Visual selection: Neurons that make up their minds R.H.S Carpenter  Current Biology  Volume 9, Issue 16, Pages R595-R598 (August 1999) DOI: 10.1016/S0960-9822(99)80382-0

Figure 1 Activity of a neuron in frontal cortex during a movement discrimination task. The monkey fixated a spot (blue, at top) while above it a pattern of moving dots was presented. The pattern was extinguished, and after a delay the monkey made a saccade to one of the targets (red) on the right or left, depending on whether it judged the motion to be to the right or left. During the trial the activity of a saccade-related neuron with a movement field (pink) that included one of the two targets was recorded. The difficulty of the task could be altered by specifying the percentage of dots moving in the required direction, rather than simply moving at random: these percentages are shown at the left. In each row across, the shaded area represents the period during which the motion was presented, and the vertical green line represents the time of the saccade. Each line of black ticks represents the pattern of action potentials recorded during one trial. On the left, trials in which the saccade was made into the response field (RF) of the neuron being recorded; on the right, trials in which the saccade went the other way. (Data from [7].) Current Biology 1999 9, R595-R598DOI: (10.1016/S0960-9822(99)80382-0)

Figure 2 Activity of a frontal eye field neuron in a different discrimination task. The monkey initially fixated a central spot (red). Then four different targets were presented, being all possible combinations of two different shapes and two different colours: the monkey had been trained to make a saccade to one of them, in this case a black cross. At the right, the individual lines of dots show the pattern of action potentials in each of a number of trials, the rows being sorted according to saccadic reaction time (the time of the saccade is shown by the green segments forming the S-shaped curve). The four sets of data correspond to the presentation of each of the four possible targets within the cell's receptive field (pink). Below, the average activity for trials is shown on the same time-scale, for each of the four cases. Activity rises similarly in each case, but falls off subsequently to a degree that depends on the degree of similarity between the target and the stimulus actually presented. (Adapted from [8].) Current Biology 1999 9, R595-R598DOI: (10.1016/S0960-9822(99)80382-0)

Figure 3 Accumulation of information by frontal neurons. The six lines plot the probability of correctly predicting the final saccade direction from averaged neuronal activity at different times after the onset of the motion (shaded area), for the six levels of difficulty of discrimination shown at the right: the numbers have the same meaning as in Figure 1. The easier the discrimination, the more rapidly this probability rises at the onset. (Adapted from [7]). Current Biology 1999 9, R595-R598DOI: (10.1016/S0960-9822(99)80382-0)