TMS SMART – scalp mapping of annoyance ratings and twitches caused by Transcranial Magnetic Stimulation

Background: The magnetic pulse generated during transcranial magnetic stimulation (TMS) also stimulates cutaneous nerves and muscle fibres, with the most commonly reported side effect being muscle twitches and sometimes painful sensations. These sensations affect behaviour during experimental tasks, presenting a potential confound for ‘online’ TMS studies. New method: Our objective was to systematically map the degree of disturbance (ratings of annoyance, pain, and muscle twitches) caused by TMS at 43 locations across the scalp. Ten participants provided ratings whilst completing a choice reaction time task, and ten different participants provided ratings whilst completing a 'flanker' reaction time task. Results: TMS over frontal and inferior regions resulted in the highest ratings of annoyance, pain, and muscle twitches caused by TMS. We predicted the difference in reaction times (RT) under TMS by scalp location and subjective ratings. Frontal and inferior scalp locations showed the greatest cost to RTs under TMS (i.e., slowing), with midline sites showing no or minimal slowing. Increases in subjective ratings of disturbance predicted longer RTs under TMS. Critically, ratings were a better predictor of the cost of TMS than scalp location or scalp-to-cortex distance. The more difficult ‘flanker’ task showed a greater effect of subjective disturbance. Comparison with existing methods: We provide the data as an online resource (www.tms-smart.info) so that researchers can select control sites that account for the level of general interference in task performance caused by online single-pulse TMS. Conclusions: The peripheral sensations and discomfort caused by TMS pulses significantly and systematically influence RTs during single-pulse, online TMS experiments. The raw data are available at www.tms-smart.info and https://osf.io/f49vn

The multisensory attentional consequences of tool use : a functional magnetic resonance imaging study

Background: Tool use in humans requires that multisensory information is integrated across different locations, from objects seen to be distant from the hand, but felt indirectly at the hand via the tool. We tested the hypothesis that using a simple tool to perceive vibrotactile stimuli results in the enhanced processing of visual stimuli presented at the distal, functional part of the tool. Such a finding would be consistent with a shift of spatial attention to the location where the tool is used. Methodology/Principal Findings: We tested this hypothesis by scanning healthy human participants’ brains using functional magnetic resonance imaging, while they used a simple tool to discriminate between target vibrations, accompanied by congruent or incongruent visual distractors, on the same or opposite side to the tool. The attentional hypothesis was supported: BOLD response in occipital cortex, particularly in the right hemisphere lingual gyrus, varied significantly as a function of tool position, increasing contralaterally, and decreasing ipsilaterally to the tool. Furthermore, these modulations occurred despite the fact that participants were repeatedly instructed to ignore the visual stimuli, to respond only to the vibrotactile stimuli, and to maintain visual fixation centrally. In addition, the magnitude of multisensory (visual-vibrotactile) interactions in participants’ behavioural responses significantly predicted the BOLD response in occipital cortical areas that were also modulated as a function of both visual stimulus position and tool position. Conclusions/Significance: These results show that using a simple tool to locate and to perceive vibrotactile stimuli is accompanied by a shift of spatial attention to the location where the functional part of the tool is used, resulting in enhanced processing of visual stimuli at that location, and decreased processing at other locations. This was most clearly observed in the right hemisphere lingual gyrus. Such modulations of visual processing may reflect the functional importance of visuospatial information during human tool use

Examining the Relationship Between Teacher Performance Ratings and District Under the Ohio Teacher Evaluation System

The soundness of the Ohio Teacher Evaluation System (OTES) depends heavily on evaluators’ uniform interpretation of the qualitative Teacher Performance rubric. This study investigates the relationship between teachers’ district of employment, and the Teacher Performance ratings they receive under OTES. For Ohio districts that implemented OTES in 2012-2013, 2013-2014, and 2014-2015, the proportion of various Teacher Performance ratings and Student Growth Measures ratings are examined and compared to statewide proportions, using descriptive data and a log-linear model. Findings speak to the importance of a continued or renewed emphasis on fostering uniform interpretation and implementation of teacher evaluation rubrics and systems

Repetitive Transcranial Magnetic Stimulation Over the Left Posterior Middle Temporal Gyrus Reduces Wrist Velocity During Emblematic Hand Gesture Imitation

Results from neuropsychological studies, and neuroimaging and behavioural experiments with healthy individuals, suggest that the imitation of meaningful and meaningless actions may be reliant on different processing routes. The left posterior middle temporal gyrus (pMTG) is one area that might be important for the recognition and imitation of meaningful actions. We studied the role of the left pMTG in imitation using repetitive transcranial magnetic stimulation (rTMS) and two-person motion-tracking. Participants imitated meaningless and emblematic meaningful hand and finger gestures performed by a confederate actor whilst both individuals were motion-tracked. rTMS was applied during action observation (before imitation) over the left pMTG or a vertex control site. Since meaningless action imitation has been previously associated with a greater wrist velocity and longer correction period at the end of the movement, we hypothesised that stimulation over the left pMTG would increase wrist velocity and extend the correction period of meaningful actions (i.e., due to interference with action recognition). We also hypothesised that imitator accuracy (actor-imitator correspondence) would be reduced following stimulation over the left pMTG. Contrary to our hypothesis, we found that stimulation over the pMTG, but not the vertex, during action observation reduced wrist velocity when participants later imitated meaningful, but not meaningless, hand gestures. These results provide causal evidence for a role of the left pMTG in the imitation of meaningful gestures, and may also be in keeping with proposals that left posterior temporal regions play a role in the production of postural components of gesture

Cortical excitability correlates with the event-related desynchronization during brain-computer interface control

Objective Brain-computer interfaces (BCIs) based on motor control have been suggested as tools for stroke rehabilitation. Some initial successes have been achieved with this approach, however the mechanism by which they work is not yet fully understood. One possible part of this mechanism is a, previously suggested, relationship between the strength of the event-related desynchronization (ERD), a neural correlate of motor imagination and execution, and corticospinal excitability. Additionally, a key component of BCIs used in neurorehabilitation is the provision of visual feedback to positively reinforce attempts at motor control. However, the ability of visual feedback of the ERD to modulate the activity in the motor system has not been fully explored. Approach We investigate these relationships via transcranial magnetic stimulation delivered at different moments in the ongoing ERD related to hand contraction and relaxation during BCI control of a visual feedback bar. Main results We identify a significant relationship between ERD strength and corticospinal excitability, and find that our visual feedback does not affect corticospinal excitability. Significance Our results imply that efforts to promote functional recovery in stroke by targeting increases in corticospinal excitability may be aided by accounting for the time course of the ERD

The effect of a regular auditory context on perceived interval Duration

In the auditory domain, the perceived duration of time intervals is influenced by background sounds – the auditory context in which the intervals are embedded – even when the background may be ignored. Previous research has shown that a regular context made of evenly spaced sounds improves participants’ discrimination of intervals close in duration to the context intervals. These results have been explained in terms of attention and anticipation. The present study reconsiders the effect of context regularity, focusing on the relationships among the intervals in the context and the interval to be estimated. The influence of a regular compared to a non-regular auditory context on interval discrimination was examined with a two interval forced choice task, which required participants to discriminate between the durations of two time intervals. Duration perception was more precise when the intervals to be discriminated were preceded by a regular compared to a non-regular context. This effect of the regular context, however, was not selective for the duration of the first interval to be estimated, contrary to suggestions based on previous evidenc

The role of primary somatosensory cortex in tactile detection and discrimination: fMRI-guided TMS investigations

Introduction The contribution of the primary somatosensory cortex (SI) to the perception of tactile stimuli at the fingers is still not fully understood. In particular, while previous reports have agreed on the crucial role of SI in tactile discrimination, its role in simple detection remains controversial. The aim of the present study is to address this issue by combining the QUEST threshold estimation method in a two-interval forced choice design (2IFC), with functional and anatomical magnetic resonance imaging (MRI)-guided single and --double pulse transcranial magnetic stimulation (TMS). Methods Participants (N=7 or 12 per experiment) underwent a series of MRI scans (localisers) to produce somatotopic maps of SI. The maps were used to stimulate over SI with TMS during subsequent experiments. In six experiments, QUEST was used to establish threshold for detection or frequency discrimination for tactile stimuli (50ms, 200Hz sinusoidal vibration) applied to the middle and/or index fingertips of one hand. In Experiments 1-3 (n=12), TMS was applied as a single (75ms after stimulus onset) or a double pulse (25 and 75ms after onset) over the contralateral SI (target site), or over contralateral supramarginal gyrus (control site), or with sham TMS (coil held away from the head, no brain stimulation). In Experiments 4-6 (n=7), double pulse TMS (0 and 50ms after onset) was applied over the median nerve at the wrist (target site), or over the extensor digitorum communis of the forearm (EDC, control site), or with sham TMS (no peripheral stimulation). Finally, in Experiment 7 double pulses of TMS were applied over SI, SMG, and away from the head in a single interval “yes-no” detection task, with tactile stimuli presented at the threshold level previously determined by QUEST. Results The results showed that 2IFC frequency discrimination thresholds at the fingers were significantly increased by double-pulse TMS over SI (Figure 1a). By contrast, 2IFC detection thresholds at the fingers were not increased by either single (Figure 1c) or double (Figure 1b) pulse TMS over SI relative to SMG (Exp. 2-3). Importantly, both frequency discrimination and simple detection thresholds at the fingers were increased by both single and double-pulse TMS applied over the median nerve at the wrist, relative to the muscle control site (Exp. 4-6, see Figure 1d-f). Finally, double-pulse TMS over SI in the yes-no task decreased the participants’ sensitivity relative to TMS over SMG (Figure 2a), while TMS over both SI and SMG increased the response criterion, making participants more conservative with TMS, regardless of stimulation site (Figure 2b). Conclusions The present findings suggest that SI is required for frequency discrimination of vibrotactile stimuli at the fingers. By contrast, SI is not necessary for forced-choice detection in a criterion-free 2IFC task, whereas it is required for detection of tactile stimuli in a single interval “yes-no” task. This discrepancy suggests a different involvement (and importance) of SI in tactile processing as a function of task demands, and with respect to tactile working memory [3,4]. This dissociation reconciles previous literature on monkey [3] and humans [4,5,6]. References [1] Watson AB, & Pelli DG (1983). QUEST: A Bayesian adaptive psychometric method. Perception & Psychophysics, 33(2): 113-120. [2] Tamè L, Charlton J, & Holmes NP (in preparation). A cost effective and fast psychophysics procedure to determine tactile thresholds at the fingers. [3] Romo R, Lemus L, & De Lafuente V (2012). Sense, memory, and decision-making in the somatosensory cortical network. Current Opinion in Neurobiology, 22, 1-6. [4] Harris JA, karlov L, & Clifford CWG (2006). Localization of tactile stimuli depends on conscious detection. Journal of Neuroscience, 26(3): 948-952. [5] Jones SR, Pritchett DL, Stufflebeam SM, Hämäläinen M, & Moore CI (2007). Neural correlates of tactile detection: a combined magnetoencephalography and biophysically based computational modeling study. Journal of Neuroscience, 27(40): 10751-10764. [6] Azzopardi P, & Cowey A (1997). Is blindsight like normal, near-threshold vision? PNAS, 94, 14190-14194

The role of primary somatosensory cortex in tactile detection and discrimination: fMRI-guided TMS investigations

We used the QUEST threshold estimation method to investigate whether tactile detection and discrimination thresholds at the fingers can be modulated by transcranial magnetic stimulation (TMS) over primary somatosensory cortex (SI). Participants underwent a series of functional MRI localiser scans with vibrotactile stimulation to produce somatotopic maps of SI for each participant separately. These maps were used to stimulate over SI with TMS during subsequent behavioural tasks. The threshold estimation method QUEST was used in a two-interval forced-choice design in order to establish threshold for detecting and discriminating a tactile stimulus (50ms, 200Hz sinusoidal vibration) applied to the middle and/or index fingertips of one hand. This was done either when a single (75ms after stimulus onset) or a double pulse of TMS (25 and 75ms after onset) was applied over the contralateral SI (target site), or over the supramarginal gyrus (control site), or with sham TMS (no brain stimulation). The results showed that frequency discrimination thresholds at the fingers were increased by paired-pulse TMS over SI. By contrast, detection thresholds at the fingers were not increased by either single or paired pulse TMS over SI. The present findings suggest that SI is required for discrimination, but may not be for detection, of tactile stimuli at the fingers

Peripersonal space: a multisensory interface for body-object interactions

Research in the last four decades has brought a considerable advance in our understanding of how the brain synthesizes information arising from different sensory modalities. Indeed, many cortical and subcortical areas, beyond those traditionally considered to be ‘associative,’ have been shown to be involved in multisensory interaction and integration (Ghazanfar and Schroeder 2006). Visuo-tactile interaction is of particular interest, because of the prominent role played by vision in guiding our actions and anticipating their tactile consequences in everyday life. In this chapter, we focus on the functional role that visuo-tactile processing may play in driving two types of body-object interactions: avoidance and approach. We will first review some basic features of visuo-tactile interactions, as revealed by electrophysiological studies in monkeys. These will prove to be relevant for interpreting the subsequent evidence arising from human studies. A crucial point that will be stressed is that these visuo-tactile mechanisms have not only sensory, but also motor-related activity that qualifies them as multisensory-motor interfaces. Evidence will then be presented for the existence of functionally homologous processing in the human brain, both from neuropsychological research in brain-damaged patients and in healthy participants. The final part of the chapter will focus on some recent studies in humans showing that the human motor system is provided with a multisensory interface that allows for continuous monitoring of the space near the body (i.e., peripersonal space). We further demonstrate that multisensory processing can be modulated on-line as a consequence of interacting with objects. This indicates that, far from being passive, the monitoring of peripersonal space is an active process subserving actions between our body and objects located in the space around us