"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.
A lasting connection<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTgxOTUyNi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MDM4MjgyMn0.Mj4AjOLAgz5CnCwNejmtWlDpoQTcVggpqu8W6c7aLU4/img.jpg?width=980" id="79e03" width="1440" height="926" data-rm-shortcode-id="ec3296400089e111af312d17ec346b68" data-rm-shortcode-name="rebelmouse-image" />
Credit: schankz/Adobe Stock<p>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 <a href="https://www.feinberg.northwestern.edu/faculty-profiles/az/profile.html?xid=32110" target="_blank">Christina Zelano</a>, is the first rigorous comparison of the strength of those connections.</p><p>It turns out that our primary olfactory cortex is a sense that's still directly connected to the hippocampus.</p><p>"This has been an enduring mystery of human experience," Zelano tells <a href="https://medicalxpress.com/news/2021-03-odors-trigger-powerful-memories.html?fbclid=IwAR2HPSJ3dfzmuNU0KGRJZNMVmodnWxvTcJ0Au-Ty0NlY-lqberm6fMF9YkM" target="_blank">Medical Xpress</a>. "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."</p><p>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.</p><p>"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."</p>
The importance of smell<p>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."</p><p>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 <a href="https://scholar.google.com/citations?user=Kf-ramYAAAAJ&hl=en" target="_blank">Guangyu Zhou</a> 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."</p><p>"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."</p><p>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."</p>
The Persian polymath and philosopher of the Islamic Golden Age teaches us about self-awareness.
A new study provides validation for the recently identified phenomenon.
- Aphantasia, a recently identified psychological phenomenon, describes when people can't conjure visualizations in their mind's eye.
- A new study published in Cortex compared the visual memories of aphantasic participants with a group of controls.
- Its results found experimental validation for the condition.
Changing our understanding of the mind's eye<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTI2NjM0Mi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0ODM2ODE5NX0.SWkNBfgO1uLsAMsetcmmwOHvJqzK1UsPMxc6tL6Je9k/img.jpg?width=1245&coordinates=0%2C228%2C0%2C873&height=700" id="2092d" width="1245" height="700" data-rm-shortcode-id="b0ee9078541b6ecdda2dab654bf1131b" data-rm-shortcode-name="rebelmouse-image" />
Francis Galton was the first to describe a condition that would today be recognized as aphantasia.
Visualizing the difference<img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTI2NjMzNS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYzMjAyMDk3M30.EYfZH3v5DRhu4ImOjpuuXdHiXbPkgTUCOxJsTQmDYA8/img.png?width=980" id="fed74" width="598" height="245" data-rm-shortcode-id="411ff90d5a21d04c844ece17c627fd3b" data-rm-shortcode-name="rebelmouse-image" />
On the left, an aphantastic participant's recreation of a photo from memory. On the right, the participant's recreation when the photo was available for reference.
Discovering a new reality in aphantasia?<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="4ce66da461c82a0293b5bf1227c94c69"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/zNHDTvqbUm4?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>And Bainbridge's study has joined an ever-growing panoply. A <a href="https://www.sciencedirect.com/science/article/abs/pii/S0010945217303581" target="_blank">2018 study, also published in Cortex</a>, measured the binocular rivalry—the visual phenomenon in which awareness fluctuates when different images are presented to each eye—of participants with and without aphantasia. When primed beforehand, control participants choose the primed stimuli more often than not. Meanwhile, aphantastic participants showed no such favoritism, whether primed or not. Like Bainbridge's study, these results suggest a physiological underpinning for aphantasia.</p><p>Another critical factor is growing awareness. As more studies and stories are published, more and more people are realizing they aren't alone. Such a realization can empower others to come forward and share their experiences, which in turn spurs researchers with new questions and experiences to study and hypothesize over.</p><p>Yet, there's still much work to be done. Because this psychological phenomenon has only recently been identified—Galton's observation notwithstanding—there has been sparingly little research on the condition and what research has been done has relied on participants who self-report as having aphantasia. While researchers have used the <a href="https://en.wikipedia.org/wiki/Vividness_of_Visual_Imagery_Questionnaire" target="_blank">Vividness of Visual Imagery Quiz</a> to test for aphantasia, there is currently no universal method for diagnosing the condition. And, of course, there is the ever-vexing question of how one can assess one mind's experiences from another.</p><p>"Skeptics could claim that aphantasia is itself a mere fantasy: describing our inner lives is difficult and undoubtedly liable to error," Zeman and his co-authors wrote in <a href="https://ore.exeter.ac.uk/repository/bitstream/handle/10871/17613/Lives%20without%20imagery%20Letter%20version%20FINAL%2017.5.15%20.pdf?sequence=7&isAllowed=y" target="_blank" rel="noopener noreferrer">their 2015 case study</a>. "We suspect, however, that aphantasia will prove to be a variant of neuropsychological functioning akin to synesthesia [a neurological condition in which one sense is experienced as another] and to congenital prosopagnosia [the inability to recognize faces or learn new ones]."</p><p>Time and further research will tell. But scientists need phenomenon to test and questions to experiment on. Thanks to researchers like Zeman and Bainbridge, alongside the many people who came forward to discuss their experiences, they now have both when it comes to aphantasia.</p><p>* Zeman also coined the term "<a href="https://www.sciencedirect.com/science/article/abs/pii/S0010945220301404" target="_blank">hyperphantasia</a>" to describe the condition in which people's psychological imagery is incredibly vivid and well-defined.</p>
A large study shows changes in the brain scans of lonely people in the area involved in imagination, memory, and daydreaming.
- A study of 40,000 participants shows specific signatures in the brain scans of lonely people.
- Loneliness is linked to variations in grey matter volume and connections in the brain default network.
- This area of the brain is connected to the use of imagination, memory, future planning, and daydreaming.
Scientists show what loneliness looks like in the brain<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="426d45d6ed6e79c14050286b188db3a6"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/wkWpqlfA_2Q?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
A new theory suggests that dreams' illogical logic has an important purpose.
Overfitting<p>The goal of machine learning is to supply an algorithm with a data set, a "training set," in which patterns can be recognized and from which predictions that apply to other unseen data sets can be derived.</p><p>If machine learning learns its training set too well, it merely spits out a prediction that precisely — and uselessly — matches that data instead of underlying patterns within it that could serve as predictions likely to be true of other thus-far unseen data. In such a case, the algorithm describes what the data set <em>is</em> rather than what it <em>means</em>. This is called "overfitting."</p><img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDc4NTQ4Ni9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2NDM4NDk1Mn0.bMHbBbt7Nz0vmmQ8fdBKaO-Ycpme5eOCxbjPLEHq9XQ/img.jpg?width=980" id="5049a" width="1440" height="585" data-rm-shortcode-id="10fc10e636fcb55325a1f4f1f8bf9db3" data-rm-shortcode-name="rebelmouse-image" />
The value of noise<p>To keep machine learning from becoming too fixated on the specific data points in the set being analyzed, programmers may introduce extra, unrelated data as noise or corrupted inputs that are less self-similar than the real data being analyzed.</p><p>This noise typically has nothing to do with the project at hand. It's there, metaphorically speaking, to "distract" and even confuse the algorithm, forcing it to step back a bit to a vantage point at which patterns in the data may be more readily perceived and not drawn from the specific details within the data set.</p><p>Unfortunately, overfitting also occurs a lot in the real world as people race to draw conclusions from insufficient data points — xkcd has a fun example of how this can happen with <a href="https://xkcd.com/1122/" target="_blank">election "facts."</a></p><p>(In machine learning, there's also "underfitting," where an algorithm is too simple to track enough aspects of the data set to glean its patterns.)</p><img class="rm-lazyloadable-image rm-shortcode" type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDc4NTQ5My9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyMDE5NjY1M30.iS2bq7WEQLeS34zNFPnXwzAZZn9blCyI-KVuXmcHI6o/img.jpg?width=980" id="cd486" width="1440" height="810" data-rm-shortcode-id="debb36da6eff5a4f368914f6bac5054d" data-rm-shortcode-name="rebelmouse-image" />
Credit: agsandrew/Adobe Stock