Specialized and independent processing of orientation and shape in visual field maps LO1 and LO2

Silson, Edward; McKeefry, Declan J.; Rodgers, Jessica; Gouws, André; Hymers, Mark; Morland, Antony B.

doi:10.1038/nn.3327

Cited by 71 publications

(68 citation statements)

References 27 publications

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“…It would thus seem that such a hierarchical strategy for the processing of forms must be used in parallel in each of the three areas that we have studied here, and possibly in other areas of the human brain that have been shown to respond well to oriented lines and that have been implicated in form perception (Vanduffel et al, 2002; Zeki et al, 2003; Fang et al, 2005; Larsson et al, 2010; McDonald et al, 2010). Recent results suggest that a parallel strategy is also used in the object-selective lateral occipital area (Silson et al, 2013). There remains the puzzle of why it is that angles produced the strongest activation in each of the three visual areas, a problem for which we have no ready answer.…”

Section: Discussionmentioning

confidence: 99%

Parallel processing in the brain's visual form system: an fMRI study

Shigihara

Zeki

2014

Front. Hum. Neurosci.

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We here extend and complement our earlier time-based, magneto-encephalographic (MEG), study of the processing of forms by the visual brain (Shigihara and Zeki, 2013) with a functional magnetic resonance imaging (fMRI) study, in order to better localize the activity produced in early visual areas when subjects view simple geometric stimuli of increasing perceptual complexity (lines, angles, rhombuses) constituted from the same elements (lines). Our results show that all three categories of form activate all three visual areas with which we were principally concerned (V1–V3), with angles producing the strongest and rhombuses the weakest activity in all three. The difference between the activity produced by angles and rhombuses was significant, that between lines and rhombuses was trend significant while that between lines and angles was not. Taken together with our earlier MEG results, the present ones suggest that a parallel strategy is used in processing forms, in addition to the well-documented hierarchical strategy.

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Section: Discussionmentioning

confidence: 99%

Parallel processing in the brain's visual form system: an fMRI study

Shigihara

Zeki

2014

Front. Hum. Neurosci.

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“…This navigation system makes use of functional and structural MRI data of each participant individually (for LO and V5/HMT + mapping specifications, see below) enabling accurate positioning of the center of the coil over either right LO or right V5/MT. Accurately monitoring the position of the TMS coil with a navigation system has allowed researchers to even successfully target subregions of LO (LO1 and LO2) recently (Silson et al, 2013). During stimulation participants were seated in a chin rest for optimal stability while using a holder to fixate the coil (Rogue Research).…”

Section: Rtms Protocolmentioning

confidence: 99%

Opposing Dorsal/Ventral Stream Dynamics during Figure-ground Segregation

Wokke

Scholte²,

Lamme³

2014

Journal of Cognitive Neuroscience

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The visual system has been commonly subdivided into two segregated visual processing streams: The dorsal pathway processes mainly spatial information, and the ventral pathway specializes in object perception. Recent findings, however, indicate that different forms of interaction (cross-talk) exist between the dorsal and the ventral stream. Here, we used TMS and concurrent EEG recordings to explore these interactions between the dorsal and ventral stream during figure-ground segregation. In two separate experiments, we used repetitive TMS and single-pulse TMS to disrupt processing in the dorsal (V5/HMT⁺) and the ventral (lateral occipital area) stream during a motion-defined figure discrimination task. We presented stimuli that made it possible to differentiate between relatively low-level (figure boundary detection) from higher-level (surface segregation) processing steps during figure-ground segregation. Results show that disruption of V5/HMT⁺ impaired performance related to surface segregation; this effect was mainly found when V5/HMT⁺ was perturbed in an early time window (100 msec) after stimulus presentation. Surprisingly, disruption of the lateral occipital area resulted in increased performance scores and enhanced neural correlates of surface segregation. This facilitatory effect was also mainly found in an early time window (100 msec) after stimulus presentation. These results suggest a "push-pull" interaction in which dorsal and ventral extrastriate areas are being recruited or inhibited depending on stimulus category and task demands.

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“…This design was employed to disrupt brain activity at two main processing time-points: 1) during target appearance and 2) during the inter-trial delay between sequence presentations. Delivery of TMS at time point 1 was used to disrupt the encoding or acquisition of the stimuli using a temporal configuration similar to that used in previous studies where disruption to the encoding of different categories of visual stimuli has been shown to be maximised when TMS pulses are delivered coincidently with stimulus onset (McKeefry, Burton, Vakrou, Barrett & Morland, 2008;Pitcher, Charles, Devlin, Walsh & Duchaine, 2009;Silson, McKeefry, Rodgers, Gouws, Hymers & Morland, 2013). Concurrent stimulation of this nature also minimizes interfence with the normal saccadic response to each target, as TMS delivered after 100ms from target onset tends to cause disruption of the motor response (Schluter, Rushworth, Passingham & Mills, 1998), which can confound any earlier encoding effects.…”

Section: Tms Protocolmentioning

confidence: 99%

The contribution of the right supra-marginal gyrus to sequence learning in eye movements

et al. 2013

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We investigated the role of the human right Supra-Marginal Gyrus (SMG) in the generation of learned eye movement sequences. Using MRI-guided transcranial magnetic stimulation (TMS) we disrupted neural activity in the SMG whilst human observers performed saccadic eye movements to multiple presentations of either predictable or random target sequences. For the predictable sequences we observed shorter saccadic latencies from the second presentation of the sequence. However, these anticipatory improvements in performance were significantly reduced when TMS was delivered to the right SMG during the inter-trial retention periods. No deficits were induced when TMS was delivered concurrently with the onset of the target visual stimuli. For the random version of the task, neither delivery of TMS to the SMG during the inter-trial period nor during the presentation of the target visual stimuli produced any deficit in performance that was significantly different from the no-TMS or control conditions. These findings demonstrate that neural activity within the right SMG is causally linked to the ability to perform short latency predictive saccades resulting from sequence learning. We conclude that neural activity in rSMG constitutes an instruction set with spatial and temporal directives that are retained and subsequently released for predictive motor planning and responses.3

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Specialized and independent processing of orientation and shape in visual field maps LO1 and LO2

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Cited by 71 publications

References 27 publications

Parallel processing in the brain's visual form system: an fMRI study

Parallel processing in the brain's visual form system: an fMRI study

Opposing Dorsal/Ventral Stream Dynamics during Figure-ground Segregation

The contribution of the right supra-marginal gyrus to sequence learning in eye movements

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