Archive for ‘Psychology and behavior’

November 5, 2011

Hippocampus plays bigger memory role than previously thought

Psychologists and neuroscientists, in their research into how memory works, distinguish several different types of memory. At the highest level, there’s declarative memory (facts, knowledge, experiences) and procedural memory (skills). Declarative memory can be further divided into episodic memory (personal experiences) and semantic memory (facts about the world).

Two processes are considered to be aspects of episodic memory: recollection and familiarity. Recollection is the ability to recall specific details about an experience or event. Familiarity is the less specific sense that one has had an experience, but without being able to recall specific details. People who read a lot are well acquainted with this distinction, usually to their frustration and annoyance. One may be sure of having read somewhere about a certain piece of information or situation in a novel – but without any clue as to when or where, which makes it pretty difficult to go back to the source in order to check one’s memory and fill in the details.

Neuroscientists have considered several questions about this issue. Are the two processes basically the same, differing only in strength of recall? Are different parts of the brain associated with these two processes? Two papers just published deal with these issues and indicates that when the subjective feeling of confidence in the memory is high (“strength”) the hippocampus is significantly involved in both processes.

Hippocampus Plays Bigger Memory Role Than Previously Thought

Prevailing research posits that recollection and familiarity memories involve different regions in the brain’s medial temporal lobe: the hippocampus for recollection, the adjacent perirhinal cortex for familiarity.

“But given the connectivity in that part of the human brain, that separation seemed too clean, too neat,” said Squire, a leading expert on the neurological bases of memory. “The idea of distinct functions was unlikely.”

Recollection-based memories are typically associated with higher confidence and accuracy than familiarity-based decisions. Accordingly, in the past, comparisons between recollection and familiarity have also involved a comparison between strong memories and weak memories. So the question is how the brain accomplishes recollection and familiarity when the effect of memory strength is taken off the table.

Larry Squire, a prominent figure in memory research, has published a number of other studies on this subject (References). In one of the two new papers, Squire and his colleagues conclude

The Hippocampus Supports Both Recollection and Familiarity When Memories Are Strong

As in earlier studies, recollected items had higher accuracy and confidence than familiar items, and hippocampal activity was higher for recollected items than for familiar items. Furthermore, hippocampal activity was similar for familiar items, misses, and correct rejections. When the accuracy and confidence of recollected and familiar items were matched, the findings were dramatically different. Hippocampal activity was now similar for recollected and familiar items. Importantly, hippocampal activity was also greater for familiar items than for misses or correct rejections (as well as for recollected items vs misses or correct rejections). Our findings suggest that the hippocampus supports both recollection and familiarity when memories are strong.

Further reading:

Medial Temporal Lobe Function and Recognition Memory: A Novel Approach to Separating the Contribution of Recollection and Familiarity

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September 27, 2011

Brain wiring continues

Well, that’s a relief! To suppose that brain development more or less stops at the end of adolescence implies all that happens afterwards is just adding data. Surely there’s more to things like prudence, levelheadedness, and understanding of others than just added data.

Brain wiring continues – University of Alberta

It has been a long-held belief in medical communities that the human brain stopped developing in adolescence. But now there is evidence when examining the development of wiring in some parts of the brain this is not in fact the case, thanks to medical research conducted in the Department of Biomedical Engineering by researcher Christian Beaulieu, an Alberta Innovates – Health Solutions scientist, and by his PhD student at the time, Catherine Lebel. Lebel recently moved to the United States to work at UCLA, where she is a post-doctoral fellow working with an expert in brain-imaging research.

“This is the first long-range study, using a type of imaging that looks at brain wiring, to show that in the white matter there are still structural changes happening during young adulthood,” says Lebel. “The white matter is the wiring of the brain; it connects different regions to facilitate cognitive abilities. So the connections are strengthening as we age in young adulthood.”

Further reading:

Longitudinal Development of Human Brain Wiring Continues from Childhood into Adulthood

September 7, 2011

Man’s Best Friends Know Who Their Best Friends Are

Dogs may know you better than you suspect…

Man’s Best Friends Know Who Their Best Friends Are – DISCOVER Magazine

Researchers and pet owners have long known that dogs can learn spoken commands and understand certain human gestures. But can they actually eavesdrop—that is, pick up information simply by watching interactions between people? Animal cognition researcher Sarah Marshall-Pescini and her colleagues at the University of Milan believe that dogs do indeed engage in interspecies snooping.

September 6, 2011

Female Orgasm Remains an Evolutionary Mystery

Talk about interesting phenomena that science still can’t explain…

Female Orgasm Remains an Evolutionary Mystery – Wired.com

After baffling biologists for decades, the female orgasm has resisted yet another attempt to explain its elusive evolutionary origins.

A survey of orgasmic function in thousands of twins found none of the statistical patterns expected if female orgasm is just a coincidental byproduct of natural selection on its male counterpart, as has been suggested.

“The evolutionary basis of human female orgasm has been subject to furious scientific debate, which has recently intensified,” wrote University of Queensland geneticist Brendan Zietsch and Pekka Santtila of Finland’s Abo Akedemi University in a Sept. 3 Animal Behavior article. “These results challenge the byproduct theory of female orgasm.”

Further reading:

Evolutionary mystery of female orgasm deepens

September 1, 2011

Promiscuousness results in genetic ‘trade-up,’ more offspring

Promiscuousness results in genetic ‘trade-up,’ more offspring – ScienceBlog.com

It’s all about the grandkids! That’s what a team led by an Indiana University biologist has learned about promiscuous female birds and why they mate outside their social pair.

Many humans find the idea of mating for life a romantic ideal, but in the natural world, non-monogamous relationships may have their benefits. According to new research published online today (Aug. 31) in Proceedings of the Royal Society B, IU postdoctoral research associate Nicole Gerlach and colleagues have uncovered one of the benefits of this promiscuity: more grandkids!

August 18, 2011

Elephants Can Use Insight to Solve Problems

Elephants Can Use Insight to Solve Problems

Via ScienceNOW, 8/18/11

Highly social and clever and cooperative with tools, elephants are often near the top of the brainiest creatures list. Now, scientists have added a new talent to elephants’ mental repertoire: The ability to solve a problem using insight—that aha! moment when your internal light bulb switches on and you figure out the solution to a puzzle. Previously, only a limited number of species, including certain primates, crows, and parrots were known to have this ability.

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