Figure 8.

(A) Body posture upon a pistol shot illustrating the startle response pattern (from Landis and Hunt 1939) initially described as “Zusammenschrecken” by Strauss (1929). Together with the immediate, brief concomitant closure of the eyes, startle serves to protect from imminent threat and to prepare the subject for fight-or-flight behavior. (B) Magnetic resonance image of a human brain, coronal slice. (C) Experimental setup for relief- and punishment-learning in humans. The subject faces a computer monitor (not shown) on which visual stimuli can be displayed. During training mild electric shock punishment can be delivered to the left forearm. During the test, a loud noise can be delivered through the earphones to induce the startle response while the subjects watch the screen on which visual stimuli are displayed. Measurement electrodes (blue) record the eye-closure component of the startle response via electromyography (EMG) from the musculus orbicularis oculi. (D) Sketch of the sequence of events for relief- or punishment-learning, using a between-group design. During training, in both groups a control stimulus (e.g., a triangle) is presented temporally removed from shock. In the relief-learning group, a second geometrical stimulus (e.g., a circle) is presented upon cessation of shock (ISI = 6 sec). During the test the startle amplitude, evoked by a loud noise from the earphones and measured by the eye-EMG, is less when subjects are viewing the relief-trained than when viewing the control stimulus. In contrast, in the punishment-learning group the second stimulus (e.g., a square) is presented before shock (ISI = −8 sec). During the test the startle amplitude is higher when subjects are viewing the punishment-trained than when viewing the control stimulus. Note that the experimental role of the geometrical shapes is counterbalanced across subjects. (E) Experimental data showing relief- or punishment-memory, dependent on the relative timing of the visual stimulus and shock during training. As in Figure 6, positive conditioned valence (“Good”) is plotted toward the top of the y-axis indicating the degree of startle attenuation; in turn, startle potentiation is plotted toward the bottom of the y-axis in order to display negative conditioned valence (“Bad”) toward the bottom. The sign of the startle modulation is presented as, respectively, negative or positive, because the actual behavior of the subjects consists of less or more startle, respectively. Box plots show the median as the bold middle line, and the 25%/75% and 10%/90% quantiles as box boundaries and whiskers, respectively. Data taken from Andreatta et al. 2010, sample sizes are N = 34 and N = 33 for the punishment- and the relief-learning groups, respectively. (F) After punishment-learning, the learned visual stimulus induces activation of the right amygdala (left panel), but not of the striatum. In contrast, a relief-conditioned visual stimulus induces activation of the right striatum (right panel), but not of the amygdala; striatum activation extends to the ventral striatum/nucleus accumbens. Both the punishment- and the relief-conditioned stimulus induce activation of the left insula as well (not shown). From Andreatta et al. (2012), sample sizes are N = 14 for both the punishment- and the relief-learning groups.