Intensity- and timing-dependent modulation of motion perception with transcranial magnetic stimulation of visual cortex.


Despite the widespread use of transcranial magnetic stimulation (TMS) in research and clinical care, the dose-response relations and neurophysiological correlates of modulatory effects remain relatively unexplored. To fill this gap, we studied modulation of visual processing as a function of TMS parameters. Our approach combined electroencephalography (EEG) with application of single pulse TMS to visual cortex as participants performed a motion perception task. During each participants' first visit, motion coherence thresholds, 64-channel visual evoked potentials (VEPs), and TMS resting motor thresholds (RMT) were measured. In second and third visits, single pulse TMS was delivered at one of two latencies, either 30 ms before the onset of motion or at the onset latency of the N2 VEP component derived from the first session. TMS was delivered at 0%, 80%, 100%, or 120% of RMT over the site of N2 peak activity, or at 120% over vertex. Behavioral results demonstrated a significant main effect of TMS timing on accuracy, with better performance when TMS was applied at the N2-Onset timing versus Pre-Onset, as well as a significant interaction, indicating that 80% intensity produced higher accuracy than other conditions at the N2-Onset. TMS effects on the P3 VEP showed reduced amplitudes in the 80% Pre-Onset condition, an increase for the 120% N2-Onset condition, and monotonic amplitude scaling with stimulation intensity. The N2 component was not affected by TMS. These findings reveal the influence of TMS intensity and timing on visual perception and electrophysiological responses, with optimal facilitation at stimulation intensities below RMT.





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Publication Info

Gamboa Arana, Olga Lucia, Hannah Palmer, Moritz Dannhauer, Connor Hile, Sicong Liu, Rena Hamdan, Alexandra Brito, Roberto Cabeza, et al. (2020). Intensity- and timing-dependent modulation of motion perception with transcranial magnetic stimulation of visual cortex. Neuropsychologia, 147. p. 107581. 10.1016/j.neuropsychologia.2020.107581 Retrieved from

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Roberto Cabeza

Professor of Psychology and Neuroscience

My laboratory investigates the neural correlates of memory and cognition in young and older adults using fMRI. We have three main lines of research: First, we distinguish the neural correlates of various episodic memory processes. For example, we have compared encoding vs. retrieval, item vs. source memory, recall vs. recognition, true vs. false memory, and emotional vs. nonemotional memory. We are particularly interested in the contribution of prefrontal cortex (PFC) and medial temporal lobe (MTL) subregions and their interactions. Second, we investigate similarities and differences between the neural correlates of episodic memory and other memory and cognitive functions (working, semantic, implicit, and procedural memory; attention; perception, etc.). The main goal of this cross-functional approach is to understand the contributions of brain regions shared by different cognitive functions. Finally, in both episodic memory and cross-function studies, we also examine the effects of healthy and pathological aging. Regarding episodic memory, we have linked processes differentially affected by aging (e.g., item vs. source memory, recall vs. recognition) to the effects of aging on specific PFC and MTL subregions. Regarding cross-function comparisons, we identify age-related changes in activity that are common to various functions. For example, we have found an age-related increase in bilaterality that occurs for many functions (memory, attention, language, perception, and motor) and is associated with functional compensation.


Simon Wilton Davis

Associate Professor in Neurology

My research centers around the use of structural and functional imaging measures to study the shifts in network architecture in the aging brain. I am specifically interested in changes in how changes in structural and functional connectivity associated with aging impact the semantic retrieval of word or fact knowledge. Currently this involves asking why older adults have particular difficulty in certain kinds of semantic retrieval, despite the fact that vocabularies and knowledge stores typically improve with age.

A second line of research involves asking questions about how this semantic system is organized in young adults, understanding which helps form a basis for asking questions about older adults. To what degree are these semantic retrieval processes lateralized? What cognitive factors affect this laterality? How are brain structures like the corpus callosum involved in mediating distributed activation patterns associated with semantic retrieval? 

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