Research Spotlights August 2019

Research Spotlights August 2019

Seeing is feeling - How Artificial Intelligence is helping us understand emotions

Recently published research supported by NIMH and NIDA sheds light on how our brains process visual information with emotional features by incorporating machine-learning innovations and human brain-imaging. The researchers started with an existing neural network, AlexNet, which enables computers to recognize objects and adapted it using prior research that identified stereotypical emotional responses to images. This new network, EmoNet, was then asked to categorize 25,000 images into 20 categories such as craving, sexual desire, horror, awe and surprise. EmoNet could accurately and consistently categorize 11 of the emotion types and reliably rate the emotional intensity of the images.

To further test and refine EmoNet, 18 human subjects had functional magnetic resonance imaging (fMRI) to measure brain activity as they were shown the same images that EmoNet “saw” in 4-second flashes of 112 images. The researchers found that when activity in the neural network (EmoNet) was compared to that in the subjects' brains, there was agreement between brain activity patterns in the occipital lobe and units in EmoNet that code for specific emotions. This finding suggests that EmoNet learned to represent emotions in a way that is biologically plausible. Interestingly, the brain imaging data also demonstrated that even a brief, basic image could elicit emotion-related activity in the visual cortex of the brain, and that the visual cortex itself also plays an important role in the processing and perception of emotion.

These results show that the brain recognizes, categorizes, and responds to emotions quickly and that the visual cortex plays an important role in this process. This research provides a new approach to research on complex emotions using artificial intelligence to analyze patterns of visual input and predict emotional responses.

Philip A. Kragel, Marianne C. Reddan, Kevin S. LaBar and Tor D. Wager. 2019. Emotion schemas are embedded in the human visual system. Scientific Advances. doi:10.1126/sciadv.aaw4358

Why give up now? Scientists gain new insights into motivation and reward seeking

Researchers funded by NIDA, NIMH, NIGMS, NCI, and the Brain and Behavior Research Foundation just published findings that add insight into motivation and reward research by elucidating the neural pathways involved in giving up. Nociceptin, an opioid-like peptide, and its receptors are widely distributed throughout the brain in regions associated with reward behavior. One such region, the ventral tegmental area (VTA), contains neurons that release dopamine when engaging in reward behaviors. In mammals, neural circuits responsible for reward seeking are regulated by homeostatic mechanisms which help to maintain internal stability and to adjust for environmental changes. For instance, in the wild, animals are less motivated to seek rewards in environments where resources are scarce due to the risks such as predation and excess energy use. In humans, deficits within these regulatory processes can result in behavioral dysfunctions, including depression, addiction, and eating disorders.

Researchers elucidated the role of nociceptin in regulating motivation by recording and manipulating a unique subpopulation of neurons in the VTA, the paranigral ventral tegmental area (pnVTA), in mice seeking a sucrose reward. In this paradigm, the mice receive a sucrose reward by poking their noses into a port. The certainty and difficulty (number of nose pokes) to get the sucrose varied over time, until eventually, all the mice “gave up’ and stopped the seeking behavior”. The neural recordings revealed that these pnVTA neurons became most active when mice stopped seeking sucrose. When active, these pnVTA neurons release nociceptin, a complex molecule that suppresses dopamine, a chemical largely associated with motivation. Through modulation of these neuronal populations, researchers were able to determine that this pathway is necessary for regulating reward motivation.

This research provides new insights into some neuromodulatory circuits that regulate reward motivated behaviors. These findings also have implications for developing targeted interventions and therapeutics that could help people with mental health disorders such as depression, where motivation is often impaired, and in substance abuse disorders to decrease motivation for drug use.

Parker KE, Pedersen CE, Gomez AM, Spangler SM, Walicki MC, Feng SY, Stewart SL, Otis JM, Al-Hasani R, McCall JG, Sakers K, Bhatti DL, Copits BA, Gereau RW, Jhou T, Kash TJ, Dougherty JD, Stuber GD, Bruchas MR. 2019. A Paranigral VTA Nociceptin Circuit that Constrains Motivation for Reward. Cell, 178 (3): 653 DOI: 10.1016/j.cell.2019.06.034.

Stress during pregnancy is linked with long-term effects on mother’s health

Recently, research supported by NICHD, NHLBI, NICHD, and OBSSR was published that investigated the associations of prenatal stress and adverse pregnancy outcomes on maternal mental health 2-7 years after pregnancy. Stress has been shown to be a risk factor for adverse pregnancy outcomes such as gestational diabetes, hypertensive disorders of pregnancy, preeclampsia, and medically indicated or spontaneous preterm birth. However, little is known about these associations and longer-term maternal mental health.

Researchers leveraged data from the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be (nuMoM2b), a cohort study of women who had previously never given birth (n = 10,028) and were then prospectively followed during a subsequent pregnancy. The current research is based on a subsample of the nuMoM2b cohort (n = 4161) who underwent follow-up 2–7 years later as part of the Heart Health Study (HHS). In their first and third trimesters, and then again during the HHS in-person visit, participants completed the10-item Perceived Stress Scale (PSS) which is a measure of how unpredictable, uncontrollable, and overloaded the individual perceives their life. The associations between the PSS and the presence of adverse pregnancy outcomes were estimated using multi-variable linear regression.

In this geographically and demographically diverse sample, prenatal stress and adverse pregnancy outcomes such as hypertensive disorders of pregnancy, preeclampsia, and medically indicated preterm births, were positively and independently associated with stress levels 2-7 years after pregnancy. This research brings attention to women’s mental, as well as physical, status during and after pregnancy and the impact on their long-term health and well-being.

Monk C, Webster RS, McNeil RB, Parker CB, Catov JM, Greenland P, Merz NB, Silver RM, Simhan HN, Ehrenthal DB, Chung JH, Haas DM, Mercer BM, Parry S, Polito L, Reddy UM, Saade GR, Grobman WA. 2019. Associations of perceived prenatal stress and adverse pregnancy outcomes with perceived stress years after delivery. 2019 Archives of Women's Mental Health.