Transcranial magnetic stimulation to lateral occipital cortex disrupts object ensemble processing

AbstractPrevious research modeling EEG, fMRI and behavioral data has identified three spatially distributed brain networks that activate in temporal sequence, and are thought to enable perceptual decision-making during face-versus-car categorization. These studies have linked late activation (>300ms post stimulus onset) in the lateral occipital cortex (LOC) to object discrimination processes. We applied paired-pulse transcranial magnetic stimulation (ppTMS) to LOC at different temporal latencies with the specific prediction, based on these studies, that ppTMS beginning at 400ms after stimulus onset would slow reaction time (RT) performance. Thirteen healthy adults performed a two-alternative forced choice task selecting whether a car or face was present on each trial amidst visual noise pre-titrated to approximate 79% accuracy. ppTMS, with pulses separated by 50ms, was applied at one of five stimulus onset asynchronies: -200, 200, 400, 450, or 500ms, and a sixth no-stimulation condition. As predicted, TMS at 400ms resulted in significant slowing of RTs, providing causal evidence in support of LOC contribution to perceptual decision processing. In addition, TMS delivered at -200ms resulted in faster RTs, indicating early stimulation may result in performance enhancement. These findings build upon correlational EEG and fMRI observations and demonstrate the use of TMS in predictive validation of psychophysiological models.

Download Full-text

Transcranial magnetic stimulation entrains alpha oscillatory activity in occipital cortex

Scientific Reports ◽

10.1038/s41598-021-96849-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yong-Jun Lin ◽

Lavanya Shukla ◽

Laura Dugué ◽

Antoni Valero-Cabré ◽

Marisa Carrasco

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Cortical Excitability ◽

Time Windows ◽

Oscillation Amplitude ◽

Occipital Cortex ◽

Oscillatory Activity ◽

Input Frequency ◽

Oscillation Phase ◽

Frequency Specificity

AbstractParieto-occipital alpha rhythms (8–12 Hz) underlie cortical excitability and influence visual performance. Whether the synchrony of intrinsic alpha rhythms in the occipital cortex can be entrained by transcranial magnetic stimulation (TMS) is an open question. We applied 4-pulse, 10-Hz rhythmic TMS to entrain intrinsic alpha oscillators targeting right V1/V2, and tested four predictions with concurrent electroencephalogram (EEG): (1) progressive enhancement of entrainment across time windows, (2) output frequency specificity, (3) dependence on the intrinsic oscillation phase, and (4) input frequency specificity to individual alpha frequency (IAF) in the neural signatures. Two control conditions with an equal number of pulses and duration were arrhythmic-active and rhythmic-sham stimulation. The results confirmed the first three predictions. Rhythmic TMS bursts significantly entrained local neural activity. Near the stimulation site, evoked oscillation amplitude and inter-trial phase coherence (ITPC) were increased for 2 and 3 cycles, respectively, after the last TMS pulse. Critically, ITPC following entrainment positively correlated with IAF rather than with the degree of similarity between IAF and the input frequency (10 Hz). Thus, we entrained alpha-band activity in occipital cortex for ~ 3 cycles (~ 300 ms), and IAF predicts the strength of entrained occipital alpha phase synchrony indexed by ITPC.

Download Full-text

Excitability of Visual V1-V2 and Motor Cortices To Single Transcranial Magnetic Stimuli in Migraine: A Reappraisal Using A Figure-Of-Eight Coil

Cephalalgia ◽

10.1046/j.1468-2982.2003.00475.x ◽

2003 ◽

Vol 23 (4) ◽

pp. 264-270 ◽

Cited By ~ 66

Author(s):

V Bohotin ◽

A Fumai ◽

M Vandenheede ◽

C Bohotin ◽

J Schoenen

Keyword(s):

Visual Cortex ◽

Transcranial Magnetic Stimulation ◽

Healthy Volunteers ◽

Migraine Attack ◽

Magnetic Stimulation ◽

Occipital Cortex ◽

Motor Threshold ◽

Phosphene Threshold

We used transcranial magnetic stimulation (TMS) with a figure-of-eight coil to excite motor and visual V1-V2 cortices in patients suffering from migraine without (MO) ( n = 24) or with aura (MA) ( n = 13) and in healthy volunteers (HV) ( n = 33). Patients who had a migraine attack within 3 days before or after the recordings were excluded. All females were recorded at mid-cycle. Single TMS pulses over the occipital cortex elicited phosphenes in 64% of HV, 63% of MO and 69% of MA patients. Compared with HV, the phosphene threshold was significantly increased in MO ( P = 0.001) and in MA ( P = 0.007), but there was no difference between the two groups of migraineurs. The motor threshold tended to be higher in both migraine groups than in HV, but the differences were not significant. In conclusion, this study shows that two-thirds (64.86%) of patients affected by either migraine type present an increased phosphene threshold in the interictal period, which suggests that their visual cortex is hypoexcitable.

Download Full-text

Modulation of visual hallucinations originating from deafferented occipital cortex by robotized transcranial magnetic stimulation

Clinical Neurophysiology ◽

10.1016/j.clinph.2020.04.009 ◽

2020 ◽

Vol 131 (8) ◽

pp. 1728-1730

Author(s):

Brice Passera ◽

Sylvain Harquel ◽

Laurent Vercueil ◽

Michel Dojat ◽

Arnaud Attye ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Occipital Cortex ◽

Visual Hallucinations

Download Full-text

Non-predictive online spatial coding in the posterior parietal cortex when aiming ahead for catching

10.1101/197160 ◽

2017 ◽

Author(s):

Sinéad A. Reid ◽

Joost C. Dessing

Keyword(s):

Transcranial Magnetic Stimulation ◽

Parietal Cortex ◽

Magnetic Stimulation ◽

Posterior Parietal Cortex ◽

Target Position ◽

Occipital Cortex ◽

Spatial Coding ◽

Posterior Parietal ◽

First Time

Catching movements must be aimed ahead of the moving ball, which may require predictions of when and where to catch. Here, using Transcranial Magnetic Stimulation we show for the first time that, although interception movements were clearly aimed at the predicted final target position, the Superior Parietal Occipital Cortex (SPOC) displayed non-predictive online spatial coding. The ability to aim ahead for catching must thus arise downstream within the parietofrontal network for reaching.

Download Full-text

The Threshold for Phosphenes is Lower in Migraine

Cephalalgia ◽

10.1046/j.1468-2982.2003.00471.x ◽

2003 ◽

Vol 23 (4) ◽

pp. 258-263 ◽

Cited By ~ 79

Author(s):

SK Aurora ◽

KMA Welch ◽

F Al-Sayed

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Occipital Cortex ◽

Logrank Test ◽

Clinical Observations ◽

Blinded Study ◽

Visual Phenomena ◽

Preliminary Study ◽

The Difference ◽

Normal Controls

We have reported a preliminary study confirming hyperexicitability of occipital cortex in migraine with aura (MwA) using transcranial magnetic stimulation (TMS). We have now completed a blinded study to investigate the occipital cortex in MwA and without aura (MwoA) compared with normal controls (NC) using TMS. TMS was performed using the Caldwell MES-10 stimulator. A circular coil 9.5 cm diameter was applied to the occipital scalp (7 cm above the inion). Stimulator intensity was increased in 10% increments until subjects reported visual phenomena or 100% intensity was reached. Stimulation intensity was then fine tuned to determine the threshold at which phosphenes were seen. Fisher's exact t-test and logrank test were used for statistical comparisons. Ten subjects with MwA and MwoA were compared to 10 NC. The difference in the proportion of subjects with phosphene generation was statistically significant (MwA 100%, MwoA 60% and NC 30%) [ P = 0.003]. The difference in threshold levels for phosphenes was also significant for MwA 42.8%, and controls 57.3% [ P = 0.0001]. There is a difference in threshold for excitability of occipital cortex in MwA and MwoA compared to NC. This is a direct neurophysiological correlate for clinical observations, which have inferred hyperexicitability of the occipital cortex in migraineurs.

Download Full-text

Involvement of the Superior Temporal Cortex and the Occipital Cortex in Spatial Hearing: Evidence from Repetitive Transcranial Magnetic Stimulation

Journal of Cognitive Neuroscience ◽

10.1162/089892904970834 ◽

2004 ◽

Vol 16 (5) ◽

pp. 828-838 ◽

Cited By ~ 44

Author(s):

Jörg Lewald ◽

Ingo G. Meister ◽

Jürgen Weidemann ◽

Rudolf Töpper

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Spatial Information ◽

Repetitive Transcranial Magnetic Stimulation ◽

Spatial Hearing ◽

Occipital Cortex ◽

Neural Representation ◽

Auditory Information ◽

Visual Spatial ◽

The Right

The processing of auditory spatial information in cortical areas of the human brain outside of the primary auditory cortex remains poorly understood. Here we investigated the role of the superior temporal gyrus (STG) and the occipital cortex (OC) in spatial hearing using repetitive transcranial magnetic stimulation (rTMS). The right STG is known to be of crucial importance for visual spatial awareness, and has been suggested to be involved in auditory spatial perception. We found that rTMS of the right STG induced a systematic error in the perception of interaural time differences (a primary cue for sound localization in the azimuthal plane). This is in accordance with the recent view, based on both neurophysio-logical data obtained in monkeys and human neuroimaging studies, that information on sound location is processed within a dorsolateral “where” stream including the caudal STG. A similar, but opposite, auditory shift was obtained after rTMS of secondary visual areas of the right OC. Processing of auditory information in the OC has previously been shown to exist only in blind persons. Thus, the latter finding provides the first evidence of an involvement of the visual cortex in spatial hearing in sighted human subjects, and suggests a close interconnection of the neural representation of auditory and visual space. Because rTMS induced systematic shifts in auditory lateralization, but not a general deterioration, we propose that rTMS of STG or OC specifically affected neuronal circuits transforming auditory spatial coordinates in order to maintain alignment with vision.

Download Full-text