Relations between the behavioral syndrome produced by lesions in the septal region of the forebrain and maze learning of the rat.

Abstract

Lesions in the septal region of the forebrain oftein produce a state of hyperirrilability in rats characterized chiefly by an exaggerated startle response lo tactile stimuli applied to the animal's back and intense and aggressive resistance to handling (Brad}' & Nauta, 1953). These behavioral manifestations (septal syndrome) tend to abate over a period of weeks (Brady & Nauta, 1955). The specific ncuroanatomic structures which must be destroyed to produce the septal syndrome have not been clearly specified (Harrison & Lyon). Nor do we understand the behavioral mechanisms which are altered by the lesions. Brady and Nauta (1953) reported that the lesions weakened a conditioned emotional response but had no effect on the acquisition of the CER. Results obtained by Tracy and Harrison suggest that septal lesions abolish lever pressing to escape an avcrsive noise stimulus but do not interfere with acquisition or retention of lever pressing for food reward with the same noise used as a discrimination stimulus (Tracy & Harrison, 1956). On the other hand, King (1958) found that rats with septal lesions learn conditioned avoidance responses in a double-grill box with even greater facility than normal controls. Subsequent lesions in the amygdala abolish the septal syndrome. Hunt (1957) has reported that rats with the septal syndrome are much more sensitive to the behavioral effects of meprobamate, alcohol, and mephenesin than are normal rats or rats with lesions in other parts of the brain.

The Effects of Hippocampal Ablation on the Behavior in the Rat

“…They would also run back and forth in the same alley in an agitated manner. Anologous observations were reported in the rats with septal lesions (Thomas, et al, 1959). Such agitated exploratory behavior of the hippocampus-ablated animals may account for their tendency to make more errors.…”

“…Several other studies indicate that the hyperactivity is often produced in animals which are subjected to bilateral ablation of the brain, e.g., the frontal area of the cortex (Kennard et al, 1941;Ruch et al, 1943), the caudate nucleus (Davis, 1958), the anterior hypothalamus (Maire & Patton, 1954), the septal region (Thomas et al, 1959), the amygdaloid nucleus (Schwartzbaum et al, 1961), and the hippocampus (Kim, 1960). In view of these findings, the question arises as to whether these brain structures are equipotential with regard to general activity.…”

Response suppression and facilitation by aversive stimuli following septal lesions in rats: A review and model

“…Dickinson (1973) found that if a successive go/no-go discrimination, in which septal damage had been shown to produce persistence , was converted into a succ~ssivg o/go discjimi na ti o n with the same st~muh and reinforcement schedules, operated anunals performed at least as efficiently as controls. Perhaps t~e strongest evidence that septal damage does not result m any general learning deficit comes from the similarity of acquisition functions of septal and intact rats in a variety of complex mazes (Thomas , Moore, Harvey, & Hunt, 1959;Ain, Lubar , Moon, & Kulig, 1969) although it should be noted that a deficit in a complex reasoning task has been reported (Stahl & Ellen, 1973). Finally in the rat, at least, septal lesions produce little detectable change in a range of species-specific behavior (Slotnick, 1967;Lubar, Herrman, Moore, & Shouse, 1973) .…”

Garth J. Thomas, Physiological Psychologist: An Appraisal of His Contributions to Memory Research

“…In a series of experimental studies, spanning over 4 decades, Thomas dissected the contribution of anatomical areas and pathways, including the precommissural fornix, septal region, septohippocampal circuitry, mediodorsal thalamus, and prelimbic cortex, to short-term spatial memory, by evaluating the effect of stereotaxic lesions with tests of reinforced alternation in a T-maze [17,18,19,20,21,22]. …”