The contribution of LM to the neuroscience of movement vision (original) (raw)
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Proceedings of the National Academy of Sciences, 2004
Biological motion'' may be defined by the pattern of movement of a small number of lights attached to the major joints of a human performing simple actions. Normal observers watching such displays immediately recognize a person and his or her actions. In the present study, we investigated the effects of lesions of anterior cortical regions on the perception of biological motion. We measured the performance on psychophysical static and motion tasks and on object and action recognition tests in four stroke patients who presented with a disorder of recognition of biological motion. We relate our results to the finding that neurons in the rostral part of the superior temporal gyrus (the superior temporal polysensory area) respond selectively to biological motion, and to the idea that the superior temporal polysensory area integrates the late stages of the dorsal and ventral cortical visual streams, as well as to recent functional MRI studies on biological motion.
Brain, 2001
We used a psychophysical task to measure sensitivity to the occipitoparietal and parietotemporal areas involving the human analogue of areas MT/V5 and MST, but not motion direction in 50 stroke patients with unilateral by lesions in the occipito-temporal or anterior frontal brain lesions and 85 control subjects. Subjects were asked areas. Patients with lesions involving the anterior temporal to discriminate the overall direction of motion in dynamic or parietal lobes displayed poor performance for stimuli stochastic random dot displays in which only a variable presented in either visual field, which is consistent with proportion of the spots moved in a single direction the large and bilateral receptive fields in these areas in while the remainder moved randomly. Behavioural and monkeys. The perception of global motion was also more neurophysiological evidence shows that the middle impaired in the centripetal than the centrifugal direction temporal (MT/V5) and middle superior temporal (MST) in the hemifield contralateral to the MT/V5 lesion. areas in the macaque monkey are indispensably involved Surprisingly, thresholds were normal in all patients when in the perception of this type of motion. In human subjects the displays contained static but not dynamic visual noise, too, lesions in the same region disrupt performance on this suggesting that their deficit reflects an inability to filter task. Here we assessed more extensively the correlation out dynamic noise. Although frequent repeated testing of between direction sensitivity for global motion and the some patients whose lesion involved the human homologue anatomical locus of the lesion. Thresholds for perceiving of MT was accompanied by an improvement in the direction of global motion were impaired in the visual performance, this was no greater than in other patients who received training on different motion tasks. field contralateral to the lesion in patients with lesions in Keywords: brain damage; motion processing; visual areas Abbreviations: fMRI ϭ functional MRI; MCT ϭ motion coherence task; MST ϭ middle superior temporal; MT ϭ middle temporal
Residual Perception of Biological Motion in Cortical Blindness
Neuropsychologia, 2016
From birth, the human visual system shows a remarkable sensitivity for perceiving biological motion. 2 This visual ability relies on a distributed network of brain regions and can be preserved even after 3 damage of high-level ventral visual areas. However, it remains unknown whether this critical 4 biological skill can withstand the loss of vision following bilateral striate damage. To address this 5 question, we tested the categorization of human and animal biological motion in BC, a rare case of 6 cortical blindness after anoxia-induced bilateral striate damage. The severity of his impairment, 7 encompassing various aspects of vision (i.e., color, shape, face, and object recognition) and causing 8 blind-like behavior, contrasts with a residual ability to process motion. We presented BC with static or 9 dynamic point-light displays (PLDs) of human or animal walkers. These stimuli were presented either 10 individually, or in pairs in two alternative forced choice (2AFC) tasks. When confronted with 11 individual PLDs, the patient was unable to categorize the stimuli, irrespective of whether they were 12 static or dynamic. In the 2AFC task, BC exhibited appropriate eye movements towards diagnostic 13 information, but performed at chance level with static PLDs, in stark contrast to his ability to 14 efficiently categorize dynamic biological agents. This striking ability to categorize biological motion 15 provided top-down information is important for at least two reasons. Firstly, it emphasizes the 16 importance of assessing patients' (visual) abilities across a range of task constraints, which can reveal 17 potential residual abilities that may in turn represent a key feature for patient rehabilitation. Finally, 18 our findings reinforce the view that the neural network processing biological motion can efficiently 19 operate despite severely impaired low-level vision, positing our natural predisposition for processing 20 dynamicity in biological agents as a robust feature of human vision.
A motion area in human visual cortex
Proceedings of the National Academy of Sciences, 1995
We have localized an area in the human brain involved in the processing of contours defined by motion differences (kinetic contours) by comparing with positron emission tomography the regional cerebral blood flow in tasks performed with kinetic and luminance-defined gratings. These tasks included passive viewing, counting the total number of grating stimuli, and counting the number of gratings of a given orientation. Comparison between the counting tasks and passive viewing with a given type of contour revealed a set of active areas that were similar for both luminance-defined and kinetic contours. Comparisons between these two types of contours revealed a single focus in the right hemisphere that did not overlap with the many regions activated by uniform motion. In particular this "kinetic focus" was clearly separated from the area previously defined as the human homologue of V5/middle temporal. Activity in this kinetic focus was stronger when orientation had to be processed than in the other two tasks. These results and control experiments with uniformly moving random dot patterns suggest the existence of an area in the human visual system that is activated much more by kinetic contours than by luminance contours or uniformly moving random dots. Up to now, such an area has not been described in the monkey visual system.
The brain activity related to residual motion vision in a patient with bilateral lesions of V5
Brain, 1994
We have used the technique of PET to chart the cortical areas activated by visual motion in the brain of a patient with a severe impairment in the ability to recognize the motion of objects (akinetopsia), following bilateral lesions which have so far been presumed to include area V5. High resolution MRI of her brain showed that the zone occupied by area V5 had indeed been destroyed bilaterally. Positron emission tomography activation images, co-registered to the MRls, showed three principal regions of the cortex activated by motion. These were located (i) bilaterally in the precuneus of superior parietal cortex (area 7 of Brodmann); (ii) bilaterally in the cuneus (a region considered to represent upper V3); (Hi) in the left lingual and fusiform gyri (possibly lower V3 and adjacent areas). In contrast to normal subjects, there was no significant activation of area VI or V2. The stimuli used for scanning were chosen by prior testing of the patient's visual capacities. The control stimulus was a static random distribution of light squares on a dark background. In the moving stimulus these squares moved coherently, the direction of motion changing periodically between the cardinal directions (left, right, up and down). It was ascertained that the patient could correctly identify these directions. We also found (i) that her occasional errors were always in the direction opposite to the motion presented, so that her identification of axis of motion (i.e. vertical or horizontal) was 100% correct; (ii) that when a few static squares were added to the moving display her identification of direction fell to chance but her identification of the axis of motion remained 100%; (Hi) that when a few squares moving opposite and orthogonal to the predominant direction of motion were incorporated, her performance on both direction and axis fell to chance; (iv) that she was unable to identify motion in oblique directions between the horizontal or vertical axes, always guessing one of the cardinal directions. In accounting for her residual vision in terms of cortex which remains active, we hypothesize: (i) that the bilateral loss of V5 has affected direction sensitive mechanisms at other sites in the cortex which are interconnected with V5 and (ii) that in consequence her performance on our tests reflects the properties of dynamic orientation selective mechanisms that were also differentially activated by the stimuli used during scanning.
Experimental Brain Research 171 Pp 558 562, 2006
Several published single case studies reveal a double dissociation between the eVects of brain damage in separate extra-striate cortical visual areas on the perception of global visual motion deWned by a diVerence in luminance (Wrst-order motion) versus motion deWned by a diVerence in contrast (second-order motion). In particular, the medial extrastriate cortical region V2/V3 seems to be crucial for the perception of Wrst-order motion, but not for second-order, whereas a lateral and more anterior portion of the cortex close to the temporo-parietooccipital junction (in the territory of the human motion area hV5/MT + ) seems to be essential only for the perception of second-order motion. In order to test the hypothesis of a functional specialization of diVerent visual areas for diVerent types of motion, we applied repetitive transcranial magnetic stimulation (rTMS) unilaterally over areas V2/V3, V5/MT, or posterior parietal cortex (PPC) while subjects performed a 2AFC task with Wrstor second-order global motion displays in the contralateral visual Weld. Results showed a comparable disruption of the two types of motion, with both rTMS over V2/V3 or over MT/V5, and little or no eVect with rTMS over PPC. The results suggest that either the previous psychophysical results with neurological patients are incorrect (highly unlikely) or that the lateral and medial regions are directly connected (as they are in macaque monkeys) such that stimulating one automatically aVects the other, in this instance disruptively
The selective impairment of the perception of first-order motion by unilateral cortical brain damage
Visual Neuroscience, 1998
First-order (Fourier) motion consists of stable spatiotemporal luminance variations. Second-order (non-Fourier) motion consists instead of spatiotemporal modulation of contrast, flicker, or spatial frequency. In spite of extensive psychophysical and computational analysis of the nature and relationship of these two types of motion, it remains unclear whether they are detected by the same mechanism or whether separate mechanisms are involved. Here we report the selective impairment of first-order motion, on a range of local and global motion tasks, in the contralateral visual hemifield of a patient with unilateral brain damage centered on putative visual areas V2 and V3 in the medial part of the occipital lobe. His perception of second-order motion was unimpaired. As his disorder is the obverse of that reported after damage in the vicinity of human visual area MT (V5), the results support models of motion processing in which first-and second-order motion are, at least in part, computed separately at the extrastriate cortical level.
The role of human ventral visual cortex in motion perception
Brain, 2013
Visual motion perception is fundamental to many aspects of visual perception. Visual motion perception has long been associated with the dorsal (parietal) pathway and the involvement of the ventral 'form' (temporal) visual pathway has not been considered critical for normal motion perception. Here, we evaluated this view by examining whether circumscribed damage to ventral visual cortex impaired motion perception. The perception of motion in basic, non-form tasks (motion coherence and motion detection) and complex structure-from-motion, for a wide range of motion speeds, all centrally displayed, was assessed in five patients with a circumscribed lesion to either the right or left ventral visual pathway. Patients with a right, but not with a left, ventral visual lesion displayed widespread impairments in central motion perception even for non-form motion, for both slow and for fast speeds, and this held true independent of the integrity of areas MT/V5, V3A or parietal regions. In contrast with the traditional view in which only the dorsal visual stream is critical for motion perception, these novel findings implicate a more distributed circuit in which the integrity of the right ventral visual pathway is also necessary even for the perception of non-form motion.