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Please quote Nature Neuroscience as the source of these items.

The June 2005 issue of Nature Neuroscience is available online.

 June 2005 Previous | Next

Wiring the brain for depression

Nature Neuroscience pp 828 - 834

Healthy carriers of a gene that increases the risk of depression have altered activity in brain circuits involved in emotion, reports a brain imaging study in the June issue of Nature Neuroscience. The findings may help to explain how genetic makeup can lead to increased susceptibility to depression.

An increased risk for depression has been linked to one variant of a gene that controls levels of the brain chemical serotonin, thought to be involved in mood regulation. People that carry this variant are more likely to develop depression, particularly if exposed to stressful or traumatic life experiences. Daniel Weinberger and colleagues imaged the brains of over one hundred healthy individuals with no prior history of depression. Carriers of the high-risk gene variant had reduced brain volume and altered interactions between regions of a brain circuit that may be important for controlling negative emotional responses.

Previous imaging studies have found changes in the brains of depressed patients, but it was not clear whether these changes were caused by depression or whether they might be present before its onset. The new results suggest that genes shape brain structure and function, which in turn may contribute to individual variation in temperament and vulnerability to mood disorders.

5-HTTLPR polymorphism impacts human cingulate-amygdala interactions: a genetic susceptibility mechanism for depression pp 828 - 834
Lukas Pezawas, Andreas Meyer-Lindenberg, Emily M Drabant, Beth A Verchinski, Karen E Munoz, Bhaskar S Kolachana, Michael F Egan, Venkata S Mattay, Ahmad R Hariri & Daniel R Weinberger
Published online: 08 May 2005 | doi:10.1038/nn1463
Abstract | Full text | PDF | Supplementary Information

Blue genes: wiring the brain for depression pp 701 - 703
Stephan Hamann
Abstract | Full text | PDF

Race-related brain activity

Nature Neuroscience pp 720 - 722

Novel, threatening or highly arousing images activate a brain area called the amygdala that is involved in emotional processing. Pictures of African-American faces are known to activate the amygdala more strongly than Caucasian-American faces, at least in Caucasian-American people, but the underlying reason for that activity has remained controversial. A paper in the June issue of Nature Neuroscience now reports that African-American people show a similar racially specific pattern of amygdala activation, suggesting that this brain activity may result from learned cultural responses to racial groups.

In participants of both races, brain regions involved in emotion and motivation were more active in response to African-American faces than to Caucasian-American faces. Since African-American subjects are presumably exposed to many faces of their own race in their daily lives, the authors conclude that amygdala activity in response to African-American faces may reflect the learning of cultural associations about the group rather than novelty. Verbally labeling the faces as African-American reduced the amygdala activity in both groups, suggesting that putting race into words may reduce its emotional impact.

An fMRI investigation of race-related amygdala activity in African-American and Caucasian-American individuals pp 720 - 722
Matthew D Lieberman, Ahmad Hariri, Johanna M Jarcho, Naomi I Eisenberger & Susan Y Bookheimer
Published online: 08 May 2005 | doi:10.1038/nn1465
Abstract | Full text | PDF | Supplementary Information

Brain changes over the menstrual cycle

Nature Neuroscience pp 797 - 804

Hormonal fluctuations over the course of the menstrual (or estrus) cycle can have noticeable effects on the brain and behavior. During different phases of the cycle, neurons express different subtypes of the receptor for the inhibitory neurotransmitter GABA, as reported in the June issue of Nature Neuroscience, which may provide a molecular basis for some of these changes.

Up to 78% of epileptic women have more seizures during the phase when progesterone declines, a condition called catamenial epilepsy. Five percent of menstruating women have premenstrual dysphoric disorder or PMDD, and routinely experience severe anxiety and depression in the week or so before menstruation. Estrogen and progesterone affect both excitatory and inhibitory signaling in the brain, but the mechanisms behind these changes in seizure susceptibility and anxiety were unknown.

In mice, Istvan Mody and colleagues found that neurons in the hippocampus -- a brain region important in seizure generation -- expressed more of a particular subtype of inhibitory GABA receptors during the phase of the cycle when progesterone levels are low. This caused a dramatic reduction in so-called 'tonic' or persistent inhibition of neural signaling, along with corresponding increases in seizure susceptibility and anxiety. In the high-progesterone phase of the cycle, the authors found the opposite pattern: expression of this subtype of GABA receptors was higher, tonic inhibition was increased, and seizure susceptibility was reduced. Thus the authors suggest that these GABA receptor changes may be responsible for the effects of the menstrual cycle on seizure and anxiety levels seen in catamenial epilepsy and PMDD.

Ovarian cycle-linked changes in GABAA receptors mediating tonic inhibition alter seizure susceptibility and anxiety pp 797 - 804
Jamie L Maguire, Brandon M Stell, Mahsan Rafizadeh & Istvan Mody
Published online: 15 May 2005 | doi:10.1038/nn1469
Abstract | Full text | PDF | Supplementary Information

A woman's prerogative pp 697 - 699
Kevin Staley & Helen Scharfman
Abstract | Full text | PDF
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