To study this question, Leber et al. used a training session to encourage observers to search for either a specific feature (e.g., a red item among other colored items) or for a color singleton (e.g., a unique-colored item among uniform items). To determine which attentional set an observer used in the test session, task-irrelevant distractors appeared that would capture attention if they matched the observer's attentional set.
1436 News From the Field observers, making them immune to 40–50 msec, in the same order on al- into adulthood. Zhou and Merzenich the dulling that they would have expe- most every trial. A specific monkey tried to determine whether it is pos- rienced without the brief prior train- might, for example, start at the lower sible to restore cortical dynamics in a ing. By contrast, the observers who left and deploy attention in a clock- developmentally impaired animal with had received three 50-trial practice wise manner. At least, that is what the intensive behavioral training. They blocks showed the same (low) levels monkeys’ reaction times (RTs) indi- compared representations of tempo- of performance on the subsequent cate in this experiment. In this case, ral modulation rates in the primary test blocks as they had during train- the RT is a saccadic latency, mea- auditory cortex of groups of rats. The ing; despite receiving more practice sured by having a monkey fixate on groups had previously been exposed than the other observers, their long- one point and only move his eyes to to structured noise that led to degraded term performance was worse. Note the target once it is found. cortical responses to high-modulation- that sleep appears to be crucial to the The exciting new finding comes rate sounds, except for one control tempering process: Without a night’s from recordings of single cells in the group that had not. In one experimental sleep between 12-trial training blocks frontal eye fields (FEF). If the target group, the rats were trained to identify and a 50-trial test block, performance on one trial falls in the receptive field a train of pulses with a specific repeti- on the test block was poor. of a cell, there is a big burst of activ- tion rate that was presented along with If what we wish to study is the ity in this cell around the time that the pulse trains with various other repeti- sharp-edged visual system that exists animal makes a saccade to that target. tion rates. After 2 months of training at the start of an experiment (as op- Suppose, however, that the target lies (rats were 35 days old at the beginning posed to the one that dulls in response one position clockwise from the pre- of training), the degraded dynamic to a task), perhaps we should consider ferred location, and this monkey likes cortical responses and response syn- running 12-trial training sessions the to move attention in a clockwise direc- chronization were alleviated across night before the real experiment. tion. Then, in a serial account, atten- the range of modulation frequencies Readers interested in pursuing this tion should be deployed to the cell’s targeted in the training phase. Indeed, topic further should see the authors’ preferred location one attentional step the experimental rats’ performance follow-up article, currently in press at before reaching the target; and indeed, was at an above-normal level relative Vision Research. —C.F.C. the FEF neuron shows a burst of ac- to the control rats. These results illus- tivity 40–50 msec before the saccade. trate that intensive behavioral training VISUAL ATTENTION This activity is gone by the time the with developmentally degraded young saccade is generated. If the target is animals leads to the neurological res- Neural Evidence for two steps away from the preferred toration of cortical temporal process- Serial Search location, the cell becomes active two ing capacity. Moreover, the benefits Buschman & Miller (2009). Serial, covert time steps earlier. The neuronal timing were sustained long after the cessation shifts of attention during visual search are re- is very similar to the behavioral timing, of training. —S.G. flected by the frontal eye fields and correlated with population oscillations. Neuron, 63, 386. and analysis of local field potentials suggests that an internal clock may ATTENTIONAL CONTROL In visual search for a target among time deployments of attention every The Persistence of distractors, some targets “pop out,” 40 msec or so. This may be the most grabbing attention immediately re- compelling neural evidence yet for Attentional Set gardless of the number of distractor Leber et al. (in press). Long-term abstract serial deployment of attention at rates learning of attentional set. JEP:HPP. items. For other
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