Alex Joyner for helpful inputs constructing the conditional FoxG1 loss-of-function allele and Dr. Frada Berenshteyn for her generous help in gene targeting and ES cell selection. We thank Lihong Yin for her technical help. We greatly appreciate

Dr. Vitor Sousa for his collaborative effort in generating the RCE EGFP reporter lines. http://www.selleckchem.com/products/frax597.html We especially wish to thank Dr. Rob Machold for his intellectual inputs in the interpretation of our data and for the generous time he devoted in discussions and assembly of this manuscript. We are also greatly appreciative of the efforts Drs. Theofanis Karayannis, Xavier Jaglin and Allison Roberta made in critically reading this manuscript. Finally, we are extremely appreciative to all of the Fishell lab members for the support and suggestions throughout this project. “
“Understanding how the brain processes emotions holds major potential for fundamental and medical research. Precisely timed neuronal activity across brain regions is crucial for cognitive processing (Singer, 1999). Studies in humans (Richardson et al., 2004) and rodents (Maren and Fanselow, 1995) indicate that cooperation between amygdala and hippocampus is critical for emotional memory formation. This communication involves the synchronization of neuronal activity at theta (θ) frequencies (4–10 Hz) across the basolateral amygdala complex (BLA) and the

CA1 hippocampal field. In fear conditioning, a model of emotional memory, animals learn to associate a negative emotional valence to an initially neutral stimulus (e.g., a tone) after its repetitive pairing with an aversive LDN193189 for stimulus (e.g., an electrical footshock) (LeDoux, 2000). Unconditioned animals show hippocampus-related θ oscillations in BLA at the levels of individual principal cells and neuron populations (as reflected in local field potentials, LFPs) (Paré and Gaudreau, 1996). Amplitude and power of this rhythm

increase after auditory, contextual or social fear learning (Jeon et al., 2010, Paré and Collins, 2000 and Seidenbecher et al., 2003). Moreover, the degree of θ synchrony between BLA and CA1 after fear conditioning predicts memory performance (Popa et al., 2010). Precise timing of activity in the BLA is likely important not only for oscillations. It may also be critical for memory encoding, by selectively assigning emotional valence to incoming sensory stimuli. However, how BLA network activities are coordinated remains unknown. Several lines of evidence suggest that GABAergic neurons may be instrumental in controlling θ oscillations and integrating salient sensory stimuli in the BLA. The BLA is a cortical-like area; in cortex, GABAergic interneurons can synchronize the activity of large cell assemblies (Bonifazi et al., 2009 and Cobb et al., 1995). Persistent BLA θ oscillations are accompanied by fear extinction deficits in GAD65 knockout mice (Sangha et al., 2009).