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Biomedical subjects

M A Goodale

Publications and source records attributed to M A Goodale.

At least 91 records · Page 5Linked to original sources
PubMed1987

Oral asymmetries during verbal and non-verbal movements of the mouth.

Asymmetries in the amplitude and velocity of oral movements were studied in 24 right-handed subjects as they produced either syllables or non-verbal movements of the mouth. Single-frame analysis of the videotaped mouth movements revealed that the right side of the mouth opened wider and faster than the left for both verbal and non-verbal movements. Moreover, the size of the right bias increased as a function of the complexity of required movements. In addition, movements embedded within a series showed a greater right bias than movements at the beginning of a series. On the whole, females exhibited larger asymmetries than males. These results provide support for the suggestion that the left hemisphere plays an important role in the control of complex motor behaviour.

Adult↗
PubMed1986

Visual control of reaching movements without vision of the limb. I. Role of retinal feedback of target position in guiding the hand.

The spatial and temporal organization of hand and eye movements were studied in normal human subjects as they pointed toward small visual targets. The experiment was designed to assess the role of information about target position in correcting the trajectory of the hand when view of the hand was not available. To accomplish this, the duration of target presentation was systematically varied across blocks of trials. The results of this experiment showed that pointing movements were about 3 times more accurate when the target was present throughout the entire pointing movement, than when the target disappeared shortly after the hand movement had begun. These data indicate that pointing movements made without view of the limb are not purely preprogrammed but instead, are corrected during their execution. These modifications to the motor program are smoothly integrated into the ongoing movement and must depend upon comparing visual information about the position of the target with nonvisual information about the position of the limb. The source of this non-visual information was not directly established in the present experiment but presumably must be derived from kinesthetic reafferences and/or efference copy.

Biofeedback, Psychology↗
PubMed1986

Visual control of reaching movements without vision of the limb. II. Evidence of fast unconscious processes correcting the trajectory of the hand to the final position of a double-step stimulus.

In this study, a visual target was localized by both limb and eye. The experimental procedure provided an opportunity to analyze the limb movement trajectories to the target whose location was displaced during saccades. Absence of visual information about position of the moving limb did not interfere with correction of the trajectory of pointing movements. These corrections reflect the new information about target position that becomes available at the end of the first saccade. Mean localization errors to stationary and to displaced targets were not significantly different. This result suggests that subjects were able to compare visual (retinal + eye position) information about the position of the target with information about the position of their moving limb derived from kinesthesis and/or efference copies of the motor commands. An analysis of velocity profiles indicates that the observed corrections of hand movement to target displacement could not be identified by an inflexion point in the trajectory. None of the subjects reported seeing the target change location. In other words, the motor command was adjustable despite the failure of changes in visual locus to reach consciousness.

Adult↗
PubMed1986

The role of the predorsal bundle in head and body movements elicited by electrical stimulation of the superior colliculus in the Mongolian gerbil.

Thirty-two Mongolian gerbils received bilateral chronic implants of stainless steel electrodes in the superior colliculus. The movements elicited by electrical stimulation were recorded on videotape and measured by means of a computer-assisted image analyzing procedure. Ipsiversive body movements were elicited by stimulation of the anterior part of the superior colliculus. Contraversive head and body movements could be elicited by stimulation over the entire superior colliculus. Amplitudes of head and body movements were dependent upon both stimulation parameters (current and train duration) and the animal's posture at stimulus onset. In a second experiment, the predorsal bundle was cut at its decussation by means of a stereotaxic microknife. After such cuts, contraversive turns were either abolished or were replaced by ipsiversive movements. Ipsiversive movements were unaffected by the knife cuts. This experiment provides evidence that the distinct types of movements that can be elicited by collicular stimulation are subserved by anatomically separate output pathways.

Animals↗
PubMed1986

Visual cortical lesions abolish the use of motion parallax in the Mongolian gerbil.

Mongolian gerbils received lesions of either the visual cortex, pretectal nuclei, superior colliculus or a sham operation. Visual distance estimation was tested by means of a jumping task on which gerbils have previously been shown to employ motion parallax information generated by head movements. Videotaped jumps were analyzed to determine latency to jump, jump distance, and head movement frequency. While all of the lesion groups showed some changes in performance, the most severe deficits in jump accuracy were seen after the visual cortical lesions. In none of the lesion groups, however, were head movements abolished. The results suggest that the visual cortex subserves a critical aspect of dynamic distance estimation but that the motor program for generating head movements is located elsewhere.

Animals↗
PubMed1985

The organization of eye and limb movements during unrestricted reaching to targets in contralateral and ipsilateral visual space.

The spatial and temporal organization of unrestricted limb movements directed to small visual targets was examined in two separate experiments. Videotape records of the subjects' performance allowed us to analyze the trajectory of the limb movement through 3-dimensional space. Horizontal eye movements during reaching were measured by infrared corneal reflection. In both experiments, the trajectories of the different reaches approximated straight line paths and the velocity profile revealed an initial rapid acceleration followed by a prolonged period of deceleration. In Experiment 1, in which the target light was presented to the right or left of a central fixation point at either 10 degrees or 20 degrees eccentricity, the most consistent differences were observed between reaches directed across the body axis to targets presented in the contralateral visual field and reaches directed at ipsilateral targets. Ipsilateral reaches were initiated more quickly, were completed more rapidly, and were more accurate than contralateral reaches. While these findings suggest that hemispherically organized neural systems are involved in the programming of visually guided limb movements, it was not clear whether the inefficiency of the contralateral movements was due to reaching across the body axis or reaching into the visual hemifield contralateral to the hand being used. Therefore, in Experiment 2, the position of the fixation point was varied such that the effects of visual field and body axis could be disembedded. In this experiment, the kinematics of the reaching movement were shown to be independent of the point of visual fixation and varied only as a function of the laterality of the target position relative to the body axis. This finding suggests that the kinematics of a reaching movement are determined by differences in the processing of neural systems associated with motor output, after the target has been localized in space. The effect of target laterality on response latency and accuracy, however, could not be attributed to a single frame of reference, or to a simple additive effect of both. These findings illustrate the complex integration of visual spatial information which must take place in order to reach accurately to goal objects in extrapersonal space. Comparison of ocular and manual performance revealed a close relationship between movement latency for both motor systems. Thus, rightward-going eye movements to a given target were initiated more quickly when accompanied by reaches with the right hand than when they were accompanied by reaches with the left hand.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Interocular transfer in the pigeon after lesions of the dorsal supraoptic decussation.

Pigeons trained to discriminate between visual stimuli in a key-pecking task normally show excellent interocular transfer of training (IOT) when trained with only one eye and then tested with the 'naive' eye. When the dorsal supraoptic decussation (DSO) was sectioned and pigeons were then trained monocularly to peck at keys in an interocular transfer experiment, they failed to show normal IOT of a simultaneous horizontal-vertical discrimination. In contrast, another group of pigeons, in which the DSO was sectioned after they had already learned the discrimination with one eye covered, showed excellent IOT postoperatively when the blindfold was moved to the other eye. Since the pigeon uses the normally binocular portion of its retina to scan the discriminative stimuli in a key-pecking task and the DSO carries converging binocular input from the retinorecipient zone of the thalamus to the visual Wulst, the results suggest that IOT in the pigeon is the simple consequence of information reaching both hemispheres from a single eye via converging binocular pathways. Thus, cutting the DSO before training with the first eye eliminates IOT whereas cutting it after training with the first eye does not (since information has already reached the two hemispheres from the normally binocular portion of that eye). These findings complement earlier work showing that IOT is absent in normal pigeons in those situations in which they scan the discriminative stimuli with the monocular portion of their visual fields.

Animals↗
PubMed1984

Cortical and tectal control of visual orientation in the gerbil: evidence for parallel channels.

Two experiments were carried out with Mongolian gerbils to determine the roles of optic tectum and visual cortex in the mediation of visually guided head turns and locomotion elicited and controlled by discrete visual targets. In Experiment 1, the behavior of animals with either a sham operation, a bilateral lesion of optic tectum, or a bilateral ablation of areas 17, 18a, and 18b was recorded on videotape as they ran from the center of a circular arena toward a small visual target projected in different locations around the perimeter of the arena. The amplitude and direction of the head turns and the accuracy of their locomotor responses were reconstructed from a frame by frame analysis of the videotapes. Sham-operate gerbils made a series of head turns before running accurately and efficiently toward the target. The gerbils with lesions of areas 17, 18a, and 18b rarely made more than one head turn before running toward the perimeter of the arena. Although the single head turn they did make was often well-correlated with the position of the target in their visual field, the direction of their locomotor response was largely determined by the direction and amplitude of that head turn. As a consequence, these animals undershot the target more often than did the sham-operate animals, and even ran into the visual half field opposite the target if their head turn had also been made into that half field. Unlike the sham operates, these animals were unable to make further adjustments in their orientation toward the stimulus after their initial head turn. The head turns and locomotor behavior of the gerbils with lesions of optic tectum were even more disorganized and inaccurate than those of the posterior decorticates. Nevertheless, when the target was presented within 45 degrees from their visual midline, their head turns and locomotor responses showed a systematic relationship with the eccentricity of the target. Their behavior to stimuli outside this central wedge of their visual field was completely disorganized and showed no relationship to the location of the target. In Experiment 2, unilateral lesions of area 17 were performed in the gerbils that had already received bilateral tectal lesions to determine whether such lesions would affect the "residual" ability of these animals to orient toward stimuli located within the central portion of their visual field. During retesting, these animals were able to respond to targets only if they were located in the central portion of the field ipsilateral to the cortical lesion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Distance estimation in the Mongolian gerbil: the role of dynamic depth cues.

The role of dynamic depth cues in distance estimation was investigated in the Mongolian gerbil. Animals were trained to jump randomly varied distances on a jumping stand under both binocular and monocular conditions. Videotape analysis revealed that prior to jumping, the gerbils executed a series of vertical head movements, the amplitude and velocity of which were related to the gap distance and to each animal's accuracy. This suggested that the gerbils were employing motion parallax cues to judge distance. An inverse relation between the magnitude of forward movement and the frequency of vertical head movements suggested that loom cues were also being used to judge distance. This hypothesis received support from a second experiment in which forward movements were constrained by a short take-off platform. In this condition, frequency of vertical head movements increased, suggesting that a compensation had occurred for the loss of information from loom.

Animals↗
PubMed1984

Eye movements of human albinos.

Albino mammals are known to suffer from misrouted optic projections and there is a growing body of evidence suggesting that human albinos have similar aberrant anatomical pathways. The present study examined the possible consequences of such aberrant pathways on the oculomotor performance of five adult human albinos. Optokinetic nystagmus to drifting grating patterns and pursuit eye movements were measured. The subjects' congenital nystagmus was also measured under different conditions of gaze position and ambient room illumination. Two of the subjects showed clear instances of an inversion in the optokinetic response and there were probable inversions observed for a third subject. The magnitude of the optokinetic nystagmus was appropriate for the rate of pattern drift, but inverted in direction. In all cases smooth pursuit was severely impaired, but reversals of the appropriate direction of pursuit eye movements were not observed. Changes in the congenital nystagmus under conditions of light and darkness were found for four of the five subjects and varied greatly between subjects. The results suggest that human albinos share many of the oculomotor deficits found in other albino species.

Albinism↗
PubMed1983

Visually guided pecking in the pigeon (Columba livia).

High-speed cinematography was used (1) to analyze the sequence of head movements made by pigeons pecking at small visual targets and (2) to determine where on the retina the target fell at different points in the sequence. In both key-pecking for food reward and normal feeding, the decision to peck the target was made during a head fixation that occurred over 80 mm from the surface on which the target was located (as measured from the center of the eyes). Once the decision to peck had been made, a second fixation (F2) occurred at an average distance of 55 mm allowing the bird to calculate the size, depth, and location of the target. Moreover, during both fixations, the target was located in the pigeon's binocular field within a region corresponding to the red area of the upper temporal quadrant of the retina.

Animals↗
PubMed1982

Progressive supranuclear palsy: the relationship between ocular motor dysfunction and psychological test performance.

The performance of patients with progressive supranuclear palsy on visual search and scanning tasks was related to the pattern of ocular deficits observed in these patients during horizontal refixation. Comparisons were made to age-matched normals and patients with Parkinson disease or cerebellar damage. The poor performance of the progressive supranuclear palsy group on visual search and scanning could not be attributed to the restricted range of vertical gaze or the large number of hypometric saccades during horizontal refixation. Instead, we believe that their impaired scanning resulted from the presence of square-wave jerks during attempted fixation.

Bulbar Palsy, Progressive↗
PubMed1981

Radial-maze performance in the rat following lesions of posterior neocortex.

The present experiment was designed t investigate the role of posterior neocortex (areas 17, 18 and 18a) in the maintenance of performance on the radial maze. Following training to criterion on the 8-arm radial maze, rats received either sham operations, bilateral eye enucleations, lesions of posterior neocortex, or combined enucleations and lesions of posterior neocortex. While the enucleated animals with intact brains showed a slight, but significant performance decrement relative to the sham-operated group, the other two groups, with lesions of areas 17, 18 and 18a, each showed a massive deficit. This large deficit was observed even in the group in which both the eyes and neocortex had been removed. These results suggest that the visual projection areas of cortex not only play an important role in the maintenance of accurate radial-maze performance in sighted animals, but that the integrity of these areas is necessary for the maintenance fo criterion performance in blind animals.

Animals↗
PubMed1979

Visual sampling after lesions of the superior colliculus in rats.

In two separate experiments, rats with bilateral lesions of the superior colliculus showed significantly poorer relearning of a horizontal/vertical stripe discrimination than control animals. In Experiment 1, all animals showed disruption of performance when a stimulus--response (S--R) separation was introduced by raising the stimuli above the site of responding. However, the colliculectomized rats were much more disturbed by the S--R separation than were animals in the control group. In Experiment 2, all animals showed lower performance levels when conflicting patterns were introduced into the upper portion of the stimulus doors, but this time the rats with collicular lesions were less disturbed than the control animals. It is suggested (a) that when the stimulus and response sites are discontiguous, animals must make an appropriate orienting response in order to effectively sample the visual stimuli and (b) that lesions of the superior colliculus alter performance by interfering with this orienting behavior. The impairment in relearning is tentatively attributed to the absence of preoperative overtraining on the discrimination task.

Animals↗
PubMed1978

Visual orientation in the rat: a dissociation of deficits following cortical and collicular lesions.

Rats with either bilateral ablations of superior colliculus, bilateral ablations of visual cortex, or sham operations were trained to run across a large arena towards a small illuminated target which varied in location from trial to trial. An impairment in this visually-guided running was apparent in the cortical group, but not in the collicular group. When, in a second experiment, the spatial relationships within the apparatus were changed by extending the entry-tunnel some distance into the arena, the running of the cortical group became even more impaired, while the collicular animals continued to run towards the targets under efficient visual control. In a third experiment, the effect of introducing a novel flashing light in various locations around the perimeter of the arena was investigated. It was found that unlike the other two groups, the collicular animals showed no orienting reflex to the novel stimulus when it was presented outside a broad central area of the visual field.

Animals↗