Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Alpha oscillations (2)
- Visual cortex (2)
- Visual perception (2)
- Attention networks (1)
- Behavioral priming (1)
-
- Brain injury (1)
- Brain processes (1)
- Conscious experience (1)
- Conscious perception (1)
- EEG (1)
- Neural oscillations (1)
- Neuroimaging (1)
- Parietal cortex (1)
- Perceptual awareness (1)
- Perceptual load (1)
- Saccadic suppression of displacement (1)
- Sensory neuronal networks (1)
- Shape priming (1)
- Transcranial magnetic stimulation (1)
- Unconscious priming (1)
- Unconscious processing (1)
- Visual stability (1)
- Visual stimuli (1)
- Α peak frequency (1)
- Α power (1)
Articles 1 - 7 of 7
Full-Text Articles in Cognitive Psychology
Visual Modulation Of Resting State Α Oscillations, Kelly Webster, Tony Ro
Visual Modulation Of Resting State Α Oscillations, Kelly Webster, Tony Ro
Publications and Research
Once thought to simply reflect passive cortical idling, recent studies have demonstrated that α oscillations play a causal role in cognition and perception. However, whether and how cognitive or sensory processes modulate various components of the α rhythm is poorly understood. Sensory input and resting states were manipulated in human subjects while electroencephalography (EEG) activity was recorded in three conditions: eyes-open fixating on a visual stimulus, eyes-open without visual input (darkness), and eyes-closed without visual input (darkness). We show that α power and peak frequency increase when visual input is reduced compared to the eyes open, fixating condition. These results …
Alpha Oscillations And Feedback Processing In Visual Cortex For Conscious Perception, Tony Ro
Alpha Oscillations And Feedback Processing In Visual Cortex For Conscious Perception, Tony Ro
Publications and Research
Variability in perception between individuals may be a consequence of different inherent neural processing speeds. To assess whether alpha oscillations systematically reflect a feedback pacing mechanism for cortical processing during visual perception, comparisons were made between alpha oscillations, visual suppression from TMS, visual evoked responses, and metacontrast masking. Peak alpha oscillation frequencies, measured through scalp EEG recordings, significantly correlated with the optimum latencies for visual suppression from TMS of early visual cortex. Individuals with shorter alpha periods (i.e., higher peak alpha frequencies) processed visual information faster than those with longer alpha periods (i.e., lower peak alpha frequencies). Moreover, peak alpha …
Dynamics Of Alpha Control: Preparatory Suppression Of Posterior Alpha Oscillations By Frontal Modulators Revealed With Combined Eeg And Event-Related Optical Signal, Kyle E. Mathewson, Diane M. Beck, Tony Ro, Edward L. Maclin, Kathy A. Low, Monica Fabiani, Gabriele Gratton
Dynamics Of Alpha Control: Preparatory Suppression Of Posterior Alpha Oscillations By Frontal Modulators Revealed With Combined Eeg And Event-Related Optical Signal, Kyle E. Mathewson, Diane M. Beck, Tony Ro, Edward L. Maclin, Kathy A. Low, Monica Fabiani, Gabriele Gratton
Publications and Research
We investigated the dynamics of brain processes facilitating conscious experience of external stimuli. Previously, we proposed that alpha (8–12 Hz) oscillations, which fluctuate with both sustained and directed attention, represent a pulsed inhibition of ongoing sensory brain activity. Here we tested the prediction that inhibitory alpha oscillations in visual cortex are modulated by top–down signals from frontoparietal attention networks. We measured modulations in phase-coherent alpha oscillations from superficial frontal, parietal, and occipital cortices using the event-related optical signal (EROS), a measure of neuronal activity affording high spatiotemporal resolution, along with concurrently recorded EEG, while participants performed a visual target detection …
Direct Control Of Visual Perception With Phase-Specific Modulation Of Posterior Parietal Cortex, Andrew Jaegle, Tony Ro
Direct Control Of Visual Perception With Phase-Specific Modulation Of Posterior Parietal Cortex, Andrew Jaegle, Tony Ro
Publications and Research
We examined the causal relationship between the phase of alpha oscillations (9–12 Hz) and conscious visual perception using rhythmic TMS (rTMS) while simultaneously recording EEG activity. rTMS of posterior parietal cortex at an alpha frequency (10 Hz), but not occipital or sham rTMS, both entrained the phase of subsequent alpha oscillatory activity and produced a phase-dependent change on subsequent visual perception, with lower discrimination accuracy for targets presented at one phase of the alpha oscillatory waveform than for targets presented at the opposite phase. By extrinsically manipulating the phase of alpha before stimulus presentation, we provide direct evidence that the …
Unconscious Priming Requires Early Visual Cortex At Specific Temporal Phases Of Processing, Marjan Persuh, Tony Ro
Unconscious Priming Requires Early Visual Cortex At Specific Temporal Phases Of Processing, Marjan Persuh, Tony Ro
Publications and Research
Although examples of unconscious shape priming have been well documented, whether such priming requires early visual cortex (V1/V2) has not been established. In the current study, we used TMS of V1/V2 at varying temporal intervals to suppress the visibility of preceding shape primes while the interval between primes and targets was kept constant. Our results show that, although conscious perception requires V1/V2, unconscious priming can occur without V1/V2 at an intermediate temporal interval but not at early (5–25 msec) or later (65–125 msec) stages of processing. Because the later time window of unconscious priming suppression has been proposed to interfere …
Unconscious Processing Of Unattended Features In Human Visual Cortex, Tatiana Aloi Emmanouil, Philip Burton, Tony Ro
Unconscious Processing Of Unattended Features In Human Visual Cortex, Tatiana Aloi Emmanouil, Philip Burton, Tony Ro
Publications and Research
Unconscious processing has been convincingly demonstrated for task-relevant feature dimensions. However, it is possible that the visual system is capable of more complex unconscious operations, extracting visual features even when they are unattended and task irrelevant. In the current study, we addressed this question by measuring unconscious priming using a task in which human participants attended to a target object's shape while ignoring its color. We measured both behavioral priming effects and priming-related fMRI activations from primes that were unconsciously presented using metacontrast masking. The results showed faster RTs and decreases in fMRI activation only when the primes were identical …
Maintenance Of Visual Stability In The Human Posterior Parietal Cortex, Erik Chang, Tony Ro
Maintenance Of Visual Stability In The Human Posterior Parietal Cortex, Erik Chang, Tony Ro
Publications and Research
Visual stability refers to our stable visuospatial perceptions despite the unstable visual input caused by saccades. Functional neuroimaging results, studies on patients with posterior parietal cortex (PPC) lesions, and single-unit recordings in the lateral intraparietal sulcus of primates indirectly suggest that the PPC might be a potential locus of visual stability through its involvement with spatial remapping. Here we directly explored the role of the PPC in visual stability by applying transcranial magnetic stimulation (TMS) while participants performed a perisaccadic displacement detection task. We show that TMS over the PPC but not a frontal control site alters sensitivity to displacement …