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. Author manuscript; available in PMC: 2020 Dec 1.
Published in final edited form as: Neurosci Biobehav Rev. 2019 Sep 8;107:229–237. doi: 10.1016/j.neubiorev.2019.09.010

Figure 2. Proposed circuitry of platform-mediated avoidance at different timepoints during the tone.

Figure 2.

A. (Left) Coronal schematics of BA (top) and PL (bottom) inactivations by infusing muscimol (MUS) or saline (SAL), showing location of cannula tips. (Right) Time spent on platform (in 3 sec bins) during the tone revealed that BLA inactivation blocked avoidance in MUS rats (top) across the entire tone compared to SAL controls (rptd meas ANOVA, post hoc Tukey). Data from Bravo-Rivera et al. (2014). PL inactivation significantly impaired in avoidance early, but not late, in the tone (bottom), in MUS rats compared to SAL controls (rptd meas ANOVA, post hoc Tukey). Modified from Diehl et al. (2018). B. (Left) Early during the tone, inhibitory responses are observed in PL neurons (dashed axon), which likely project to inhibitory interneurons in the VS. Inhibitory responses in PL would promote avoidance by disinhibiting the response of VS output neurons to BA inputs. PL neurons also show excitatory responses at platform mounting, which could project to BA neurons and facilitate avoidance. (Right) Late in the tone, as avoidance becomes more urgent, PL disinhibition of VS is maintained and BA excitation of VS increases in response to other inputs (thick axon), thereby over-riding inhibition from PL. Thus, expression of urgent avoidance (when shock is imminent) occurs independently of PL. Grey trace is hypothetical neural activity with black box indicating activity signal during the tone. All data shown as mean ±SEM. *p<0.05. Abbreviations: BA – basal amygdala; BLA – basolateral amygdala; CeA – central nucleus of the amygdala; IL – infralimbic cortex; LA – lateral amygdala; PL – prelimbic cortex; VS – ventral striatum.