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Trace Eyeblink Conditioning in Mice Is Dependent upon the Dorsal Medial Prefrontal Cortex, Cerebellum, and Amygdala: Behavioral Characterization and Functional Circuitry(1,2,3).

Siegel JJ, Taylor W, Gray R, Kalmbach B, Zemelman BV, Desai NS, Johnston D, Chitwood RA - eNeuro (2015)

Bottom Line: To identify the circuitry involved, we made restricted lesions of the medial prefrontal cortex (mPFC) and found that learning was prevented.Anatomical data from these critical regions showed that mPFC and amygdala both project to the rostral basilar pons and overlap with eyelid-associated pontocerebellar neurons.The data further reveal a specific role for the amygdala as providing a conditioned stimulus-associated input to the cerebellum.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Learning and Memory, University of Texas at Austin , Austin, Texas 78712.

ABSTRACT
Trace eyeblink conditioning is useful for studying the interaction of multiple brain areas in learning and memory. The goal of the current work was to determine whether trace eyeblink conditioning could be established in a mouse model in the absence of elicited startle responses and the brain circuitry that supports this learning. We show here that mice can acquire trace conditioned responses (tCRs) devoid of startle while head-restrained and permitted to freely run on a wheel. Most mice (75%) could learn with a trace interval of 250 ms. Because tCRs were not contaminated with startle-associated components, we were able to document the development and timing of tCRs in mice, as well as their long-term retention (at 7 and 14 d) and flexible expression (extinction and reacquisition). To identify the circuitry involved, we made restricted lesions of the medial prefrontal cortex (mPFC) and found that learning was prevented. Furthermore, inactivation of the cerebellum with muscimol completely abolished tCRs, demonstrating that learned responses were driven by the cerebellum. Finally, inactivation of the mPFC and amygdala in trained animals nearly abolished tCRs. Anatomical data from these critical regions showed that mPFC and amygdala both project to the rostral basilar pons and overlap with eyelid-associated pontocerebellar neurons. The data provide the first report of trace eyeblink conditioning in mice in which tCRs were driven by the cerebellum and required a localized region of mPFC for acquisition. The data further reveal a specific role for the amygdala as providing a conditioned stimulus-associated input to the cerebellum.

No MeSH data available.


Related in: MedlinePlus

Trained mice receiving a 7 (n = 10) or 14 d (n = 4) break in training showed long-term memory for the task. A, Asymptotic (Prebreak) CR rates and postbreak performance for mice that received a 7 (left) or 14 d (right) break in training (shown separately but analyzed together). Red markers indicate median observed each day. Mice showed a significant decrease in performance during the first postbreak sessions (paired t = 5.69, df = 13, p < 0.001), which recovered with additional training sessions (t = 1.02, p = 0.33). B, Example sessions from two mice before (Prebreak) and after (Postbreak) training breaks. Note that mice showed CRs early in the first postbreak session, even when overall performance was low (top), suggesting that mice remembered rather than quickly relearned the task. C, Similar to CR rate, CR amplitude decreased between prebreak and postbreak sessions (t = 3.99, p = 0.001), which recovered with additional training (t = 0.25, p = 0.81). D, In contrast, the appropriate timing for the task (latency to CR peak) was conserved between prebreak and postbreak sessions (t = 0.69, p = 0.51).
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Figure 4: Trained mice receiving a 7 (n = 10) or 14 d (n = 4) break in training showed long-term memory for the task. A, Asymptotic (Prebreak) CR rates and postbreak performance for mice that received a 7 (left) or 14 d (right) break in training (shown separately but analyzed together). Red markers indicate median observed each day. Mice showed a significant decrease in performance during the first postbreak sessions (paired t = 5.69, df = 13, p < 0.001), which recovered with additional training sessions (t = 1.02, p = 0.33). B, Example sessions from two mice before (Prebreak) and after (Postbreak) training breaks. Note that mice showed CRs early in the first postbreak session, even when overall performance was low (top), suggesting that mice remembered rather than quickly relearned the task. C, Similar to CR rate, CR amplitude decreased between prebreak and postbreak sessions (t = 3.99, p = 0.001), which recovered with additional training (t = 0.25, p = 0.81). D, In contrast, the appropriate timing for the task (latency to CR peak) was conserved between prebreak and postbreak sessions (t = 0.69, p = 0.51).

Mentions: To test the ability of mice to maintain and recall the CS–US relationship, mice trained using the trace 50–250 interval were given a 7 (n = 10) or 14 d (n = 4) break in training after initial acquisition. The rate of CR expression for the first session after the break was highly variable (7 d median = 30%, IQR = 26–46%; 14 d median = 46%, IQR = 26–68%), but clearly shows that most mice remembered the task (H0: mean = 0%, t = 6.47, df = 13, p < 0.01k; Fig. 4A,B; data from the 7 and 14 d training breaks are plotted separately but were not significantly different, Mann–Whitney–Wilcoxon test: U = 25, n = 4 and 10, p = 0.27l, and so were pooled for testing). In fact, half of the mice showed a CR on the very first training trial, indicating that mice remembered the CS–US relationship rather than rapidly reacquiring the task. Mice with relatively low initial CR rates expressed learned responses intermittently during the entire first postbreak session, rather than gradually increasing the expression of CRs or developing CRs late in the session as would be expected if mice reacquired rather than remembered the task (Fig. 4B, top). As noted, however, mice did show a decrease in performance in the first session after the breaks (prebreak: mean = 73±5% CR rate, postbreak: mean = 41±6% CR rate, paired t = 5.69, df = 13, p < 0.001m), which recovered after 3–4 d of additional training (+3 sessions: mean = 68±3% CR rate, paired t = 1.02, df = 13, p = 0.33n; Fig. 4A). The initial decreased performance appeared to be associated with a decrease in CR amplitude (prebreak: mean = 0.36 ± 0.04 FEC, postbreak: mean = 0.20±0.03 FEC; paired t = 3.99, df = 13, p = 0.001p), which also recovered with additional training (+3 sessions: mean=0.35±0.05 FEC, paired t = 0.25, df = 13, p = 0.81q; Fig. 4C, data plotted separately but pooled for testing). In contrast, the timing of CRs (taken as the latency to the peak amplitude of responses during CS-only probe trials) was not affected by the break in training (prebreak: mean=294 ± 13 ms, postbreak: mean = 324 ± 38 ms; paired t = 0.69, df = 13, p = 0.51r; Fig. 4D). The data suggest that mice can show long-term retention of the CS–US relationship and the timing of CRs.


Trace Eyeblink Conditioning in Mice Is Dependent upon the Dorsal Medial Prefrontal Cortex, Cerebellum, and Amygdala: Behavioral Characterization and Functional Circuitry(1,2,3).

Siegel JJ, Taylor W, Gray R, Kalmbach B, Zemelman BV, Desai NS, Johnston D, Chitwood RA - eNeuro (2015)

Trained mice receiving a 7 (n = 10) or 14 d (n = 4) break in training showed long-term memory for the task. A, Asymptotic (Prebreak) CR rates and postbreak performance for mice that received a 7 (left) or 14 d (right) break in training (shown separately but analyzed together). Red markers indicate median observed each day. Mice showed a significant decrease in performance during the first postbreak sessions (paired t = 5.69, df = 13, p < 0.001), which recovered with additional training sessions (t = 1.02, p = 0.33). B, Example sessions from two mice before (Prebreak) and after (Postbreak) training breaks. Note that mice showed CRs early in the first postbreak session, even when overall performance was low (top), suggesting that mice remembered rather than quickly relearned the task. C, Similar to CR rate, CR amplitude decreased between prebreak and postbreak sessions (t = 3.99, p = 0.001), which recovered with additional training (t = 0.25, p = 0.81). D, In contrast, the appropriate timing for the task (latency to CR peak) was conserved between prebreak and postbreak sessions (t = 0.69, p = 0.51).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4596016&req=5

Figure 4: Trained mice receiving a 7 (n = 10) or 14 d (n = 4) break in training showed long-term memory for the task. A, Asymptotic (Prebreak) CR rates and postbreak performance for mice that received a 7 (left) or 14 d (right) break in training (shown separately but analyzed together). Red markers indicate median observed each day. Mice showed a significant decrease in performance during the first postbreak sessions (paired t = 5.69, df = 13, p < 0.001), which recovered with additional training sessions (t = 1.02, p = 0.33). B, Example sessions from two mice before (Prebreak) and after (Postbreak) training breaks. Note that mice showed CRs early in the first postbreak session, even when overall performance was low (top), suggesting that mice remembered rather than quickly relearned the task. C, Similar to CR rate, CR amplitude decreased between prebreak and postbreak sessions (t = 3.99, p = 0.001), which recovered with additional training (t = 0.25, p = 0.81). D, In contrast, the appropriate timing for the task (latency to CR peak) was conserved between prebreak and postbreak sessions (t = 0.69, p = 0.51).
Mentions: To test the ability of mice to maintain and recall the CS–US relationship, mice trained using the trace 50–250 interval were given a 7 (n = 10) or 14 d (n = 4) break in training after initial acquisition. The rate of CR expression for the first session after the break was highly variable (7 d median = 30%, IQR = 26–46%; 14 d median = 46%, IQR = 26–68%), but clearly shows that most mice remembered the task (H0: mean = 0%, t = 6.47, df = 13, p < 0.01k; Fig. 4A,B; data from the 7 and 14 d training breaks are plotted separately but were not significantly different, Mann–Whitney–Wilcoxon test: U = 25, n = 4 and 10, p = 0.27l, and so were pooled for testing). In fact, half of the mice showed a CR on the very first training trial, indicating that mice remembered the CS–US relationship rather than rapidly reacquiring the task. Mice with relatively low initial CR rates expressed learned responses intermittently during the entire first postbreak session, rather than gradually increasing the expression of CRs or developing CRs late in the session as would be expected if mice reacquired rather than remembered the task (Fig. 4B, top). As noted, however, mice did show a decrease in performance in the first session after the breaks (prebreak: mean = 73±5% CR rate, postbreak: mean = 41±6% CR rate, paired t = 5.69, df = 13, p < 0.001m), which recovered after 3–4 d of additional training (+3 sessions: mean = 68±3% CR rate, paired t = 1.02, df = 13, p = 0.33n; Fig. 4A). The initial decreased performance appeared to be associated with a decrease in CR amplitude (prebreak: mean = 0.36 ± 0.04 FEC, postbreak: mean = 0.20±0.03 FEC; paired t = 3.99, df = 13, p = 0.001p), which also recovered with additional training (+3 sessions: mean=0.35±0.05 FEC, paired t = 0.25, df = 13, p = 0.81q; Fig. 4C, data plotted separately but pooled for testing). In contrast, the timing of CRs (taken as the latency to the peak amplitude of responses during CS-only probe trials) was not affected by the break in training (prebreak: mean=294 ± 13 ms, postbreak: mean = 324 ± 38 ms; paired t = 0.69, df = 13, p = 0.51r; Fig. 4D). The data suggest that mice can show long-term retention of the CS–US relationship and the timing of CRs.

Bottom Line: To identify the circuitry involved, we made restricted lesions of the medial prefrontal cortex (mPFC) and found that learning was prevented.Anatomical data from these critical regions showed that mPFC and amygdala both project to the rostral basilar pons and overlap with eyelid-associated pontocerebellar neurons.The data further reveal a specific role for the amygdala as providing a conditioned stimulus-associated input to the cerebellum.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Learning and Memory, University of Texas at Austin , Austin, Texas 78712.

ABSTRACT
Trace eyeblink conditioning is useful for studying the interaction of multiple brain areas in learning and memory. The goal of the current work was to determine whether trace eyeblink conditioning could be established in a mouse model in the absence of elicited startle responses and the brain circuitry that supports this learning. We show here that mice can acquire trace conditioned responses (tCRs) devoid of startle while head-restrained and permitted to freely run on a wheel. Most mice (75%) could learn with a trace interval of 250 ms. Because tCRs were not contaminated with startle-associated components, we were able to document the development and timing of tCRs in mice, as well as their long-term retention (at 7 and 14 d) and flexible expression (extinction and reacquisition). To identify the circuitry involved, we made restricted lesions of the medial prefrontal cortex (mPFC) and found that learning was prevented. Furthermore, inactivation of the cerebellum with muscimol completely abolished tCRs, demonstrating that learned responses were driven by the cerebellum. Finally, inactivation of the mPFC and amygdala in trained animals nearly abolished tCRs. Anatomical data from these critical regions showed that mPFC and amygdala both project to the rostral basilar pons and overlap with eyelid-associated pontocerebellar neurons. The data provide the first report of trace eyeblink conditioning in mice in which tCRs were driven by the cerebellum and required a localized region of mPFC for acquisition. The data further reveal a specific role for the amygdala as providing a conditioned stimulus-associated input to the cerebellum.

No MeSH data available.


Related in: MedlinePlus