Effects of lateral amygdala lesions on the responses to novelty in mice

Influence of dystrophin-gene mutation onmdx mouse behavior. I. Retention deficits at long delays in spontaneous alternation and bar-pressing tasks

“…However, in the free-exploration test, a rapid and pronounced decrease in avoidance responses toward the novel environment was noted in mdx mice. This suggests that mutants had reduced defensive reactions to novel environmental stimuli, compared to controls (Misslin and Ropartz, 1981).…”

“…The apparatus, previously described by Misslin and Ropartz (1981), consisted of an opaque PVC box (30 • 20 X 20 cm) covered with Plexiglas and subdivided into six (10 X 10-cm) exploration units which were all interconnected by small doors. It could be divided in half lengthwise in two compartments (three exploration units each) by closing three temporary partitions.…”

“…The subject was observed in red light (I < 20 lux) for 10 rain. The time spent in the novel compartment, considered as an indication of novelty preference (Misslin and Ropartz, 1981), and the number of approach responses followed by avoidance reactions (attempts) toward the novel compartment were recorded each min using a keyboard connected to a computer system. Interstrain differences were evaluated statistically by a twofactor (strain, time) ANOVA with repeated measures on one factor (time).…”

Neotic preferences in laboratory rodents: Issues, assessment and substrates

“…Lesions to structures in the amygdaloid complex have been shown to increase preferences for novelty in mice in the form of lack of avoidance of a novel location shown by control subjects (Misslin and Ropartz, 1981c), and decreased latencies to approach novel objects (Sargolini et al, 1999). As the amygdala is heavily implicated in the mediation of fear responses (LeDoux, 1995), it seems likely that these effects arose from attenuated fear and thus a reduced neophobic tendency to avoid novel stimuli.…”

Shortcuts for fear in hierarchical visual systems

“…Interestingly, lesions specifically to the subregion of the amygdala that initially receives sensory input (the lateral amygdala; Lanuza et al, 2008) decreases defensiveness to predators (Martinez et al, 2011) and novelty (Misslin and Ropartz, 1981), and impairs the acquisition of conditioned fears (Blair et al, 2005). Thus, we might expect these functions to be the most affected by rapid sensory input to the amygdala via neural shortcuts.…”