Parvalbumin and GABA Microcircuits in the Mouse Superior Colliculus

Front Neural Circuits. 2018 May 4;12:35. doi: 10.3389/fncir.2018.00035. eCollection 2018.


The mammalian superior colliculus (SC) is a sensorimotor midbrain structure responsible for orienting behaviors. Although many SC features are known, details of its intrinsic microcircuits are lacking. We used transgenic mice expressing reporter genes in parvalbumin-positive (PV+) and gamma aminobutyric acid-positive (GABA+) neurons to test the hypothesis that PV+ neurons co-localize GABA and form inhibitory circuits within the SC. We found more PV+ neurons in the superficial compared to the intermediate SC, although a larger percentage of PV+ neurons co-expressed GABA in the latter. Unlike PV+ neurons, PV+/GABA+ neurons showed predominantly rapidly inactivating spiking patterns. Optogenetic activation of PV+ neurons revealed direct and feedforward GABAergic inhibitory synaptic responses, as well as excitatory glutamatergic synapses. We propose that PV+ neurons in the SC may be specialized for a variety of circuit functions within the SC rather than forming a homogeneous, GABAergic neuronal subtype as they appear to in other regions of the brain.

Keywords: GABAergic neurons; attention; mouse; optogenetics; orienting movements; parvalbumin; superior colliculus (SC).

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • GABAergic Neurons / metabolism
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Optogenetics / methods
  • Parvalbumins / metabolism*
  • Superior Colliculi / physiology*
  • Synapses / physiology*
  • gamma-Aminobutyric Acid / metabolism*


  • Parvalbumins
  • gamma-Aminobutyric Acid