gamma-Aminobutyric acid A (GABAA) channels responsible for inhibitory synap
tic transmission possess a consistent heterogeneity of structure in terms o
f distinct constitutive subunits. During the past 10 years, considerable pr
ogress has been made in understanding the magnitude of this large diversity
. Structural requirements for clinically important drugs such as benzodiaze
pines and barbiturates have been elucidated, and the anatomical distributio
n in distinct neuronal populations and the developmental profiles of indivi
dual subunits have been elucidated with various techniques. However, the re
levance of subunit heterogeneity to synaptic transmission is still largely
lacking. Recently, substantial progress has been achieved in understanding
the crucial role of desensitization as a molecular determinant in defining
the duration and frequency responses of inhibitory synaptic transmission. T
his development, together with a combination of different experimental appr
oaches, including patch-clamp recordings and ultrafast agonist applications
in brain slices and mammalian cells expressing recombinant GABA(A) recepto
r, has begun to shed light on a possible role for subunit composition of sy
naptic receptors in shaping the physiological characteristics of synaptic t
ransmission. Nowhere else in the central nervous system is the anatomical a
nd developmental profile of GABA receptor heterogeneity as well understood
as it is in the cerebellum. This review summarizes advances in the understa
nding of functional correlates to subunit heterogeneity in the cerebellum r
elevant for inhibitory synaptic function.