Human V5 demonstrated by magnetoencephalography using random dot kinematograms of different coherence levels
Introduction
To understand the cortical mechanisms of human motion perception, it is important to detect response variables specific to the characteristics of visual stimuli. It has been widely accepted that human V5 is activated by moving stimuli (Zeki et al., 1991, Sunaert et al., 1999, Ahlfors et al., 1999). Human V5 is located posterior to the junction of the ascending limb of the inferior temporal and lateral occipital sulci (Zeki et al., 1991) and contains a high concentration of neurons that are sensitive to the speed and orientation of motion stimulus (Zeki, 1978, Baker et al., 1981, Maunsell and Van Essen, 1983, Albright, 1984). Human V5 can detect the direction of movement of many dots in which only a small portion moves coherently, while the remaining portion moves incoherently (Baker et al., 1991, Newsome and Pare, 1988). In this case, the motion of each dot must first be detected in the local area then integrated in a large spatial scale (Williams and Sekuler, 1984). Thus, random dot kinematograms (RDKs) can be appropriate stimuli for eliciting this kind of perception. As for the orientation of stimulus motion, there are a few studies that investigated the relationship between brain responses and coherence levels of the motion using functional magnetic resonance imaging (fMRI) or visual evoked potential (VEP) (Heeger et al., 2000, Rees et al., 2000, Niedeggen and Wist, 1999). However, these data might not have provided sufficient information due to the limitation in terms of temporal or spatial resolution. However, magnetoencephalography (MEG) has a high spatial and temporal resolution on the order of mm and ms, respectively. It also allows the tracking of weak evoked responses from more concentrated brain regions compared with the EEG technique, since the skull is transparent to magnetic fields but not to electric fields (Malmivuo et al., 1997). Despite these advantages, there are few MEG studies that investigated the correlation between brain response and coherence levels. Therefore, our present experiment used changing coherence levels to more systematically investigate the effects of coherent motion on transient evoked cortical responses in humans.
Section snippets
Subjects
Eight healthy right-handed subjects (six men and two women) with no ophthalmologic or neurological abnormality participated in this study. Handedness was evaluated by the Edinburgh Handedness Inventory (mean±S.D., LQ=0.96±0.077). Their ages ranged from 22 to 35 (mean±S.D., 30.4±5.7) years. All subjects had normal or corrected-to-normal visual acuity at the time of this study. Informed consent was obtained from each subject after a full explanation of the experiment.
Visual stimulation
We used RDKs for visual
Waveforms of magnetic fields evoked by coherent dot motion
Fig. 2A shows magnetic responses of one subject (S2) induced by horizontal coherent motion with 100% coherence level. A mono phasic peak was recognized over the bilateral temporo-parietal area and the middle occipital area. Fig. 2B shows the largest channel from both hemispheres and represents the magnetic responses at three coherence levels (50, 70, 100%). The peak was 20.8 fT/cm in amplitude at 244 ms for 50% coherence level, 21.6 fT/cm at 229 ms for 70% and 42.9 fT/cm at 211 ms for 100% in
Discussion
We investigated visual human motion perception with MEG by presenting dot motion at three different coherence levels. Since the first ECD locations were estimated in a consistent area within the extrastriate region of each hemisphere irrespective of coherence levels and no additional ECDs were detected in this area, the use of RMS over the temporal area was appropriate to represent local neuronal activity for intra-subject comparisons. Therefore, we could compare cortical activities even when
Acknowledgements
This study was partly supported by Grants-in-Aids for Scientific Research on Priority Area (C) (Advanced Brain Science) 12210012 from the Japan Ministry of Education, Culture, Sports, Science and Technology.
References (32)
- et al.
Perimetric motion thresholds are elevated in glaucoma suspects and glaucoma patients
Vision Res.
(1997) - et al.
The development of hemispheric asymmetry in human motion VEPs
Vision Res.
(2000) - et al.
Magnetic response of human extrastriate cortex in the detection of coherent and incoherent motion
Neuroscience
(2000) - et al.
Visual evoked potentials to stimuli in apparent motion
Vision Res.
(1988) - et al.
Human cortical responses to coherent and incoherent motion as measured by magnetoencephalography
Neurosci. Res.
(2002) - et al.
Characteristics of visual evoked potentials generated by motion coherence onset
Cogn. Brain Res.
(1999) - et al.
Coherent global motion percepts from stochastic local motions
Vision Res.
(1984) - et al.
Spatiotemporal activity of a cortical network for processing visual motion revealed by MEG and fMRI
J. Neurophysiol.
(1999) Direction and orientation selectivity of neurons in visual area MT of the macaque
J. Neurophysiol.
(1984)- et al.
Visual response properties of neurons in four extrastriate visual areas of the owl monkey (Aotus trivirgatus): a quantitative comparison of medial, dorsomedial, dorsolateral, and middle temporal areas
J. Neurophysiol.
(1981)
Residual motion perception in a “motion-blind” patient, assessed with limited-lifetime random dot stimuli
J. Neurosci.
Responses of neurons in macaque MT to stochastic motion signals
Vis. Neurosci.
Neuronal and psychophysical sensitivity to motion signals in extrastriate area MST of the macaque monkey
J. Neurosci.
Human area V5 and motion in the ipsilateral visual field
Eur. J. Neurosci.
Spikes versus BOLD: what does neuroimaging tell us about neuronal activity
Nat. Neurosci.
Properties of visual evoked potentials to onset of movement on a television screen
Doc. Ophthalmol.
Cited by (60)
Motion processing after sight restoration: No competition between visual recovery and auditory compensation
2018, NeuroImageCitation Excerpt :For the visual global motion and for the sound motion EEG experiment there were two levels for condition: (1) Low coherence was defined as the average of 30 and 50% and High coherence was defined as the average of 70 and 90%; (2) for the sound motion EEG experiment Low SNR was defined as the average of SNR levels 1 and 2 and High SNR as the average of SNR levels 3 and 4. In order to test whether each group displayed a modulation of the ERPs by motion coherence (e.g. Niedeggen and Wist, 1999; Nakamura et al., 2003) a series of three within-group cluster permutation analysis (Maris and Oostenveld, 2007) was performed for 80 ms time-windows centered on each group N1 peak latency by comparing Low (average between 30 and 50% coherence) and High (70 and 90% coherence) motion coherence levels. To compensate for interindividual differences in latency, the N1 peak latencies were assessed semi-automatically for each single participant using a custom made Matlab program.
Differential electrophysiological responses to biological motion in children and adults with and without autism spectrum disorders
2014, Research in Autism Spectrum Disorders