Inescapable shock increases finickiness about drinking quinine-adulterated water in rats

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Rats were selectively bred for high versus low saccharin ingestion, a putative measure of enhanced stress and emotionality (Dess, 1991). In Experiment 1, third-generation Occidental highsaccharin (HiS) and low-saccharin (LoS) rats were tested for saccharin ingestion and emotionality. The saccharin test confirmed that the lines differed on the selection phenotype. In addition, LoS rats were more emotional, as evidenced by longer emergence latencies and more defecation in a modified open-field test. In Experiment 2, LoS rats had lower quinine preference scores and drank saccharin-adulterated glucose less avidly. These outcomes are reminiscent of the behavior shown by inescapably shocked rats. Unlike helpless rats, however, LoS rats drank less avidly during a dilute sucrose test, an effect more reminiscent of chronic mild stress. The lines did not differ reliably on intake of concentrated glucose or Polycose, even when the latter was mixed with saccharin. In Experiment 3, LoS rats preferred saccharin less strongly than did HiS rats at concentrations of 0.05% to 0.7%and had an aversion to a 1.0% solution. In Experiment 4, LoS rats were affected more by shock, as assessed by stress-induced anorexia. These and other recent findings support the notion of shared mechanisms for taste, emotionality, and stress vulnerability.Ingestion interacts extensively with affective processes, such as fear and distress (Dess, 1991). For instance, exposure to intermittent electric shock alters the distribution of meals and eating rate in a manner suggestive of

Section: Methodsmentioning

confidence: 88%

Taste and emotionality in rats selectively bred for high versus low saccharin intake

Dess

Minor

1996

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“…The shock parameters used in Experiment 2 reliably produce a variety of disorders that are characteristic of helplessness in rats (Dess, Chapman, & Minor, 1988;Haracz, Minor, Wilkins, & Zimmermann, 1988;Minor, Jackson, & Maier, 1984;Minor & LoLordo, 1984). If the ability to control shock reduces the level of fear conditioned to the pretreatment odor, then escapably shocked rats should show faster acquisition of drinking (less overall suppression) than do inescapably shocked rats when that odor is presented in a novel test context.…”

Section: Methodsmentioning

confidence: 99%

Conditioned fear and neophobia following inescapable shock

Minor¹

1990

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Lick-suppression tests were used in seven experiments to assess the transsituational transfer of fear in the learned helplessness paradigm. Two sources of fear combined to suppress test drinking in inescapably shocked rats. A situational odor was strongly associated with shock pretreatments and mediated the transfer of conditioned fear during testing. Fear of the pretreatment odor was greater following inescapable shock than after escapable shock or restraint. This conditioned suppression was retained for at least 72 h after pretreatment. Neophobia was enhanced as a second, nonassociative reaction to inescapable shock. Unconditioned fear was augmented by a novel odor in the test context, but otherwise was weak and dissipated within 72 h. However, neophobia was necessary for differential conditioned suppression in inescapably shocked rats. The pretreatment odor elicited fear only when tested in a novel context. Initial habituation to the test apparatus reduced conditioned fear. These data provide additional evidence for odor-mediated transfer of helplessness. Conditioned fear and neophobia are discussed in relation to recent anxiety interpretations of the phenomenon.

“…Sonoda (1990) also found the interfering effects of exposure to inescapable shocks on an appetitive barpress discrimination task. However, some experiments have yielded a possible alternative to appetitive helplessness (e.g., Dess, Chapman, & Minor, 1988).…”

mentioning

confidence: 99%

Loss of controllability in appetitive situations interferes with subsequent learning in aversive situations

Sonoda

Okayasu

Hirai

1991

In two experiments, we examined whether or not a loss of control over food availability would interfere with subsequent two-way shuttle-escape learning. Rats that had experienced loss of control over food delivery were impaired in their acquisition of a shuttle-escape response, relative to the response-contingent and the continuous-reinforcement control rats (in Experiments 1 and 2) and to the lack-of-control and home cage control rats (in Experiment 2). Rats that had received noncontingent food delivery without a prior history of control over food exhibited poorer performance than did the home cage control rats. Moreover, loss of control resulted in a larger interference effect than did lack of control, supporting the view that the learning of response-outcome noncontingency is the main determinant of the interference effect.