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A circuit mechanism for differentiating positive and negative associations.

Namburi P, Beyeler A, Yorozu S, Calhoon GG, Halbert SA, Wichmann R, Holden SS, Mertens KL, Anahtar M, Felix-Ortiz AC, Wickersham IR, Gray JM, Tye KM - Nature (2015)

Bottom Line: Here we show that BLA neurons projecting to the nucleus accumbens (NAc projectors) or the centromedial amygdala (CeM projectors) undergo opposing synaptic changes following fear or reward conditioning.We characterize these functionally distinct neuronal populations by comparing their electrophysiological, morphological and genetic features.Overall, we provide a mechanistic explanation for the representation of positive and negative associations within the amygdala.

View Article: PubMed Central - PubMed

Affiliation: 1] The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [2] Neuroscience Graduate Program, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

ABSTRACT
The ability to differentiate stimuli predicting positive or negative outcomes is critical for survival, and perturbations of emotional processing underlie many psychiatric disease states. Synaptic plasticity in the basolateral amygdala complex (BLA) mediates the acquisition of associative memories, both positive and negative. Different populations of BLA neurons may encode fearful or rewarding associations, but the identifying features of these populations and the synaptic mechanisms of differentiating positive and negative emotional valence have remained unknown. Here we show that BLA neurons projecting to the nucleus accumbens (NAc projectors) or the centromedial amygdala (CeM projectors) undergo opposing synaptic changes following fear or reward conditioning. We find that photostimulation of NAc projectors supports positive reinforcement while photostimulation of CeM projectors mediates negative reinforcement. Photoinhibition of CeM projectors impairs fear conditioning and enhances reward conditioning. We characterize these functionally distinct neuronal populations by comparing their electrophysiological, morphological and genetic features. Overall, we provide a mechanistic explanation for the representation of positive and negative associations within the amygdala.

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RNA-Seq identification of candidate genes differentially expressed in NAc and CeM projecting BLA neuronsa, Candidate differentially expressed genes were required to be enriched in only one group (either CeM or NAc projectors) in two independent experiments (NAc projectors collected from n=8 mice; CeM projectors collected from n=9 mice, total) at the indicated quantile fold change threshold (light blue column). One of the chance estimates (“flip-flopped”) is taken from genes that passed the quantile thresholds but were enriched in the opposite groups in the two experiments. Another chance estimate (“permuted”) is determined based on an analysis in which fold differences for each gene were permuted across genes within each of the two experiments before determining differential expression. A 0.02 quantile threshold was chosen to identify candidate differentially expressed genes (light blue columns) in order to balance specificity and sensitivity, resulting in an estimated false discovery rate of 41.5%: [expected by chance (flip-flopped)]/Differentially expressed genes (see Extended Data Fig. 9c for candidate gene list). In Fig. 4k, a 0.01 quantile threshold was chosen to identify a more conservative list of differentially expressed candidate genes at a lower false discovery rate of 26.2%. b, Distribution of differentially expressed genes between NAc and CeM projectors from RNA-Seq experiments 1 and 2. Light blue shaded areas represent the 2nd and 98th percentiles of the distributions. c, RNA-Seq heatmap showing normalized expression levels of differentially expressed genes in NAc and CeM projecting BLA neurons. Differentially expressed genes were required to be enriched in either NAc or CeM projectors in two independent experiments (samples used in experiment 1 are indicated in black text below the heatmap; experiment 2 samples are indicated in blue text) at a 0.02 quantile threshold (Extended Data Fig. 9a). Each RNA-Seq library was prepared from 35–60 manually sorted retrobead-labeled cells taken from the BLA.
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Figure 9: RNA-Seq identification of candidate genes differentially expressed in NAc and CeM projecting BLA neuronsa, Candidate differentially expressed genes were required to be enriched in only one group (either CeM or NAc projectors) in two independent experiments (NAc projectors collected from n=8 mice; CeM projectors collected from n=9 mice, total) at the indicated quantile fold change threshold (light blue column). One of the chance estimates (“flip-flopped”) is taken from genes that passed the quantile thresholds but were enriched in the opposite groups in the two experiments. Another chance estimate (“permuted”) is determined based on an analysis in which fold differences for each gene were permuted across genes within each of the two experiments before determining differential expression. A 0.02 quantile threshold was chosen to identify candidate differentially expressed genes (light blue columns) in order to balance specificity and sensitivity, resulting in an estimated false discovery rate of 41.5%: [expected by chance (flip-flopped)]/Differentially expressed genes (see Extended Data Fig. 9c for candidate gene list). In Fig. 4k, a 0.01 quantile threshold was chosen to identify a more conservative list of differentially expressed candidate genes at a lower false discovery rate of 26.2%. b, Distribution of differentially expressed genes between NAc and CeM projectors from RNA-Seq experiments 1 and 2. Light blue shaded areas represent the 2nd and 98th percentiles of the distributions. c, RNA-Seq heatmap showing normalized expression levels of differentially expressed genes in NAc and CeM projecting BLA neurons. Differentially expressed genes were required to be enriched in either NAc or CeM projectors in two independent experiments (samples used in experiment 1 are indicated in black text below the heatmap; experiment 2 samples are indicated in blue text) at a 0.02 quantile threshold (Extended Data Fig. 9a). Each RNA-Seq library was prepared from 35–60 manually sorted retrobead-labeled cells taken from the BLA.

Mentions: Finally, we compared the transcriptomes of BLA neurons projecting to the NAc or CeM (Fig. 4j; Extended Data Fig. 9). Following retrobead injections into the NAc or CeM, we dissociated labeled neurons and performed RNA-Seq (Fig. 4j). RNA-Seq revealed relatively few candidate genes expressed differentially between NAc and CeM projectors, consistent with the idea that these two populations are closely related (Fig. 4k; Extended Data Fig. 9). However, these differentially expressed candidate genes may underpin the mechanisms that contribute to the wiring of these distinct populations through development and/or rapidly biasing gain modulation of synaptic transmission during valence-specific learning.


A circuit mechanism for differentiating positive and negative associations.

Namburi P, Beyeler A, Yorozu S, Calhoon GG, Halbert SA, Wichmann R, Holden SS, Mertens KL, Anahtar M, Felix-Ortiz AC, Wickersham IR, Gray JM, Tye KM - Nature (2015)

RNA-Seq identification of candidate genes differentially expressed in NAc and CeM projecting BLA neuronsa, Candidate differentially expressed genes were required to be enriched in only one group (either CeM or NAc projectors) in two independent experiments (NAc projectors collected from n=8 mice; CeM projectors collected from n=9 mice, total) at the indicated quantile fold change threshold (light blue column). One of the chance estimates (“flip-flopped”) is taken from genes that passed the quantile thresholds but were enriched in the opposite groups in the two experiments. Another chance estimate (“permuted”) is determined based on an analysis in which fold differences for each gene were permuted across genes within each of the two experiments before determining differential expression. A 0.02 quantile threshold was chosen to identify candidate differentially expressed genes (light blue columns) in order to balance specificity and sensitivity, resulting in an estimated false discovery rate of 41.5%: [expected by chance (flip-flopped)]/Differentially expressed genes (see Extended Data Fig. 9c for candidate gene list). In Fig. 4k, a 0.01 quantile threshold was chosen to identify a more conservative list of differentially expressed candidate genes at a lower false discovery rate of 26.2%. b, Distribution of differentially expressed genes between NAc and CeM projectors from RNA-Seq experiments 1 and 2. Light blue shaded areas represent the 2nd and 98th percentiles of the distributions. c, RNA-Seq heatmap showing normalized expression levels of differentially expressed genes in NAc and CeM projecting BLA neurons. Differentially expressed genes were required to be enriched in either NAc or CeM projectors in two independent experiments (samples used in experiment 1 are indicated in black text below the heatmap; experiment 2 samples are indicated in blue text) at a 0.02 quantile threshold (Extended Data Fig. 9a). Each RNA-Seq library was prepared from 35–60 manually sorted retrobead-labeled cells taken from the BLA.
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Figure 9: RNA-Seq identification of candidate genes differentially expressed in NAc and CeM projecting BLA neuronsa, Candidate differentially expressed genes were required to be enriched in only one group (either CeM or NAc projectors) in two independent experiments (NAc projectors collected from n=8 mice; CeM projectors collected from n=9 mice, total) at the indicated quantile fold change threshold (light blue column). One of the chance estimates (“flip-flopped”) is taken from genes that passed the quantile thresholds but were enriched in the opposite groups in the two experiments. Another chance estimate (“permuted”) is determined based on an analysis in which fold differences for each gene were permuted across genes within each of the two experiments before determining differential expression. A 0.02 quantile threshold was chosen to identify candidate differentially expressed genes (light blue columns) in order to balance specificity and sensitivity, resulting in an estimated false discovery rate of 41.5%: [expected by chance (flip-flopped)]/Differentially expressed genes (see Extended Data Fig. 9c for candidate gene list). In Fig. 4k, a 0.01 quantile threshold was chosen to identify a more conservative list of differentially expressed candidate genes at a lower false discovery rate of 26.2%. b, Distribution of differentially expressed genes between NAc and CeM projectors from RNA-Seq experiments 1 and 2. Light blue shaded areas represent the 2nd and 98th percentiles of the distributions. c, RNA-Seq heatmap showing normalized expression levels of differentially expressed genes in NAc and CeM projecting BLA neurons. Differentially expressed genes were required to be enriched in either NAc or CeM projectors in two independent experiments (samples used in experiment 1 are indicated in black text below the heatmap; experiment 2 samples are indicated in blue text) at a 0.02 quantile threshold (Extended Data Fig. 9a). Each RNA-Seq library was prepared from 35–60 manually sorted retrobead-labeled cells taken from the BLA.
Mentions: Finally, we compared the transcriptomes of BLA neurons projecting to the NAc or CeM (Fig. 4j; Extended Data Fig. 9). Following retrobead injections into the NAc or CeM, we dissociated labeled neurons and performed RNA-Seq (Fig. 4j). RNA-Seq revealed relatively few candidate genes expressed differentially between NAc and CeM projectors, consistent with the idea that these two populations are closely related (Fig. 4k; Extended Data Fig. 9). However, these differentially expressed candidate genes may underpin the mechanisms that contribute to the wiring of these distinct populations through development and/or rapidly biasing gain modulation of synaptic transmission during valence-specific learning.

Bottom Line: Here we show that BLA neurons projecting to the nucleus accumbens (NAc projectors) or the centromedial amygdala (CeM projectors) undergo opposing synaptic changes following fear or reward conditioning.We characterize these functionally distinct neuronal populations by comparing their electrophysiological, morphological and genetic features.Overall, we provide a mechanistic explanation for the representation of positive and negative associations within the amygdala.

View Article: PubMed Central - PubMed

Affiliation: 1] The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [2] Neuroscience Graduate Program, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

ABSTRACT
The ability to differentiate stimuli predicting positive or negative outcomes is critical for survival, and perturbations of emotional processing underlie many psychiatric disease states. Synaptic plasticity in the basolateral amygdala complex (BLA) mediates the acquisition of associative memories, both positive and negative. Different populations of BLA neurons may encode fearful or rewarding associations, but the identifying features of these populations and the synaptic mechanisms of differentiating positive and negative emotional valence have remained unknown. Here we show that BLA neurons projecting to the nucleus accumbens (NAc projectors) or the centromedial amygdala (CeM projectors) undergo opposing synaptic changes following fear or reward conditioning. We find that photostimulation of NAc projectors supports positive reinforcement while photostimulation of CeM projectors mediates negative reinforcement. Photoinhibition of CeM projectors impairs fear conditioning and enhances reward conditioning. We characterize these functionally distinct neuronal populations by comparing their electrophysiological, morphological and genetic features. Overall, we provide a mechanistic explanation for the representation of positive and negative associations within the amygdala.

Show MeSH
Related in: MedlinePlus