PROJECT SUMMARY
Cortical subregions are often implicated in a variety of behavioral functions, but it is not well understood how
these areas encode such diverse information. The anterior cingulate cortex (ACC) is necessary for emotional
processing and social cognition, but how it encodes stimuli relevant to both processes is unknown. The goal of
this proposal is to understand the functional heterogeneity of ACC circuits, and how this impacts encoding of
diverse stimuli and cognitive function. In Aim 1, we will determine the functional heterogeneity of ACC inhibitory
circuits during social and anxiety-like behaviors. To monitor interneuron activity, we will first inject an adeno-
associated virus (AAV) that expresses GCaMP6f, a fluorescent Ca2+ indicator, in a Cre-dependent manner into
the ACC of somatostatin (SST)- or parvalbumin (PV)-cre transgenic mice. Next, we will use the 3D-printed
miniature miniscopes to perform in vivo single-cell resolution calcium imaging in either somatostatin or
parvalbumin interneurons in the ACC to investigate their functional heterogeneity while mice performed tasks to
assay anxiety-like behaviors, general sociability and social novelty. In Aim 2, we will determine whether specific
populations of excitatory pyramidal cells (Pyr) in the ACC encode particular behavioral stimuli. First, to target
specific populations of Pyr in the ACC, we will inject an AAV that expresses Cre recombinase and can
retrogradely label cells into either the contralateral ACC, anterior thalamic nucleus, or the retrosplenial cortex.
Next, we will inject an AAV that expresses GCaMP6 in a cre-dependent manner to label Pyr in the ACC and
project to either the contralateral ACC, anterior thalamic nucleus or retrosplenial cortex. Three weeks later, we
will use approaches described in Aim 1 to monitor the activity of specific populations of Pyr during particular
behaviors. We will also determine the laminar sources of synaptic input to VIP interneurons in the ACC. To test
this, we will first cross VIP-cre mice to a cre-dependent fluorescent reporter line. Next, we will inject an AAV
expressing ChETA, a light-activated channel, into the contralateral ACC, anterior thalamic nucleus or
retrosplenial cortex. Four weeks after viral injections, we will combine electrophysiological recordings in acute
brain slices with optogenetic stimulation to characterize the laminar organization of specific projections unto VIP
interneurons in the ACC. In addition to determining the connectivity probability of these inputs, we will correlate
the cortical depth of the soma to morphological, and electrophysiological properties and molecular markers.
While reductionist and simplified models of cortical networks have established a framework to understand their
function, it is now evident that to understand the role of cortical networks in complex, adaptive behavior,
optimized models will need to incorporate the functional heterogeneity of these circuits. Completion of these
aims will dissect the functional heterogeneity of inhibitory circuits in the ACC.
