Figure 3

Both humans and monkeys follow others’ gazes, a tendency that is reduced in autism. A. Gaze-following, which occurs as early as 3 months of age in humans, promotes the phenomenon of joint visual attention. Image from [59]B. Social gaze enhances neural firing in lateral intraparietal cortex (LIP) during a visual target selection task. Left, LIP neurons in rhesus macaques are sensitive to particular locations in space. Here, the location of one of these so-called “response fields” is depicted for a single LIP neuron. Firing frequencies (hotter colors = higher firing rates, cooler colors = lower firing rates, in spikes per second) are overlaid in the form of a colorimetric map onto the visual scene. This particular neuron fires most when the monkey makes an eye movement to the right part of the monitor. Right, peri-stimulus time histogram of the same neuron firing when the eye movement is preceded by a picture of a monkey looking towards the response field (thick red line) or away from the response field (thick blue line). X-axis denotes time during a single trial, aligned at zero to cue, target, or saccade (eye movement) onset. Y-axis is spikes per second, i.e., the mean firing rate for this neuron. Note the increase in neuronal firing in response to an image of a familiar monkey looking towards the response field. Similar to humans, rhesus macaques exhibit gaze-following tendencies, as evidenced by decreased response times when monkeys saccade towards a target accompanied by a congruent social gaze stimulus. Image reproduced from [51].