New Research on Emotions

Source: Image by Rami Gabriel

In this post, I describe two exciting research programs that get at the core of forces shaping the world we live in: treatment of psychopathology and the technological manipulation of choice. After describing some findings, I close with a discussion of issues concerning reductionism, and the value of securing objective measures for the measurement of emotional states in animals and humans.

Jeffrey Burgdorf at the Falk Institute of Northwestern University studies emotions in rats and is in the late stages of development of a new generation of mood medications which locate the sources of depression at a different level than current antidepressives. Burgdorf is known for his work with Jaak Panksepp which demonstrated that rats laugh in response to tickling. This set the stage for his further work on eliciting positive emotions in rats and studying their moods and behaviors.

The first point he discussed in a paper given to the International Neuropsychoanalytic Association earlier this month is that emotions are primarily induced by active social interaction. During these days of social distancing, this may come as no surprise to us and may even explain the sense of loss and disorientation many of us are experiencing. Burgdorf demonstrates that rats exhibit emotions when they are active (which means rough and tumble playing around), and it invariably motivates our mammalian cousins to seek each other out.

Another finding is that psychopathologies like mood and anxiety disorders seem to be related to the shift between when an animal seeks out stimulation and when stimulation is perceived as bothersome. Consider how our moods shift — we are content, agitated, impassive, joyful, morbid, bored, etc. Sometimes these moods can all happen in less than an hour. Burgdorf calls this shift a state change, and he argues the threshold at which an animal shifts from seeking stimulation to avoiding it may be one of the best objective measures of emotional experience. Our individual thresholds for state changes may be a significant identifier of mood disorder.

What interpretation can we draw from this state change evidence? Dr. Burgdorf investigates the states at the level of brain waves in the medial prefrontal lobe via an EEG (electroencephalograph). He finds that positive mood tends to correlate with theta waves, whereas negative moods correlate with delta waves. One way to look at this is that theta waves are conducive to long-term potentiation, which is the building of neuronal connections that form long-term memories or neural networks that may be more easily activated in the future or provide the basis for larger specified assembles.

On the other hand, delta waves seem to induce long-term depression of neuronal connectivity. This leads Dr. Burgdorf to suggest a couple of objective measures of emotion to be used therapeutically: portable EEG machines and a microphone that records active social sounds. Calls made by rats can be measured and categorized in correlation with their behaviors. It turns out that the frequency of their calls and correlated behavior fall into three categories: hedonic-appetitive, hedonic-consummatory, and aversive avoidance. While there are plenty of studies of nonverbal communication of emotions in humans (the field is called proxemics), linguists, social psychologists, and anthropologists research how the voice, regardless of the meaning of the sounds, correlates with mood and intention.

This research, of which I only skim the surface, is in pursuit of establishing methods that will provide measures of mood that are more accurate than self-report, which is notoriously unreliable in humans due to demand characteristics and the self-conscious nature of the therapeutic encounter. These methods will surely be beneficial to practitioners as the treatment of psychological disorders moves forward towards more accurate and humane procedures.

Professor of Psychology and Neuroscience at Stanford University, Dr. Brian Knutson researches the mechanisms of positive arousal. His work engages with the larger question of how to best model the relationship between brain areas, emotional states, and behavior. He conceives of affect as a form of anticipation that has influence over choice. That is, that the purpose of positive arousal is the phenomenological process generated by physiology that sharpens the perception of possible choices in decision-making.

The Anticipatory Affect Model sharpens these accounts by positing that positive arousal promotes approach, while negative arousal instead promotes avoidance. Taking the late Jaak Panksepp’s notion of "SEEKING" as a starting point, Dr. Knutson pinpoints the contribution of three areas in the brain. The Nucleus Accumbens, known for its role in the mesolimbic reward circuit, seems to be implicated in scaled anticipation, whereas the Anterior Insula, known for its involvement in emotional awareness, seems to be implicated in the anticipation of loss. Finally, the Medial Prefrontal Cortex, known for many roles including somatic marker in the orbitofrontal cortex, seems to be an area where the value of perceived objects is integrated with other inputs concerning the physical state of the animal.

Decision-Making Essential Reads

Cultivating Discernment

Decision Strategies: 4 Steps to Success

Through a series of ingenious methods, including monetary incentive delay and optogenetic tools, Dr. Knutson and his lab build up to a set of experiments that investigate how affect may be more generalizable than cost-benefit analysis. They suggest that appetitive behavior is correlated with low-level activity in the Nucleus Accumbens, and that Prefrontal Cortex glutamate tunes the activity of Dopamine in the region. Furthermore, at the level of connections in the brain, they claim that the connectivity of white matter is a direct reflection of the amount of impulsivity displayed in the animal’s behaviors. Connecting this work to that of Dr. Burgdorf, Dr. Knutson suggests that Delta waves in the Nucleus Accumbens may be caused by Dopamine activity and that the different EEG waveforms are related to switches in the state of the animal.

Interesting issues arise here about how to connect levels of analysis. Dr. Knutson is pursuing a deep analysis which seeks to identify critical components in adjacent levels of studying human behavior, and then to connect them. One concern is how differing resolutions relate to postulating the function of the area; there is also the tangled relation of excitatory and inhibitory neurotransmitter activity. Knutson suggests “neural measures should offer millimeter subcortical spatial resolution as well as second-to-second temporal resolution, while measures of affect should match a similar timescale.”

While the masters of industry would love a reductive story about how activity in one particular part of the brain is directly related to consumer decision-making, it is important to understand the complicated story that surrounds our fundamental drives. In particular, the social and cultural entrainment that occurs across an individual’s lifetime structures her cognitive and emotional interpretation of her perception of the world. A reductionist story about a lever for anticipation or aversion, which is not what either of the rich research reviewed above is suggesting, would be a dangerous ending point.

We are in a world where scientific findings are often stripped of their subtlety and jammed into technological innovations to manipulate people as consumers. And yet, enhancing our understanding of mammalian emotional circuits provides clues as to how to more appropriately treat mood disorders and understand how emotional states determine our decision-making abilities and, ultimately, the quality of our lives. We are lucky that these heirs of Jaak Panksepp are carefully pushing knowledge forward into deep analyses of our mammalian nature.