Figure 2.

Some properties of Class 1 and 2 inputs in thalamus and cortex; data are from slice preparations of mouse brain (reviewed in Sherman 2012; Sherman and Guillery 2006, 2011). (A) Some Class 1 properties. At lower frequency stimulation (15 Hz), the evoked EPSPs show paired-pulse depression (i), and the responses at this frequency are completely abolished with application of iGluR antagonists (ii). High-frequency stimulation (10 shocks at 130 Hz) in the presence of iGluR antagonists evokes no mGluR response (iii). (B) Some Class 2 properties, conventions as in (A). Stimulation at 15 Hz leads to paired-pulse facilitation (i); responses at 15 Hz are blocked by iGluR (ii), but high-frequency stimulation evokes a sustained EPSP (iiia) that is blocked by further addition of a group I (type 1) mGluR antagonist (iiib). (C) More Class 2 properties, which are the same as shown in (B), except that the mGluRs activated are group II and thus produce a sustained IPSP (iii). (C) Three-dimensional scatterplot showing distribution of parameters for Class 1 and 2 inputs. The parameters shown are the ratio of the amplitude of the second EPSP evoked in a train to that of the first (Paired-Pulse Effects), the amplitude of the first EPSP evoked in a train (first EPSP Amplitude), and the maximum voltage change evoked in the 300-ms period after high-frequency stimulation in the presence of jGluR antagonists (Max. mGluR Response). iGluR = ionotropic glutamate receptor; mGluR = metabotropic glutamate receptor; EPSP = excitatory postsynaptic potential; IPSP = inhibitory postsynaptic potential. From Sherman (2012).