Publications

Applied Filters: First Letter Of Title: T Reset
3 Publications

T

Cohen, J. D., Perlstein, W. M., Braver, T. S., Nystrom, L. E., Noll, D., Jonides, J., & Smith, E. E. (1997). Temporal dynamics of brain activation during a working memory task. Nature, 386, 604–608. https://doi.org/10.1038/386604a0
Working memory is responsible for the short-term storage and online manipulation of information necessary for higher cognitive functions, such as language, planning and problem-solving1,2. Traditionally, working memory has been divided into two types of processes: executive control (governing the encoding manipulation and retrieval of information in working memory) and active maintenance (keeping information available online ). It has also been proposed that these two types of processes may be subserved by distinct cortical structures, with the prefrontal cortex housing the executive control processes, and more posterior regions housing the content-specific buffers (for example verbal versus visuospatial) responsible for active maintenance3,4. However, studies in non-human primates suggest that dorsolateral regions of the prefrontal cortex may also be involved in active maintenance5–8. We have used functional magnetic resonance imaging to examine brain activation in human subjects during performance of a working memory task. We used the temporal resolution of this technique to examine the dynamics of regional activation, and to show that prefrontal cortex along with parietal cortex appears to play a role in active maintenance.
Nystrom, L. E., & McClelland, J. L. (1992). Trace synthesis in cued recall. Journal of Memory and Language, 31, 591–614. https://doi.org/10.1016/0749-596x(92)90030-2

Several memory models propose that recall may combine traces of different memories. Such models predict blend errors during cued recall. To examine memory blending during recall, four experiments were performed. In each experiment, subjects rated the plausibility of several sentences, many of which shared words with one other sentence. Later, they were asked to recall words from a single sentence to complete partial-sentence cues. When the cue matched two study sentences, subjects made blend errors, recalling one word from each study sentence more frequently than in a control condition. Blend errors were relatively infrequent, however, occurring on about 5% of opportunities. A good account of the results was provided by a stochastic interactive activation model that causes blend errors by synthesizing traces during retrieval.

Delgado, M. R., Nystrom, L. E., Fissell, K., Noll, D., & Fiez, J. A. (2000). Tracking the Hemodynamic Responses to Reward and Punishment in the Striatum. Journal of Neurophysiology, 84, 3072–3077. https://doi.org/10.1152/jn.2000.84.6.3072
Research suggests that the basal ganglia complex is a major component of the neural circuitry that mediates reward-related processing. However, human studies have not yet characterized the response of the basal ganglia to an isolated reward, as has been done in animals. We developed an event-related functional magnetic resonance imaging paradigm to identify brain areas that are activated after presentation of a reward. Subjects guessed whether the value of a card was higher or lower than the number 5, with monetary rewards as an incentive for correct guesses. They received reward, punishment, or neutral feedback on different trials. Regions in the dorsal and ventral striatum were activated by the paradigm, showing differential responses to reward and punishment. Activation was sustained following a reward feedback, but decreased below baseline following a punishment feedback.