Article Figures & Data
Figures
- Fig. 1.
Top row, Magnified view (400×) of an ibotenic acid-lesioned and intact amygdala demonstrating a complete loss of neurons with infiltration of glial cells in the lesioned animal. Bottom rows, Coronal sections (magnification 4.5×) through the anteroposterior (topto bottom) extent of the amygdala and anterior hippocampus of a control and AT41 (95.2% amygdala damage). Thefirst column displays an intact left amygdala and thesecond column displays the left amygdala of AT41. Note that AT41 has a complete lesion with tissue shrinkage in the amygdala region with no damage to the hippocampus.
- Fig. 2.
Extent of the lesions displayed on standardized templates from the nine animals with >70% bilateral amygdala lesions that are described in Table 1. In relation to the interaural line, coronal sections are arranged top tobottom from 18.5 to 12.5 mm, anteroposterior.
- Fig. 3.
Effects of >70% lesions (solid bars; n = 6) compared with controls (open bars; n = 10) on the latency to retrieve a treat in the presence of a real snake, fake snake, roll of tape, and nothing. Across all trials, lesioned animals more rapidly retrieved a treat placed above the real snake than did control animals. This effect was also observed in the presence of the fake snake during the first three trials (*p < 0.05; **p < 0.01). No significant differences in retrieval latency between lesioned and control animals were found in response to the roll of tape or nothing.
- Fig. 4.
a, Mean NEC-induced freezing for animals before and after and lesioning. Freezing was not affected by the amygdala lesions (solid bars, n= 9; open bars, controls, n = 10).b, In the entire group of lesioned animals (≤70%; n = 17), the stability of individual differences in NEC-induced freezing was unaffected by the lesions. c, Mean frontal EEG asymmetric electrical activity (log right to log left, 4–8 Hz band) was not changed by amygdala lesions (lesion group, n = 6, solid bars; controls, n = 10, open bars). d, Individual differences in frontal asymmetry remained stable in all animals that received lesions (n = 14).
Tables
Table 1.The total and percent destruction of central (C), lateral (L), basal (B), and accessory basal (AB) nuclei for the nine animals with >70% ibotenic acid lesions. Percentage of destruction for each nucleus is indicated as follows: −, No destruction; +, up to 25%; ++, 26–50%; +++, 51–75%; ++++, 76–100%.
No. of control subjects (n = 10) No. of lesion subjects (n = 6) p < Fear grimace 7 0 0.02 Submit 9 2 0.04 Coo 9 1 0.01 Bark 7 0 0.04 The effects of the amygdala lesions on behaviors expressed in the social threat paradigm are displayed. Significantly fewer subjects in the >70% group engaged in fearful and defensive behaviors in response to the threatening adult male than did controls (n = 10) as determined by Fisher's exact test.
