Men, Women and Emotional Stress Responses

Psychoneuroendocrinology (November 2014) is publishing a fascinating paper authored by Sarah Lupis, Michelle Lerman and Jutta Wolf titled Anger responses to psychosocial stress predict heart rate and cortisol stress responses in men but not women.

473People can experience a wide range of emotions when under stress, including feelings of anger and fear. In recent years researchers have sought to understand how these emotion stress responses are linked to biological stress responses. In particular, some evidence suggests that anger and fear may be linked to cardiovascular changes in differential ways. It is less clear, however, how emotions during stress may predict increases in levels of the stress hormone cortisol. These deficits in our understanding are partly due to the methodological difficulties in measuring emotion in the context of stress. Much prior research has relied solely on retrospective self-report (after the stress has passed, a questionnaire asks a study participant to reflect on how he felt in the moment of stress). By this time, the participant may have forgotten how he felt, or may already be utilizing coping strategies to process those emotions. In addition, he may not feel comfortable reporting how the stressor made him feel, leading to less-than-honest responses. Unsurprisingly, prior research has not shown consistent links between these self-report measures and biological stress responses. In the current study, we therefore added facial coding of emotion expression to assess emotions occurring during stress. Our aim was to determine how expressions of anger and fear were linked to heart rate and cortisol stress responses.

We recruited 32 healthy Brandeis students and exposed them to a brief psychosocial stressor. A certified coder assessed facial expressions shown during the stressful situation. Heart rate and cortisol levels were measured throughout. After the stressor, the participants also self-reported how they felt during the stressor. A first notable finding showed that what participants self-reported feeling and the expressions they actually showed did not correlate. With regards to self-report, men who reported feeling fear showed blunted cortisol stress responses. Consistent with prior research, self-report was otherwise not associated with heart rate or cortisol stress responses. When looking at facial expressions, a consistent pattern appeared: men who showed more anger during the stressful situation also showed exaggerated heart rate and cortisol stress responses. For women, neither anger nor fear were linked to biological stress responses (see Figure).

Our findings first emphasize the importance of assessing emotion using multiple means. In this case, facial expressions revealed an emotion-stress link for males that would not be apparent using self-report alone. Facial coding may thus be a useful addition to current stress paradigms. Further, if men who react with anger in stressful situations do respond with exaggerated stress responses, it could have important down-stream health effects. Exaggerated, prolonged, or dysfunctional stress responses could, over time, lead to changes in basal stress systems. This kind of ‘allostatic load’ is associated with negative health outcomes including diabetes and cardiovascular disease. Anger and fear do not seem to drive these responses in females, and further study is needed to determine if similar relationships exist for a different set of emotions, perhaps self-conscious emotions like shame. By better understanding these relationships, more healthful ways of coping with stress can be developed, which is particularly important given that for many, stress has become an unavoidable part of daily life.

 

The “Fly on the Wall” Blog

fruit_fly_drawingBethany Christmann, a Neuroscience Ph.D. student in Leslie Griffith’s lab at Brandeis University has created a blog titled Fly on the Wall. The blog’s purpose is to introduce fly science to a broader audience of non-fly scientists. Check it out if you want to learn more about fly life, current research and how fruit fly research has already made huge contributions to understanding human biology and will continue to do so in the future.

Learn more about research in the Griffith Lab.

 

Why we love basic research

Brandeis PhD students Jonathan Napoline (Graduate Program in Chemistry, Thomas lab) and Sara Haddad (Graduate Program in Neuroscience, Marder lab) tell PBS NewsHour why they’re excited about basic research

 

 

Deep inside a worm’s nose

In a new paper in eLIFE, a team spearheaded by Brandeis postdocs David Doroquez and Cristina Berciu provide a strikingly detailed look at key structures called cilia on neurons involved in sensory perception in the nematode C. elegans. Primary cilia are the antenna-like structures onsensory neurons that gather information about the animal’s environment, such as chemicals, temperature, humidity, and touch. The genetic tools available to manipulate individual, identifiable neurons in C. elegans make worms an excellent model organism to study the assembly and function of cilia. This study requires a description of the structure of the cilia and their immediate surrounding glial support cells, and this new paper, a collaboration of the Sengupta and Nicastro labs, provides high-resolution 3D models showing how diverse and specialized these structures are.

worm-01-2

A bouquet of sensory antennae. The 3D ultrastructure of all sensory cilia
and other neuronal projections in the head of the soil roundworm C.
elegans have been reconstructed using serial section transmission electron
microscopy. Shown are 3D isosurface-rendering models emerging from a
transmission electron microscopic cross-section of the worm.

The key techniques in this study were serial section transmission electron microscopy and electron tomography, with structures well-preserved by high-pressure freezing and freeze-substitution. With these techniques, the authors achieved the first high-resolution 3D reconstructions of 50/60 cilia from C. elegans. They describe several previously uncharacterized features — for example, there are distinct types of branching patterns – in one, the two cilia originate from independent basal bodies (as previously seen in Chlamydomonas). In the second, the cilia branch after the basal transition zone, the ciliary gatekeeper region. In the latter case, this basically means that whatever is needed for the cilia to branch has to be transported through the transition zone, suggest there might be novel mechanisms of ciliary protein trafficking. In a third pattern, the branching occurs proximally before the transition zone, and represent therefore dendritic microvilli, rather than ciliary branching. The study also showed different organizations  of microtubules in different cilia types and vesicles in regions of the cilia which have never been seen before, again pointing to new mechanisms of protein transport. They also describe new cilia-glial interactions, which might suggest that cilia and glia talk to each other.

For more about these structures (with lots of pretty pictures and movies), see:

Fast-spiking interneurons and the critical period

How do children learn to play instruments and speak languages so much easier than adults, and why does brain damage result in worse outcomes in the mature brain vs. the young brain?  These questions are central to the study of how “critical periods” are regulated in the brain.

fs-interneuron

Electron micrograph from a single 70 nm cross-section through a fast-spiking parvalbumin-containing (gold labeling = white dots) presynaptic terminal forming a synapse (red dots) with a pyramidal soma. Original colors are inverted, contours have been raised and membranous structures are highlighted in aqua for ease of visualization. Presynaptic vesicles (colored ovals) within perisomatic fast spiking terminals mostly cluster within ∼200 nm of the synapse, with a few close enough (≤2 nm) to be deemed docked.

Critical periods in brain development define temporal windows when neuronal physiology and anatomy are most sensitive to changes in sensory input or experience (e.g. sound, touch, light, etc.).  The maturation of inhibitory cells that release the neurotransmitter GABA, especially a subset called fast-spiking (FS) interneurons, is thought to gate this period of neuronal ‘plasticity’ in the mammalian primary visual cortex.  However, it has remained unclear what aspects of FS cell development are important for permitting this period of neuronal malleability in the visual cortex. A new paper in Journal of Neuroscience from the Turrigiano lab addresses the question.

To explore how FS cell development might be linked to critical period plasticity, Brandeis postdoc Marc Nahmani and Professor Gina Turrigiano employed a well-established assay for cortical plasticity in visual cortex called monocular deprivation (MD), and measured FS cell connections using confocal and electron microscopy, as well as optogenetic stimulation of the FS cell population (i.e. shining light onto FS cells possessing light-gated channels to make them fire action potentials).

Following up on previous work from the Turrigiano lab (Maffei et al., 2006), they found that MD induces a coordinated increase in FS interneuron to pyramidal cell (the major excitatory output cells of the cortex) pre- and postsynaptic strength.  These changes occur if MD is performed during, but not before the critical period in visual cortex, suggesting they may play a role in gating this period of heightened neuronal plasticity.  Future studies are aimed at determining the timeline for these changes across the extent of the critical period in visual cortex.

see: Nahmani M, Turrigiano GG (2014) Deprivation-Induced Strengthening of Presynaptic and Postsynaptic Inhibitory Transmission in Layer 4 of Visual Cortex during the Critical Period. Journal of Neuroscience 34:2571-2582.

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