Successful overshadowing and blocking in hippocampectomized rats

Attention, configuration, and hippocampal function

“…In addition, the model exhibits blocking in normal, HPL, and CL cases. In agreement with Rickert et al (1981), Rickert et al (1978), Solomon (1977), and Gallo and Candido (1995), but not with Garrud et al (1984), the model anticipates that HFL lesions eliminate (not simply attenuate) blocking. Furthermore, this prediction is consistent with data showing that depletion of norepinephrine in the hippocampus following lesions of the dorsal noradrenergic bundle also results in the elimination of blocking (Lorden et al, 1980).…”

“…Figure 4 shows that simulated normal, HPL, and CL cases exhibit overshadowing. Consistent with Rickert et al (1979) and Schmajuk et al (1983), but not with Garrud et al (1984), the model predicts that overshadowing is completely disrupted by HFL lesions. In addition, the model exhibits blocking in normal, HPL, and CL cases.…”

Brain mechanisms for changes in processing of conditioned stimuli in Pavlovian conditioning: Implications for behavior theory

“…The results of several studies have implicated the hippocampus in blocking (Rickert et al, 1978;Solomon, 1977). In a better controlled study, however, Garrud et al (1984) failed to find such an effect. Recently, Mark Baxter examined the effects of MSA/VDB lesions on blocking in our Pavlovian conditioning preparation.…”

“…Many theorists (e.g., Schmajuk & DiCarlo, 1991), and several investigators, have noted that nonspe- cific hippocampal lesions disrupt latent inhibition (e.g., Solomon & Moore, 1975), blocking (e.g., Rickert, Bennet, Lane, & French, 1978;Solomon, 1977) and other examples of reductions in CS associability during conditioning (Kaye & Pearce, 1987), although the data are mixed (e.g., Garrud et al, 1984;Honey & Good, 1993). In this section, I will describe experiments in our labs in which we examined the effects of damage to the hippocampal system on decremental and incremental changes in the associability of CSs.…”

Evidence for dopamine D 1 receptor involvement in the stimulus selection task: overshadowing in the rat

“…Holland 1999;Blaisdell et al 2000), little is known about which neuroanatomical or neurochemical systems are specifically involved in the phenomenon of stimulus selection. Some early studies have shown that lesions to the hippocampus or caudate-putamen do not affect overshadowing in rats (Garrud et al 1984;Mitchell and Hall 1988; but see Schmajuk et al 1983) or in pigeons (Good and MacPhail 1994). However, these studies were carried out with the aim of establishing neuroanatomical function of the hippocampus and did not investigate further hypothetical substrates to overshadowing.…”