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PubMed2001

Adaptation reveals a neural code for the visual location of orientation change.

We apply an adaptation technique to explore the neural code for the visual location of textures defined by modulation of orientation over space. In showing that adaptation to textures modulated around one orientation shifts the perceived location of textures modulated around a different orientation, we demonstrate the existence of a neural code for the location of orientation change that generalises across orientation content. Using competitive adaptation, we characterise the neural processes underlying this code as single-opponent for orientation, that is with concentric excitatory/inhibitory receptive areas tuned to a single orientation.

Adaptation, Physiological↗
PubMed2003

Orientation-selective adaptation to crowded illusory lines.

Visual adaptation has been successfully used as a psychophysical tool for studying the functional organisation of visual awareness. It has been shown that orientation-selective adaptation to a grating pattern occurs in crowded conditions. In such conditions, simultaneous presentation of flanking distractors pushes the target stimulus out of conscious perception and severely impairs orientation discrimination in the periphery of the visual field. In the present study, orientation-selective adaptation to illusory lines induced by two line gratings abutting each other with a phase shift was examined in crowded and non-crowded conditions. To rule out the effects of lower level adaptations we used an animation paradigm in which the orientations of the two line gratings were altered repeatedly during adaptation phase without any change in the orientation of the resulting illusory line. Although performance of subjects in reporting the orientation of crowded illusory lines was at chance level, orientation-selective adaptation was preserved for crowded as well as non-crowded adapting targets. Two control experiments demonstrated that adaptation to endpoints of real lines at the location of abutting grating lines had minimal effect on the adaptation to illusory lines; and changes in the configuration of endpoints could not be responsible for better performance when adapting and test stimuli were different. We conclude that a crowding effect occurs after illusory lines have been processed in the visual stream. Since illusory lines seem to be represented at relatively early stages of visual processing (e.g. area V2), adaptation to crowded illusory stimuli suggests that neuronal activation in those early stages is not necessarily correlated with conscious perception.

Adaptation, Ocular↗
PubMed1996

Evidence of strategic effects in the modulation of orienting of attention.

Two models of visual orienting of attention are frequently described. Voluntary orienting is usually induced by central cues that direct subjects' attention to a given location in the visual space. Automatic orienting is provoked by presentation of peripheral cues. It is shown that automatic orienting induces greater attentional costs and benefits, and is less under a subject's control (Jonides 1981). Furthermore, it is not similarly affected by factors such as signal eccentricity (Umiltà et al. 1991). The present experiment was undertaken to investigate how sensitive automatic orienting produced by peripheral cues is to voluntary modulations of attention. In experiment 1, subjects facing situations daily in which attentional requirements are high, were compared to non-practiced ones. In experiment 2, other groups of practiced subjects facing high or low attentional-demanding situations were tested. In both experiments, subjects were asked to respond to signals, presented in rapid succession, in one of two possible locations in space, on each side of central fixation point. The cue signal automatically oriented attention to one of the two locations in which a first stimulus was presented with 100% probability; 100 ms after the first response (RT1), a second response signal (RT2) was delivered either in the same location (valid condition) or in the opposite location (invalid condition). Four cue probabilities were manipulated for this second stimulus: 100%/0%, 80%/20%, 50%/50%, and 20%/80%. Two eccentricities of 3 degrees and 6 degrees were tested. RT2 data demonstrated that (1) there was no eccentricity effect; (2) the higher the cue probability, the greater were the attentional costs; (3) the attentional effects were smaller in the practiced subjects who faced attention-demanding situations daily, than in the other groups. Put together, these data suggest that automatic orienting of attention can be modulated by voluntary attentional processes, according to cue probability. Furthermore, experienced subjects seem to be able to better distribute their attentional resources in space, with increased task requirements. The adoption of an optimal criterion might lead to the use of a cost minimizing strategy.

Adult↗
PubMed1992

Set-shifting and spatial orientation in patients with Parkinson's disease.

Individuals with Parkinson's disease were compared to normal control subjects on a series of widely used neuropsychological measures. The two groups were matched for gender, handedness, age, education, and occupation. The neuropsychological tests were chosen to measure two specific functions: (a) spatial orientation (i.e., measures of personal orientation, extrapersonal orientation, right/left orientation, and mental rotation), and (b) the ability to shift mental set (e.g., generating responses from alternating categories). The tests chosen to measure spatial orientation had no set-shifting component, and the tests chosen to measure set-shifting had no spatial orientation component. Multivariate statistical analyses revealed a significant difference between the subjects with Parkinson's disease and the control subjects on the measures of set-shifting ability. In contrast, no significant difference between the groups was observed on the measures of spatial orientation. These results are discussed in terms of the current speculation in the literature regarding the relationship between set-shifting deficits and a disruption of dopaminergic fibers to the prefrontal cortex in Parkinson's disease.

Aged↗
PubMed1986

Cognitive behavioural strategies and anxiety in elite orienteers.

The primary purpose of this exploratory field study was to examine the use of cognitive behavioural strategies by highly skilled orienteers prior to and during competition. A secondary purpose of the study was to investigate whether differences in the level of qualification in orienteering is related to state anxiety. The subjects were divided into three classes with respect to their international and national records. The first two classes (A and B) were composed of international and national level athletes. The third class (C) included orienteers with unknown international records. Examination of the use of behavioural cognitive strategies during competition indicated that all orienteers reported a moderate use of mental imagery, above moderate use of inner talk and a focus of attention on present action rather than past or future. The other major findings were that prior to competition, superior orienteers reported use of higher self-efficacy, more positive outcome expectations and more task demand orientation than their less successful counterparts. Top orienteers coped more successfully with pre-competition anxiety by lowering their anxiety to a more moderate level prior to the actual performance.

Anxiety↗
PubMed1998

Improving orientation in head injured adults by repeated practice, multi-sensory input and peer participation.

The efficacy of using antecedent control procedures (practice, multi-sensory input and peer participation) in facilitating orientation to person, place and time with two survivors of traumatic brain injuries were tested in two studies. In the first investigation, a 23-year-old male was treated by presenting the orientation questions orally while being shown questions on written flashcards. Results suggest that correct responses to orientation questions only occurred when flashcards were coupled with oral questioning. The participant responded correctly to nearly 100% of all orientation questions within 2 weeks of initiating flashcards. In the second study, a 19-year-old male was asked to respond in writing to 20 orientation questions in a small group. The group had a leader and 4 TBI patients. Following this, group members who correctly answered the orientation questions, took turns reading orientation questions and providing the correct responses.

Adult↗
PubMed2002

Visual orienting in college athletes: explorations of athlete type and gender.

Covert orienting was measured in 50 college athletes and 51 nonathletes of both genders. Visual environments of the sports were both static (swimming, track) and dynamic (soccer, volleyball). Participants made speeded responses in a task measuring vigilance, alerting, automatic orienting, voluntary orienting, modulation of automatic orienting, and modulation of inhibition of return. Gender differences werefound in the overall response times of nonathletes and in the alerting measures for all participants. However, all participants were similar in their automatic orienting. Sport-specific effects were seen in voluntary orienting and in the modulation of automatic orienting. These gender and sports-related findings are interpreted in light of the experience athletes have in the dynamic control of spatial attention.

Adult↗
PubMed2002

Deficits and recovery of head and trunk orientation and stabilization after unilateral vestibular loss.

The aim of the study was to analyse changes in the orientation and stabilization of the head and trunk and their recovery after complete unilateral loss of vestibular information in humans. The ability of nine Ménière's patients to orient and stabilize their heads and trunks in space was investigated during a simple dynamic task of knee-bends and compared with the performance of 10 healthy subjects. Patients' performance was recorded before unilateral vestibular neurotomy (UVN) and during the time-course of recovery (1 week, 1 month, 3 months). Experiments were performed both in eyes open (EO) and eyes closed (EC) conditions to evaluate the role of visual cues in the recovery process. Head and trunk mean angular position (orientation) and mean maximal angular rotation (stabilization) in the roll plane and the yaw plane were recorded using a video motion analysis system. The results indicate that, in the acute stage after UVN (1 week), patients exhibit marked impairments in head and trunk orientation in both visual conditions. In the EC condition, head and trunk were deviated towards the operated side in the roll plane and the yaw plane. Head and trunk stabilization in space was impaired in the roll plane and associated with increased stabilization of the head on the shoulders. Interestingly, vision caused a complete inversion of the orientation pattern, with head and trunk rotations towards the intact side in the roll plane and the yaw plane. Relative to darkness, vision also reduced head and trunk oscillations. Recovery from abnormal head orientation in the light and impaired head stability in both visual conditions was achieved within 1 month and 3 months after UVN, respectively. However, head and trunk orientation in the dark and trunk stabilization in the roll plane remained uncompensated 3 months post-lesion. These results suggest that unilateral vestibular loss leads to a postural syndrome similar to that described previously for various animal species. They confirm the necessity of vestibular inputs for properly stabilizing head and trunk during self-generated displacements in healthy subjects. They also support the notion that vestibular compensation relies on visual cues whose substitution role gradually decreases after UVN.

Adaptation, Physiological↗
PubMed2004

Neck proprioception and spatial orientation in cervical dystonia.

Neck muscle vibration is known to influence body orientation and posture during locomotion and stance in normal subjects. To verify the hypothesis that neck proprioceptive input can be misinterpreted in patients with cervical dystonia (CD), lateral continuous vibration was applied to the sternocleidomastoid muscle during both stepping-in-place and quiet stance, with eyes closed. The orienting responses of CD patients were compared with those of normal subjects. Vibration effects on body orientation during stepping and stance were apparently different from normal, since no effects were seen when all patients' data collapsed were analysed. However, while some patients did not respond to vibratory stimuli regardless of the vibrated side, others had a 'good' side, the stimulation of which produced effects on body orientation similar to those observed in normal subjects. Homogeneous groups within the patient population were identified, based on the vibration-induced responses under stepping conditions. The different orienting or postural responses observed in CD patients were correlated with disease-related features such as spontaneous head position, maximum range of voluntary head yaw, presence or absence of a botulinum toxin treatment and disease duration. Our data suggest that, in CD patients, the reference system used in the control of body orientation in space is either refractory to the lateralized proprioceptive neck input or modified such that the input from both sides produces an orientation shift in the same sense. This would depend on the pathogenesis of the disease or on an adaptive process connected to the head abnormal posture. It seems that this refractoriness spreads to both sides of the neck with the advancement of the disease, thereby possibly entraining a progressive shift from a reference system based on the head to a more reliable egocentric reference.

Adult↗
PubMed2002

Relationships of local inhibitory and excitatory circuits to orientation preference maps in ferret visual cortex.

The contribution and precise role of intracortical circuits in generating orientation tuned responses in visual cortical neurons is still controversial. To address this question, the relationship between excitatory and inhibitory synaptic connections and orientation maps in ferret striate cortex was investigated by combining in vivo optical imaging and in vitro scanning laser photostimulation. Excitatory and inhibitory inputs to pyramidal cells originated preferentially from regions with similar orientation preference. Prominent cross-orientation inhibition was not observed, arguing against cross-orientation models of orientation selectivity. The tuning of inhibitory inputs was significantly broader in both layer 2/3 and layer 5/6 pyramidal neurons compared to the tuning of excitatory inputs. Local excitatory inputs were more prominent in the 0-20 degrees tuning difference range between pre- and postsynaptic cells than inhibitory inputs, whereas inhibition dominated in the 20-40 degrees tuning difference range. These differences in tuning of excitatory and inhibitory inputs onto individual cells are consistent with the predictions of recurrent models of orientation selectivity.

Animals↗
PubMed2002

Measuring recovery of orientation during acute rehabilitation for traumatic brain injury: value and expectations of recovery.

OBJECTIVES: To further evaluate the use of the orientation log (O-Log) in an acute rehabilitation program for adults with traumatic brain injury (TBI), specifically focusing on prediction of rehabilitation outcome, possible use of the O-Log to promote recovery, and development of templates of orientation recovery. DESIGN: Stepwise discriminant function analysis was used in one study and ANOVA based on between-groups comparisons in another. Confidence intervals were established in the third study. SETTING: Acute rehabilitation hospital. PATIENTS: Samples were taken from an overall pool of 389 subjects with predominantly severe TBI based on Glasgow Coma Scale score. RESULTS: A combination of initial O-Log performance, time since injury, and number of O-Log assessments correctly predicted resolution of disorientation for 76% of the sample. Individuals attaining orientation before discharge achieved higher discharge scores on functional measures. Administration of the O-Log 3 versus 5 times a week did not result in more rapid resolution of disorientation. A similar pattern of steady improvement in orientation was evident for mild-moderate and severe injury cases across 10 administrations. CONCLUSIONS: Recovery of orientation provides important information about recovery following TBI and is predictive of rehabilitation outcome. More frequent administration of a formal orientation measure does not seem to expedite the recovery of orientation, which on average seems to progress at a steady pace in a rehabilitation setting regardless of the time since injury or severity of injury.

Activities of Daily Living↗
PubMed2001

Topography of orientation centre connections in the primary visual cortex of the cat.

The functional topography of lateral connections to orientation-centre zones was studied by optical imaging of intrinsic signals in combination with tracer injections (fluorescent beads and biocytin) and electrophysiological recordings. Three-dimensional reconstruction of anterogradely labelled axon terminals and retrogradely labelled somata revealed a uniform distribution across all orientations in a non-patchy manner. The overall lateral extent of the labelling was 3-4 mm in layer 3, that is about half of the extent observed for orientation domain connections in the same layer. These bulk injection data are in contrast with the reportedly sharp orientation tuning of neurons of centre zones and suggest that orientation specificity here does not require highly specific connections. Nonetheless, another plausible scenario is that orientation centre connections are orientation specific but their specificity present at the single cell level cannot be revealed by bulk labelling due to their large spatial overlap.

Animals↗
PubMed1983

Clinical problem-solving skills of internists trained in the problem-oriented system.

In the study reported here, the authors test the hypothesis that internists completing residencies in a highly structured, problem-oriented residency program approach clinical problem-solving differently than do internists whose residencies were not problem-oriented. The vehicle for the study was the certifying examination of the American Board of Internal Medicine (ABIM) in 1978, 1979, and 1980. Performance on patient management problems (PMPs) and multiple-choice questions was analyzed for candidates for ABIM certification whose residency had been problem-oriented, for candidates whose residencies had been classified as nonproblem-oriented, and for the national pool of U.S. medical graduates. Internists trained in the problem-oriented residency program achieved significantly higher PMP scores than did the national pool in two of the three years and on true-false questions in one of the years. No differences were detected between the problem-oriented group and their nonproblem-oriented colleagues.

Clinical Competence↗
PubMed2002

Trunk orientation induces neglect-like lateral biases in covert attention.

The purpose of this study was to resolve a paradox in the literature on the effects of body orientation on spatial attention. Neuropsychological studies have found that real or simulated trunk rotation relieves contralesional inattention in patients with unilateral neglect, suggesting that trunk orientation affects how attention is allocated to space. However in two previous studies, trunk orientation did not affect spatial attention in other populations. In this study we investigated the effects of trunk orientation on the performance of a covert attention task by neurologically intact adults. The covert attention task allowed the evaluation of the effects of trunk orientation on both the allocation of attention to space and the ability to shift that attention to new locations. As in previous research, trunk orientation did not affect participants' response times (RTs) to validly cued targets. However rotating participants' trunks to the left increased their RTs to invalidly cued targets on the right and decreased their RTs to invalidly cued targets on the left. These results indicate that trunk orientation induces directional biases in the ability to shift attention. Thus, for intact participants, trunk rotation created lateral biases in the covert attention task similar to those seen in neglect patients.

Adult↗
PubMed2003

The effect of object and event orientation on perception of biological motion.

Detection and recognition of point-light walking is reduced when the display is inverted, or turned upside down. This indicates that past experience influences biological motion perception. The effect could be the result of either presenting the human form in a novel orientation or presenting the event of walking in a novel orientation, as the two are confounded in the case of walking on feet. This study teased apart the effects of object and event orientation by examining detection accuracy for upright and inverted displays of a point-light figure walking on his hands. Detection of this walker was greater in the upright display, which had a familiar event orientation and an unfamiliar object orientation, than in the inverted display, which had a familiar object orientation and an unfamiliar event orientation. This finding supports accounts of event perception and recognition that are based on spatiotemporal patterns of motion associated with the dynamics of an event.

Adult↗
PubMed1991

Neuroanatomical correlates of skin conductance orienting in normal humans: a magnetic resonance imaging study.

Although little is known about the neuroanatomical basis of skin conductance orienting in intact normal humans, the limited literature on animals and humans with neurological and clinical disorders implicate prefrontal, temporal/amygdala, and pons brain areas in mediating skin conductance orienting. This study relates area of these structures using magnetic resonance imaging techniques to skin conductance orienting responses in 17 normal humans in order to test hypotheses that larger area of these excitatory structures will be associated with more orienting responses. Left and right hand skin conductance orienting was significantly associated with left and right prefrontal area (r = .44-.60), area of the pons (r = .43-.54), and left but not right temporal/amygdala area (r = .47-.53). No relationships were observed with areas thought to be unrelated to skin conductance activity (cerebellum, nonfrontal cortical area), medial prefrontal cortex, or the third ventricle. This appears to be the first study relating brain structure to skin conductance orienting in intact normal humans. Although preliminary at the present time, these results implicate prefrontal, pons, and temporal/amygdala areas in the mediation of skin conductance orienting in normal humans.

Adult↗
PubMed1992

Alternative spinal, somatosensory pathways investigated with the tactile orienting reaction in the cat.

Previous results indicated the possibility of abolishing the orienting reaction to light tactile stimulation of specific areas below lesions encompassing three sectors of the transverse spinal plane, if all sectors were transected simultaneously. Hence presumably interrupting three different ascending pathways. Two sectors corresponded to the sites of the well known, somatosensory, dorsal column and spino-cervical pathways. Single stage lesion technique now has been used to pinpoint the site of the third pathway. Immediate orienting reactions to both sides were seen before surgery. The orienting reactions remained postoperatively to stimuli applied on the hind limb contralateral to the dorsal column and the spino-cervical lesions. When the hind limb ipsilateral to the dorsal column and the spino-cervical lesions was stimulated five cats showed an absence of orienting reactions. The cats' lesions included the dorsal column and the spino-cervical on one side and the border area between the lateral and ventral funiculi on the other side of the cord. The remaining cats showed either partial or no deficiency of the orienting reactions. These cats' spinal lesions spared the area between the ventral and lateral funiculi. The findings show the possibility of abolishing the tactile orienting reactions from one hind limb with single stage lesions, which include the dorsal column and the spino-cervical pathway on one side, and a pathway located in the border area between the contralateral lateral, and ventral funiculi. This site corresponds to the morphological position of ascending spino-mesencephalic and/or spino-thalamic fibres. Consequently, all of these pathways might provide alternative routes for information about the place of tactile stimuli, which may evoke orienting reactions.

Afferent Pathways↗
PubMed1985

Binocular interaction in the VEP to grating stimulation. I. Orientational effects.

The orientational effects of monocular stimulation with sinusoidal grating patterns were studied with transient VEP technique in 10 subjects with normal vision and binocular functions. No significant variation in amplitude with orientation was obtained. The latency for 45 degrees (oblique) orientation was slightly longer than the latency for other orientations. The orientational effects on binocular interaction in dichoptic stimulation were determined with sinusoidal grating patterns at a reversing rate of 1.9 and 2.1 Hz for each eye respectively. The binocular interaction was assessed as the binocular/monocular ratio of the VEP amplitude for each eye. There was a significantly reduced binocular interaction for dichoptically presented perpendicular gratings as compared to parallel gratings at the spatial frequencies of 2, 4 and 6 cycles/degree, when mean values of the whole group of subjects were statistically analysed. A broad orientation tuning of about 45 degree was found for the binocular interaction at 4 cycles/degree for the group as a whole, although tuning was hard to establish in the VEP of each individual. This compares well with other neurophysiological and electrophysiological data but is broader than the orientation tuning demonstrated psychophysically.

Adult↗