Motivation concepts in behavioral neuroscience
Introduction
Motivation has resurged as a topic for behavioral neuroscience. Motivational concepts are becoming widely recognized as needed to help neuroscience models explain more than mere fragments of behavior. Yet, if our motivational concepts are seriously wrong, our quest for closer approximation to brain-behavior truths will be obstructed as much as if we had no concepts at all. We need motivational concepts, and we need the right ones, to properly understand how real brains generate real behavior.
The time seems right to review and evaluate some major concepts of motivation of traditional or contemporary importance in behavioral neuroscience. Eating and drinking motivation will be highlighted here because this collection of journal articles is targeted principally to hunger, thirst, and related ingestive motivation, but the concepts are relevant to a wide range of other motivated behaviors too. This review is not complete and omits many motivational concepts that also deserve consideration. But my hope is to provide an initial assortment that may be useful to students and colleagues in behavioral neuroscience as they continue to evaluate brain systems of motivation in light of new discoveries.
For over 100 years, motivation concepts have been considered necessary, chiefly to understand two features of behavior. First is the variability of an individual's behavior over time in the face of constant stimuli. That is, why do individuals choose to do different things at different times? Internal brain and physiological processes of motivation are especially useful in explaining behavioral variability when the external environment stays constant. Second is the short-term stability and directedness of behavior as an individual seeks to obtain a goal or avoid a threat. That is, why do individuals seek out specific things at particular times? And why do they react as they do to affectively important stimuli encountered on the way? Motivation concepts are aimed at helping us understand these questions. When we combine these concepts with behavioral neuroscience research, we gain a better understanding of both brain and behavior.
Section snippets
Homeostasis and drives
Chief among the concepts of motivation in behavioral neuroscience is homeostasis and drive. Among the oldest in the motivation armamentarium, homeostatic drive concepts continue to underlie the thinking of many behavioral neuroscientists today. Hence, it is fitting that we start with homeostasis and drive. In practice, these concepts have usually been combined into one: homeostatic drive.
Homeostasis means maintaining a stable internal state. The word was coined in 1925 by the physiologist,
Raising the bar for motivation: flexible goals, affective displays
We have seen that drives, triggered by internal depletion cues and directly activating behavioral responses, are one way of conceiving of internal motivational states. But the intervening variable is only the most minimalist concept of motivation. It is relatively impoverished and sterile, leaving out lots of what makes motivation interesting in the psychological sense and lots about how motivation actually works in brain systems. Even a mere hungry fly has motivation in the intervening
Incentive motivation concepts
Incentive motivation concepts rose as drive concepts fell beginning in the 1960s. Several new realizations about brain and motivation, including some already mentioned, led many psychologists and behavioral neuroscientists to reject simple drive and drive-reduction theories. Specific alternative theories were developed in the form of incentive motivation theories [11], [19], [21], [109], [117], [156], [169], [177], [195].
To give you a sense of how these concepts developed in 1970s and 1980s, it
Brain concepts of drive and motivation
Finally, we consider the concepts of functional brain wiring. In behavioral neuroscience, drive and motivation have often been conceived as arising from neural activation of a dedicated brain center or dedicated brain circuit, made up of dedicated brain neurons. A neural substrate is dedicated to its motivation if the neuronal activation of that substrate always produces that particular motivation. Early brain models of motivation typically viewed motivation to be mediated by a particular brain
Conclusion
Motivational concepts are needed to understand the brain, just as brain concepts are needed to understand motivation. Motivation concepts can aid behavioral neuroscience to live up to its potential of providing brain-based explanations of motivated behavior in real life. Without them, neuroscience models would remain oversimplified fragments, removed from the behavioral reality they purport to explain.
Trying to explain how the brain controls motivated behavior without motivational concepts is
Acknowledgements
This article is dedicated to Elliot S. Valenstein, an early scientific role model for me and, later, a long-prized colleague and an influential shaper of several behavioral neuroscience concepts described in this article.
I am grateful to the editors for their invitation to write a review of motivation concepts for this series. I thank Susana Peciña, Jay Schulkin, Elliot S. Valenstein, and anonymous reviewers for helpful comments on an earlier version. I also thank Susana Peciña for help with
References (196)
- et al.
Individual behavioral-responses to hypothalamic-stimulation persist despite destruction of tissue surrounding electrode tip
Physiol. Behav.
(1979) - et al.
Goal-directed instrumental action: contingency and incentive learning and their cortical substrates
Neuropharmacology
(1998) - et al.
Experimental sodium depletion and salt taste in normal human volunteers
Am. J. Clin. Nutr.
(1990) Measuring hedonic impact in animals and infants: microstructure of affective taste reactivity patterns
Neurosci. Biobehav. Rev.
(2000)Pleasures of the brain
Brain Cogn.
(2003)- et al.
Parsing reward
Trends Neurosci.
(2003) - et al.
What is the role of dopamine in reward: hedonic impact, reward learning, or incentive salience?
Brain Res. Rev.
(1998) Multiple neural systems controlling food intake and body weight
Neurosci. Biobehav. Rev.
(2002)- et al.
Conditioned reversal of reactions to normally avoided tastes
Physiol. Behav.
(1990) On the origin of consciousness, a postulate and its corollary
Neurosci. Biobehav. Rev.
(1996)