ABSTRACT
The discovery of gamma-band synchronization in visual cortex (Gray et al., 1989) and the hippocampus (Bragin et al., 1995) has sparked intense research on its mechanistic underpinnings, and its function in cortical computation. After two decades, the emerging picture is that gamma-band synchronization plays an important role in both information encoding (König et al., 1995; Fries et al., 2007) and selective information transmission (Fries, 2005). Here, we review evidence showing that: (i) an exquisite machinery exists to generate cortical gamma-band oscillations (Section 23.1); (ii) gamma-band synchronization is an ubiquitous phenomenon in the cortex (Section 23.2); (iii) gamma-band synchronization likely bears strong network consequences, due to feedforward coincidence detection (Abeles, 1982) and coherent phase coupling across structures (Fries, 2005) (Section 23.3); (iv) gamma-band synchronization may serve as a mechanism for exible signal routing (Fries, 2005), and attention strongly enhances both local gamma-band synchronization (Fries et al., 2001b) and cross-areal gamma-band coherence (Gregoriou et al., 2009); (v) gamma-band oscillations serve as a temporal reference frame, allowing spike phases to convey stimulus information (Fries et al., 2007) (Section 23.5); (vi) gamma-band synchronization may be an important determinant of the rate code itself (Section 23.5).
