Department of Psychology
1202 West Johnson Street
University of Wisconsin
Madison, WI 53706
Tel: (608) 262-9945
Topics of Interest
Sparse modeling of auditory receptive fieldsWe have recently shown that Spectro-Temporal Receptive Fields (STRFs) can be estimated from both multi-neuron clusters and high-gamma power responses in human auditory cortex. Traditional methods for estimating STRFs from single-unit recordings, such as spike-triggered-averages, tend to be noisy and are less robust to other response signals such as local field potentials. We use generalized linear models (GLM) and regularization that penalizes non-zero coefficients, which results in a sparse solution to the GLM. We have shown that the frequency-time structure of the STRF tends toward grouping in different regions of frequency-time and we have demonstrated that group sparsity-inducing penalties applied to GLM estimates of STRFs reduces the background noise while preserving the complex internal structure. We used this approach to identify an abrupt change in the best frequency of estimated STRFs along posteromedial-to-anterolateral recording locations along the long axis of Heschl’s gyrus. This change correlates well with a proposed transition from core to non-core auditory fields in humans.
Humans are faced every day with economic decisions that involve choosing between different alternatives. Should I invest in stocks versus bonds today? A critical question is where in the brain is value computed? This is a fundamental question posed in Neuroeconomics. Neuroeconomics is a relatively new field whose goal is to bridge brain neuroscience with behavioral economics and decision-making. To answer questions related to simple choice we have been recording intracranially from patients undergoing study for medically intractable epilepsy. These patients are actively engaged in cognitively demanding tasks, and provide the opportunity to study the neural correlates of decision-making. A number of areas of the brain compute different forms of value, and our particular focus has been on the amygdala and orbitofrontal cortex (OFC). Point-process models are developed to track the dynamics of the evolving value signal in single-unit and multi-unit activity.
Information flow between the human amygdala and OFC
There is a consensus that value signals computed in the OFC and amygdala play a critical role in the choice process. What is the nature and direction of the flow of information between OFC and amygdala at the time of decision-making? In order to study this question, we simultaneous record local field potentials from OFC and amygdala in human patients while they perform a simple food choice task. Although the interaction of these circuits has been studied in animals, these studies examine the effective connectivity directly in the human brain on a moment-by-moment basis. We apply spectral conditional Granger causality analysis to test the direction of information flow. We have observed that influence from amygdala-to-OFC is dominant prior to the revealed choice, with a small but significant OFC influence on the amygdala earlier in the trial. Alpha band oscillation amplitudes analyzed with the Hilbert-Huang transform reveal differences in choice valence coincident with temporally specific amygdala influence on the OFC.
Effects of methylphenidate (MPH) on decision-making
Impulsivity, a cardinal symptom of ADHD, has been linked to alterations within the dopamine system, and treated predominantly with psychostimulants that alter dopamine neurotransmission. Decision-making is often based on selecting what is thought to be the most rewarding option. However, when faced with a choice between a small but immediate reward and a larger but more delayed reward, humans and animals tend to prefer the smaller reward if the difference in magnitude is sufficiently small or if the delay to receive the larger reward is too long. This seemingly irrational choice is thought to be the result of the subjective value of the larger reward decaying as a function of delay, a process known as temporal discounting. We have modeled the effects of psychostimulants on inter-temporal choice using logistic probability models and hyperbolic discounting functions. Under control conditions the probability of choosing the smaller-sooner (SS) reward becomes larger when the magnitude of the SS reward increases and the delay of the larger-longer (LL) reward becomes longer. Generally, as the dose of MPH increases, the probability of choosing the SS reward decreases reflecting a decrease in impulsivity. Increasing the dose further may also result in an increase in choosing randomly. We hypothesize that MPH may reduce temporal discounting and impulsivity by increasing dopamine levels in the striatum and prefrontal cortex.
UW2020: Building a Next Generation, Whole Brain Imaging Platform Using Simultaneous PET, fMRI, Behavioral Pharmacology, and Mathematical Modeling of Decision Making
- Jenison R.L., Reale R.A., Armstrong A.L., Oya H., Kawasaki H. and Howard III M.A. (2015) Sparse Spectro-temporal Receptive fields based on Multi-unit and High-gamma responses in Human Auditory Cortex, PLoS ONE, e0137915. doi:10.1371/ journal.pone.0137915
- Rajala A.Z., Jenison R.L., and Populin L.C. (2015) Decision making: effects of methylphenidate on temporal discounting in nonhuman primates, Journal of Neurophysiology 114: 70-79.
- Jenison R. L. (2014) Directional Influence between the Human Amygdala and Orbitofrontal Cortex at the Time of Decision-Making. PLoS ONE 9(10): e109689. doi:10.1371/journal.pone.0109689
- Kovach C.K., Sutterer M.J., Rushia S.N., Teriakidis A., and Jenison R.L. (2014) Two Systems drive attention to rewards. Frontiers in Decision Neuroscience 5:46. doi: 10.3389/fpsyg.2014.00046
- Nourski, K.V., Brugge, J.F., Reale, R.A., Kovach, C.K., Oya, H., Kawasak, H., Jenison, R.L., and Howard, M.A. (2013) Coding of repetitive transients by auditory cortex on posterolateral superior temporal gyrus in humans: an intracranial electrophysiology study. Journal of Neurophysiology 109: 1283-1295.
- Devilbiss D.M., Jenison R.L., Berridge C.W. (2012) Stress-Induced Impairment of a Working Memory Task: Role of Spiking Rate and Spiking History Predicted Discharge. PLoS Comput Biol 8(9): e1002681. doi:10.1371/journal.pcbi.1002681
- Alexander J.M., Jenison R.L. and Kluender K.R. (2011) Real-Time Contrast Enhancement to Improve Speech Recognition. PLoS ONE 6(9): e24630. doi:10.1371/journal.pone.0024630
- Jenison R. L., Rangel A., Oya H., Kawasaki H, Howard MA (2011) Value encoding in single neurons in the human amygdala during decision making, , Supplement, Journal of Neuroscience, 31, 331-338.
Courses Recently Taught
PSY210 - Basic Statistics
PSY411 - Neuroeconomics
PSY733 - Statistical Analysis of Neural Data