Showing papers by "Brian Knutson published in 2004"

Incentive-Elicited Brain Activation in Adolescents: Similarities and Differences from Young Adults

Abstract: Brain motivational circuitry in human adolescence is poorly characterized. One theory holds that risky behavior in adolescence results in part from a relatively overactive ventral striatal (VS) motivational circuit that readily energizes approach toward salient appetitive cues. However, other evidence fosters a theory that this circuit is developmentally underactive, in which adolescents approach more robust incentives (such as risk taking or drug experimentation) to recruit this circuitry. To help resolve this, we compared brain activation in 12 adolescents (12-17 years of age) and 12 young adults (22-28 years of age) while they anticipated the opportunity to respond to obtain monetary gains as well as to avoid monetary losses. In both age groups, anticipation of potential gain activated portions of the VS, right insula, dorsal thalamus, and dorsal midbrain, where the magnitude of VS activation was sensitive to gain amount. Notification of gain outcomes (in contrast with missed gains) activated the mesial frontal cortex (mFC). Across all subjects, signal increase in the right nucleus accumbens during anticipation of responding for large gains independently correlated with both age and self-rated excitement about the high gain cue. In direct comparison, adolescents evidenced less recruitment of the right VS and right-extended amygdala while anticipating responding for gains (in contrast with anticipation of nongains) compared with young adults. However, brain activation after gain outcomes did not appreciably differ between age groups. These results suggest that adolescents selectively show reduced recruitment of motivational but not consummatory components of reward-directed behavior.

Behavior. Sweet revenge

Abstract: 20 to 30 minutes to reach a stable state. What do these findings suggest about spatial processing within the hippocampus? One possibility is that CA3 encodes the animal's location with reference to the current environmental context. This would be a useful extension to the coding scheme in the entorhi-nal cortex, where \" place cells \" appear to be relatively immune to changes in the environment (8). The context-dependent representation in CA3 might allow spatial memory to differentiate between different environments and so, for example, allow me to locate my car in the supermarket parking lot without interference from occasions when I parked it at the mall. But what about CA1? Leutgeb et al.'s finding that the pattern of activity in CA3 can change without affecting CA1 activity suggests that the CA1 region responds to direct inputs from the entorhinal cortex rather than to information routed through CA3 (9, 10). But why would CA1 echo the entorhinal representation? One possibility is that CA1 melds information that was not explicitly examined by Leutgeb et al. into the spatial representation. Such information could include nongeometric features of the environment, such as odor or behavioral contingencies, or internal states such as hunger, thirst, or motivation. Alternatively, because remapping is known to take place in this region following manipulations of the spatial relationship between local and distal cues (10), CA1 may help to represent intercue associations. With these questions still waiting to be answered, it will be interesting to see how future studies gradually tease apart the components of the entorhinal-hippocampal memory system. This process will lead to a clearer picture of how neural networks in these regions interact during memory storage and retrieval. Now, where did I leave my keys? Y ou've been waiting in line in traffic for what seems like hours, when a red sports car whips past on the shoulder. Eventually, the sports car creeps back into view—the driver has run out of shoulder and signals to be let in. Instead of giving way, you stare ahead and accelerate, inching dangerously close to the bumper in front of you. After squeezing back the intruder , you can't help but notice a smile creep onto your face. Judges worry, whereas filmmakers delight , in the fact that revenge feels good. Evolutionary theorists argue that such an \" eye-for-an-eye \" strategy makes sense, preventing future damage to one's self or kin (1, 2). …