Caution Influences Avoidance and Approach Behaviors Differently

Abstract

While conflict between incompatible goals has well-known effects on actions, in many situations the same action may produce harmful or beneficial consequences during different periods in a nonconflicting manner, e.g., crossing the street during a red or green light. To avoid harm, subjects must be cautious to inhibit the action specifically when it is punished, as in passive avoidance, but act when it is beneficial, as in active avoidance or active approach. In mice of both sexes performing a signaled action to avoid harm or obtain reward, we found that addition of a new rule that punishes the action when it occurs unsignaled delays the timing of the signaled action in an apparent sign of increased caution. Caution depended on task signaling, contingency, and reinforcement type. Interestingly, caution became persistent when the signaled action was avoidance motivated by danger but was only transient when it was approach motivated by reward. Although caution is represented by the activity of neurons in the midbrain, it developed independent of frontal cortex or basal ganglia output circuits. These results indicate that caution disrupts actions in different ways depending on the motivational state and may develop from unforeseen brain circuits.SIGNIFICANCE STATEMENT Actions, such as crossing the street at a light, can have benefits during one light signal (getting somewhere) but can be harmful during a different signal (being run over). Humans must be cautious to cross the street during the period marked by the appropriate signal. In mice performing a signaled action to avoid harm or obtain reward, we found that addition of a new rule that punishes the action when it occurs unsignaled, delays the timing of the signaled action in an apparent sign of increased caution. Caution became persistent when the signaled action was motivated by danger, but not when it was motivated by reward. Moreover, the development of caution did not depend on prototypical frontal cortex circuits.

Keywords: approach; avoidance; basal ganglia; frontal cortex; midbrain.

Figure 1.

Punishing an action when it occurs unsignaled leads to caution about producing the signaled action. A, Performance of signaled active avoidance during two different procedures (AA1 and AA2) that vary only with respect to the consequence of producing ITCs. In AA1, ITCs have no consequence. In AA2, ITCs are punished. Percentage of active avoidance responses (upper), avoidance latency (middle), and ITCs (lower) of a group of mice during AA1 followed by AA2 on consecutive daily sessions. Punishing ITCs virtually abolishes these responses but also delays the timing of the active avoidance latencies with little effect on the percentage of avoidance responses. B, Probability histogram (%) of active avoidance latencies during AA1 and AA2 fitted with an exponential Gaussian. Note the rightward shift of the latencies indicating that the mice delayed their action in a sign of caution. C, Speed traces (mean ± SEM) of active avoidance responses (upper) and escape responses (bottom) during AA1 and AA2 procedures aligned by the CS onset. Escapes are responses driven by the US when mice failed to avoid. Note the faster avoidance responses during AA2 despite starting at a lower baseline. D, Same as C but speed traces are aligned by the response occurrence (crossing into the safe compartment) and baseline speed (before trial onset) is subtracted to show the change in speed (Δ Speed). E, F, Comparison of the peak baseline speed (E) and Δ Speed (F) for avoidance and escape responses during different windows in relation to CS onset. Δ Speed was faster for avoidance response and peaked later during AA2 compared with AA1. G, Avoidance response time onset estimated from the speed traces. Mice begin moving later to avoid in AA2 compared with AA1.

Figure 2.

Punishing the unsignaled action leads to caution about producing the signaled action regardless of the duration of the avoidance interval. A, Performance of signaled active avoidance during three different AA1 procedures in which the avoidance interval lasted 4, 7, or 15 s. Addition of AA2, which punishes ITCs, in any of these procedures caused delayed avoidance latencies, regardless of the duration of the avoidance interval. B, Probability histogram (%) of avoidance latencies during AA1 and AA2 fitted with an exponential Gaussian for the procedures in A. Note the rightward shift of the latencies indicating the mice delayed the signaled action in a sign of caution.

Figure 3.

Random punishment noncontingent to the unsignaled action (Yoked) or signaling the interval when the action is punished does not lead to caution about producing the signaled action. A, Performance of signaled active avoidance during the AA1 procedure followed by Yoked procedures. Yoked mice receive random presentations of punishment (US) during the intertrial interval at the same rate experienced by animals performing AA2, but noncontingent to ITCs. During Yoked, the number of ITCs increased and the signaled avoidance latency was not delayed. Subsequent training in AA2 lead to virtual abolishment of ITCs and a concomitant delay of avoidance latencies. Thus, random punishment does not lead to caution about producing the signaled action. B, Probability histogram (%) of avoidance latencies during AA1, Yoked, and AA2 fitted with an exponential Gaussian. Note the rightward shift of the latencies during AA2 indicating the mice delayed their action in a sign of caution only when the unsignaled action was punished, not when the same amount of punishment was delivered unrelated to the action. C, Performance of signaled active avoidance during AA1 followed by AA3 and AA3rev. AA3 is a discrimination procedure that requires mice to continue active avoidance during presentation of CS1 (8-kHz tone) but crossings are punished during CS2 (4-kHz tone) only, not during the intertrial interval. As in AA1, during AA3 mice must actively avoid during CS1 but passively avoid during CS2 only (not during the whole intertrial period as in AA2). Signaling the period when the action is punished (AA3) did not lead to the development of caution about producing the signaled action. Subsequently, reversal of the tones that signal CS1 and CS2 contingencies (AA3rev) led to the development of strong caution about generating the signaled action. This occurred concomitant with worse performance and a reduction of ITCs, although ITCs are not punished. D, Probability histogram (%) of avoidance latencies during AA1, AA3, and AA3rev fitted with an exponential Gaussian. Note the rightward shift of the latencies during AA3rev indicating the mice delayed their action in a sign of caution only when the meaning of the signaling was reversed.

Figure 4.

Anxiolytics do not abolish action caution. A, Performance of signaled active avoidance during the AA1 and AA2 procedures in mice injected with buspirone (2 mg/kg, i.p.). Training in AA2 led to the usual abolishment of ITCs and a sharp delay in avoidance latencies without impaired performance. Being cautious about producing the signaled action when the unsignaled action is punished is not alleviated by an anxiolytic. B, Probability histogram (%) of avoidance latencies during AA1 and AA2 fitted with an exponential Gaussian for mice injected with buspirone. Note the rightward shift of the latencies indicating the mice delayed their action in a sign of caution. C, Speed traces (mean ± SEM) of active avoidance responses aligned by the CS onset (upper) and baselined-corrected avoidance responses aligned by the response occurrence (bottom) during AA1 and AA2 procedures. Note the faster avoidance responses during AA2 despite starting at a lower baseline. D, Performance of signaled active avoidance during the AA1 and AA2 procedures in mice injected with paroxetine (10 mg/kg, i.p.) or diazepam (1 mg/kg, i.p.). Training in AA2 led to the usual abolishment of ITCs and a sharp delay in avoidance latencies without impaired performance. Being cautious about producing the signaled action when the unsignaled action is punished is not alleviated by two different additional anxiolytics.

Figure 5.

Lesions of the frontal cortex. A, Examples of frontal cortex lesions centered in the frontal association cortex (green volume and lower right) or the medial prefrontal cortex (red volume and upper right; mPFC). The 3D plot (left) overlays the tracings of lesions from two animals (one from each group) on one side of the brain. The 3D reconstruction is shown in Movie 1 (top panel). The colored volumes depict the minimal lesion area for each group because there was always damage extending into the adjacent area. According to atlas nomenclature (Franklin and Paxinos, 2008), the frontal association cortex lesion eliminated FrA and rostral part of M2, while the medial prefrontal cortex lesion eliminated PrL, IL, and the rostral part of Cg1 and Cg2. The x, y, z arrows point in the posterior, dorsal, and lateral directions, respectively, and represent 1 mm. The bottom panels show dark-field images taken from sagittal sections of both lesion types. B, Lesions reconstructed on the atlas for the medial prefrontal cortex (PFC) and frontal association cortex groups. The traced areas show the lesions for all animals in sagittal plane sections at different distances from the midline.

Figure 6.

Lesions of the frontal cortex do not interfere with the development of caution when the unsignaled action is punished. A, B, Performance of signaled active avoidance during the AA1 procedure before and after frontal cortex lesions (with both lesion groups shown in Fig. 5 combined), and subsequent training of lesioned mice in AA2. During AA1, frontal cortex lesions had no effect on the percentage of avoidance responses or avoidance latencies, but increased the number of ITCs. Subsequent training in AA2 led to abolishment of the ITCs and a sharp delay in avoidance latencies without impaired performance. Being cautious about producing the signaled action when the unsignaled action is punished does not require the frontal cortex. C, Probability histogram (%) of avoidance latencies during AA1 and AA2 fitted with an exponential Gaussian for frontal cortex lesion and sham lesion mice. Note the rightward shift of the latencies indicating the mice delayed their action in a sign of caution. D, Speed traces (mean ± SEM) of active avoidance responses aligned by the CS onset (upper) and baselined-corrected avoidance responses aligned by the response occurrence (bottom) during AA1 (prelesion and postlesion) and AA2 procedures. Note the faster avoidance responses during AA2 despite starting at a lower baseline.

Figure 7.

Deactivating the basal ganglia output via the SNr does not interfere with the development of caution when the unsignaled action is punished. A, Performance of signaled active avoidance during the AA1 and AA2 procedures when SNr GABAergic neurons are inhibited during the avoidance interval and a period preceding it. The data are taken from Hormigo et al. (2021b), which did not consider avoidance latencies. Training in AA2 led to abolishment of the ITCs and a sharp delay in avoidance latencies without impaired performance indicating that basal ganglia output via SNr is not required for being cautious about producing the signaled action. A No opsin group of mice that underwent the same optogenetic procedures but did not express Arch is included for comparison. B, Probability histogram (%) of avoidance latencies during AA1 and AA2 fitted with an exponential Gaussian for the data in A. Note the rightward shift of the latencies indicating the mice delayed their action in a sign of caution in both the Opsin and No Opsin groups.

Figure 8.

When the signaled action is an active approach, punishing the unsignaled action leads only to transient caution about producing the signaled action. A, Performance of signaled active approach (AR1) to obtain water (reward) in water-restricted mice. The task is similar to AA1 but mice shuttle during the CS presentation (approach interval) to obtain water instead of avoiding the US. Subsequent training in AR2, which punishes ITCs, led only to brief caution about producing the signaled action (initial 1–4 AA2 sessions; blue) but thereafter (5–10 AA2 sessions; red) caution was not evident in response timing. B, Probability histogram (%) of approach latencies during AA1 and AA2 fitted with an exponential Gaussian. Note the slight rightward shift of the latencies during the initial one to four sessions but subsequently (5–10 sessions) latencies shift left producing a sharp short-latency peak. During AR2, when the action is an approach, mice only display caution transiently. C, Speed traces (mean ± SEM) of active approach responses aligned by the CS onset (left) and baseline-corrected approach responses aligned by the response occurrence (right) during AR1 and AR2 procedures.

Figure 9.

When the signaled action is both an active approach and an active avoidance, mice behave as they are performing active approach. Punishing the unsignaled action leads only to transient caution about producing the signaled action. A, Performance of a combined signaled active approach and active avoidance (AA1+AR1) in water-restricted mice. Subsequent training in AA2+AR2, which punishes ITCs, led only to brief caution about producing the signaled action (initial 1–4 AA2 sessions; blue), but thereafter (5–10 AA2 sessions; red) caution was not evident in response timing. B, Probability histogram (%) of avoidance latencies during AA1+AR1 and AA2+AR2 fitted with an exponential Gaussian. Note the slight rightward shift of the latencies during the initial one to four sessions but subsequently (5–10 sessions) latencies shift left producing a sharp short-latency peak. During AA2+AR2, mice behave as if they are only performing AR2 and only display caution transiently. C, Speed traces (mean ± SEM) of active approach responses aligned by the CS onset (left) and baselined-corrected responses aligned by the response occurrence (right) during AA1+AR1 and AA2+AR2 procedures.

Figure 10.

Comparison of signaled active avoidance and approach responses. A, Probability histogram (%) of response latencies for two groups of mice fitted with an exponential Gaussian. One group performed AR1 and AR2 (proper), the other group performed AA1 and AA2. B, Mean speed traces for the data in A aligned by the CS onset (left) or by the response occurrence (right; baselined-corrected).