Schmitzer-Torbert

Academic Positions

  • Present 2016

    Coordinator of Faculty Development

    Wabash College

  • Present 2012

    Associate Professor

    Wabash College, Department of Psychology

  • 2018 2014

    Daniel F. Evans Associate Professor in Social Sciences

    Wabash College

  • 2012 2006

    Assistant Professor

    Wabash College, Department of Psychology

  • 2008 2006

    Byron K. Trippet Assistant Professor

    Wabash College, Department of Psychology

  • 2006 2005

    Visiting Assistant Professor

    Knox College, Department of Psychology

Education & Training

  • Ph.D. 2005

    Ph.D. in Neuroscience

    University of Minnesota

  • B.A.2000

    Bachelor of Arts in Psychology

    Knox College

Current Teaching

  • Fall 2018

    Introduction to Psychology (PSY 101)

    Psychology is broadly defined as "the science of behavior and mental processes, and the application of research findings to the solution of problems." Psychology 101 is an introduction to this vast area of research. Our specific purposes in the course are fivefold: To gain an understanding of scientific investigation and an ability to evaluate psychological research critically. To gain experience in investigating important applied psychological questions. To notice how psychological principles are relevant in our everyday lives. To appreciate the history of psychology and the breadth of current psychological inquiry. To become familiar with major content areas of psychology.

  • Fall 2018

    Research in Behavioral Neuroscience (NSC/PSY 333)

    Students in this course will become involved with research in an area of behavioral neuroscience. The topic covered will reflect contemporary research issues in the field and may differ in different years. Major course components will be discussion of primary literature in neuroscience and collaboration with the professor in conducting and writing up an experiment that is directed toward possible publication. Recent topics have focused on memory and drug addiction, and how neural recordings are used to understand how information is encoded by the brain.

  • Fall 2018

    Literature Review (PSY 301)

    An introduction to the principles of searching for and reporting on published literature in psychology. Students will learn strategies for searching databases, identifying credible sources, and developing a theoretical background on a topic. This course features extensive training and practice in writing APA-style manuscripts, and is intended to prepare students for PSY 495/496, Senior Project.

  • 2017-18

    Senior Capstone (PSY 495/496)

    Students in this two half-course sequence will complete a year-long capstone project intended to integrate the content and skills they have learned in the major and develop expertise in an area of interest. This project will consist of either an empirical study or a community-based practicum. The empirical study will be one that the student plans and carries out with general guidance from a faculty mentor. For the community-based practicum option, students will work with a professional involved in the delivery of psychological services. All projects will culminate in an APA-style manuscript, poster presentation, and a talk at a regional undergraduate research conference.

  • Fall 2018

    Neuroscience Capstone (NSC 400)

    Students will enroll in the fall semester of the senior year and meet with the instructors approximately once every two weeks for journal article discussions focused on seminal publications in neuroscience.

Teaching History

  • Spring 2018

    Fundamentals of Neuroscience (NSC/PSY 104)

    An introduction to the study of the nervous system, with a focus on basic anatomy and physiology. Students will learn about the basic organization of the nervous system, neurophysiology, sensory processing, movement, development, and neuroplasticity through a systems approach to brain function. Several laboratory experiences will be built into the course to reinforce the principles discussed in class.

  • Spring 2018

    Behavioral Neuroscience (PSY 233)

    An introduction to the biological bases of behavior. Examination of nervous system structure and function is followed by an examination of the neurophysiological foundations of motor ability, sexual behavior, ingestive behavior, sleep and arousal, learning and memory, reinforcement, and language.

  • Fall 2017

    Freshman Tutorial: Me, My Self, and My Brain (FRT)

    Imagine you’ve created a machine that is able to make an exact, physical copy of any object. However, the process of making the copy requires that the machine destroys the original. So, if you put your phone in and turn on the machine, the phone is instantly vaporized. But, in another compartment you find an exact duplicate of your device. Such a machine would be quite interesting, but we might imagine that it has little practical value. However, what happens if you step into the machine, and turn it on? You are instantly (and, let’s assume painlessly!) vaporized, and out of the second compartment steps your exact duplicate. Who is this duplicate? Does he think he is you? If he does, then are you actually dead? What if the machine malfunctions and you are not vaporized: are you and your duplicate both “you”? If you then kill your duplicate, was there in fact a murder? What if he kills you? In this class, we will take these types of thought experiments seriously, and use them to look carefully at the problem of self, and what it means to be a person. Through works of science fiction, philosophical thought experiments, and stories about the lives of humans with brain damage, we will try to locate our “I”, our sense of self. We will also look at gender, sexuality and inquire about how these accidental facets impact our personal identity. Finally, we will look beyond our own selves to examine other kinds of persons, such as aliens, artificial intelligences and genetically modified humans, who might share the world with someday. Some of the texts we will read include Brok’s Into the Silent Land, selections from Rorty’s Philosophy and the Mirror of Nature, and a number of science fiction short stories and novels (such as The Mote in God’s Eye and Le Guin’s The Left Hand of Darkness). We will also watch several films in the course, including The Thirteenth Floor and Arrival.

  • Fall 2017

    Human Sexual Behavior (GEN/PSY 102)

    An overview of human sexual anatomy, development, function, and diversity. Emphasis is on the psychological aspects of sexuality including the study of attitudes towards sexuality, sexual preference, love and marriage, contraception, and commercial sex. Particular attention is paid to the development and enactment of sex roles, the construction of gender, and sex differences.

  • Fall 2016

    Research Methods & Statistics I/II (PSY 201/202)

    An introduction to the principles and techniques involved in the design and analysis of psychological research. Development of abilities in quantitative analysis and reasoning, decision-making, and hypothesis testing are aided by conducting behavioral research projects.

  • Fall 2013

    Special Topics: Drugs and Behavior (PSY 210)

    Psychoactive drugs (including alcohol, caffeine, nicotine, and many others) are widely used in many societies in order to manipulate behavior and experience. This course will examine drug use (both legal and illicit) from psychological perspectives ranging from the biological to the social. The main focus will be on the factors which promote the use of a drug, the acute and long term effects of drug use, and cross-cultural differences in patterns of drug use. Of particular interest will be factors that promote drug addiction and the consequences of long term use of addictive drugs

Capstone Research Projects

  • 2017-18

    Nhien 'Nigel' Dao '18

    Diet-induced Obesity Impairs Male Rat Copulation and Dopamine Synthesis in the Medial Preoptic Area

  • Brian Rice '18

    The Effectiveness of Tech Breaks to Protect Working Memory Performance From Cell Phone-Related Distractions

  • 2016-17

    Zack King '17

    The Effects of Race on Eyewitness Identification

  • Andrew Tutsie '17

    Effect of Video Game Addiction and Urge to Game on Working Memory

  • Rory Willats '17

    The Function of Incentivization as Intervention for Collaborative Inhibition

  • 2015-16

    Daniel Bowes '16

    The relationship between stress, mindfulness, and hippocampally-dependent learning strategies

  • Max Gallivan '16

    Cognitive Deficits of Diabetes as a Target of Neuroinflammatory Treatment

  • Matt Gibson '16

    Comparing Affects of Self-Administration and Passive Administration (injection) of Cocaine in a Morris Water Maze

  • Giacomo Visconti '16

    Priming: Does it affect the type of information that we recall from an advertisement?

  • 2014-15

    Adam Boehm '16

    The Effect of Pornography on Attention and Outlook Towards Women in Males

  • Hezekiah Eibert '16

    Cell Phone Dependency: Relationship to Impulsivity and Distraction

  • Ollie Bauer '15, Zack Boston '15 and Brock Smith '15

    Patterns of Habitual Behavior in Control and Cocaine Exposed Rats

  • Austin Hawn '15

    Examining the Mediators of Exercise Addiction: The Motives for Continued Exercise

  • 2013-14

    Joel Beier '14

    An Investigation Into Possible Memory Effects of the Alcohol Hangover State

  • Derrick McQuiston '14

    The Influence of Current Pain on Accuracy of Recalled Pain States Following an Orthopedic Procedure

  • Spencer Peters '14

    Effects of Alcohol Expectation on Impulsivity

  • Josh Stowers '14

    Effect of Direct Infusion of BDNF into the Medial Pre-Frontal Cortex on Habit Learning

  • 2010-11

    Ben Burkett '11

    Senior capstone looking at the effect of sleep on strategies used by humans in virtual navigation.

  • Robert John Karry Jr. '11

    Senior capstone testing if people who have extensive experience with meditation adopt different strategies during virtual navigation.

  • 2009-10

    Robert Ritz '10 and Jordon Blackwell '10

    The Role of the Infralimbic Cortex in the Facilitation of Habit Learning by Cocaine

    Senior capstone testing if damage to the infralimbic cortex or dorsolateral striatum can block the facilitation of habit learning by cocaine in rats.

  • Kyle Hitt '10

    Human Learning in Virtual Environments: Investigation of Place vs. Response Learning Strategies

    Senior capstone testing the effect of working memory load on the use of place- and response-strategies in virtual navigation.

  • 2008-09

    Michael Kaster '09, Michael Nowak '09 and Nathan Powell

    Lesions in The Infralimic Cortex: A look at Goal-Directed vs. Response Learning in Cocaine-facilitated Habits

    Senior capstone testing the ability of cocaine to facilitate habit learning in rats.

  • Andrew Rode '09

    The Effect of Glucose Administration on Place- and Response-strategies in Humans

    Senior capstone looking at the effect of pre-training glucose administration on strategies used by humans in virtual navigation.

  • Artur Banks '09

    Epistemic Confidence, Religious Orientation, and Prejudice

  • JT Moore '09

    Role of Sleep in Place and Response Learning

    Senior capstone looking at the effect of sleep on strategies used by humans in virtual navigation.

Summer Research Interns

  • 2018

    Thach 'Ben' Huynh '20

    Validating a new experiential foraging task.

  • 2017

    Niki Kazahaya '18 and Neil Dittmann '19

    Research internship testing the relationship between trait mindfulness and the use of spatial navigation strategies in humans, and testing an spatial memory task in rats.

  • 2016

    Nhien 'Nigel' Dao '18

    Research internship testing the effectiveness of mindfulness-based stress reduction to increase the use of spatial navigation strategies in adults reporting high levels of stress.

  • 2015

    Adam Rains

    Research internship testing the relationship between trait mindfulness and the use of spatial navigation strategies.

  • 2012

    Josh Stowers '14, Jacob Owens '14 and Romeo Amoa '13

    Research internship testing if cocaine infusion into the infralimbic cortex or dorsolateral striatum can facilitate habit learning in rats.

  • 2011

    Drew Casey '12, Connor O'Rear '14, Josh Stowers '14 and Steven Aposotlidis '12

    Research internship testing if cocaine infusion into the infralimbic cortex can facilitate habit learning in rats.

  • 2010

    Steven Aposotlidis '12, Romeo Amoa'13 and Xumin Sun '13

    Research internship testing if damage to the infralimbic cortex or dorsolateral striatum can block the facilitation of habit learning by cocaine in rats.

  • 2009

    Steven Aposotlidis '12

    Research internship testing if damage to the infralimbic cortex can block the facilitation of habit learning by cocaine in rats.

  • 2007

    Krishna Meibalane '08

    Parks Intern in Psychology. Tested the effects of lesions to the dorsolateral striatum in rat on place- and response-learning in navigation.

Independent Study

  • 2007-08

    David Braitman '09

    Independent study testing the importance of the dorsolateral striatum in place- and response-learning.

  • Fall 2007

    Michael Heighway '08, Chris Brown '08 and Jacob Peerman '09

    Independent study testing humans in a virtual navigation experiment.

  • Fall 2006

    Barron Hewetson '07

    Independent study testing humans in a virtual navigation experiment. Results were presented at the Society for Neuroscience Annual Meeting (San Diego, 2007).

  • Fall 2006

    Paul Heinemann '07

    Independent study training rats in a complex maze.

Filter by type:

Sort by year:

Mindfulness and decision-making: Sunk-costs or escalation of commitment?

Schmitzer-Torbert, N.
Preprint January, 2018

Abstract

Mindfulness is related to a number of positive health outcomes, such as decreased stress, anxiety and improved physical functioning. Recent studies have also identified cognitive benefits of mindfulness, including work by Hafenbrack, Kinias and Barsade (2014) who found that higher trait mindfulness and brief mindfulness inductions significantly improved decision-making, by reducing escalation of commitment to a course of action which has proven to be disadvantageous. Such work demonstrates that beyond well-being, mindfulness may be related to a broader range of cognitive benefits beyond health outcomes. However, while Hafenbrack, Kinias and Barsade proposed that mindfulness may reduce escalation of commitment by reducing the influence of sunk-costs on decision-making, methodological limitations make it difficult to determine if mindfulness is specifically related to sensitivity to the sunk-cost bias. The present study extends previous work by replicating the finding that trait mindfulness is related to reduced escalation of commitment, and by using additional measures of decision-making to test the relationship of mindfulness specifically to the sunk-cost bias. The results replicated previous findings, but suggest that mindfulness is consistently related to reduced escalation of commitment, and that the relationship between trait mindfulness and sunk-costs is weaker and inconsistent.

A low-cost Morris Water Maze for undergraduate research: Construction and demonstration in a rat model of obesity-induced diabetes

Gallivan, L. M.*, & Schmitzer-Torbert, N.
Preprint December, 2017

Abstract

The Morris Water Maze (MWM) is a standard task for assessing hippocampal-dependent learning and memory, but the cost of commercial versions of the task may be prohibitive for some undergraduate research projects. We describe the construction of a low-cost MWM for use with rats, and demonstrate the effectiveness of the MWM in a study of the effect of diet-induced obesity on cognitive function in rats. Previous studies have described an impairment in MWM performance in rats fed a high-fat diet combined with streptozotocin injection (to model Type 2 diabetes). We attempted to replicate this finding, and to test the ability of a novel anti-inflammatory treatment to reduce cognitive deficits in the diabetic model. Across five days of hidden-platform training, rats in all groups (normal pellet diet vs. high-fat diet, vehicle vs. treatment) improved on the water maze at similar rates. On a 30-second probe trial, each group showed a preference for the target quadrant used during training. On the probe trial, rats in the high-fat diet group receiving vehicle injections performed significantly better than rats on a normal pellet diet receiving vehicle injections, or on a high-fat diet receiving treatment. These results did not replicate previous findings that a high-fat diet combined with streptozotocin injections produces deficits in the water maze. However, the results did validate the effectiveness of a low-cost water maze constructed from commonly available materials for hidden platform water maze training, which we expect may be of use to other undergraduate researchers interested in learning and memory.

Post-training cocaine administration facilitates habit learning and requires the infralimbic cortex and dorsolateral striatum

Schmitzer-Torbert, N., Apostolidis, S.*, Amoa, R.*, O’Rear, C. *, Kaster, M.*, Stowers, J.*, Ritz, R.* (2015)
Journal article Neurobiology of Learning and Memory, 118, 105-112

Abstract

Human drug addiction is a complex disorder, in which exogenous substances are able to recruit and maintain behaviors involved in drug taking. Many drugs that are addictive in humans are able to act on natural brain systems for learning and memory, and while many memory systems may be affected by addictive drugs, work with operant tasks has shown that addictive drugs (e.g. cocaine and alcohol) are particularly effective in recruiting habit learning systems, compared to natural rewards. It is currently unknown if the ability of addictive drugs to facilitate habit learning depends on a direct action on habit learning systems in the brain, versus the rewarding properties of drug administration. To differentiate between these options, rats were trained to perform two actions (lever pressing), each of which was rewarded with a different natural reward. After acquiring the behavior, rats received three training sessions which were followed by post-training injections of saline or cocaine (5 or 10 mg/kg, i.p.). Using sensory-specific satiety, extinction tests revealed that lever pressing for actions which were paired with saline were sensitive to devaluation (typical of goal-directed behaviors) while actions which were paired with cocaine were not sensitive to devaluation (typical of habitual behaviors). Lesions of the infralimbic or dorsolateral striatum were able to block the action of post-training cocaine injections. These data indicate that, within individual rats, cocaine injections facilitate the transition of behavior to habitual control for actions that have been recently performed, without a general facilitation of habit learning, and that this action of cocaine requires brain areas that are critical for learning natural habits.

Triple dissociation of information processing in dorsal striatum, ventral striatum, and hippocampus on a learned spatial decision task

van der Meer, M., Schmitzer-Torbert, N.C. and and Redish, A.D. (2010)
Journal article Neuron 67, 25-32

Abstract

Decision-making studies across different domains suggest that decisions can arise from multiple, parallel systems in the brain: a flexible system utilizing action-outcome expectancies, and a more rigid system based on situation-action associations. The hippocampus, ventral striatum and dorsal striatum make unique contributions to each system, but how information processing in each of these structures supports these systems is unknown. Recent work has shown covert representations of future paths in hippocampus, and of future rewards in ventral striatum. We developed new analyses in order to use a comparative methodology and apply the same analyses to all three structures. Covert representations of future paths and reward were both absent from the dorsal striatum. In contrast, dorsal striatum slowly developed situation representations that selectively represented action-rich parts of the task. This triple dissociation suggests that the different roles these structures play are due to differences in information processing mechanisms.

Task-dependent encoding of space and events by striatal neurons is dependent on neural subtype

Schmitzer-Torbert, N.C. and Redish, A.D. (2008)
Journal article Neuroscience, 153(2), 349-60

Abstract

The dorsal striatum plays a critical role in procedural learning and memory. Current models of basal ganglia assume that striatal neurons and circuitry are critical for the execution of overlearned, habitual sequences of action. However, less is known about how the striatum encodes task information that guides the performance of actions in procedural tasks. To explore the striatal encoding of task information, we compared the behavioral correlates of striatal neurons tested in two tasks: a multiple T-maze task in which reward delivery was entirely predictable based on spatial cues (the Multiple-T task), and a task in which rats ran on a rectangular track, but food delivery depended on the distance traveled on the track and was not dependent solely on spatial location (the Take-5 task). Striatal cells recorded on these tasks were divisible into three cell types: phasic-firing neurons (PFNs), tonically firing neurons (TFNs), and high-firing neurons (HFNs) and similar proportions of each cell type were found in each task. However, the behavioral correlates of each cell type were differentially sensitive to the type of task rats were performing. PFNs were responsive to specific task-parameters on each task. TFNs showed reliable burst-and-pause responses following food delivery and other events that were consistent with tonically active neurons (TANs) on the Take-5 (non-spatial) task but not on the Multiple-T (spatial) task. HFNs showed spatial oscillations on the Multiple-T (spatial) task but not the Take-5 (non-spatial) task. Reconstruction of the rats' position on the maze was highly accurate when using striatal ensembles recorded on the Multiple-T (spatial) task, but not when using ensembles recorded on the Take-5 (non-spatial) task. In contrast, reconstruction of time following food delivery was successful in both tasks. The results indicated a strong task dependency of the quality of the spatial, but not the reward-related, striatal representations on these tasks. These results suggest that striatal spatial representations depend on the degree to which spatial task-parameters can be unambiguously associated with goals.

Place- and response-learning in human virtual navigation: Behavioral measures and gender differences

Schmitzer-Torbert, N.C. (2007)
Journal article Behavioral Neuroscience, 121(2), 277-290

Abstract

Two experiments examined the use of place and response strategies by humans navigating virtual multiple T mazes. In Experiment 1, probe trials revealed that participants commonly used place and response strategies, and place strategies were more frequent early in training, whereas response strategies were more frequent late in training. Compared with women, men learned the correct path through the maze more quickly and developed a more stable route through the maze. In Experiment 2, participants were trained to locate 2 targets. One target required participants to use either a place or response strategy, whereas the other target could be found using either strategy. Accuracy improved faster for place training compared with response training, and women outperformed men in both groups. Probe trials testing transfer of the imposed strategy to the other target found faster transfer for place training than for response training and that women demonstrated faster transfer than men. Accuracy on probe trials was correlated with poor route stability in the place-trained group and with good route stability in the response-trained group, indicating that navigation strategy use may be related to measures of improvement in performance on normal trials.

Two quantitative measures for evaluating the quality of extracellularly recorded neurons

Schmitzer-Torbert, N.C., Jackson, J.C., Henze, D., Harris, K., and Redish, A.D. (2005)
Journal article Neuroscience, 131, 1-11

Abstract

While the use of multi-channel electrodes (stereotrodes and tetrodes) has allowed for the simultaneous recording and identification of many neurons, quantitative measures of the quality of neurons in such recordings are lacking. In multi-channel recordings, each spike waveform is discriminated in a high-dimensional space, making traditional measures of unit quality inapplicable. We describe two measures of unit isolation quality, Lratio and Isolation Distance, and evaluate their performance using simulations and tetrode recordings. Both measures quantified how well separated the spikes of one cluster (putative neuron) were from other spikes recorded simultaneously on the same multi-channel electrode. In simulations and tetrode recordings, both Lratio and Isolation Distance discriminated well- and poorly-separated clusters. In data sets from the rodent hippocampus in which neurons were simultaneously recorded intracellularly and extracellularly, values of Isolation Distance and Lratio were related to the correct identification of spikes.

Striatal local field potentials signal initiation of movement in rats

Masimore, B., Schmitzer-Torbert, N.C., Kakalios, J., and Redish, A.D. (2005)
Journal article NeuroReport, 16,(18) 2021-4

Abstract

Transient coherent neural oscillations, as indicated by local field potentials, are thought to underlie key perceptual and cognitive events. We report a transient, state-dependent 50 Hz oscillation recorded from electrodes placed in the striatum of awake, behaving rats. These coherent oscillations, which we term gamma(50), occurred in brief (150 ms) events co-incident with the initiation of movement. On navigation tasks, the animal's speed increased dramatically at the precise moment of the gamma(50) event. This synchronous oscillation may provide a key to understanding striatal function, as well as basal ganglia pathology, which often impairs the control of voluntary movements.

Neuronal activity in the rodent dorsal striatum in sequential navigation: Separation of spatial and reward responses on the multiple T task

Schmitzer-Torbert, N. and Redish, A. D. (2004)
Journal article Journal of Neurophysiology, 91,(5) 2259-72

Abstract

The striatum plays an important role in “habitual” learning and memory and has been hypothesized to implement a reinforcement-learning algorithm to select actions to perform given the current sensory input. Many experimental approaches to striatal activity have made use of temporally structured tasks, which imply that the striatal representation is temporal. To test this assumption, we recorded neurons in the dorsal striatum of rats running a sequential navigation task: the multiple T maze. Rats navigated a sequence of four T maze turns to receive food rewards delivered in two locations. The responses of neurons that fired phasically were examined. Task-responsive phasic neurons were active as rats ran on the maze (maze-responsive) or during reward receipt (reward-responsive). Neither mazenor reward-responsive neurons encoded simple motor commands: maze-responses were not well correlated with the shape of the rat's path and most reward-responsive neurons did not fire at similar rates at both food-delivery sites. Maze-responsive neurons were active at one or more locations on the maze, but these responses did not cluster at spatial landmarks such as turns. Across sessions the activity of maze-responsive neurons was highly correlated when rats ran the same maze. Maze-responses encoded the location of the rat on the maze and imply a spatial representation in the striatum in a task with prominent spatial demands. Maze-responsive and reward-responsive neurons were two separate populations, suggesting a divergence in striatal information processing of navigation and reward.

Development of path-stereotypy in a single day in rats on a multiple-T maze

Schmitzer-Torbert, N. and Redish, A. D. (2002)
Conference Paper Archives Italiennes Biologie, 140,(4) 295-301

Abstract

Humans and animals trained on sequential reaction tasks show decreases in reaction time and increases in anticipatory movements even long after they have ceased to make errors. Humans show these changes even when they do not explicitly recognize that they performed a repeating sequence. We have developed a task which rats learn to perform error-free quickly, but in which they continue to show path-refinement on a single day. This task may enable the study of performance strategy changes occurring within a single day.

Development and validation of a short form of the Concurrent Spatial Discrimination Learning Task to identify early pathology in the hippocampus and entorhinal cortex

Schmitzer-Torbert, N.C., Lee, J.Y., Ducharme, D., Weintraub, S., Mesulam, M.M., Gershon, R.C., and Bohbot, V.D.
Poster (2017). Presented at the Society for Neuroscience Annual Meeting, Washington, D.C., 802.02

Abstract

Aim: Disorders such as Alzheimer’s Disease involve memory deficits and grey matter loss in the hippocampus and entorhinal cortex are predictors of future clinical diagnosis. Early identification of memory deficits is critical for treatment. Our lab has developed a navigation task, the Concurrent Spatial Discrimination Learning Task (CSDLT), to assess the use of hippocampal-dependent memory in healthy adults.

Methods: In the virtual navigation task, participants navigate on a 12-arm radial maze, to find objects hidden at the end of the arms of the maze. The twelve arms are divided into six pairs of adjacent arms, which are presented in a pseudorandom order. In each pair, one arm is rewarded, and participants are trained until they can correctly choose the rewarded arm in each pair. After reaching criterion, participants complete a set of probe trials in which they are presented with a recombined set of adjacent arms, in which the previously rewarded arm is paired with a new unrewarded arm. In the recombined pairs, participants relying on a hippocampal strategy will learn the location of the correct arm relative to distal cues, hence perform well on this probe trial. Participants using non-hippocampal strategies make more errors, tending to choose an arm based on its stimulus-response associations (e.g. “choose the left path”). In this study, we developed a short static version of the CSDLT task, in which participants are presented with images of the pairs of arms, but were not required to navigate in virtual reality to the end of the arm on each trial. Instead, participants click on a button to select the arm displayed on an image. Participants are given feedback whether their choice was correct or incorrect. To validate the short version of the CSDLT task, we tested participants recruited through Amazon’s Mechanical Turk (mTurk) service on an automated version of the original CSDLT task, and the new shortened version.

Results: Participants (n = 35 who completed both tasks) completed the short CSDLT task much faster (M = 7.4 minutes, SD = 4.2) compared to the original CSDLT (M = 18.2, SD = 7.3, t(34) = 8.3, p < 0.0001, d = 1.4). Performance on the probe trials was correlated across the two tasks (r(33) = 0.412, p = 0.014) and a similar relationship was obtained when the short version was administered as the first (r(18) = 0.47, p = 0.036) or second (r(13) = 0.49, p = 0.061) task.

Conclusion: These preliminary data support the use of the shortened CSDLT task to assess an individual’s preference for spatial strategies in navigation. While this task was not validated against MRIs, it may be helpful as a screening tool for an initial rapid assessment in clinics when time is limited, which can be followed by more extensive testing in at risk individuals.

Characterizing spatial and response navigation in rats in a novel maze: Effects of hippocampal lesions.

Kazahaya, N.*, Dittmann, N.*, and Schmitzer-Torbert, N.C.
Poster (2017). Poster presented in the Faculty for Undergraduate Neuroscience Poster Session of the Society for Neuroscience Annual Meeting in Washington, D.C. (in 2017) and at the Midwest/Great Lakes Undergraduate Research Symposium in Neuroscience in Delaware, OH. (in 2016)

Abstract

A previous study by Packard and McGaugh (1996) examined the use of spatial and egocentric navigation strategies by training rats to obtain a food reward in a plus-shaped maze. With one arm closed off to form a T-shaped maze, rats were trained to find food placed in one arm of the T. During the training phase, the rat began and retrieved food from the same locations. On a probe trial, rats were placed in the arm opposite to the starting location. If the rat could accurately locate the reward, it was demonstrating a place strategy. Conversely, if the rat turned in the same direction as it did in the training phase, it was navigating via a response strategy. However, the experimental paradigm used by Packard and McGaugh may have its limitations. When conducting a probe trial in a plus-shaped maze, it is difficult to confirm that animals are relying specifically on either a place or response strategy, as any choice made by the animal, even a random search, counts as a strategy: when approaching the food reward, rats were only able to turn in two directions. As a result, the rats have no other choice than to exhibit either a response or place strategy. In the present study, we introduced a modified maze design that included other areas where the rat could travel during a probe trial, using a symmetrical maze with four starting locations and four goal locations. Using this new maze configuration, we aimed to replicate the findings of Packard and McGaugh. We hypothesized that rats will adopt a place strategy, and transition to a response strategy after extended training. We expected also that two rats with excitotoxic lesions of the hippocampus would show a deficit in the use of a place strategy. We also will examine other behavioral measures (reaction time, latency to reach the food reward, and consistency of the path taken to the reward) to identify other measures (beyond accuracy) that identify the use of place and response strategies. We expect that rats using a place strategy to take significantly longer reaction time, and will take a more variable path to the food reward.

Use of HPC-dependent navigation strategies is associated with low self-reported stress and high trait mindfulness.

Bowes, D.*, Rains, A.*, Konishi, K., Dahmani, L., Bohbot, V.D., and Schmitzer-Torbert, N.C.
Poster (2016). Poster presented at the Society for Neuroscience Annual Meeting in San Diego, CA.

Abstract

Mindfulness training (mindfulness-based stress reduction, MBSR) has been found to be effective in reducing stress and improving cognitive function, and to produce changes in regional grey matter density in brain areas including the hippocampus. Most studies of MBSR’s effects on cognitive function have focused on improvements in attention and working memory, but some studies have found improvements in declarative memory following MBSR training. Other work has shown that even in participants who have not completed mindfulness training, regional grey matter density in the hippocampus is positively associated with measures of dispositional (trait) mindfulness. Here, we investigated if dispositional mindfulness was associated with the use of hippocampally-dependent navigation strategies in a set of virtual navigation tasks. Participants (n = 111) were recruited through Amazon’s Mechanical Turk service after completing the Five Facet Mindfulness Scale (FFM). Participants completed up to four new, automated versions of standard navigation tasks: the 4 on 8 virtual maze (Iaria, Petrides, Dagher, Pike, & Bohbot, 2003), the Concurrent Spatial Discrimination Task (CSDLT, Etchamendy, Konishi, Pike, Marighetto, & Bohbot, 2012), a wayfinding task set in a virtual town and a virtual water maze. Results from the behavioral tasks fit our expectations based on previous research (performance on the wayfinding and water maze task was strongly related, and flexible performance on the CSDLT was associated with better performance on the wayfinding and water maze task). Only the 4 on 8 task was associated with trait mindfulness, with participants who reported using hippocampus-dependent spatial strategies also reporting higher scores on the Describe FFM subscale but not other FFM subscales. In a second study, participants completed the Calgary Symptoms of Stress Inventory (C-SOSI), and participants (n = 96) with high (C-SOSI > 50) and low (C-SOSI < 50) stress scores were recruited to complete the FFM and the 4 on 8 virtual maze. C-SOSI scores were negatively correlated with several FFM subscales, and participants reporting high levels of stress were less likely to use hippocampus-dependent spatial strategies (though, a small number of participants reporting very high scores, C-SOSI > 100, were more likely to use spatial strategies). These data provide some support for the claim that hippocampus-dependent spatial strategies may be associated with both dispositional mindfulness and self-reported stress. Programs which aim to reduce stress by increasing mindfulness (as in MBSR programs) may thus be associated with an increase in the use of hippocampally-dependent navigation strategies.

Pilot test of an online mindfulness-based stress reduction program to improve the use of hippocampal-dependent navigation strategies in individuals reporting high stress levels.

Dao, N.*, Dahmani, L., Konishi, K., Bohbot, V.D. and Schmitzer-Torbert, N.C.
Poster (2016). Poster presented in the Faculty for Undergraduate Neuroscience Poster Session of the Society for Neuroscience Annual Meeting in San Diego, CA.

Abstract

Trait mindfulness is not associated with the greater use of hippocampally-dependent navigation strategies.

Rains, A.*, Dahmani, L., Konishi, K., Ducharme, D., Bohbot, V.D. and Schmitzer-Torbert, N.C.
Poster (2015). Poster presented in the Faculty for Undergraduate Neuroscience Poster Session of the Society for Neuroscience Annual Meeting in Chicago, IL.

Abstract

Assessing navigation performance in virtual environments on mobile devices.

Hong, L.*, Dahmani, L., Bohbot, V.D. and Schmitzer-Torbert, N.C.
Poster (2014). Poster presented at the Society for Neuroscience Annual Meeting, Washington, D.C.

Abstract

Facilitation of habit-learning by post-training infusion of cocaine into the infralimbic cortex.

O’Rear, C.*, Owens, J.*, Stowers, S.*, Amoa, R.* and Schmitzer-Torbert, N.C.
Poster (2013). Poster presented in the Psi Chi section of the Midwestern Psychological Association Annual Meeting in Chicago, IL.

Abstract

Many addictive drugs facilitate release of dopamine in the basal ganglia, and drug addiction may involve the recruitment of brain systems that support habitual behaviors. Work with operant tasks has shown that relative to natural rewards, rats develop habits for actions rewarded with drugs such as cocaine and alcohol. Using post-training injections of cocaine, our lab has shown that cocaine can act directly to facilitate habit learning, and that the infralimbic cortex is required for habit facilitation by cocaine. The present study addressed if cocaine infusion directly into the infralimbic cortex was sufficient for the facilitation of habit learning. Twenty seven Sprague-Dawley rats were implanted with bilateral cannula targeting the infralimbic cortex. Rats were trained after surgery to perform two actions (lever pressing) which were rewarded with either grain or sucrose flavored pellets. After acquiring both lever presses, rats received three training sessions on each lever, rewarded on a random interval 30 second schedule (RI-30s). After each RI-30s training session, rats received infusions of cocaine (200 micograms/microliter) or vehicle. Using sensory-specific satiety, extinction tests revealed that for the lever paired with cocaine infusions, lever pressing was not sensitive to devaluation of the reward while the lever paired with saline injections were sensitive to devaluation. These data suggest that drugs such as cocaine can act directly during memory consolidation in brain areas required for habitual behavior in order to facilitate habit learning.

Facilitation of habit learning by post-training infusion of cocaine into the infralimbic cortex.

Schmitzer-Torbert, N.C., Stowers, J.*, Casey, D.*, O’Rear, C.*, Apostolidis, S.*
Poster (2012). Poster presented at the Society for Neuroscience Annual Meeting, New Orleans, LA.

Abstract

Many addictive drugs facilitate release of dopamine in the basal ganglia, and drug addiction may involve the recruitment of brain systems that support habitual behaviors. Work with operant tasks has shown that relative to natural rewards, rats develop habits for actions rewarded with drugs such as cocaine and alcohol. Using post-training injections of cocaine, our lab has shown that cocaine can act directly to facilitate habit learning, and that the infralimbic cortex is required for habit facilitation by cocaine. The present study addressed if cocaine infusion directly into the infralimbic cortex was sufficient for the facilitation of habit learning. Sixteen Sprague-Dawley rats were implanted with bilateral cannula targeting the infralimbic cortex. Rats were trained after surgery to perform two actions (lever pressing) which were rewarded with either grain or sucrose flavored pellets. After acquiring both lever presses, rats received three training sessions on each lever, rewarded on a random interval 30 second schedule (RI-30s). After each RI-30s training session, rats received infusions of cocaine (200 g/L) or vehicle. Using sensory-specific satiety, extinction tests revealed that for the lever paired with cocaine infusions, lever pressing was not sensitive to devaluation of the reward while the lever paired with saline injections were sensitive to devaluation. These data suggest that drugs such as cocaine can act directly during memory consolidation in brain areas required for habitual behavior in order to facilitate habit learning.

Relationship between individual differences in navigation strategies and addiction vulnerability.

Schmitzer-Torbert, N.C. and MacDonald, A.
Poster (2011). Poster presented at the Society for Neuroscience Annual Meeting, Washington, D.C.

Abstract

Lesions targeting the rat infralimbic cortex and dorsolateral striatum block facilitation of habit learning by post-training cocaine injections.

Apostolidis, S.*, Amoa, R.*, Sun, X.*, Ritz, R.*, Blackwell, J.* and Schmitzer-Torbert, N.C.
Poster (2010). Poster presented at the Society for Neuroscience Annual Meeting, San Diego, CA.

Abstract

This is your rat on drugs: The effect of cocaine on habit learning in rats.

Schmitzer-Torbert, N.C.
Talk (2010) Department of Psychology, DePauw University

Post-training cocaine injections facilitate habitual lever pressing in rats.

Kaster, M.* and Schmitzer-Torbert, N.C.
Poster (2009). Poster presented at the Society for Neuroscience Annual Meeting, Chicago, IL.

Abstract

Effects of dorsolateral striatal lesions on place- and response-learning in a complex maze.

Schmitzer-Torbert, N.C. and Braitman, D.*
Poster (2008). Poster presented at the Society for Neuroscience Annual Meeting, Washington, D.C.

Abstract

Place- and response-learning in human virtual navigation: Sensitivity to training parameters.

Schmitzer-Torbert, N.C. and Hewetson, B.*
Poster (2007). Poster presented at the Society for Neuroscience Annual Meeting, San Diego, CA.

Abstract