The GABA_A receptor (GABA_AR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), a major neurotransmitter in the central nervous system. Although GABA ends up producing an inhibitory effect on neurotransmitter release, GABA is not an inhibitory neurotransmitter itself as it stimulates the GABA receptor; therefore, directly it is a stimulatory neurotransmitter. Upon activation, the GABA_A receptor selectively conducts Cl^- through its pore, resulting in hyperpolarization of the neuron. This causes an inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring. The reversal potential of the GABAA-mediated IPSP in normal solution is -75 mV, contrasting the GABA_B IPSP.

The active site of the GABA_A receptor is the binding site for GABA and several drugs such as muscimol, gaboxadol, and bicuculline. The protein also contains a number of different allosteric binding sites which modulate the activity of the receptor indirectly. These allosteric sites are the targets of various other drugs, including the benzodiazepines, nonbenzodiazepines, barbiturates, ethanol,neuroactive steroids, inhaled anaesthetics, and picrotoxin, among others.

Christopher Doyle (traditional Chinese: 杜可風; simplified Chinese: 杜可风; pinyin: Dù Kěfēng; born 2 May 1952) is a cinematographer. He has won the AFI Award for cinematography, the Cannes Technical Grand Prize, Golden Osella, the Golden Horse awards (four times), and Hong Kong Film Award (six times). Doyle is an affiliate of the Hong Kong Society of Cinematographers.

Doyle was born in Sydney, Australia in 1952. In the late 1970s, he went to Taiwan from Hong Kong and then settled in Taipei. While living in Taipei, he studied Mandarin Chinese at the Taipei Language Institute. He worked as an oil driller in India, a cow herder in Israel, and a doctor of Chinese medicine in Thailand. In 1978, he worked as a photographer for the Cloud Gate Dance Theatre and Zuni Icosahedron. In 1983, he was a cinematographer for That Day, On the Beach, the feature debut of director Edward Yang. For that film, Doyle won the Best Cinematography Award in the 1983 Asia-Pacific Film Festival.

He has worked with major Chinese directors such as Zhang Yimou, Zhang Yuan and, most notably, Wong Kar-wai, for whom he contributed, wholly or partially, to the cinematography of all his movies from Days of Being Wild through to 2046.