( ( These ( pyramidal cells ) ) ( reciprocally ( ( ( synapse back ) ( on ( thalamic neurons ) ) ) . ) ) )
(ROOT (S (NP (DT These) (JJ pyramidal) (NNS cells)) (ADVP (RB reciprocally)) (VP (VBP synapse) (ADVP (RB back)) (PP (IN on) (NP (JJ thalamic) (NNS neurons)))) (. .)))
These pyramidal cells reciprocally synapse back on thalamic neurons.
(ROOT (S (NP (NNP Synapse)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (DT a) (NN connection)) (PP (IN between) (NP (NP (DT a) (NN neuron)) (CC and) (NP (PRP$ its) (NN target) (NN cell)))))))) (. .)))