Effects of striatal lesions on components of choice: Reward discrimination, preference, and relative valuation

2016

eNeuro

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The striatum is a key brain region involved in reward processing. Striatal activity has been linked to encoding reward magnitude and integrating diverse reward outcome information. Recent work has supported the involvement of striatum in the valuation of outcomes. The present work extends this idea by examining striatal activity during dynamic shifts in value that include different levels and directions of magnitude disparity. A novel task was used to produce diverse relative reward effects on a chain of instrumental action. Rats (Rattus norvegicus) were trained to respond to cues associated with specific outcomes varying by food pellet magnitude. Animals were exposed to single-outcome sessions followed by mixed-outcome sessions, and neural activity was compared among identical outcome trials from the different behavioral contexts. Results recording striatal activity show that neural responses to different task elements reflect incentive contrast as well as other relative effects that involve generalization between outcomes or possible influences of outcome variety. The activity that was most prevalent was linked to food consumption and post-food consumption periods. Relative encoding was sensitive to magnitude disparity. A within-session analysis showed strong contrast effects that were dependent upon the outcome received in the immediately preceding trial. Significantly higher numbers of responses were found in ventral striatum linked to relative outcome effects. Our results support the idea that relative value can incorporate diverse relationships, including comparisons from specific individual outcomes to general behavioral contexts. The striatum contains these diverse relative processes, possibly enabling both a higher information yield concerning value shifts and a greater behavioral flexibility.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Striatal Activity and Reward Relativity: Neural Signals Encoding Dynamic Outcome Valuation

Webber

Mankin

2016

eNeuro

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“…To better understand choice behavior and its components, we have developed a novel paradigm that enables an examination of these components of choice together as animals perform in a multiweek series of reward comparisons. The context of choice can make a crucial difference in guiding and maintaining behavior as well as illuminate the roles for different elements of choice (Fisher et al ., ; Suzuki, ; Kim et al ., ; Blanchard & Hayden, ; Ricker et al ., ,b). The diverse components of choice can involve 1) discrimination of reward outcomes that mimics work using mazes and alleyways to examine choice (Hill, ; Logan, ; Cousins & Salamone, ; Kearns & Gomez‐Serrano, ); 2) reward preference typically observed in operant (Marshall & Kirkpatrick, ) and conditioned place preference tasks (i.e., CPP; Knutson et al ., ); and 3) continual updating of relative reward values that can shift appetitive and consummatory behaviors for reward (i.e., incentive contrast; Crespi, , ; Flaherty, ).…”

Section: Introductionmentioning

confidence: 99%

“…Shifts in variable outcomes led to a greater dissociation of choice components with reduced optimal responding in the self‐paced environment. These results suggest that choice may be optimal for one component but not others depending on specific reward comparisons and the type and degree of outcome alterations (Ricker et al ., ,b).…”

Section: Introductionmentioning

confidence: 99%

“…Ricker et al . (,b) examined reward discrimination, preference and incentive contrast by pitting constant and variable reward outcomes against each other and shifting reward magnitude levels among testing weeks. Importantly, the paradigm enabled animals to self‐pace their choices which altered key parameters of seeking (Ricker et al ., ).…”

Section: Introductionmentioning

confidence: 99%

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The effects of ethanol on diverse components of choice in the rat: reward discrimination, preference and relative valuation

McGraw

Zona

2017

Eur J of Neuroscience

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Alcohol consumption impairs judgment and choice. How alcohol alters these crucial processes is primarily unknown. Choice can be fractionated into different components including reward discrimination, preference and relative valuation that can function together or in isolation depending upon diverse factors including choice context. We examined the diverse components and contextual effects by analyzing the effects of alcohol drinking on choice behavior in a task with a reduced level of temporal and spatial constraints. Rats were trained to drink 10% ethanol during 6 weeks of behavior testing using a combined sucrose-fade and two-bottle free-choice procedure. Two different sucrose pellet outcomes (e.g., constant vs. variable) were presented each week to examine the impact of voluntary drinking on reward-based decision-making. Behavioral contexts of single option, free choice and extinction were examined for each outcome set. Comparisons were made between alcohol and control groups and within the alcohol group over time to inspect choice profiles. Between-group results showed alcohol drinking animals expressed altered place preference and modified sucrose reward approach latencies. The within-group profile showed that alcohol drinking animals can express adequate reward discrimination, preference and incentive contrast during free choice. All of these components were significantly reduced during the context of extinction. Control animals were also impacted by extinction but not as severely. The findings point to a need for a greater focus on the context and the diverse components of choice when examining external and internal factors influencing decision-making during alcohol or other substance of abuse exposure.

Translating striatal activity from brain slice to whole animal neurophysiology: A guide for neuroscience research integrating diverse levels of analysis

J of Neuroscience Research

2019

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An important goal of this review is highlighting research in neuroscience as examples of multilevel functional and anatomical analyses addressing basic science issues and applying results to the understanding of diverse disorders. The research of Dr. Michael Levine, a leader in neuroscience, exemplifies this approach by uncovering fundamental properties of basal ganglia function and translating these findings to clinical applications. The review focuses on neurophysiological research connecting results from in vitro and in vivo recordings. A second goal is to utilize these research connections to produce novel, accurate descriptions for corticostriatal processing involved in varied, complex functions. Medium spiny neurons in striatum act as integrators combining input with baseline activity creating motivational “events.” Basic research on corticostriatal synapses is described and links developed to issues with clinical relevance such as inhibitory gating, self‐injurious behavior, and relative reward valuation. Work is highlighted on dopamine–glutamate interactions. Individual medium spiny neurons express both D1 and D2 receptors and encode information in a bivalent manner depending upon the mix of receptors involved. Current work on neurophysiology of reward processing has taken advantage of these basic approaches at the cellular and molecular levels. Future directions in studying physiology of reward processing and action sequencing could profit by incorporating the divergent ways dopamine modulates incoming neurochemical signals. Primary investigators leading research teams should mirror Mike Levine's efforts in “climbing the mountain” of scientific inquiry by performing analyses at different levels of inquiry, integrating the findings, and building comprehensive answers to problems unsolvable without this bold approach.