excavator Marina Kilunovskaya explained this to Archaeology.org, "This discrepancy in the norms of the funeral rite received an unexpected explanation: firstly, the young man turned out to be a girl, and this young 'Amazon' had not yet reached the age of 14 years."
The research team will now attempt to get a more accurate dating of the remains and will use CT scans to try and learn precisely how this young warrior died. The various artifacts discovered in the coffin will also be analyzed for metal composition and preserved.
Who were the Scythians and why did they have little girls as warriors?
The Scythians were the rulers of the Steppes from Ukraine to Xinjiang and the probable inventors of horseback riding. These nomadic warriors also had a reasonably egalitarian society for the ancient world. Many sources agree that cross-dressing was common in their culture, and some go so far as to suggest their idea of gender was fluid.
Across the steppes, women were trained to be warriors just as men were and could prove fearsome in battle. Skeletal remains proven to be female (about a fifth of all discovered remains) often show the same battle injuries as males. Burial sites with weapons and all the honors of a warrior are common for both sexes. Just last year, the gravesite of other female warriors were found.
They were known as a warlike people, and it is thought entire tribes participated in battles. It was said that no nation could stand against them without outside help. However, they also made beautiful art, had an elaborate religious system, and were known for their unique clothing. They had no written language, but descriptions of their culture endure in the writings of their neighbors.
Even if the Amazons weren't quite real, they were based on an existing culture. As we learn more about how the Scythians lived and died, we're better able to contextualize the stories and myths they appear in. As with all archaeological discoveries, it also allows us to better understand where humanity has been, so we might make a better choice of where we're going.
The author of 'How We Read' Now explains.
During the pandemic, many college professors abandoned assignments from printed textbooks and turned instead to digital texts or multimedia coursework.
As a professor of linguistics, I have been studying how electronic communication compares to traditional print when it comes to learning. Is comprehension the same whether a person reads a text onscreen or on paper? And are listening and viewing content as effective as reading the written word when covering the same material?
The answers to both questions are often “no," as I discuss in my book “How We Read Now," released in March 2021. The reasons relate to a variety of factors, including diminished concentration, an entertainment mindset and a tendency to multitask while consuming digital content.
Print versus digital reading
The benefits of print particularly shine through when experimenters move from posing simple tasks – like identifying the main idea in a reading passage – to ones that require mental abstraction – such as drawing inferences from a text. Print reading also improves the likelihood of recalling details – like “What was the color of the actor's hair?" – and remembering where in a story events occurred – “Did the accident happen before or after the political coup?"
Studies show that both grade school students and college students assume they'll get higher scores on a comprehension test if they have done the reading digitally. And yet, they actually score higher when they have read the material in print before being tested.
Educators need to be aware that the method used for standardized testing can affect results. Studies of Norwegian tenth graders and U.S. third through eighth graders report higher scores when standardized tests were administered using paper. In the U.S. study, the negative effects of digital testing were strongest among students with low reading achievement scores, English language learners and special education students.
My own research and that of colleagues approached the question differently. Rather than having students read and take a test, we asked how they perceived their overall learning when they used print or digital reading materials. Both high school and college students overwhelmingly judged reading on paper as better for concentration, learning and remembering than reading digitally.
The discrepancies between print and digital results are partly related to paper's physical properties. With paper, there is a literal laying on of hands, along with the visual geography of distinct pages. People often link their memory of what they've read to how far into the book it was or where it was on the page.
But equally important is mental perspective, and what reading researchers call a “shallowing hypothesis." According to this theory, people approach digital texts with a mindset suited to casual social media, and devote less mental effort than when they are reading print.
Podcasts and online video
Given increased use of flipped classrooms – where students listen to or view lecture content before coming to class – along with more publicly available podcasts and online video content, many school assignments that previously entailed reading have been replaced with listening or viewing. These substitutions have accelerated during the pandemic and move to virtual learning.
Surveying U.S. and Norwegian university faculty in 2019, University of Stavanger Professor Anne Mangen and I found that 32% of U.S. faculty were now replacing texts with video materials, and 15% reported doing so with audio. The numbers were somewhat lower in Norway. But in both countries, 40% of respondents who had changed their course requirements over the past five to 10 years reported assigning less reading today.
A primary reason for the shift to audio and video is students refusing to do assigned reading. While the problem is hardly new, a 2015 study of more than 18,000 college seniors found only 21% usually completed all their assigned course reading.
Maximizing mental focus
Researchers found similar results with university students reading an article versus listening to a podcast of the text. A related study confirms that students do more mind-wandering when listening to audio than when reading.
Results with younger students are similar, but with a twist. A study in Cyprus concluded that the relationship between listening and reading skills flips as children become more fluent readers. While second graders had better comprehension with listening, eighth graders showed better comprehension when reading.
Research on learning from video versus text echoes what we see with audio. For example, researchers in Spain found that fourth through sixth graders who read texts showed far more mental integration of the material than those watching videos. The authors suspect that students “read" the videos more superficially because they associate video with entertainment, not learning.
The collective research shows that digital media have common features and user practices that can constrain learning. These include diminished concentration, an entertainment mindset, a propensity to multitask, lack of a fixed physical reference point, reduced use of annotation and less frequent reviewing of what has been read, heard or viewed.
Digital texts, audio and video all have educational roles, especially when providing resources not available in print. However, for maximizing learning where mental focus and reflection are called for, educators – and parents – shouldn't assume all media are the same, even when they contain identical words.
Humans may have evolved to be tribalistic. Is that a bad thing?
- From politics to every day life, humans have a tendency to form social groups that are defined in part by how they differ from other groups.
- Neuroendocrinologist Robert Sapolsky, author Dan Shapiro, and others explore the ways that tribalism functions in society, and discuss how—as social creatures—humans have evolved for bias.
- But bias is not inherently bad. The key to seeing things differently, according to Beau Lotto, is to "embody the fact" that everything is grounded in assumptions, to identify those assumptions, and then to question them.
Ancient corridors below the French capital have served as its ossuary, playground, brewery, and perhaps soon, air conditioning.