Reactivity in the hippocampectomized gerbil

Some effects of hippocampal lesions on the behavior of mongolian gerbils

“…This argues against a simple responseperseveration view of the hippocampal lesion effect. Rather, as Douglas [4] has observed, such shifts could be explained in terms of some kind of sensory gating mechanism which results in hippocampectomized animals overreacting to some stimuli [8] and underreacting to others [16,17,27]. This could also be compatible with the elevated non-decremental response to the open field situation and with the relatively reduced response to novel stimulus objects observed in the present study.…”

“…These were either restricted to the dorsal neocortex overlying the hippocampus, or included both neocortex and as much of the underlying hippocampus as Could be practically removed. These procedures have been described in detail as they apply to the rat [12] and a similar technique has been used with the gerbil both in the present study and in a previous publication [8].…”

Deficient go, no-go brightness discrimination in rats following hippocampal lesions

“…Hippocampally lesioned animals are less distracted than controls by the introduction of novel stimuli which have a visual component (Wickelgren & Isaacson, 1963;Raphelson et al, 1965). Ireland and Isaacson (1968) found that low-intensity visual or auditory stimulation produced a diminished behavioral reaction while more intense stimulation produced exaggerated reactions in hippocampally damaged gerbils. It is likely, therefore, that the intensity of stimulation is of critical importance for the lesioned Ss, and, though the hippocampally lesioned animals failed to use the visual signals of the operant chamber, they may have been able to do so if the lights had been more intense, had flickered, been in different positions, or in some other way been more attention-provoking.…”

The hippocampus and motivation.

“…While it is not possible to know the extent to which the increases in activity described above may be the result of increases in reactivity, there have been several studies designed to look specifically at how animals with hippocampal lesions react to external stimuli. Hippocampal lesions do not result in increases in reactivity to presentation of either photic (Green et al, 1967;Kaplan, 1968) or auditory (Gotsick, 1969) stimuli unless the stimulation is intense (see Ireland & Isaacson, 1968). Kamback (1967) found slower habituation in hippocampals bar pressing for stimulus change under both ad-lib and food deprivation conditions.…”