Figure 1.

Content-specific sensory and episodic information can be decoded from frequency and phase-specific oscillations. A) Importance map for decoding visual letters using human intracranial recordings as a function of time and frequency. Decoding is best when using power in the theta and high-gamma bands. Modified with permission from [25]. B) Decoding accuracy for naturalistic auditory stimuli using power or phase in monkeys (left) and humans (right). Note that decoding accuracy is largest using theta phase in both species and that theta phase is better than firing rate in monkeys. Modified with permission from [28]. C) Heat map depicting the relative contribution of power and phase (represented jointly in the complex plane) to representations of facial expressions. Maps are shown separately in different bins of the complex plane at two different frequencies. Note that representations of different aspects of the faces (eyes vs. mouths) are multiplexed at different frequencies and phases. Reproduced with permission from [29]. D) Phase-amplitude coupling (PAC) occurs at a variety of phases (left) and frequency combinations (right) in humans, fulfilling two of the requirements for a coding scheme based on frequency and phase-specific neural firing/PAC. The distribution of coupling phases may be either monophasic or biphasic (left). Whereas phase-providing frequencies varied in the delta-alpha band, amplitude-providing frequencies varied in the beta-gamma bands. Reproduced with permission from [47]. E) Difference in phase-locking for items encoded at a flickering frequency of 6Hz versus 10Hz (left). Successful recognition of items encoded at 6Hz was accompanied by frequency-specific phase-locking (right), implicating frequency-specificity in both encoding and retrieval. Modified with permission from [55]. F) Primate neurons fire to frequency-specific (lower) inter-regional oscillatory phase coupling patterns, which constitute an “internal receptive field” (IRF) for the neuron (upper left) and are a strong predictor of firing rate (upper right). Recreating an assembly’s IRF may be sufficient to activate it in support of memory retrieval for a content-specific event. Modified with permission from [36]. See original text for full details in each panel.