A Simple Subcortical Feeding Circuit Linking Interoceptive Inputs to Consummatory Behavior
The brain processes an array of stimuli enabling the selection of an appropriate behavioural response but the neural pathways linking interoceptive inputs to outputs for feeding are poorly understood. Here we delineate a subcortical circuit in which brain-derived neurotrophic factor (BDNF) expressing neurons in the ventromedial hypothalamus (VMH) directly connect interoceptive inputs to motor centers controlling food consumption and jaw movements. VMHBDNF neuron inhibition increases food intake by gating motor sequences of feeding through projections to premotor areas of the jaw. When food is unavailable, VMHBDNF inhibition elicits consummatory behaviors directed at inanimate objects such as a wooden block and inhibition of mesencephalic trigeminal area (Me5) projections evokes rhythmic jaw movements. The activity of these neurons is decreased during food consumption and increases when food is in proximity but not consumed. Activity is also increased in obese animals and after leptin treatment. VMHBDNF neurons receive monosynaptic inputs from both agouti-related peptide (AgRP) and proopiomelanocortin (POMC) neurons in the arcuate nucleus (Arc) and constitutive VMHBDNF activation blocks the orexigenic effect of AgRP activation. These data delineate an Arc[->]VMHBDNF[->]Me5 circuit that senses the energy state of an animal and regulates consummatory behaviors in a state dependent manner.