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A stimulus apparatus for the presentation of moving visual stimuli
VisionRes.Vol.12, pp. 333-336.Pergamon Press1972. Printid inC&atBritain
TECHNICAL A STIMULUS APPARATUS
REPORT
FOR THE PRESENTATION OF MOVING
VISUAL STIMULI B. E. STEIN, N. DODICH and L. KRUGER Dept. of Anatomy, MedicalCenter, School of Medicine,University of California, Los Angeles,U.S.A. (Received 10 September
1971)
SYSTEMATICanalysis of neuronal activity in the visual system is to some extent limited by existing methods of stimulus presentation. Recently, it has become apparent that stimulus repetition, direction and speed of movement are important variables in the study of the visual system (GR~~SSER-~ORNHELS, GROSSERand BULLOCK, 1963; BARLOW, HILL and LEVICK,1964; RODIECKand STONE,1965; HILL, 1966; MICHAEL,1970; STRASCHILL and TAGHAVY,1967; MCILWAINand BUSER,1968; HENN and GROSSER,1969; STERLINGand WICKELGREN,1969). These findings make it clear that in many situations, complete and simultaneous control of the stimulus variable of direction and velocity of movement, as well as stimulus presentation rate might be required. Attempts to study these variables have included presenting stimuli with hand-held or hand-operated mirrors, wands, magnets, ophthalmoscopes or projectors (MCILWAINand BUSER, 1968 ; HUMPHREY and SALTER,1967; MASLANJI, CHOW and STEWART, 1971; STERLING and WICKELGREN, 1969), manually sliding stimuli along mounted railings (MARCHJAFAVA and PEPEU, 1966) and gear or motor operated devices (KOZAK, RODIECKand MEARS,1963; BARLOWet al., 1964; SPINELLI,1966; HENNand GRUSS~, 1969). With manual stimulus presentation it is virtually impossible to maintain or reproduce a constant velocity to precisely control stimulus repetition rate. Mechanically operated devices employing gear-operated mechanisms or the servo-mechanisms of XY plotters either fail to provide a continuous, or a wide range of stimulus velocities, and the stimuli to be presented would be limited in size and weight according to the force of the system. These devices present inertial problems with heavy loads and are often complex and expensive. A simple, inexpensive device for the presentation of moving visual stimuli with which one can exercise precise, independent control over size, shape, background intensity, orientation and velocity of movement over a large traverse is described for possible use by other investigators. Two double-acting, air-operated hydraulic cylinders (“Little Giant”) connected by an oil-filled ain. hydraulic hose on one side (driven) and a iin. low pressure pneumatic hose on the other (driver) form the basis of this system. Pressurized air is allowed to enter and activate the first unit of a dual solenoid valve (Skinner 4-way valve) when the manual control is switched to the right (R). This directs compressed air to cylinder A, forcing its piston (8gin. traverse) to travel to the right (solid arrow). The oil contained in this cylinder 333
334
TECHNICAL REPORT
FIG. 1. Diagramatic representation of an apparatus for the presentation of moving or stationary visual stimuli.
flows into cylinder B, displacing its piston (3in. length of traverse) to the left (solid arrow). A needle valve located on the hydraulic line between cylinders A and B controls the rate of oil flow between these cylinders, thereby governing the speed with which their pistons move. This speed may also be altered by changing incoming air pressure. Switching the manual control to the left (L) activates the second unit of the air valve, directing compressed air to cylinder B. This reverses the flow of air, oil and the direction of travel of both pistons. Piston movement is registered as a variable voltage on an oscilloscope via a linear potentiometer connected to and activated by piston shaft B. At an approximate distance from the eye of 45 cm, velocity can be varied over a continuous range from < l”/sec to approx. lOO”/sec and acceleration is sufficiently rapid to reach constant velocity prior to the entry of the stimulus to the receptive field. The length of traverse of both pistons is controlled by a pair of threaded screw stops located on either side of piston B. The apparatus can be automatically operated by a simple programming arrangement consisting of a waveform generator, pulse generator and a relay. A rectangular metal plate (24in. x 15in) sliding on aluminum runners paralleling the piston shaft serves as a base to which a variety of stimuli may be attached. The entire assembly is of considerable size and weight and is capable of maintaining constant velocities with heavy loads. Thus, electroluminescent panels of varying shapes and sizes (KRUGER, SCHWASSMANNand SIMINOFF, 1966) with magnetic backing, or cardboard cutouts can easily be mounted on this plate without altering velocity. The cylinder and plate arrangement can be oriented in any axis by manipulation of the ball-joint to which it is attached, and the height of this arrangement can be selected by sliding it and the ball-joint along a vertical
335
TECHNICALREPORT
metal shaft (31in. in height). The height of the plate, its direction, velocity of movement and length of traverse may thus be manipulated independently, and given stimulus parameters may be accurately maintained on successive stimulus presentations, for quantitative studies. The limitations of this system are its weight and size which require a shock-mount of sufficient size and strength to prevent vibration of the stimulus plate at high speeds. High pressure cylinders are required in order to avoid air leaking into the hydraulic system. lOO”/sec
5cfkec
25hec
lO”/sec
2.5%~~
FIG. 2. The relationship between stimulus velocity and direction of movement. Arrows represent the direction with which a black rectangular bar was moved through the receptive field of a single unit in the superior colliculus of the cat. At velocities of 5O”/sec and IO’/ set responsiveness to movement from upper left to lower right (bottom trace) is best, whereas at 2*5”/sec movement from lower left to upper right (top trace) evokes the best responses. The linear potentiometer trace is reproduced here only for the most rapid stimulus movement (lOO”/sec).
This apparatus has been employed in studies of the superior colliculus of the cat in order to determine neuronal sensitivity to direction and velocity of moving visual stimuli, as well as responsiveness to repeated identical stimulus presentations. Figure 2 displays records from one of these studies and shows that directional selectivity is a function of stimulus velocity. Independent, simultaneous control over these stimulus variables appears to be critical in the analysis of responsiveness to moving stimuli. Acknowledgements-We are indebted to Dr. H. 0. SCHWASSMANN and Mr. K. PECK who constructed an earlier prototype which led to the construction of a working model in which the essential variables could be controlled. The construction
of this apparatus was aided by USPHS Grant EY-571.
REFERENCES BARUIW, H. B., HILL, R. M. and LEVICK, W. R. (1964). Retinal ganglion cells responding selectively to direction and speed of image motion in the rabbit. J. Physiol., Land. 173,377407. GR~~SSER-CORNHELS, U., GR~~SSER,0. and BULLOCK,T. H. (1963). Unit responses in the frog’s tectum to moving and nonmoving visual stimuli. Science, N. Y. 141,820-822. H.xNN, V. and GROSSER,O.-J. (1969). The summation of excitation in the receptive fields of movement sensitive neurons of the frog’s retina. Vision Res. 9, 57-69. HILL, R. M. (1966). Receptive field properties of the superior colliculus of the rabbit. Nature, Lund. 211, 1407-1409. HMB~~Y, N. K. and SALTER,S. H. (1967). Receptive fields of single units in the visual system: A new method for mapping their characteristics and extents. Vision Res. 7, 497-498. KOZAK, W., RODIECK,R. W. and MeAas, C. J. (1963). A new perimeter and moving figure generator for visual research. Vision Res. 3, 389-396. KRUGER, L., SCHWASSMIWN, H. 0. and SIMINOFF,R. (1966). Electroluminescent lamps for visual stimulus presentation. Vision Res. 6, 349-351. McILWAIN, J. T. and BUSER,P. (1968). Receptive fields of single cells in the cat’s superior colliculus. Exp. Brain Res. 5, 314-325.
336
TECHNICALREPCIRT
MARCHIAFAVA,P. L. and PEPEU, G. (1966). The response of units in the superior colliculus of the cat to moving visual stimulus. Experientia 22, 51-53. MASLAND,R. H., CHOW, K. L. and STEWART,D. L. (1971). Receptive-field characteristics of superior colliculus neurons in the rabbit. J. Neurophysiol. 34, 148-156. MICHAEL,CH. R. (1970). Integration of retinal and cortical information in the superior colliculus of the ground squirrel. Brain Behav. Evol. 3,205-209. RODIECK,T. W. and STONE,J. (1965). Response of cat retinal ganglion cells to moving visual patterns. J. Neurophysiol. 28,819-832.
SPINELLI,D. N. (1966). Visual receptive fields in the cat’s retina: Complications. Science, N. Y. 152, 17681769. STERLING,P. and WICKELGREN,B. G. (1969). Visual receptive fields in the superior colliculus of the cat. J. Neurophysiol. 32, l-15.
STRASCHILL,M. and TAGHAVY,A. (1967). Neuronale reaktionen im tectum opticum der katze auf bewegte und stationare lichtreize. Exp. Brain Res. 3, 353-367.
TECHNICAL A STIMULUS APPARATUS
REPORT
FOR THE PRESENTATION OF MOVING
VISUAL STIMULI B. E. STEIN, N. DODICH and L. KRUGER Dept. of Anatomy, MedicalCenter, School of Medicine,University of California, Los Angeles,U.S.A. (Received 10 September
1971)
SYSTEMATICanalysis of neuronal activity in the visual system is to some extent limited by existing methods of stimulus presentation. Recently, it has become apparent that stimulus repetition, direction and speed of movement are important variables in the study of the visual system (GR~~SSER-~ORNHELS, GROSSERand BULLOCK, 1963; BARLOW, HILL and LEVICK,1964; RODIECKand STONE,1965; HILL, 1966; MICHAEL,1970; STRASCHILL and TAGHAVY,1967; MCILWAINand BUSER,1968; HENN and GROSSER,1969; STERLINGand WICKELGREN,1969). These findings make it clear that in many situations, complete and simultaneous control of the stimulus variable of direction and velocity of movement, as well as stimulus presentation rate might be required. Attempts to study these variables have included presenting stimuli with hand-held or hand-operated mirrors, wands, magnets, ophthalmoscopes or projectors (MCILWAINand BUSER, 1968 ; HUMPHREY and SALTER,1967; MASLANJI, CHOW and STEWART, 1971; STERLING and WICKELGREN, 1969), manually sliding stimuli along mounted railings (MARCHJAFAVA and PEPEU, 1966) and gear or motor operated devices (KOZAK, RODIECKand MEARS,1963; BARLOWet al., 1964; SPINELLI,1966; HENNand GRUSS~, 1969). With manual stimulus presentation it is virtually impossible to maintain or reproduce a constant velocity to precisely control stimulus repetition rate. Mechanically operated devices employing gear-operated mechanisms or the servo-mechanisms of XY plotters either fail to provide a continuous, or a wide range of stimulus velocities, and the stimuli to be presented would be limited in size and weight according to the force of the system. These devices present inertial problems with heavy loads and are often complex and expensive. A simple, inexpensive device for the presentation of moving visual stimuli with which one can exercise precise, independent control over size, shape, background intensity, orientation and velocity of movement over a large traverse is described for possible use by other investigators. Two double-acting, air-operated hydraulic cylinders (“Little Giant”) connected by an oil-filled ain. hydraulic hose on one side (driven) and a iin. low pressure pneumatic hose on the other (driver) form the basis of this system. Pressurized air is allowed to enter and activate the first unit of a dual solenoid valve (Skinner 4-way valve) when the manual control is switched to the right (R). This directs compressed air to cylinder A, forcing its piston (8gin. traverse) to travel to the right (solid arrow). The oil contained in this cylinder 333
334
TECHNICAL REPORT
FIG. 1. Diagramatic representation of an apparatus for the presentation of moving or stationary visual stimuli.
flows into cylinder B, displacing its piston (3in. length of traverse) to the left (solid arrow). A needle valve located on the hydraulic line between cylinders A and B controls the rate of oil flow between these cylinders, thereby governing the speed with which their pistons move. This speed may also be altered by changing incoming air pressure. Switching the manual control to the left (L) activates the second unit of the air valve, directing compressed air to cylinder B. This reverses the flow of air, oil and the direction of travel of both pistons. Piston movement is registered as a variable voltage on an oscilloscope via a linear potentiometer connected to and activated by piston shaft B. At an approximate distance from the eye of 45 cm, velocity can be varied over a continuous range from < l”/sec to approx. lOO”/sec and acceleration is sufficiently rapid to reach constant velocity prior to the entry of the stimulus to the receptive field. The length of traverse of both pistons is controlled by a pair of threaded screw stops located on either side of piston B. The apparatus can be automatically operated by a simple programming arrangement consisting of a waveform generator, pulse generator and a relay. A rectangular metal plate (24in. x 15in) sliding on aluminum runners paralleling the piston shaft serves as a base to which a variety of stimuli may be attached. The entire assembly is of considerable size and weight and is capable of maintaining constant velocities with heavy loads. Thus, electroluminescent panels of varying shapes and sizes (KRUGER, SCHWASSMANNand SIMINOFF, 1966) with magnetic backing, or cardboard cutouts can easily be mounted on this plate without altering velocity. The cylinder and plate arrangement can be oriented in any axis by manipulation of the ball-joint to which it is attached, and the height of this arrangement can be selected by sliding it and the ball-joint along a vertical
335
TECHNICALREPORT
metal shaft (31in. in height). The height of the plate, its direction, velocity of movement and length of traverse may thus be manipulated independently, and given stimulus parameters may be accurately maintained on successive stimulus presentations, for quantitative studies. The limitations of this system are its weight and size which require a shock-mount of sufficient size and strength to prevent vibration of the stimulus plate at high speeds. High pressure cylinders are required in order to avoid air leaking into the hydraulic system. lOO”/sec
5cfkec
25hec
lO”/sec
2.5%~~
FIG. 2. The relationship between stimulus velocity and direction of movement. Arrows represent the direction with which a black rectangular bar was moved through the receptive field of a single unit in the superior colliculus of the cat. At velocities of 5O”/sec and IO’/ set responsiveness to movement from upper left to lower right (bottom trace) is best, whereas at 2*5”/sec movement from lower left to upper right (top trace) evokes the best responses. The linear potentiometer trace is reproduced here only for the most rapid stimulus movement (lOO”/sec).
This apparatus has been employed in studies of the superior colliculus of the cat in order to determine neuronal sensitivity to direction and velocity of moving visual stimuli, as well as responsiveness to repeated identical stimulus presentations. Figure 2 displays records from one of these studies and shows that directional selectivity is a function of stimulus velocity. Independent, simultaneous control over these stimulus variables appears to be critical in the analysis of responsiveness to moving stimuli. Acknowledgements-We are indebted to Dr. H. 0. SCHWASSMANN and Mr. K. PECK who constructed an earlier prototype which led to the construction of a working model in which the essential variables could be controlled. The construction
of this apparatus was aided by USPHS Grant EY-571.
REFERENCES BARUIW, H. B., HILL, R. M. and LEVICK, W. R. (1964). Retinal ganglion cells responding selectively to direction and speed of image motion in the rabbit. J. Physiol., Land. 173,377407. GR~~SSER-CORNHELS, U., GR~~SSER,0. and BULLOCK,T. H. (1963). Unit responses in the frog’s tectum to moving and nonmoving visual stimuli. Science, N. Y. 141,820-822. H.xNN, V. and GROSSER,O.-J. (1969). The summation of excitation in the receptive fields of movement sensitive neurons of the frog’s retina. Vision Res. 9, 57-69. HILL, R. M. (1966). Receptive field properties of the superior colliculus of the rabbit. Nature, Lund. 211, 1407-1409. HMB~~Y, N. K. and SALTER,S. H. (1967). Receptive fields of single units in the visual system: A new method for mapping their characteristics and extents. Vision Res. 7, 497-498. KOZAK, W., RODIECK,R. W. and MeAas, C. J. (1963). A new perimeter and moving figure generator for visual research. Vision Res. 3, 389-396. KRUGER, L., SCHWASSMIWN, H. 0. and SIMINOFF,R. (1966). Electroluminescent lamps for visual stimulus presentation. Vision Res. 6, 349-351. McILWAIN, J. T. and BUSER,P. (1968). Receptive fields of single cells in the cat’s superior colliculus. Exp. Brain Res. 5, 314-325.
336
TECHNICALREPCIRT
MARCHIAFAVA,P. L. and PEPEU, G. (1966). The response of units in the superior colliculus of the cat to moving visual stimulus. Experientia 22, 51-53. MASLAND,R. H., CHOW, K. L. and STEWART,D. L. (1971). Receptive-field characteristics of superior colliculus neurons in the rabbit. J. Neurophysiol. 34, 148-156. MICHAEL,CH. R. (1970). Integration of retinal and cortical information in the superior colliculus of the ground squirrel. Brain Behav. Evol. 3,205-209. RODIECK,T. W. and STONE,J. (1965). Response of cat retinal ganglion cells to moving visual patterns. J. Neurophysiol. 28,819-832.
SPINELLI,D. N. (1966). Visual receptive fields in the cat’s retina: Complications. Science, N. Y. 152, 17681769. STERLING,P. and WICKELGREN,B. G. (1969). Visual receptive fields in the superior colliculus of the cat. J. Neurophysiol. 32, l-15.
STRASCHILL,M. and TAGHAVY,A. (1967). Neuronale reaktionen im tectum opticum der katze auf bewegte und stationare lichtreize. Exp. Brain Res. 3, 353-367.