Cross-frequency interaction of the eye-movement related LFP signals in V1 of freely viewing monkeys

Abstract

Recent studies have emphasized the functional role of neuronal activity underlying oscillatory local field potential (LFP) signals during visual processing in natural conditions. While functionally relevant components in multiple frequency bands have been reported, little is known about whether and how these components interact with each other across the dominant frequency bands. We examined this phenomenon in LFP signals obtained from the primary visual cortex of monkeys performing voluntary saccadic eye movements (EMs) on still images of natural-scenes. We identified saccade-related changes in respect to power and phase in four dominant frequency bands: delta-theta (2–4 Hz), alpha-beta (10–13 Hz), low-gamma (20–40 Hz), and high-gamma (>100 Hz). The phase of the delta-theta band component is found to be entrained to the rhythm of the repetitive saccades, while an increment in the power of the alpha-beta and low-gamma bands were locked to the onset of saccades. The degree of the power modulation in these frequency bands is positively correlated with the degree of the phase-locking of the delta-theta oscillations to EMs. These results suggest the presence of cross-frequency interactions in the form of phase-amplitude coupling (PAC) between slow (delta-theta) and faster (alpha-beta and low gamma) oscillations. As shown previously, spikes evoked by visual fixations during free viewing are phase-locked to the fast oscillations. Thus, signals of different types and at different temporal scales are nested to each other during natural viewing. Such cross-frequency interaction may provide a general mechanism to coordinate sensory processing on a fast time scale and motor behavior on a slower time scale during active sensing.

Coregistering functional near-infrared spectroscopy with underlying cortical areas in infants

“…51 The AC location was marked on a 3-D rendered volume using MRIcron 52 by placing a 2-mm spherical mask on the location. 53 Preauricular points were also defined at the anterior roots of the tragi on MRI slices in addition to the nasion (a dent at the upper root of the nose bridge) and the inion (an external occipital proturberance). 54 In infants, these scalp markers are used in lieu of external markers (such as vitamin-E capsules or digitized channel recordings) so they should be detectable both on the participant’s head from the photographs and on his/her MRI.…”

“…The head measurements and photographs of the infants wearing the fNIRS arrays and headgear (see earlier section for further details) were used to identify four fiducial landmarks on the 3-D-rendered MRI volume of the infant head (for similar work coregistering EEG electrodes see Ref. 53). Fiducials were placed as spherical masks (i) on the MRI volume at the front of the headgear over a centered marker on the headband which was aligned with the nasion, (ii) on the right and left sides at the lower-middle optode location which on an average 4- to 6-month-old infant are aligned with the preauricular points (or T3 and T4: 10 to 20 system), and (iii) over the rear at the location where the bottom of the headband met the medial location on the head.…”

The activation of embedded words in spoken word recognition

“…In these studies, listeners are presented with degraded speech, or must simultaneously engage in a distracting task (cf. Mattys, Davis, Bradlow, & Scott, 2012; Mattys & Liss, 2008; Rönnberg, Lunner, Zekveld, Sörqvist, Danielsson, Lyxell, et al, 2013). …”

Eye movement-related brain activity during perceptual and cognitive processing

“…They found that emotional processing depends on the overt attentional resources. Ito et al (2013) observed interaction between low and high frequency components in the local field potentials (LFP) recorded in the visual cortex of monkeys performing voluntary saccades during natural scene viewing. They concluded that the cross-frequency interaction is a manifestation of the mechanism which coordinates oculomotor behavior and sensory processing.…”

“…The most common methodological approach is examination of the EEG activity time-aligned to certain eye movement events, such as the onset of a fixation or a start of a saccadic eye movement (Fischer et al, 2013;Frey et al, 2013;Henderson et al, 2013;Hutzler et al, 2013;Nikolaev et al, 2013;Richards, 2013;Simola et al, 2013). Several works employ the time-frequency and synchrony analysis (Fischer et al, 2013;Hoffman et al, 2013;Ito et al, 2013;.…”