Older news items (pre-2010) brought over from the old website
August 2009
Alcoholics show abnormal brain activity when processing facial expressions
Excessive chronic drinking is known to be associated with deficits in comprehending emotional information, such as recognizing different facial expressions. Now an imaging study of abstinent long-term alcoholics has found that they show decreased and abnormal activity in the amygdala and hippocampus when looking at facial expressions. They also show increased activity in the lateral prefrontal cortex, perhaps in an attempt to compensate for the failure of the limbic areas. The finding is consistent with other studies showing alcoholics invoking additional and sometimes higher-order brain systems to accomplish a relatively simple task at normal levels. The study compared 15 abstinent long-term alcoholics and 15 healthy, nonalcoholic controls, matched on socioeconomic backgrounds, age, education, and IQ.
Marinkovic, K. et al. 2009. Alcoholism and Dampened Temporal Limbic Activation to Emotional Faces. Alcoholism: Clinical and Experimental Research, Published Online: Aug 10 2009
http://www.eurekalert.org/pub_releases/2009-08/ace-edc080509.php
http://www.eurekalert.org/pub_releases/2009-08/bumc-rfa081109.php
June 2009
Measuring brain atrophy in patients with mild cognitive impairment
A study involving 269 patients with mild cognitive impairment provides evidence that a fully automated procedure called Volumetric MRI (that can be done in a clinical setting) can accurately and quickly measure parts of the medial temporal lobe and compare them to expected size. It also found that not only atrophy in the hippocampus but also the amygdala is associated with a greater risk of conversion to Alzheimer’s.
Kovacevic, S. et al. 2009. High-throughput, Fully Automated Volumetry for Prediction of MMSE and CDR Decline in Mild Cognitive Impairment. Alzheimer Disease & Associated Disorders, 23 (2), 139-145.
http://www.eurekalert.org/pub_releases/2009-06/uoc--mba061609.php
December 2008
Aging brains allow negative memories to fade
Another study has found that older adults (average age 70) remember fewer negative images than younger adults (average age 24), and that this has to do with differences in brain activity. When shown negative images, the older participants had reduced interactions between the amygdala and the hippocampus, and increased interactions between the amygdala and the dorsolateral prefrontal cortex. It seems that the older participants were using thinking rather than feeling processes to store these emotional memories, sacrificing information for emotional stability. The findings are consistent with earlier research showing that healthy seniors are able to regulate emotion better than younger people.
St. Jacques, P.L., Dolcos, F. & Cabeza, R. 2009. Effects of Aging on Functional Connectivity of the Amygdala for Subsequent Memory of Negative Pictures: A Network Analysis of Functional Magnetic Resonance Imaging Data. Psychological Science, 20 (1), 74-84.
http://www.eurekalert.org/pub_releases/2008-12/uoaf-aba121608.php
http://www.eurekalert.org/pub_releases/2008-12/dumc-oay121508.php
June 2008
Long-term cannabis users may have structural brain abnormalities
An imaging study of 15 men who smoked more than five cannabis joints daily for more than 10 years has found that, compared with individuals who were not cannabis users, the heavy cannabis users tended to have a smaller hippocampus and amygdala. They also performed significantly worse on verbal learning, but this didn’t correlate with regional brain volumes.
Yücel, M. et al. 2008. Regional Brain Abnormalities Associated With Long-term Heavy Cannabis Use . Archives of General Psychiatry, 65(6), 694-701.
http://www.eurekalert.org/pub_releases/2008-06/usmc-usr061208.php
December 2007
Some brain injuries may reduce the likelihood of PTSD
A study of combat-exposed Vietnam War veterans shows that those who suffered injuries to the amygdala or the ventromedial prefrontal cortex were less likely to develop post-traumatic stress disorder than those who suffered damage in other areas or had no head injuries (in fact none of those whose amygdala was damaged developed PTSD). The findings suggest that treatment designed to inhibit the activity of these two areas might provide relief from PTSD.
Koenigs, M. et al. 2007. Focal Brain Damage Protects Against Post-Traumatic Stress Disorder in Combat Veterans. Nature Neuroscience, published on-line December 23
http://www.eurekalert.org/pub_releases/2007-12/nion-sss122107.php
September 2006
Anticipation strengthens memory
An imaging study has revealed that the amygdala and the hippocampus become activated when a person is anticipating a difficult situation (some type of gruesome picture). Moreover, the higher the level of activation during this anticipation, the better the pictures were remembered two weeks later. The study demonstrates how expectancy can affect long-term memory formation, and suggests that the greater our anxiety about a situation, the better we’ll remember that situation. If it’s an unpleasant one, this will only reinforce the anxiety, setting up a vicious cycle. The study has important implications for the treatment of psychological conditions such as post-traumatic stress disorder and social anxiety.
Mackiewicz, K.L., Sarinopoulos, I., Cleven, K.L. & Nitschke, J.B. 2006. The effect of anticipation and the specificity of sex differences for amygdala and hippocampus function in emotional memory. PNAS, 103, 14200-14205.
http://www.eurekalert.org/pub_releases/2006-09/uow-apa090106.php
February 2006
How emotions interfere with memory
We know emotion can interfere with cognitive processes. Now an imaging study adds to our understanding of how that occurs. Emotional images evoked strong activity in typical emotional processing regions (amygdala and ventrolateral prefrontal cortex) while simultaneously deactivating regions involved in memory processing (dorsolateral prefrontal cortex and lateral parietal cortex). The researchers also found individual differences among the subjects in their response to the images. People who showed greater activity in a brain region associated with the inhibition of response to emotional stimuli rated the emotional distracters as less distracting.
Dolcos, F. & McCarthy, G. 2006. Brain Systems Mediating Cognitive Interference by Emotional Distraction. Journal of Neuroscience, 26, 2072-2079.
http://www.eurekalert.org/pub_releases/2006-02/dumc-he021506.php
A single memory is processed in three separate parts of the brain
A rat study has demonstrated that a single experience is indeed processed differently in separate parts of the brain. They found that when the rats were confined in a dark compartment of a familiar box and given a mild shock, the hippocampus was involved in processing memory for context, while the anterior cingulate cortex was responsible for retaining memories involving unpleasant stimuli, and the amygdala consolidated memories more broadly and influenced the storage of both contextual and unpleasant information.
Malin, E.L. & McGaugh, J.L. 2006. Differential involvement of the hippocampus, anterior cingulate cortex, and basolateral amygdala in memory for context and footshock. Proceedings of the National Academy of Sciences, 103 (6), 1959-1963.
http://www.eurekalert.org/pub_releases/2006-02/uoc--urp020106.php
September 2005
Memory of fear more complex than supposed
It seems that fear memory is more complex than has been thought. A new mouse study has shown that not only the hippocampus and amygdala are involved, but that the prefrontal cortex is also critical. The development of the fear association doesn’t occur immediately after a distressing event, but develops over time. The process, it now seems, depends directly on a protein called NR2B.
Zhao, M-G. et al. 2005. Roles of NMDA NR2B Subtype Receptor in Prefrontal Long-Term Potentiation and Contextual Fear Memory. Neuron, 47, 859-872.
http://www.eurekalert.org/pub_releases/2005-09/uot-sco091505.php
July 2005
How trauma triggers long-lasting memories in the brain
A rat study sheds more light on why emotional experiences tend to be better remembered than emotionally neutral events. The study found that emotionally arousing events activated the amygdala, which then increased a specific protein — activity-regulated cytoskeletal protein ("Arc") — in the neurons in the hippocampus. It's thought that Arc helps store these memories by strengthening the synapses.
McIntyre, C.K., Miyashita, T., Setlow, B., Marjon, K.D., Steward, O., Guzowski, J.F. & McGaugh, J.L. 2005. Memory-influencing intra-basolateral amygdala drug infusions modulate expression of Arc protein in the hippocampus. Proceedings of the National Academy of Sciences, 102 (30), 10718-10723.
http://www.eurekalert.org/pub_releases/2005-07/uoc--nih072505.php
February 2005
Why traumatic memories have the power they do
In the first imaging study to look at retrieval of emotional memories after a long period (one year after encoding), researchers found that people did recall emotional images, both pleasant and unpleasant, better than emotionally-neutral images. This recall was associated with higher activity in both the amygdala and the hippocampus. The synchronicity of activity between these two regions suggested that each region triggers the other, creating a self-reinforcing "memory loop" in which an emotional cue might trigger recall of the event, which then loops back to a re-experiencing of the emotion of the event. The findings suggest why people subject to traumatic events may be trapped in a cycle of emotion and recall that aggravates post-traumatic stress disorder, and may also suggest why therapies in which people relive such memories and reshape perspective to make it less traumatic can help people cope with such memories.
Dolcos, F., LaBar, K.S. & Cabeza, R. 2005. Remembering one year later: Role of the amygdala and the medial temporal lobe memory system in retrieving emotional memories. PNAS, 102 (7), 2626-2631.
http://www.eurekalert.org/pub_releases/2005-03/du-ems030805.php
March 2004
Different brain regions for arousing and non-arousing words
An imaging study has found that words representing arousing events (e.g., “rape”, “slaughter”) activate cells in the amygdala, while nonarousing words (e.g., “sorrow”, “mourning”) activated cells in the prefrontal cortex. The hippocampus was active for both type of words. On average, people remembered more of the arousing words than the others, suggesting stress hormones, released as part of the response to emotionally arousing events, are responsible for enhancing memories of those events.
Kensinger, E.A. & Corkin, S. 2004. Two routes to emotional memory: Distinct neural processes for valence and arousal. PNAS, 101, 3310-3315. Published online before print February 23 2004, 10.1073/pnas.0306408101
http://www.eurekalert.org/pub_releases/2004-03/miot-mlu030104.php
August 2003
Key brain link in associative learning directly observed
Rat studies have now shown that the amygdala supports the formation of new associations by changing nerve cell firing patterns in a different but connected part of the brain. In earlier studies, the researchers had demonstrated that nerve cells in the amygdala and the orbitofrontal cortex changed their firing patterns to reflect new associations between cues and outcomes. In this later study, they examined how changes in neural activity in amygdala might be supporting changes in the orbitofrontal cortex. Rats were first deprived of water, then repeatedly given either desirable drinking water, laced with sugar, or undesirable drinking water, laced with quinine. The associations then learned would show up in the orbitofrontal cortex when the rats smelled the odor cue. The same activation patterns did not however, show up in those rats who had their amygdala chemically lesioned (although these rats still learned to avoid the undesirable drinking water). Specifically, although lesioned rats had neurons in the orbitofrontal cortex that were responsive to the odor cues, they did not have neurons that were responsive in anticipation of the predicted outcome. The responsive neurons were also less associative, more responsive to the identity of the cue rather than the association betwen odor and consequence.
Schoenbaum, G., Setlow, B., Saddoris, M.P. & Gallagher, M. 2003. Encoding Predicted Outcome and Acquired Value in Orbitofrontal Cortex during Cue Sampling Depends upon Input from Basolateral Amygdala. Neuron, 39, 855-867.
http://www.eurekalert.org/pub_releases/2003-08/jhu-kbl082803.php
April 2002
Fear-conditioning study demonstrates long-suspected link between longterm potentiation and learning
It has long been felt that learning and memory must require physical changes in neurons that increase their responsivity to other neurons, so that they will continue to respond in the long-term even in the absence of external stimuli. Until now, however, noone has been able to actually demonstrate that this long-term potentiation occurs during learning. A new direction has proved to be more successful. Investigation of changes in the amygdala (a part of the brain associated with emotional response) after rats had been trained to fear a sound, found that postsynaptic neurons in the amygdala failed to produce any noticeable increase in electrical current, suggesting they had already been potentiated by their presynaptic partners.
Tsvetkov, E., Carlezon Jr.,W.A., Benes, F.M., Kandel, E.R. & Bolshakov, V.Y. 2002. Fear Conditioning Occludes LTP-Induced Presynaptic Enhancement of Synaptic Transmission in the Cortical Pathway to the Lateral Amygdala. Neuron, 34, 289-300.
May 2001
Amygdala may be critical for allowing perception of emotionally significant events despite inattention
We choose what to pay attention to, what to remember. We give more weight to some things than others. Our perceptions and memories of events are influenced by our preconceptions, and by our moods. Researchers at Yale and New York University have recently published research indicating that the part of the brain known as the amygdala is responsible for the influence of emotion on perception. This builds on previous research showing that the amygdala is critically involved in computing the emotional significance of events. The amygdala is connected to those brain regions dealing with sensory experiences, and the theory that these connections allow the amygdala to influence early perceptual processing is supported by this research. Dr. Anderson suggests that “the amygdala appears to be critical for the emotional tuning of perceptual experience, allowing perception of emotionally significant events to occur despite inattention.”
Anderson, A.K. & Phelps, E.A. 2001. Lesions of the human amygdala impair enhanced perception of emotionally salient events. Nature, 411, 305-309.
http://www.eurekalert.org/pub_releases/2001-05/NYU-Infr-1605101.php