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Tsuruhara A, Nagata Y, Suzuki M, Inui K, Kakigi R. Effects of spatial frequency on visual evoked magnetic fields. Exp Brain Res 2013; 226:347-55. [DOI: 10.1007/s00221-013-3440-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 02/02/2013] [Indexed: 11/25/2022]
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Virsu V, Oksanen-Hennah H, Vedenpää A, Jaatinen P, Lahti-Nuuttila P. Simultaneity learning in vision, audition, tactile sense and their cross-modal combinations. Exp Brain Res 2008; 186:525-37. [PMID: 18183376 DOI: 10.1007/s00221-007-1254-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2006] [Accepted: 12/11/2007] [Indexed: 11/28/2022]
Abstract
Latencies of sensory neurons vary depending on stimulus variables such as intensity, contrast, distance and adaptation. Therefore, different parts of an object and simultaneous environmental events could often elicit non-simultaneous neural representations. However, despite the neural discrepancies of timing, our actions and object perceptions are usually veridical. Recent results suggest that this temporal veridicality is assisted by the so-called simultaneity constancy which actively compensates for neural timing asynchronies. We studied whether a corresponding compensation by simultaneity constancy could be learned in natural interaction with the environment without explicit feedback. Brief stimuli, whose objective simultaneity/non-simultaneity was judged, consisted of flashes, clicks or touches, and their cross-modal combinations. The stimuli were presented as two concurrent trains. Twenty-eight adult participants practised unimodal (visual, auditory and tactile) and cross-modal (audiovisual, audiotactile and visuotactile) simultaneity judgement tasks in eight sessions, two sessions per week. Effects of practice were tested 7 months later. All tasks indicated improved judgements of simultaneity that were also long-lasting. This simultaneity learning did not affect relative temporal resolution (Weber fraction). Transfer of learning between practised tasks was minimal, which suggests that simultaneity learning mechanisms are not centralised but modally specific. Our results suggest that natural perceptual learning can generate simultaneity-constancy-like phenomena in a well-differentiated and long-lasting manner and concomitantly in several sensory systems. Hebbian learning can explain how experience with environmental simultaneity and non-simultaneity can develop the veridicality of perceived synchrony.
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Affiliation(s)
- Veijo Virsu
- Department of Psychology, University of Helsinki, POBox 9, Siltavuorenpenger 20 D, 00014, Helsinki, Finland.
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Chakor H, Bertone A, McKerral M, Faubert J, Lachapelle P. Visual evoked potentials and reaction time measurements to motion-reversal luminance- and texture-defined stimuli. Doc Ophthalmol 2006; 110:163-72. [PMID: 16328924 DOI: 10.1007/s10633-005-3694-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE Previous studies have suggested that compared to first-order (FO) motion stimuli, second-order (SO) motion stimuli required more cortical time to be processed. The purpose of this study was: 1- to verify this claim with Visual Evoked Potential (VEP) and eye-hand Reaction Time (RT) measurements and 2- examine if the VEP and RT responses are similarly modulated by the same trigger features of the stimuli. METHODS The VEPs and eye-hand RT for motion-reversal luminance- (first-order) and texture-defined (second-order) stimuli were recorded from ten normal human subjects. VEPs and RTs were measured for each motion class at eight different modulation depths (from 3 to 100%). RESULTS Our results reveal that for stimuli of low contrast levels, the SO-FO timing differences are approximately 100 ms (RT) or 20 ms (VEP), while for contrasts >or= 15-20% (VEP) or >or= 50% (RT), the SO-FO difference is no longer significant (p < 0.007), suggesting either that the brain can no longer distinguish SO from FO stimuli or that in spite of the added complexity of SO stimuli the brain takes equal time to process both. CONCLUSION Interestingly, the above contrast discrepancy in SO-FO resolution threshold suggests that, compared to the VEP, the more psychophysical RT measurement can process and thus distinguish a larger spectrum of motion stimuli, thus further confirming the latter measure of the retinocortical processing time as a valid alternative to the VEP.
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Affiliation(s)
- Hadi Chakor
- Visual Psychophysics and Perception Laboratory, Ecole d'optométrie, Université de Montréal, Canada
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Saint-Amour D, Saron CD, Schroeder CE, Foxe JJ. Can whole brain nerve conduction velocity be derived from surface-recorded visual evoked potentials? Neuropsychologia 2005; 43:1838-44. [PMID: 16154459 DOI: 10.1016/j.neuropsychologia.2005.02.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 02/11/2005] [Accepted: 02/28/2005] [Indexed: 11/22/2022]
Abstract
Reed, Vernon, and Johnson [Reed, T. E., Vernon, P. A., & Johnson, A. M. (2004). Sex difference in brain nerve conduction velocity in normal humans. Neuropsychologia, 42, 1709-1714] reported that "nerve conduction velocity" (NCV) of visual transmission from retina to the primary visual area (V1) is significantly faster in males than females. The authors estimated the NCV by dividing head length (nasion-to-inion distance) by the latency of the well-known P100 component of the visual evoked potential (VEP). Here, we critically examine these metrics and we contend that knowledge of the underlying physiology of neural transmission across the initial stages of the visual processing hierarchy dictates that a number of their assumptions cannot be reasonably upheld. Alternative, and we believe, more parsimonious interpretations of the data are also proposed.
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Affiliation(s)
- Dave Saint-Amour
- The Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute for Psychiatric Research, Program in Cognitive Neuroscience and Schizophrenia, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA
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Abstract
Reaction times (RTs) are obtained for a wide range of contrasts of vertical sinusoidal gratings. The data are plotted as a function of the reciprocal of contrast. In some conditions, a single linear function accounts for the data. In others a clear bi-linear function is obtained. The low and high contrast regions of the function are interpreted as representing magno and parvo activity, respectively. RT-based supra-threshold sensitivity functions are obtained for different luminances, stimulus durations and eccentricities and these are compared with conventional threshold-based sensitivities to establish the extent to which RTs and contrast sensitivity are constrained by the same sensory processes.
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Affiliation(s)
- I J Murray
- Visual Sciences Laboratory, Department of Optometry and Neuroscience, UMIST, PO Box 88, Manchester M60 1QD, UK.
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Vassilev A, Mihaylova M, Bonnet C. On the delay in processing high spatial frequency visual information: reaction time and VEP latency study of the effect of local intensity of stimulation. Vision Res 2002; 42:851-64. [PMID: 11927350 DOI: 10.1016/s0042-6989(01)00300-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Saleh and Bonnet [Fechner Day 98, p. 344] have shown that, upon parafoveal stimulation and up to 6.5 c/deg, reaction time (RT) is a function of grating contrast multiplied by grating period. The present experiments extend these findings to foveal stimulation within a wider spatial-frequency (SF) range and to stimuli of different duration. Both RT and latency of visually evoked potentials (VEP) were measured. The findings might be explained by the following assumption: Most RT and VEP latency variations across the SF range are a result of local intensity factors (retinal contrast and width of grating bars). Residual RT variations were found that might be due to processing of high SFs by slower mechanisms than those processing low and medium SFs.
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Affiliation(s)
- Angel Vassilev
- Institute of Physiology, Bulgarian Academy of Sciences, Acad G Bonchev St Bl 23, 1113 Sofia, Bulgaria.
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Plainis S, Murray IJ. Neurophysiological interpretation of human visual reaction times: effect of contrast, spatial frequency and luminance. Neuropsychologia 2001; 38:1555-64. [PMID: 11074078 DOI: 10.1016/s0028-3932(00)00100-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Neurophysiological studies have demonstrated that in primates Magno and Parvo neurons have distinct contrast gain properties. Reaction Times (RTs) can be used to study supra-threshold contrast coding in humans over the same range of stimulus parameters. RTs to achromatic sinusoidal gratings were measured for a range of spatial frequencies (0.49-17.7 c/degree), stimulus luminances (0.005-20 cd/m2) and contrasts (from threshold to 0.5). The stimuli subtended an angle of 7.2 degrees at a viewing distance of 114 cm. RTs exhibit a linear relationship when plotted against the reciprocal of suprathreshold contrast. The slope of these functions reveals how contrast is linked to RT and can, therefore, be referred to as the RT-contrast factor with units of msec x contrast. A general equation is derived which accounts for all stimulus combinations. RT-based contrast functions resemble closely those obtained neurophysiologically for Magno (M) and Parvo (P) cells. Furthermore, the RT equivalent of contrast gain exhibits qualitatively similar gain characteristics to these neurons for a wide range of luminances and spatial frequencies. Our data support the notion that the sensory component of RTs is limited by the properties of pre-cortical neurons.
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Affiliation(s)
- S Plainis
- Department of Optometry and Neuroscience, Visual Sciences Laboratory, UMIST, PO Box 88, M60 1QD, Manchester, UK
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McKerral M, Lepore F, Lachapelle P. Response characteristics of the normal retino-cortical pathways as determined with simultaneous recordings of pattern visual evoked potentials and simple motor reaction times. Vision Res 2001; 41:1085-90. [PMID: 11301081 DOI: 10.1016/s0042-6989(01)00037-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE In an attempt to explain the existing discrepancies regarding the relationship between electrophysiological and psychophysical measurements of visual transmission time we compared, in humans, the response characteristics of the normal retino-cortical pathways with simultaneously obtained pattern visual evoked potentials (PVEP) and simple motor reaction times (RT). METHODS PVEPs and manual RTs were recorded simultaneously using a reversing checkerboard with different spatial frequency and contrast combinations chosen to elicit responses favoring the magnocellular or parvocellular pathways. The amplitude and peak time of the P1 wave of the PVEP were compared to the mean RT. Other parameters of the RT, such as mode and standard deviation were also considered. RESULTS The RT is not modified in the same fashion as the peak time of the P1 wave of the PVEP, the peak time of the PVEP demonstrating a spatial frequency selectivity, while the RT does not. Further comparative analysis of the PVEP and RT shows that the RT is faster for stimuli of lower contrast and spatial frequency, while the PVEP amplitude is larger and its peak time shorter for higher contrast and spatial frequency stimuli. CONCLUSIONS Our findings suggest that PVEP and RT measures recruit distinct physiological characteristics and appear to be differently modulated while travelling along the retino-cortical pathway. Our results also show the importance of obtaining electrophysiological and psychophysical measures concomitantly to insure elimination of combined inter-stimulus and inter-session variability.
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Affiliation(s)
- M McKerral
- Centre de réadaptation Lucie-Bruneau, Programme d'intégration dans la communauté (PIC), 2275, Avenue Laurier Est, H2H 2N8, Montréal, QC, Canada
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Galbraith GC, Chae BC, Cooper JR, Gindi MM, Ho TN, Kim BS, Mankowski DA, Lunde SE. Brainstem frequency-following response and simple motor reaction time. Int J Psychophysiol 2000; 36:35-44. [PMID: 10700621 DOI: 10.1016/s0167-8760(99)00096-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Simple motor reaction times (RT) in humans show marked trial-to-trial variations. In the present study, a brief tone (400 Hz, 37.5 ms duration) that was the imperative stimulus in a RT paradigm evoked the brainstem frequency-following response (FFR). Horizontal and vertical montage FFRs were recorded to evaluate neural responses with putative origins in auditory nerve and central brainstem, respectively. The main question concerned the possible relationship between trial-to-trial variations in RT speed and FFR response properties. The results showed a reliable pattern in which fast RT trials yielded larger amplitudes (relative to slow trials) in earlier milliseconds of the FFR, and slow RT trials yielded relatively larger amplitudes in later milliseconds of the response. These results support the conclusion that early processing in the auditory brainstem is not automatic and invariant. Rather, short-latency evoked potentials appear to reflect trial-to-trial variations related to events far removed from the first synapse of sensory coding, perhaps depending upon cortically mediated influences such as cognition or attention.
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Affiliation(s)
- G C Galbraith
- University of California, Los Angeles, School of Medicine, Mental Retardation Research Center, Los Angeles, CA, USA.
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McKerral M, Roy MS, Benoit J, Leporé F, Lachapelle P. Hemiretinal contribution to the timing of the full-field PVEP as determined with the motor reaction time. Vision Res 1997; 37:3193-9. [PMID: 9463700 DOI: 10.1016/s0042-6989(97)00117-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
With the use of the simple motor reaction time (RT), we examined the contribution of the hemiretinas to the timing of the pattern reversal visual evoked potential (PVEP). RTs were obtained to the reversal of a progressively dimmer check falling either on the central, nasal, temporal, superior or inferior retina. Results were correlated with the peak time of the P1 wave evoked to the reversal of the entire checkerboard stimulus to the same luminance conditions as that used to generate the RT measurements. Our results clearly indicate that the time taken to trigger a manual response depends not only on the luminance of the stimulus, but also on where it falls on the retina. Comparing the above data with the peak time of the PVEP obtained to the reversal of the entire screen indicates that at brighter luminance the peak time of the P1 wave correlates with that measured from the most central retina, while at dimmer intensities it correlates with the mathematical average of all the retinal locations tested.
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Affiliation(s)
- M McKerral
- Dép. de Psychologie, Université de Montréal, Québec, Canada
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Hudnell HK, Otto DA, House DE. The influence of vision on computerized neurobehavioral test scores: a proposal for improving test protocols. Neurotoxicol Teratol 1996; 18:391-400. [PMID: 8866529 DOI: 10.1016/0892-0362(96)00040-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Computerized tests of neurobehavioral function are frequently administered in neurotoxicological studies with little attention given to the optical properties of test stimuli or to the vision of subjects. Yet many test stimuli are small or briefly presented, and test endpoints often involve short reaction times. Stimulus detection and reaction time are known to be strongly dependent upon stimulus luminance, contrast, and size, as well as on the subject's visual abilities. The current study assessed the influence of visual contrast sensitivity on Neurobehavioral Evaluation System 2 (NES2) test results in three data sets. Analyses indicated that vision was associated with up to 24% of the variance (Hand Eye Coordination test) in NES2 scores, even when visual acuity was normal, and that vision often influenced the significance of group differences. It is suggested that researchers measure the luminance, contrast, and size of test stimuli, the distance from the subject's eyes to the monitor, and the subject's visual contrast sensitivity. The measurement and control of stimulus parameters and the inclusion of visual function scores in analysis models could reduce the variability among computerized test scores both within and between studies. Models that assess the influence of vision on computerized test results may help to identify the CNS domains and specialized functions adversely affected by neurotoxicant exposures.
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Affiliation(s)
- H K Hudnell
- U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711, USA.
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Hartwell RC, Cowan JD. Covariability of visually evoked potentials and simple motor reaction times. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1994; 92:487-90. [PMID: 7527766 DOI: 10.1016/0168-5597(94)90132-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Visually evoked potentials (VEPs) were recorded during simple motor reaction time (RT) experiments using spatially localized, contrast modulated visual stimuli. VEPs were averaged in groups, called "subensembles," depending on the speed of the subject's motor response. To a specific visual stimulus, the VEP response time of a subensemble covaries with motor response latency according to the same linear relationship found to describe conventionally averaged VEPs and RTs over a wide range of stimuli.
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Affiliation(s)
- R C Hartwell
- Department of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia 19104
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