Older news items (pre-2010) brought over from the old website
December 2008
MRI brain scans accurate in early diagnosis of Alzheimer's disease
Adding to the growing body of evidence indicating MRI brain scans provide valuable diagnostic information about Alzheimer's disease, a study in which a new visual rating system for evaluating the severity of shrinkage in the medial temporal lobe was used on brain scans of 260 people has found that scores accurately distinguished those with Alzheimer’s from those with mild cognitive impairment and those without memory problems. The test also accurately predicted those who would move from one group to another within a year or two.
Duara, R. et al. 2008. Medial temporal lobe atrophy on MRI scans and the diagnosis of Alzheimer disease. Neurology, 71, 1986-1992.
http://www.eurekalert.org/pub_releases/2008-12/uosf-mbs121808.php
August 2007
Maturity brings richer memories
New research suggests adults can remember more contextual details than children, and that this is related to the development of the prefrontal cortex. While in a MRI scanner, 49 volunteers aged eight to 24 were shown pictures of 250 common scenes and told they would be tested on their memory of these scenes. In both children and adults, correct recognition of a scene was associated with higher activation in several areas of the prefrontal cortex and the medial temporal lobe when they were studying the pictures. However, the older the volunteers, the more frequently their correct answers were enriched with contextual detail. These more detailed memories correlated with more intense activation in a specific region of the PFC. A number of studies have suggested that the PFC develops later than other brain regions.
The report appeared in the August 5 advance online edition of Nature Neuroscience.
http://www.physorg.com/news105549812.html
http://www.eurekalert.org/pub_releases/2007-08/miot-msm080107.php
August 2005
Rating familiarity: how we do it
Previous research has indicated that recognizing a familiar object is accompanied by a reduction in activity in the medial temporal lobe. A new imaging study has confirmed the reduced activity and demonstrated that the degree of reduction is correlated with the degree of familiarity of the object (a face in this instance). The reduction began very rapidly in the recognition process. The researchers suggested that the graded response of medial temporal structures are what allows us to assess how familiar an object is.
Gonsalves, B.D., Curran, T., Norman, K.A. & Wagner, A.D. 2005. Memory Strength and Repetition Suppression: Multimodal Imaging of Medial Temporal Cortical Contributions to Recognition. Neuron, 47, 751–761.
http://www.eurekalert.org/pub_releases/2005-08/cp-tt082505.php
June 2005
Single cell recognition research finds specific neurons for concepts
An intriguing study surprises cognitive researchers by showing that individual neurons in the medial temporal lobe are able to recognize specific people and objects. It’s long been thought that concepts such as these require a network of cells, and this doesn’t deny that many cells are involved. However, this new study points to the importance of a single brain cell. The study of 8 epileptic subjects found variable responses from subjects, but within subjects, individuals showed remarkably specific responses to concepts. For example, a single neuron in the left posterior hippocampus of one subject responded to all pictures of actress Jennifer Aniston, and also to Lisa Kudrow, her co-star on the TV hit "Friends", but not to pictures of Jennifer Aniston together with actor Brad Pitt, and not, or only very weakly, to other famous and non-famous faces, landmarks, animals or objects. In another patient, pictures of actress Halle Berry activated a neuron in the right anterior hippocampus, as did a caricature of the actress, images of her in the lead role of the film "Catwoman," and a letter sequence spelling her name. The results suggest an invariant, sparse and explicit code, which might be important in the transformation of complex visual percepts into long-term and more abstract memories.
Quiroga, R.Q., Reddy, L., Kreiman, G., Koch, C & Fried, I. 2005. Invariant visual representation by single neurons in the human brain. Nature, 435, 1102-1107.
http://www.eurekalert.org/pub_releases/2005-06/uoc--scr062005.php
May 2005
Long-term storage of autobiographical memories
By studying in detail the ability of patients with selective brain damage to recall events in their past, researchers have helped settle a long-standing controversy about whether long-term memory of one's personal experiences continue to be stored in the medial temporal lobe, or whether they gradually become independent of this area. The evidence from this new study suggests that autobiographical memories gradually become distributed throughout the neocortex.
Bayley, P.J., Gold, J.J., Hopkins, R.O. & Squire, L.R. 2005. The Neuroanatomy of Remote Memory. Neuron, 46, 799–810.
http://www.eurekalert.org/pub_releases/2005-06/cp-wlm052605.php
October 2004
An imaging study of 20 healthy 8- to 30-year-olds has shed new light on the development of working memory. The study found that pre-adolescent children relied most heavily on the prefrontal cortex and parietal regions of the brain during the working memory task; adolescents used those regions plus the anterior cingulate; and in adults, a third area of the brain, the medial temporal lobe, was brought in to support the functions of the other areas. Adults performed best. The results support the view that a person's ability to have voluntary control over behavior improves with age because with development, additional brain processes are used.
http://www.eurekalert.org/pub_releases/2004-10/uopm-dow102104.php
September 2004
New technique sheds light on autobiographical memory
A new technique for studying autobiographical memory has revealed new findings about autobiographical memory, and may prove useful in studying age-related cognitive impairment. Previous inconsistencies between controlled laboratory studies of memory (typically, subjects are asked to remember items they have previously seen in the laboratory, such as words presented on a computer screen) and studies of autobiographical memory have seemed to indicate that the brain may function differently in the two processes. However, such differences might instead reflect how the memories are measured. In an effort to provide greater control over the autobiographical memories, volunteer subjects were given cameras and instructed to take pictures of campus scenes. The subjects were also instructed to remember the taking of each picture as an individual event, noting the physical conditions and their psychological state, such as their mood and associations with the subject of the images. The subjects were then shown a selection of campus photos they had not taken. While their brains were scanned, they were then shown a mix of their own photos with those they had not taken, and asked to indicate whether each photo was new, seen earlier in the lab, or one they had taken themselves. The researchers found that recalling the autobiographical memories activated many of the same brain areas as laboratory memories (the medial temporal lobe and the prefrontal cortex); however, they also activated brain areas associated with "self-referential processing" (processing information about one's self), and regions associated with retrieval of visual and spatial information, as well as showing a higher level of activity in the recollection areas in the hippocampus.
The report will appear in the November issue of the Journal of Cognitive Neuroscience.
http://www.eurekalert.org/pub_releases/2004-09/du-blm092904.php
November 2003
Questioning the medial temporal lobe
The medial temporal lobe includes the hippocampus, the amygdala, and the entorhinal and perirhinal cortices. It is often talked about as a single unit, but recently a prominent neurobiologist has questioned this usage. For one thing, the region didn’t evolve as one unit — the different regions arose at different times during primate evolution. Therefore, can it really be an integrated system with a common function? Her work with rhesus monkeys suggests rather that these different parts may serve cooperative and even competitive functions.
Magnetic resonance imaging may help predict future memory decline
A six-year imaging study of 45 healthy seniors assessed changes in brain scans against cognitive decline. They found that progressive atrophy in the medial temporal lobe was the most significant predictor of cognitive decline, which occurred in 29% of the subjects.
Rusinek, H., De Santi, S., Frid, D., Tsui, W-H., Tarshish, C.Y., Convit, A., & de Leon, M.J. 2003. Regional Brain Atrophy Rate Predicts Future Cognitive Decline: 6-year Longitudinal MR Imaging Study of Normal Aging. Radiology, 229, 691-696.
http://www.eurekalert.org/pub_releases/2003-11/rson-mhr111703.php
March 2003
Activity in the mediotemporal lobe lower in elderly with poor memory
An imaging study has revealed that, although there is no difference on standard MRI scans,scans showing the amount of oxygen (and thus activity) find that elderly persons with a poor memory have less activity in the mediotemporal lobe when storing new information than elderly persons with a normally functioning memory.This more sensitive scan may help early diagnosis of Alzheimer's.
The research was done as part of a doctoral thesis by Dr Sander Daselaar.
http://www.eurekalert.org/pub_releases/2003-03/nofs-svp032103.php
November 2001
Imaging study confirms role of medial temporal lobe in memory consolidation
Lesions in the medial temporal lobe (MTL) typically produce amnesia characterized by the disproportionate loss of recently acquired memories. Such memory loss has been interpreted as evidence for a memory consolidation process guided by the MTL. A recent imaging study confirms this view by showing temporally graded changes in MTL activity in healthy older adults taking a famous faces remote memory test. Evidence for such temporally graded change in the hippocampal formation was mixed, suggesting it may participate only in consolidation processes lasting a few years. The entorhinal cortex (also part of the MTL) was associated with temporally graded changes extending up to 20 years, suggesting that it is the entorhinal cortex, rather than the hippocampal formation, that participates in memory consolidation over decades. The entorhinal cortex is damaged in the early stages of Alzheimer’s disease (AD).
Haist, F., Gore, J.B. & Mao, H. 2001. Consolidation of human memory over decades revealed by functional magnetic resonance imaging. Nature neuroscience, 4 (11), 1139-1145.
http://www.nature.com/neurolink/v4/n11/abs/nn739.html
Competition between memory systems
Learning and memory in humans rely upon several memory systems. For example, the medial temporal lobe (MTL) is associated with declarative learning (facts and events). The basal ganglia is associated with nondeclarative learning (learning you derive from experience, that may not be conscious). A recent imaging study looked at how these memory systems interact during classification learning. During the nondeclarative learning task, there was an increase in activity in the basal ganglia, and a decrease in activity in the MTL. During the memorization task (testing declarative learning), the reverse was true. Further examination found rapid modulation of activity in these regions at the beginning of learning, suggesting that subjects relied upon the medial temporal lobe early in learning. However, this dependence rapidly declined with training.
Poldrack, R.A., Clark, J., Paré-blagoev, E.J., Shohamy, D., Moyano, J.C., Myers, C. & Gluck, M.A. 2001. Interactive memory systems in the human brain. Nature, 414, 546 - 550.
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v414/n6863/abs/414546a0_fs.html
http://www.eurekalert.org/pub_releases/2001-11/mgh-isi112601.php