Visual Perception; Processing in the Brain
Vision Res 1999 Aug;39(16):2749-66
Motion detection in insect orientation and navigation.
Srinivasan MV, Poteser M, Kral K
Centre for Visual Science, Research School of Biological Sciences, Australian National University, Canberra, Australia. m.srinivasan@anu.edu.au
The visual systems of insects are exquisitely sensitive to motion. Over the past 40 years or so, motion processing in insects has been studied and characterised primarily through the optomotor response. This response, which is a turning response evoked by the apparent movement of the visual environment, serves to stabilise the insect's orientation with respect to the environment. Research over the past decade, however, is beginning to reveal the existence of a variety of other behavioural responses in insects, that use motion information in different ways. Here we review some of the recently characterised behaviours, describe the inferred properties of the underlying movement-detecting processes, and propose modified or new models to account for them.
J Opt Soc Am A Opt Image Sci Vis 1999 May;16(5):953-78
Neural model of first-order and second-order motion perception and magnocellular dynamics.
Baloch AA, Grossberg S, Mingolla E, Nogueira CA
Department of Cognitive and Neural Systems, Boston University, Massachusetts 02215, USA.
A neural model of motion perception simulates psychophysical data concerning first-order and second-order motion stimuli, including the reversal of perceived motion direction with distance from the stimulus (gamma display), and data about directional judgments as a function of relative spatial phase or spatial and temporal frequency. Many other second-order motion percepts that have ascribed to a second non-Fourier processing stream can also be explained in the model by interactions between ON and OFF cells within a single, neurobiologically interpreted magnocellular processing stream. Yet other percepts may be traced to interactions between form and motion processing streams, rather than to processing within multiple motion processing streams. The model hereby explains why monkeys with lesions of the parvocellular layers, but not of the magnocellular layers, of the lateral geniculate nucleus (LGN) are capable of detecting the correct direction of second-order motion, why most cells in area MT are sensitive to both first-order and second-order motion, and why after 2-amino-4-phosphonobutyrate injection selectively blocks retinal ON bipolar cells, cortical cells are sensitive only to the motion of a moving bright bar's trailing edge. Magnocellular LGN cells show relatively transient responses, whereas parvocellular LGN cells show relatively sustained responses. Correspondingly, the model bases its directional estimates on the outputs of model ON and OFF transient cells that are organized in opponent circuits wherein antagonistic rebounds occur in response to stimulus offset. Center-surround interactions convert these ON and OFF outputs into responses of lightening and darkening cells that are sensitive both to direct inputs and to rebound responses in their receptive field centers and surrounds. The total pattern of activity increments and decrements is used by subsequent processing stages (spatially short-range filters, competitive interactions, spatially long-range filters, and directional grouping cells) to determine the perceived direction of motion.
How does the cerebral cortex work? Learning, attention, and grouping by the laminar circuits of visual cortex.
Grossberg S
Department of Cognitive and Neural Systems and Center for Adaptive Systems, Boston University, MA 02215, USA.
The organization of neocortex into layers is one of its most salient anatomical features. These layers include circuits that form functional columns in cortical maps. A major unsolved problem concerns how bottom-up, top-down, and horizontal interactions are organized within cortical layers to generate adaptive behaviors. This article models how these interactions help visual cortex to realize: (i) the binding process whereby cortex groups distributed data into coherent object representations; (ii) the attentional process whereby cortex selectively processes important events; and (iii) the developmental and learning processes whereby cortex shapes its circuits to match environmental constraints. New computational ideas about feedback systems suggest how neocortex develops and learns in a stable way, and why top-down attention requires converging bottom-up inputs to fully activate cortical cells, whereas perceptual groupings do not.
Single units and visual cortical organization.
Lennie P
Center for Visual Science, University of Rochester, NY 14627, USA. pl@cvs.rochester.edu
The visual system has a parallel and hierarchical organization, evident at every stage from the retina onwards. Although the general benefits of parallel and hierarchical organization in the visual system are easily understood, it has not been easy to discern the function of the visual cortical modules. I explore the view that striate cortex segregates information about different attributes of the image, and dispatches it for analysis to different extrastriate areas. I argue that visual cortex does not undertake multiple relatively independent analyses of the image from which it assembles a unified representation that can be interrogated about the what and where of the world. Instead, occipital cortex is organized so that perceptually relevant information can be recovered at every level in the hierarchy, that information used in making decisions at one level is not passed on to the next level, and, with one rather special exception (area MT), through all stages of analysis all dimensions of the image remain intimately coupled in a retinotopic map. I then offer some explicit suggestions about the analyses undertaken by visual areas in occipital cortex, and conclude by examining some objections to the proposals.
On the neural correlates of visual perception.
Pollen DA
Department of Neurology, University of Massachusetts Medical Center, Worcester 01655, USA. daniel.pollen@ummed.edu
Neurological findings suggest that the human striate cortex (V1) is an indispensable component of a neural substratum subserving static achromatic form perception in its own right and not simply as a central distributor of retinally derived information to extrastriate visual areas. This view is further supported by physiological evidence in primates that the finest-grained conjoined representation of spatial detail and retinotopic localization that underlies phenomenal visual experience for local brightness discriminations is selectively represented at cortical levels by the activity of certain neurons in V1. However, at first glance, support for these ideas would appear to be undermined by incontrovertible neurological evidence (visual hemineglect and the simultanagnosias) and recent psychophysical results on 'crowding' that confirm that activation of neurons in V1 may, at times, be insufficient to generate a percept. Moreover, a recent proposal suggests that neural correlates of visual awareness must project directly to those in executive space, thus automatically excluding V1 from a related perceptual space because V1 lacks such direct projections. Both sets of concerns are, however, resolved within the context of adaptive resonance theories. Recursive loops, linking the dorsal lateral geniculate nucleus (LGN) through successive cortical visual areas to the temporal lobe by means of a series of ascending and descending pathways, provide a neuronal substratum at each level within a modular framework for mutually consistent descriptions of sensory data. At steady state, such networks obviate the necessity that neural correlates of visual experience project directly to those in executive space because a neural phenomenal perceptual space subserving form vision is continuously updated by information from an object recognition space equivalent to that destined to reach executive space. Within this framework, activity in V1 may engender percepts that accompany figure-ground segregations only when dynamic incongruities are resolved both within and between ascending and descending streams. Synchronous neuronal activity on a short timescale within and across cortical areas, proposed and sometimes observed as perceptual correlates, may also serve as a marker that a steady state has been achieved, which, in turn, may be a requirement for the longer time constants that accompany the emergence and stability of perceptual states compared to the faster dynamics of adapting networks and the still faster dynamics of individual action potentials. Finally, the same consensus of neuronal activity across ascending and descending pathways linking multiple cortical areas that in anatomic sequence subserve phenomenal visual experiences and object recognition may underlie the normal unity of conscious experience.
The neuronal basis of visual memory and imagery in the primate: a neurophysiological approach.
Nakahara K, Ohbayashi M, Tomita H, Miyashita Y
Mind Articulation Project, ICORP, Tokyo, Japan.
To understand the biological basis of memory is one of the most exciting frontiers of science. Single unit recording is a powerful method to investigate neuronal correlates of various brain functions such as memory in awake animals. Anatomical, neuropsychological, and neurophysiological evidence indicates that the IT has an important role not only for synthesizing the analyzed visual attribute into a unique configuration, but also for the storehouse of visual memory in humans and primates. We performed single unit recordings in the primate IT, and found neuronal correlates of visual long-term memory: the IT neurons could reflect learned associative relations among stimuli. The findings reviewed here support the hypothesis that the IT is a region of the brain where visual perception meets memory and imagery.
Single units and conscious vision.
Logothetis NK
Max Planck Institute for Biological Cybernetics, Tubingen, Germany. nikos.logothetis@tuebingen.mpg.de
Figures that can be seen in more than one way are invaluable tools for the study of the neural basis of visual awareness, because such stimuli permit the dissociation of the neural responses that underlie what we perceive at any given time from those forming the sensory representation of a visual pattern. To study the former type of responses, monkeys were subjected to binocular rivalry, and the response of neurons in a number of different visual areas was studied while the animals reported their alternating percepts by pulling levers. Perception-related modulations of neural activity were found to occur to different extents in different cortical visual areas. The cells that were affected by suppression were almost exclusively binocular, and their proportion was found to increase in the higher processing stages of the visual system. The strongest correlations between neural activity and perception were observed in the visual areas of the temporal lobe. A strikingly large number of neurons in the early visual areas remained active during the perceptual suppression of the stimulus, a finding suggesting that conscious visual perception might be mediated by only a subset of the cells exhibiting stimulus selective responses. These physiological findings, together with a number of recent psychophysical studies, offer a new explanation of the phenomenon of binocular rivalry. Indeed, rivalry has long been considered to be closely linked with binocular fusion and stereopsis, and the sequences of dominance and suppression have been viewed as the result of competition between the two monocular channels. The physiological data presented here are incompatible with this interpretation. Rather than reflecting interocular competition, the rivalry is most probably between the two different central neural representations generated by the dichoptically presented stimuli. The mechanisms of rivalry are probably the same as, or very similar to, those underlying multistable perception in general, and further physiological studies might reveal much about the neural mechanisms of our perceptual organization.
Perceiving visually presented objects: recognition, awareness, and modularity.
Treisman AM, Kanwisher NG
Department of Psychology, Princeton University, New Jersey 08544-1010, USA. treisman@phoenix.princeton.edu
Object perception may involve seeing, recognition, preparation of actions, and emotional responses--functions that human brain imaging and neuropsychology suggest are localized separately. Perhaps because of this specialization, object perception is remarkably rapid and efficient. Representations of componential structure and interpolation from view-dependent images both play a part in object recognition. Unattended objects may be implicitly registered, but recent experiments suggest that attention is required to bind features, to represent three-dimensional structure, and to mediate awareness.
Neurobiological bases of spatial learning in the natural environment: neurogenesis and growth in the avian and mammalian hippocampus.
Lee DW, Miyasato LE, Clayton NS
Section of Neurobiology, Physiology and Behavior, University of California, Davis 95616, USA.
Multiple developmental pathways for motion processing.
Banton T, Bertenthal BI
Department of Psychology, University of Virginia, Charlottesville, USA.
PURPOSE: Image flow across the retina can be classified into several types of motion specifying information about spatial layout and self-movement. Adults process these types of motion via different functional pathways. This article investigates the development of these functional pathways. METHODS: The development of sensitivity to several classes of motion is reviewed and correlated with the neural development of the visual system. RESULTS: Different types of motion processing develop at different rates. The clearest example is that sensitivity to direction of translation shows an earlier onset and a different developmental trajectory than sensitivity to shearing motion. In addition, the onset of sensitivity to translation direction and shearing motion coincides with the development of striate laminae 5/6 and 4B, respectively. This earlier development of the deeper striate laminae is also consistent with reports of neonatal direction discrimination in displays undergoing optical expansion and rotation. CONCLUSIONS: Sensitivity to at least two types of motion, translation and shearing, develop in different ways and continue to be processed differently in adulthood. The differential development of sensitivity to these motion types coincides with the laminar development of striate cortex. It thus follows that the nonuniform development of the motion-processing system must be recognized to assess infant motion sensitivity correctly.
Neural mechanisms of visual motion perception in primates.
Andersen RA
Division of Biology, California Institute of Technology, Pasadena 91125, USA.
Neural mechanisms for visual memory and their role in attention.
Desimone R
Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD 20892-4415, USA.
Recent studies show that neuronal mechanisms for learning and memory both dynamically modulate and permanently alter the representations of visual stimuli in the adult monkey cortex. Three commonly observed neuronal effects in memory-demanding tasks are repetition suppression, enhancement, and delay activity. In repetition suppression, repeated experience with the same visual stimulus leads to both short- and long-term suppression of neuronal responses in subpopulations of visual neurons. Enhancement works in an opposite fashion, in that neuronal responses are enhanced for objects with learned behavioral relevance. Delay activity is found in tasks in which animals are required to actively hold specific information "on-line" for short periods. Repetition suppression appears to be an intrinsic property of visual cortical areas such as inferior temporal cortex and is thought to be important for perceptual learning and priming. By contrast, enhancement and delay activity may depend on feedback to temporal cortex from prefrontal cortex and are thought to be important for working memory. All of these mnemonic effects on neuronal responses bias the competitive interactions that take place between stimulus representations in the cortex when there is more than one stimulus in the visual field. As a result, memory will often determine the winner of these competitions and, thus, will determine which stimulus is attended.
Behav Brain Res 1996 Apr;76(1-2):143-54
Cortical mechanisms for visual perception of object motion and position in space.
Battaglini PP, Galletti C, Fattori P
Institute of Physiology, University of Trieste, Italy.
The present review is aimed at analyzing and discussing some of the cortical mechanisms possibly involved in the perception of object motion and object localization in the visual field. A comprehensive approach to these topics would be beyond the scope of this work. The highest priority, therefore, will be given to the cortical machinery involved in these processes, while very little (or nothing at all) will be said on the possible role played by subcortical structures such as the lateral geniculate nucleus and the superior colliculus which, albeit not directly involved in perception, might contribute to it.
The representation of shape in the temporal lobe.
Gochin PM
Department of Psychology, Princeton University, NJ 08544, USA.
Anatomical substrates for early stages in cortical processing of visual information in the macaque monkey.
Levitt JB, Lund JS, Yoshioka T
Department of Visual Science, Institute of Ophthalmology, London UK. j.levitt@ucl.ac.uk
Visual object recognition.
Legothetis NK, Sheinberg DL
Division of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA.
Visual object recognition is of fundamental importance to most animals. The diversity of tasks that any biological recognition system must solve suggests that object recognition is not a single, general purpose process. In this review, we consider evidence from the fields of psychology, neuropsychology, and neurophysiology, all of which supports the idea that there are multiple systems for recognition. Data from normal adults, infants, animals, and brain damaged patients reveal a major distinction between the classification of objects at a basic category level and the identification of individual objects from a homogeneous object class. An additional distinction between object representations used for visual perception and those used for visually guided movements provides further support for a multiplicity of visual recognition systems. Recent evidence from psychophysical and neurophysiological studies indicates that one system may represent objects by combinations of multiple views, or aspects, and another may represent objects by structural primitives and their spatial interrelationships.
Inferotemporal cortex and object vision.
Tanaka K
The Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
Cells in area TE of the inferotemporal cortex of the monkey brain selectively respond to various moderately complex object features, and those that cluster in a columnar region that runs perpendicular to the cortical surface respond to similar features. Although cells within a column respond to similar features, their selectivity is not necessarily identical. The data of optical imaging in TE have suggested that the borders between neighboring columns are not discrete; a continuous mapping of complex feature space within a larger region contains several partially overlapped columns. This continuous mapping may be used for various computations, such as production of the image of the object at different viewing angles, illumination conditions, and articulation poses.
Receptors, photoreception and brain perception. New insights.
Mansilla AO, Barajas HM, Arguero RS, Alba CC
Division of Research and Teaching, Cardiology Hospital, National Medical Center Siglo XXI, Mexico, D.F.
Once photons have activated photosensitive cell receptors, a biochemical process mediated by G-proteins transforms the initial signal into nerve potentials. The generated impulses transmit the information through ganglion cells, after a complex interaction with other neurons by means of different neurotransmitters. Since visual function is processed in parallel, ganglion cells are divided into M-neurons which are in charge of capturing large objects, P-neurons capable of analyzing fine details and colors, and non-M, non-P neurons which are sensitive to changes in light intensity. Retina, bipolar and ganglion cells share circular receptive fields with an antagonistic surround whereas the lateral geniculate nucleus possesses rectangular receptive fields. Thus, when central cones are stimulated, ON-center cells depolarize, while OFF-center cells hyperpolarize. At the brain cortex, the magnocellular layers lead to orientation and achromatic perception, the parvocellular layers perform color vision in the blobs and achromatic contrast and orientation in the interblobs, and eventually, binocular perception is the result of multiple disparities phenomenon. On these bases, patients with agnosia for form and pattern or for depth and movement have been described. Likewise, color blindness is another disease that could be the result of photoreceptor dysfunctions or brain perception defects.
Visual feature integration and the temporal correlation hypothesis.
Singer W, Gray CM
Max Planck Institute for Brain Research, Frankfurt, Germany.
Visual-vestibular interaction in the control of head and eye movement: the role of visual feedback and predictive mechanisms.
Barnes GR
MRC Human Movement and Balance Unit, Institute of Neurology, London, U.K.
Luminance.
Lennie P, Pokorny J, Smith VC
Center for Visual Science, University of Rochester, New York 14627.
Luminance was introduced by the CIE as a photometric analog of radiance. This implies that an additive spectral-luminosity function characterizes the human observer. In practice, many different spectral-sensitivity functions characterize human vision, although few produce the additive spectral-luminosity function V (lambda), which is suitable for use in practical photometry. Methods that give rise to additive spectral-sensitivity functions that most resemble V (lambda) tend to have in common the use of spatial or temporal frequencies that will discriminate against signals from the short-wavelength-sensitive cone pathways or against signals in other chromatic pathways. Some of the difference among results obtained with different techniques seems to reflect the extent to which the methods can bring about changes in the state of chromatic adaptation, but it also seems likely that not all tasks tap the same postreceptoral mechanisms. Psychophysical evidence is equivocal regarding the nature of the postreceptoral mechanisms: some evidence suggests just three mechanisms, one of which has a spectral sensitivity that is like V (lambda); other evidence suggests the existence of multiple mechanisms with different spectral sensitivities. Physiological recordings from neurons in the macaque's visual pathway suggest that the properties of the magnocellular system may be sufficient to account for spectral-sensitivity functions measured with the techniques of heterochromatic flicker photometry, minimally distinct border, and critical flicker fusion. These are the psychophysical methods that yield spectral sensitivities that are most like V (lambda). Other methods of measuring spectral sensitivity seem more likely to depend on signals that travel through the parvocellular system.
Prog Brain Res 1993;95:317-37
Visual pathways to perception and action.
Milner AD, Goodale MA
Department of Psychology, University of St. Andrews, Fife, U.K.
Directional selectivity in vertebrate retinal ganglion cells.
Amthor FR, Grzywacz NM
Department of Psychology, University of Alabama, Birmingham 35294.
Movement detection in arthropods.
Egelhaaf M, Borst A
Max-Planck-Institut fur biologische Kybernetik, Tubingen, Germany.
Decoding of retinal image flow in insects.
Hausen K
Zoologisches Institut der Universitat Koln, Germany.
Motion psychophysics.
Thompson P
Department of Psychology, University of York, U.K.
Information processing in the primate visual system: an integrated systems perspective.
Van Essen DC, Anderson CH, Felleman DJ
Biology Division, California Institute of Technology, Pasadena 91125.
The primate visual system contains dozens of distinct areas in the cerebral cortex and several major subcortical structures. These subdivisions are extensively interconnected in a distributed hierarchical network that contains several intertwined processing streams. A number of strategies are used for efficient information processing within this hierarchy. These include linear and nonlinear filtering, passage through information bottlenecks, and coordinated use of multiple types of information. In addition, dynamic regulation of information flow within and between visual areas may provide the computational flexibility needed for the visual system to perform a broad spectrum of tasks accurately and at high resolution.