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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

Distribution of cerebellar cortex (n = 3) or deep nuclei projecting cells (n = 3) and regions of potential interaction between mPFC, amygdala inputs and eyeblink-associated pontocerebellar cells. A, Dextran infusion sites from three mice overlapped with the anterior cerebellar cortex, at the border of lobules 4/5 and 6 around the ventral bank. B, Retrogradely labeled neurons resulting from cerebellar cortex infusions were observed throughout the anterior–posterior basilar pons (top to middle sections; green markers represent each putatively labeled soma) and into and throughout the RTN (middle to bottom). Magenta and cyan shaded regions represent mPFC and amygdala terminal labeling observed in more than half of the mice (4/6 and 3/5, respectively). Substantial overlap between mPFC and amygdala terminals was observed in the anterior basilar pons, both of which overlapped with labeled eyeblink-associated pontocerebellar neurons. C, Dextran infusion sites from three mice overlapped with the anterior dentate and/or anterior interpositus deep cerebellar nuclei. D, Retrogradely labeled neurons resulting from cerebellar deep nuclei infusions were restricted to the caudal basilar pons (middle sections) and in the anterior RTN (middle to bottom). Substantial overlap of these labeled pontocerebellar neurons with mPFC terminals was limited to the RTN of deep nuclei infused mice, in which amygdala terminals were not observed. Br, Bregma; py, pyramidal tract; ml, medial lemniscus; L6, cerebellar cortex lobule 6; L4/5, cerebellar cortex lobule 4/5; DN, dentate nucleus; IN, interpositus nucleus.
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Figure 14: Distribution of cerebellar cortex (n = 3) or deep nuclei projecting cells (n = 3) and regions of potential interaction between mPFC, amygdala inputs and eyeblink-associated pontocerebellar cells. A, Dextran infusion sites from three mice overlapped with the anterior cerebellar cortex, at the border of lobules 4/5 and 6 around the ventral bank. B, Retrogradely labeled neurons resulting from cerebellar cortex infusions were observed throughout the anterior–posterior basilar pons (top to middle sections; green markers represent each putatively labeled soma) and into and throughout the RTN (middle to bottom). Magenta and cyan shaded regions represent mPFC and amygdala terminal labeling observed in more than half of the mice (4/6 and 3/5, respectively). Substantial overlap between mPFC and amygdala terminals was observed in the anterior basilar pons, both of which overlapped with labeled eyeblink-associated pontocerebellar neurons. C, Dextran infusion sites from three mice overlapped with the anterior dentate and/or anterior interpositus deep cerebellar nuclei. D, Retrogradely labeled neurons resulting from cerebellar deep nuclei infusions were restricted to the caudal basilar pons (middle sections) and in the anterior RTN (middle to bottom). Substantial overlap of these labeled pontocerebellar neurons with mPFC terminals was limited to the RTN of deep nuclei infused mice, in which amygdala terminals were not observed. Br, Bregma; py, pyramidal tract; ml, medial lemniscus; L6, cerebellar cortex lobule 6; L4/5, cerebellar cortex lobule 4/5; DN, dentate nucleus; IN, interpositus nucleus.

Mentions: The most extensive retrograde labeling in pontine regions was observed in mice as a result of cerebellar cortex infusions. A relatively dense population of labeled somata was observed bilaterally in the RTN, located dorsal to the caudal basilar pons and pyramidal tract and extending >300 μm posterior throughout the extent of that structure (bregma −4.60 to −4.84; Figs. 14B, 11A). Labeled somata were also observed in the caudal basilar pons (reported to receive primarily sensory inputs in rodents; Wiesendanger and Wiesendanger, 1982; Leergaard and Bjaalie, 2007), which extended along the entire anterior–posterior axis into the rostral basilar pons (bregma −3.88 to −4.48; Figs. 14B, 11A). Labeling in the basilar pons was also bilateral but much denser in the pons contralateral to the cerebellar infusion site. The axons of labeled pontocerebellar cells were observed crossing the midline of the pons and entering the middle cerebellar peduncle ipsilateral to the infusion site (Fig. 11A, top). At the level of the rostral pons, most labeled somata were concentrated in the medial region (a putative region of cerebral motor cortex inputs in rodents; Wiesendanger and Wiesendanger, 1982; Leergaard and Bjaalie, 2007), with more sparsely labeled somata observed in the dorsal and lateral regions of the rostral pons (bregma −3.88 to −4.16; Figs. 14B, 11A).


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)

Distribution of cerebellar cortex (n = 3) or deep nuclei projecting cells (n = 3) and regions of potential interaction between mPFC, amygdala inputs and eyeblink-associated pontocerebellar cells. A, Dextran infusion sites from three mice overlapped with the anterior cerebellar cortex, at the border of lobules 4/5 and 6 around the ventral bank. B, Retrogradely labeled neurons resulting from cerebellar cortex infusions were observed throughout the anterior–posterior basilar pons (top to middle sections; green markers represent each putatively labeled soma) and into and throughout the RTN (middle to bottom). Magenta and cyan shaded regions represent mPFC and amygdala terminal labeling observed in more than half of the mice (4/6 and 3/5, respectively). Substantial overlap between mPFC and amygdala terminals was observed in the anterior basilar pons, both of which overlapped with labeled eyeblink-associated pontocerebellar neurons. C, Dextran infusion sites from three mice overlapped with the anterior dentate and/or anterior interpositus deep cerebellar nuclei. D, Retrogradely labeled neurons resulting from cerebellar deep nuclei infusions were restricted to the caudal basilar pons (middle sections) and in the anterior RTN (middle to bottom). Substantial overlap of these labeled pontocerebellar neurons with mPFC terminals was limited to the RTN of deep nuclei infused mice, in which amygdala terminals were not observed. Br, Bregma; py, pyramidal tract; ml, medial lemniscus; L6, cerebellar cortex lobule 6; L4/5, cerebellar cortex lobule 4/5; DN, dentate nucleus; IN, interpositus nucleus.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 14: Distribution of cerebellar cortex (n = 3) or deep nuclei projecting cells (n = 3) and regions of potential interaction between mPFC, amygdala inputs and eyeblink-associated pontocerebellar cells. A, Dextran infusion sites from three mice overlapped with the anterior cerebellar cortex, at the border of lobules 4/5 and 6 around the ventral bank. B, Retrogradely labeled neurons resulting from cerebellar cortex infusions were observed throughout the anterior–posterior basilar pons (top to middle sections; green markers represent each putatively labeled soma) and into and throughout the RTN (middle to bottom). Magenta and cyan shaded regions represent mPFC and amygdala terminal labeling observed in more than half of the mice (4/6 and 3/5, respectively). Substantial overlap between mPFC and amygdala terminals was observed in the anterior basilar pons, both of which overlapped with labeled eyeblink-associated pontocerebellar neurons. C, Dextran infusion sites from three mice overlapped with the anterior dentate and/or anterior interpositus deep cerebellar nuclei. D, Retrogradely labeled neurons resulting from cerebellar deep nuclei infusions were restricted to the caudal basilar pons (middle sections) and in the anterior RTN (middle to bottom). Substantial overlap of these labeled pontocerebellar neurons with mPFC terminals was limited to the RTN of deep nuclei infused mice, in which amygdala terminals were not observed. Br, Bregma; py, pyramidal tract; ml, medial lemniscus; L6, cerebellar cortex lobule 6; L4/5, cerebellar cortex lobule 4/5; DN, dentate nucleus; IN, interpositus nucleus.
Mentions: The most extensive retrograde labeling in pontine regions was observed in mice as a result of cerebellar cortex infusions. A relatively dense population of labeled somata was observed bilaterally in the RTN, located dorsal to the caudal basilar pons and pyramidal tract and extending >300 μm posterior throughout the extent of that structure (bregma −4.60 to −4.84; Figs. 14B, 11A). Labeled somata were also observed in the caudal basilar pons (reported to receive primarily sensory inputs in rodents; Wiesendanger and Wiesendanger, 1982; Leergaard and Bjaalie, 2007), which extended along the entire anterior–posterior axis into the rostral basilar pons (bregma −3.88 to −4.48; Figs. 14B, 11A). Labeling in the basilar pons was also bilateral but much denser in the pons contralateral to the cerebellar infusion site. The axons of labeled pontocerebellar cells were observed crossing the midline of the pons and entering the middle cerebellar peduncle ipsilateral to the infusion site (Fig. 11A, top). At the level of the rostral pons, most labeled somata were concentrated in the medial region (a putative region of cerebral motor cortex inputs in rodents; Wiesendanger and Wiesendanger, 1982; Leergaard and Bjaalie, 2007), with more sparsely labeled somata observed in the dorsal and lateral regions of the rostral pons (bregma −3.88 to −4.16; Figs. 14B, 11A).

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