David LK Murphy

Duke University Medical Center | DUMC · Department of Psychiatry and Behavioral Science

In this study, repetitive transcranial magnetic stimulation was applied to either the right inferior frontal junction or the right inferior parietal cortex during a difficult aerial reconnaissance search task to test its capacity to improve search performance. Two stimulation strategies previously found to enhance cognitive performance were tested:...

BACKGROUND: Electromagnetic forces in transcranial magnetic stimulation (TMS) coils generate a loud clicking sound that produces confounding auditory activation and is potentially hazardous to hearing. To reduce this noise while maintaining stimulation efficiency similar to conventional TMS coils, we previously developed a quiet TMS double containm...

Measurement of the input–output (IO) curves of motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) can be used to assess corticospinal excitability and motor recruitment. While IO curves have been used to study disease and pharmacology, few studies have compared the IO curves across the body. This study sought to char...

Eye movements alter the relationship between the visual and auditory spatial scenes. Signals related to eye movements affect neural pathways from the ear through auditory cortex and beyond, but how these signals contribute to computing the locations of sounds with respect to the visual scene is poorly understood. Here, we evaluated the information...

Auditory and visual information involve different coordinate systems, with auditory spatial cues anchored to the head and visual spatial cues anchored to the eyes. Information about eye movements is therefore critical for reconciling visual and auditory spatial signals. The recent discovery of eye movement-related eardrum oscillations (EMREOs) sugg...

Auditory and visual information involve different coordinate systems, with auditory spatial cues anchored to the head and visual spatial cues anchored to the eyes. Information about eye movements is therefore critical for reconciling visual and auditory spatial signals. The recent discovery of eye movement-related eardrum oscillations (EMREOs) sugg...

A unique type of low-frequency otoacoustic emission (OAE) time-locked to the onset (and offset) of saccadic eye movements was recently discovered in our laboratory (Gruters et al., 2018). The specific underlying mechanisms that generate these eye-movement-related eardrum oscillations (termed EMREOs) and their possible role in auditory perception ar...

Eye movements alter the relationship between the visual and auditory spatial scenes. Signals related to eye movements affect neural pathways from the ear through auditory cortex and beyond, but how these signals contribute to computing the locations of sounds with respect to the visual scene is poorly understood. Here, we evaluated the information...

TMS has become a powerful tool to explore cortical function, and in parallel has proven promising in the development of therapies for various psychiatric and neurological disorders. Unfortunately, much of the inference of the direct effects of TMS has been assumed to be limited to the area a few centimeters beneath the scalp, though clearly more di...

Eye movements alter the relationship between the visual and auditory spatial scenes. Signals related to eye movements affect the brain's auditory pathways from the ear through auditory cortex and beyond, but how these signals might contribute to computing the locations of sounds with respect to the visual scene is poorly understood. Here, we evalua...

This paper presents proof-of-concept of a novel photovoltaic (PV) inverter with integrated short-term storage, based on the modular cascaded double H-bridge (CHB²) topology, and a new look-up table control approach. This topology combines and extends the advantages of various distributed converter concepts, such as string inverters, microinverters,...

Objective: Robotic positioning systems for transcranial magnetic stimulation (TMS) promise improved accuracy and stability of coil placement, but there is limited data on their performance. Investigate the usability, accuracy, and limitations of robotic coil placement with a commercial system, ANT Neuro, in a TMS study. Approach: 21 subjects under...

Objective: Robotic positioning systems for transcranial magnetic stimulation (TMS) promise improved accuracy and stability of coil placement, but there is limited data on their performance. This text investigates the usability, accuracy, and limitations of robotic coil placement with a commercial system, ANT Neuro, in a TMS study. Approach: 21 subj...

Brain stimulation technologies have seen increasing application in basic science investigations, specifically toward the goal of improving memory function. However, proposals concerning the neural mechanisms underlying cognitive enhancement often rely on simplified notions of excitation. As a result, most applications examining the effects of trans...

Brain stimulation technologies have seen increasing application in basic science investigations, specifically towards the goal of improving memory functioning. However, proposals concerning the neural mechanisms underlying cognitive enhancement often rely on simplified notions of excitation and, most applications examining the effects of transcrani...

Interactions between sensory pathways such as the visual and auditory systems are known to occur in the brain, but where they first occur is uncertain. Here, we show a novel multimodal interaction evident at the eardrum. Ear canal microphone measurements in humans (n = 19 ears in 16 subjects) and monkeys (n = 5 ears in 3 subjects) performing a sacc...

Interactions between sensory pathways such as the visual and auditory systems are known to occur in the brain, but where they first occur is uncertain. Here, we show a multimodal interaction evident at the eardrum. Ear canal microphone measurements in humans (n = 19 ears in 16 subjects) and monkeys (n = 5 ears in three subjects) performing a saccad...

Interactions between sensory pathways such as the visual and auditory systems are known to occur in the brain, but where they first occur is uncertain. Here we show a novel multimodal interaction evident at the eardrum. Ear canal microphone measurements in humans ( n =19 ears in 16 subjects) and monkeys ( n =5 ears in 3 subjects) performing a sacca...

A growing literature has focused on the brain's ability to augment processing in local regions by recruiting distant communities of neurons in response to neural decline or insult. In particular, both younger and older adult populations recruit bilateral prefrontal cortex (PFC) as a means of compensating for increasing neural effort to maintain suc...

A growing literature has focused on the brain’s ability to augment processing in local regions by recruiting distant communities of neurons in response to neural decline or insult. In particular, both younger and older adult populations recruit bilateral prefrontal cortex (PFC) as a means of compensating for increasing neural effort to maintain suc...

Background: Intensive bimanual therapy can improve hand function in children with unilateral spastic cerebral palsy (USCP). We compared the effects of structured bimanual skill training versus unstructured bimanual practice on motor outcomes and motor map plasticity in children with USCP. Objective: We hypothesized that structured skill training...

A significant limitation of transcranial magnetic stimulation (TMS) is that the magnetic pulse delivery is associated with a loud clicking sound as high as 140 dB resulting from electromagnetic forces. The loud noise significantly impedes both basic research and clinical applications of TMS. It effectively makes TMS less focal since every click act...

Objective: This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach: We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates s...

Transcranial magnetic stimulation (TMS) is widely used for noninvasive activation of neurons in the brain for research and clinical applications. The strong, brief magnetic pulse generated in TMS is associated with a loud (>100 dB) clicking sound that can impair hearing and that activates auditory circuits in the brain. We introduce a two-pronged s...

Commercially available transcranial magnetic stimulation (TMS) devices provide very limited control over the pulse parameters. We present a third generation controllable pulse parameter device (cTMS3) that uses a novel full-bridge circuit topology with two energy storage capacitors and incorporates a number of implementation and functionality advan...

Introduction Commercially available transcranial magnetic stimulation (TMS) devices induce electric field (E-field) pulses with damped cosine shape and provide very limited control over the pulse parameters. Furthermore, conventional TMS devices consisting of a single power stage cannot produce rapid bursts (<10 ms inter pulse interval) with equal...

This study tested whether mothers with interpersonal violence-related posttraumatic stress disorder (IPV-PTSD) vs healthy controls (HC) would show greater limbic and less frontocortical activity when viewing young children during separation compared to quiet play. Mothers of 20 children (12–42 months) participated: 11 IPV-PTSD mothers and 9 HC with...

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT...

We describe a novel transcranial magnetic stimulation (TMS) device that uses a circuit topology incorporating two energy-storage capacitors and two insulated-gate bipolar transistors (IGBTs) to generate near-rectangular electric field E-field) pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable-pu...

Disturbances in neural systems that mediate voluntary self-regulatory processes may contribute to bulimia nervosa (BN) by releasing feeding behaviors from regulatory control. To study the functional activity in neural circuits that subserve self-regulatory control in women with BN. We compared functional magnetic resonance imaging blood oxygenation...