Dr. Joni Wallis
Professor Department of Psychology, University of California Berkeley
Professor Helen Wills Neuroscience Institute, University of California Berkeley
PhD in Neuroscience University of Cambridge
Joni's curiosity about the brain first arose from her interest in philosophy. She enjoyed engaging in thought experiments posited by philosophers and writers like Douglas Hofstader. For instance, if you could make an exact copy of yourself, would you be the same person? Would your copy be conscious? She was fascinated by such questions, but frustrated at our inability to rigorously seek answers to them. As an undergraduate student in 1990s England, she sought a way to study neuroscience that combined the more popular approaches of medicine and psychology. She enrolled in a joint honors neuroscience program at the University of Manchester that did just that. She heard lectures on a variety of topics, from Freudian psychoanalysis to the lobster central pattern generator, yet, she noticed that her professors would “hand-wave” their explanations when it came to questions on high-level cognition in the brain. To get closer to answering some of those questions herself, Joni decided to pursue her PhD in neuroscience. Now as a Professor at UC Berkeley, Joni continues to make important contributions to our understanding of the hidden cognitive processes underlying decision-making. For Joni, a PhD felt like an obvious route for getting closer to answering these questions.
Joni's particular interest in high-level cognition led her to the lab of Dr. Angela Roberts at Cambridge University, which was split between the Anatomy and Psychology departments. Angela’s laboratory studies cognition and behavior in marmosets, a small, new-world primate, due to their cognitive abilities and their brain homology with humans, specifically in the prefrontal regions. As Joni contemplated possible thesis projects, Angela gave her a book – Descartes’ Error by António Damásio. This book describes the behaviors of human patients with damage to their orbitofrontal cortex, a sub-region of the prefrontal cortex. These patients had difficulty making decisions, from very important life-altering ones to trivial moment-to-moment ones. Because they took an extraordinarily long time to deliberate over their choices, Damásio thought these patients had trouble “going with their gut feeling.” This fascinated Joni and inspired her to research the role of the orbitofrontal cortex in high-level cognition. For her thesis project, Joni used excitotoxic lesioning to demonstrate that marmosets with lesioned orbitofrontal and lateral prefrontal cortex had difficulty deciding on strategies for reaching for food rewards [1]. Afterwards, Joni wanted to investigate decision making in the orbitofrontal cortex in greater detail, like how groups of neurons contribute to the process. To do so, she would have to learn a new technique: electrophysiology.
Around this time, Joni was fascinated by Dr. Earl Miller’s work in which he investigated whether neurons in the prefrontal cortex responded to the spatial location and identity of objects. Following the advice of Angela and others, Joni began her postdoctoral work in the then-new laboratory of Dr. Earl Miller at the MIT Brain and Cognitive Sciences Department. Joni already had an idea for an experiment when she entered Earl's lab. She wanted to determine whether neurons in the prefrontal cortex of monkeys encode abstract rules during decision-making. In this experiment, monkeys had to report whether two pictures presented in succession were the same or different depending on the current 'rule'. Although Earl doubted that rhesus macaques could learn this task, he encouraged Joni to try it. With the help of a bright monkey that was able to learn the task, Joni found neurons in its prefrontal cortex that displayed different activity depending on which rule was in effect. These neurons were selective for the rule that was in effect, regardless of which sensory cue was used to signify the rule, or which object the monkey remembered [2]. Joni and Earl interpret these as neurons that encode rule information. Throughout her postdoctoral work, Joni recorded from different regions of the prefrontal cortex, while maintaining her focus on the orbitofrontal region, in an effort to better understand how the prefrontal areas encode task-relevant information.
Her success in Earl’s laboratory propelled her to a faculty position at UC Berkeley, where she now runs her own laboratory. She began by investigating the neural representation of value in the orbitofrontal cortex. The first discovery of her lab was that neural firing rates in the orbitofrontal cortex generally reflect the expected values of different options. This finding furthered her desire to understand how neuronal activity contributes to other hidden components of the decision process. She emphasizes that the main difficulty in studying hidden cognitive processes is that they are not directly measurable. At best, we can measure behavior and infer the presence of a cognitive process.
Recently, Joni has observed neural activity that may be indicative of a hidden process underlying decision making [3]. When choosing between two options, monkeys seem to “weigh” the options against each other. Joni’s lab has inferred this “weighing” process from the neural activity patterns they observe in the moments leading up to a decision. For instance, imagine that a subject learns that apples and bananas are both rewarding. The observed neural activity has a specific pattern when the subject anticipates receiving apples, and a different specific pattern when the subject anticipates receiving bananas. But when the subject is trained to choose between apples and bananas, the neural activity alternates between both patterns. Sometimes neural activity alternates back and forth frequently, and sometimes infrequently. When monkeys alternate back and forth frequently before their final decision, they are more likely to choose sub-optimally. Her lab’s discovery of this process is truly fascinating because it allows us to watch the hidden cognitive process of decision making as it unfolds in time. Remarkably, the neural activity pattern seen during suboptimal decision making is reminiscent of the behavior of orbitofrontal patients from Descartes’ Error as they make a trivial decision. For example, when deciding whether to meet on a Wednesday or a Thursday, these patients would deliberate indefinitely until Damásio stopped them.
The biggest challenge Joni has navigated in her scientific journey is also her biggest life challenge: being a transgender woman. Joni describes how her life has changed throughout her process of awareness, coming out, and transitioning with intention. She was perhaps most surprised at how much her personality has bloomed, and is grateful to be able to deepen her understanding of herself. An important figure for Joni was Dr. Ben Barres. “He existed as a transgender person in neuroscience… that was very important for me,” she recalls. This importance stems from a major difficulty that we subject transgender people to – we dismiss their real experiences, or deny their existence.
Joni explains that the process of coming out publicly is newer territory for her, where she could only venture upon feeling relatively safe and stable. Becoming a tenured professor certainly helped her feel that her career would be secure, an option Joni acknowledges that not all transgender people have. Furthermore, the notion of workplace equality for transgender people feels far away for her. “We’re still struggling for basic needs, like using the bathroom,” she reminds me. Despite the long road ahead for transgender people and for society, Joni is moving forward with her very real existence. She is here – making new discoveries in the lab, and within herself.
Learn more about Joni and her lab’s exciting research here.
Listen to Daniela’s interview with Joni below or wherever you get your podcasts!
References:
[1] Wallis, J. D., R. Dias, T. W. Robbins, and A. C. Roberts. 2001. “Dissociable Contributions of the Orbitofrontal and Lateral Prefrontal Cortex of the Marmoset to Performance on a Detour Reaching Task.” The European Journal of Neuroscience 13 (9): 1797–1808. https://doi.org/10.1046/j.0953-816x.2001.01546.x.
[2] Wallis, J. D., K. C. Anderson, and E. K. Miller. 2001. “Single Neurons in Prefrontal Cortex Encode Abstract Rules.” Nature 411 (6840): 953–56. https://doi.org/10.1038/35082081.
[3] Rich, E. L., and J. D. Wallis. 2016. “Decoding Subjective Decisions from Orbitofrontal Cortex.” Nature Neuroscience 19 (7): 973–80. https://doi.org/10.1038/nn.4320.
