The Persistence of Attentional Set by ProQuest


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									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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