Objective: Measure social interaction and exploration behavior of resident mice toward juvenile intruders in their home cage, and assess how amygdala-hippocampus projections bidirectionally modulate social behavior
Materials & Equipment Checklist
6 items1 from ConductScience
Gather these items before starting the experiment. Check off items as you prepare.
Equipment2
Not specified • Not specified • Not specified • Not mentioned
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Protocol Steps
View Abstract
Impairments in social interaction represent a core symptom of a number of psychiatric disease states, including autism, schizophrenia, depression, and anxiety. Although the amygdala has long been linked to social interaction, little is known about the functional role of connections between the amygdala and downstream regions in noncompetitive social behavior. In the present study, we used optogenetic and pharmacological tools in mice to study the role of projections from the basolateral complex of the amygdala (BLA) to the ventral hippocampus (vHPC) in two social interaction tests: the resident-juvenile-intruder home-cage test and the three chamber sociability test. BLA pyramidal neurons were transduced using adeno-associated viral vectors (AAV 5 ) carrying either channelrhodopsin-2 (ChR2) or halorhodopsin (NpHR), under the control of the CaMKIIα promoter to allow for optical excitation or inhibition of amygdala axon terminals. Optical fibers were chronically implanted to selectively manipulate BLA terminals in the vHPC. NpHR-mediated inhibition of BLA-vHPC projections significantly increased social interaction in the resident-juvenile intruder home-cage test as shown by increased intruder exploration. In contrast, ChR2-mediated activation of BLA-vHPC projections significantly reduced social behaviors as shown in the resident-juvenile intruder procedure as seen by decreased time exploring the intruder and in the three chamber sociability test by decreased time spent in the social zone. These results indicate that BLA inputs to the vHPC are capable of modulating social behaviors in a bidirectional manner.
1
Viral transduction of BLA pyramidal neurons
BLA pyramidal neurons are transduced using adeno-associated viral vectors (AAV5) carrying either channelrhodopsin-2 (ChR2) for excitation or halorhodopsin (NpHR) for inhibition, under control of the CaMKIIα promoter
Not specifiedNot specified
Note: CaMKIIα promoter allows for cell-type specific expression in pyramidal neurons
View evidence from paper
“BLA pyramidal neurons were transduced using adeno-associated viral vectors (AAV 5) carrying either channelrhodopsin-2 (ChR2) or halorhodopsin (NpHR), under the control of the CaMKIIα promoter”
2
Chronic implantation of optical fibers
Optical fibers are chronically implanted to target BLA terminals in the ventral hippocampus for selective optogenetic manipulation
Not specifiedNot specified
Note: Fibers allow for selective manipulation of BLA-vHPC projections
View evidence from paper
“Optical fibers were chronically implanted to selectively manipulate BLA terminals in the vHPC”
3
Resident-juvenile-intruder home-cage test
Resident mice are tested in their home cage with juvenile intruders introduced. Social interaction is measured through exploration behavior of the resident toward the intruder
Note: Test measures intruder exploration and social interaction behaviors
View evidence from paper
“the resident-juvenile-intruder home-cage test and the three chamber sociability test”
4
NpHR-mediated inhibition of BLA-vHPC projections
Halorhodopsin is activated to inhibit BLA terminals in the ventral hippocampus during the resident-juvenile-intruder test
Not specifiedNot specified
Note: Inhibition significantly increased social interaction as shown by increased intruder exploration
View evidence from paper
“NpHR-mediated inhibition of BLA-vHPC projections significantly increased social interaction in the resident-juvenile intruder home-cage test as shown by increased intruder exploration”
5
ChR2-mediated activation of BLA-vHPC projections
Channelrhodopsin-2 is activated to excite BLA terminals in the ventral hippocampus during the resident-juvenile-intruder test
Not specifiedNot specified
Note: Activation significantly reduced social behaviors as shown by decreased time exploring the intruder
View evidence from paper
“ChR2-mediated activation of BLA-vHPC projections significantly reduced social behaviors as shown in the resident-juvenile intruder procedure as seen by decreased time exploring the intruder”
Subjects / Specimens
Species
mouse
Strain
Not specified in provided text
Age
Not specified in provided text
Sex
unknown
Weight
Not specified in provided text
Resident mice and juvenile intruders used in home-cage setting
