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PubMed1979

Effects of dimepramine fumarate on physiological and cognitive behaviors of Parkinson patients.

Nine patients 55 to 74 years old with Parkinson's disease were tested before and after treatment with 50 to 225 mg dimepramine fumarate (CIBA G-31406) for about three weeks daily in order to determine the drug's effects on electrodermal responsiveness to a series of unpredictably occurring loud sounds. Twelve control subjects were tested and retested with the same procedure. In addition, the Parkinson patients received a number of cognitive tests before and after drug treatment. Results indicated that the drug tends to decrease autonomic arousal responses as measured by resting conductance levels, number of fluctuations in skin conduction per minute, orienting response, and habituation rate. These decreases in measures of arousal generally were accompanied by lowered performance scores on several tests of memory and temporal discrimination ability.

Aged↗
PubMed1995

Agrammatic sentence production: the use of a temporal--spatial strategy.

We report the sentence production of a left-handed man with a right-hemisphere infarct. He demonstrated an inability to correctly map grammatical categories (subject, object) onto thematic roles (agent, patient) even for simple active sentences. The patient's performance appears to be the result of selective damage to the functional level (Garrett, 1980) of sentence production. His failure could not be accounted for by theories of agrammatism that implicate memory deficits, phonologic processing impairments, or deficits in processing complex transformations. The patient's performance revealed the consistent application of a temporal-spatial strategy in sentence production, despite adequate lexical-semantic abilities.

Aged↗
PubMed1995

Asyntactic thematic role assignment: the use of a temporal-spatial strategy.

We report syntactic comprehension performance of a left-handed man with a right-hemisphere infarct. He was unable to accurately map grammatical categories (subject, object) onto thematic roles (agent, patient), despite demonstrating intact conceptual knowledge of these thematic roles. He performed poorly on both active and passive reversible sentences. His asyntactic thematic role assignment cannot be accounted for by a short-term memory impairment or any hypothesis that predicts selective vulnerability to passive sentence constructions. Rather than performing randomly, our patient used a temporal or spatial strategy in assigning thematic roles. Because he also had a production-mapping deficit and used the same temporal-spatial strategy in production tasks, we hypothesize that the mapping of thematic roles onto grammatical categories and vice versa may be a specific aspect of sentence processing that is common to sentential production and comprehension. We also raise the possibility that thematic roles have underlying spatial representations prior to being elaborated by grammar.

Aged↗
PubMed2002

Temporal processing and phonological impairment in dyslexia: effect of phoneme lengthening on order judgment of two consonants.

The evidence of supporting phonological deficit as a cause of developmental dyslexia has been accumulating rapidly over the past 2 decades, yet the exact mechanisms underlying this deficit remain controversial. Some authors assume that a temporal processing deficit is the source of the phonological disorder observed in dyslexic children. Others maintain that the phonological deficit in dyslexia is basically linguistic, not acoustic, in nature. Three experiments were conducted and tested the impact of the temporal alteration and the impact of complex syllabic structure on consonant order judgments. Thirteen phonological dyslexics (age 10-13) and 10 controls matched for chronologial age were compared on a Temporal Order Judgment (TOJ) task using the succession of two consonants (/p/ /s/) within a cluster. In order to test the possible relevance of the temporal deficit hypothesis, the task also included two additional conditions where either the two stimuli were artificially slowed or two phonological structures were opposed (CCV and CVCV). As expected, the TOJ performance was significantly poorer in dyslexics than in controls. Moreover, in the "slowed speech" condition dyslexics' performance improved to reach the normal controls' level, whereas manipulating the phonological structure complexity provided no significant improvement. Finally dyslexics' performances, especially on the slowed condition, were found correlated with several tests of phonological processing. These results lend support to the general temporal deficit theory of dyslexia.

Adolescent↗
PubMed2001

Visual-auditory events: cross-modal perceptual priming and recognition memory.

Modality specificity in priming is taken as evidence for independent perceptual systems. However, Easton, Greene, and Srinivas (1997) showed that visual and haptic cross-modal priming is comparable in magnitude to within-modal priming. Where appropriate, perceptual systems might share like information. To test this, we assessed priming and recognition for visual and auditory events, within- and across- modalities. On the visual test, auditory study resulted in no priming. On the auditory priming test, visual study resulted in priming that was only marginally less than within-modal priming. The priming results show that visual study facilitates identification on both visual and auditory tests, but auditory study only facilitates performance on the auditory test. For both recognition tests, within-modal recognition exceeded cross-modal recognition. The results have two novel implications for the understanding of perceptual priming: First, we introduce visual and auditory priming for spatio-temporal events as a new priming paradigm chosen for its ecological validity and potential for information exchange. Second, we propose that the asymmetry of the cross-modal priming observed here may reflect the capacity of these perceptual modalities to provide cross-modal constraints on ambiguity. We argue that visual perception might inform and constrain auditory processing, while auditory perception corresponds to too many potential visual events to usefully inform and constrain visual perception.

Auditory Perception↗
PubMed1998

Object individuation in infancy: the use of featural information in reasoning about occlusion events.

Recent findings by Xu and Carey (1996) indicate that, after seeing two distinct objects (e.g., a duck and a ball) emerge on the opposite sides of a screen, 10-month-olds show no surprise when the screen is removed to reveal one (e.g., a duck) as opposed to two objects (e.g., a duck and a ball). The authors took their results to mean that 10-month-olds are unable to use featural information to individuate objects. The present research examined a different interpretation of the results. This interpretation was based on a distinction between event mapping, in which infants see a sequence of two distinct events and judge whether the two are consistent, and event monitoring, in which infants see a single event and judge whether successive portions of the event are consistent. The present research contrasted infants' performances in event-mapping tasks in which they saw first an occlusion and then a no-occlusion situation (as in Xu & Carey) and in event-monitoring tasks in which they saw only an occlusion situation. It was hypothesized that infants would be more likely to give evidence of correct individuation when tested with the event-monitoring as opposed to the event-mapping tasks. Eight experiments were conducted with infants ages 7.5 to 11.5 months. These experiments yielded two main findings. First, when tested with an event-monitoring task, even 7.5-month-olds give evidence that they can use featural information to individuate the objects involved in an occlusion event. Second, when tested with an event-mapping task, even 9.5-month-olds give evidence that they can use featural information to interpret an occlusion event as long as the event is made extremely simple. These findings give weight to the distinction between event mapping and monitoring and more generally begin to shed light on the fundamental processes involved in infants' formation and use of event representations.

Analysis of Variance↗
PubMed1997

The representation of tonality and meter in children aged 7 and 9.

The aim of this study was to explore the development of the representations of tonality and meter in children. Eighty children with a mean age of 7 (Grade 2) and 9 years (Grade 4) were compared on both melodic and rhythmic discrimination and classification tasks. The findings were considered in relation to their specificity to both task and age effects. The results revealed a developmental progression in the representation of tonality that was consistent across tasks. The rhythmic results also supported the existence of a representation of meter that developed with age, however these findings were more subject to task effects. The influence of stimulus length and likeableness on subject performance was also examined. Increased length was found to assist discrimination performance particularly with tonal, nontonal, and nonmetrical stimuli. No effects of stimulus likeableness were observed in the data.

Analysis of Variance↗
PubMed1999

MRI of functional deactivation: temporal and spatial characteristics of oxygenation-sensitive responses in human visual cortex.

Magnetic resonance imaging (MRI) of neuronal "activation" relies on the elevation of blood flow and oxygenation and a related increase of the blood oxygenation level-dependent (BOLD) MRI signal. Because most cognitive paradigms involve both switches from a low degree of activity to a high degree of activity and vice versa, we have undertaken a baseline study of the temporal and spatial characteristics of positive and negative BOLD MRI responses in human visual cortex. Experiments were performed at 2.0 T using a multislice gradient-echo EPI sequence (TR = 1 s, mean TE = 54 ms, flip angle 50 degrees) at 2x2-mm2 spatial resolution. Activation and "deactivation" processes were accomplished by reversing the order of stimulus presentations in paradigms using homogeneous gray light and an alternating checkerboard as distinct functional states. For sustained stimulation (> or = 60 s) the two conditions resulted in markedly different steady-state BOLD MRI signal strengths. The transient responses to brief stimulation (< or = 18 s) differed insofar as activation processes temporally separate positive BOLD and negative undershoot effects by about 10 s, whereas negative BOLD effects and undershoot contributions overlap for deactivation processes. Apart from differences in stimulus features (e.g., motion) the used activation and deactivation protocols revealed similar maps of neuronal activity changes.

Adult↗
PubMed2000

Discrimination of speech and of complex nonspeech sounds of different temporal structure in the left and right cerebral hemispheres.

The key question in understanding the nature of speech perception is whether the human brain has unique speech-specific mechanisms or treats all sounds equally. We assessed possible differences between the processing of speech and complex nonspeech sounds in the two cerebral hemispheres by measuring the magnetic equivalent of the mismatch negativity, the brain's automatic change-detection response, which was elicited by speech sounds and by similarly complex nonspeech sounds with either fast or slow acoustic transitions. Our results suggest that the right hemisphere is predominant in the perception of slow acoustic transitions, whereas neither hemisphere clearly dominates the discrimination of nonspeech sounds with fast acoustic transitions. In contrast, the perception of speech stimuli with similarly rapid acoustic transitions was dominated by the left hemisphere, which may be explained by the presence of acoustic templates (long-term memory traces) for speech sounds formed in this hemisphere.

Adolescent↗
PubMed1984

Spatio-temporal processing in multiple sclerosis.

The processing of spatial and temporal detail was investigated in patients with multiple sclerosis. Normal observers and 13 patients with optic neuritis secondary to multiple sclerosis performed a battery of visual tests that included contrast sensitivity, temporal integration, evoked potentials, and visual masking. The multiple sclerosis patients exhibited losses of pattern processing, and these deficits became more noticeable when the patterns were presented briefly. Moreover, these patients exhibited diverse response patterns for the different visual tests. For some, temporal integration functions appeared severely attenuated, while evoked potential latency was within normal limits. Others displayed poor performance in the visual masking test, yet contrast sensitivity functions were comparable to those of the control group. We suggest that a battery of tests that incorporates spatial as well as temporal stimuli is necessary for the detection of visual dysfunction in multiple sclerosis.

Adult↗
PubMed1995

Haptic localization and the internal representation of the hand in space.

As the hand actively explores the environment, contact with an object leads to neuronal activity in the topographic maps of somatosensory cortex. However, the brain must combine this somatotopically encoded tactile information with an internal representation of the hand's location in space if it is to determine the position of the object in three-dimensional space (3-D haptic localization). To investigate the fidelity of this internal representation in human subjects, a small tactual stimulator, light enough to be worn on the subject's hand, was used to present a brief mechanical pulse (6-ms duration) to the right index finger before, during, or after a fast, visually evoked movement of the right hand. In experiment 1, subjects responded by pointing to the perceived location of the mechanical stimulus in 3-D space. Stimuli presented shortly before or during the visually evoked movement were systematically mislocalized, with the reported location of the stimulus approximately equal to the location occupied by the hand 90 ms after stimulus onset. This pattern of errors indicates a representation of the movement that fails to account for the change in the hand's location during somatosensory delays and, in some subjects, inaccurately depicts the velocity of the actual movement. In experiment 2, subjects were instructed to verbally indicate the perceived temporal relationship of the stimulus and the visually evoked movement (i.e., by reporting whether the stimulus was presented "before," "during," or "after" the movement). On average, stimuli presented in the 38-ms period before movement onset were more likely to be perceived as having occurred during rather than before the movement. Similarly, stimuli in the 145-ms period before movement termination were more likely to be perceived as having occurred after rather than during the movement. The analogous findings of experiments 1 and 2 indicate that the same inaccurate representation of dynamic hand position is used to both localize tactual stimuli in 3-D space and construct the perception of arm movement.

Adult↗
PubMed1990

Gating and reversal of reflexes in ankle muscles during human walking.

Phase-dependent reflex modulation was studied by recording the electromyographic (EMG) responses in ankle flexors (Tibialis Anterior, TA) and extensors (Gastrocnemius Medialis, GM and Soleus, SOL) to a 20 ms train of electrical pulses, applied to the tibial or sural nerve at the ankle, in human volunteers walking on a treadmill at 4 km/h. For low intensity stimuli (i.e. 1.6 times perception threshold), given during the swing phase, the most common response was a suppression of the TA activity with a latency of 67 to 118 ms. With high intensity of stimulation (i.e. 2.8 x T), a facilitatory response appeared in TA with a latency of 74 ms. This latter response was largest during the middle of the swing phase, when it was correlated with exaggerated ankle dorsiflexion. The TA reflex amplitude was not a simple function of the level of spontaneous ongoing activity. During stance, TA responses were small or absent and accompanied by a suppression of the GM activity with a latency ranging from 62 to 101 ms. A few subjects showed an early facilitatory, instead of a suppressive, GM response (88 to 136 ms latency). They showed a phase-dependent reflex reversal from a dominant TA response during swing to a facilitatory GM response with an equivalent latency during stance. The GM facilitation occurred exclusively during the early stance phase and habituated more than the TA responses. It is concluded that phase-dependent gating of reflexes occurs in ankle muscles of man, but only when vigorous extensor reflexes are present. More commonly, a phase-dependent modulation is seen, both of facilitatory and suppressive responses.

Adolescent↗
PubMed1979

A model for processing of movement in the visual system.

Processing of spatio-temporal information in the human visual system has been investigated thoroughly during the past decade, but is still far from being properly understood. Moreover, the theory of separation of information by means of sustained and transient channels already at the retinal level is not satisfactory, as experimental results indicate that these two types of channels span a continuum of temporal characteristics. It is however obvious, that the process of pattern recognition and velocity perception calls for their separation at some level of the hierarchy. In this communication, we extend our model of three-dimensional spatio-temporal frequency expansion in the visual system (Gafni and Zeevi, 1977) to show how velocity-information extraction channels, sensitive to direction and velocity exclusively, can be formed by simple summation of signals from well-defined sets of channels representing points in the frequency space. Correspondence of these channels to characteristics of the cortical neurons is discussed.

Depth Perception↗
PubMed1978

Effects of d-amphetamine on temporal and spatial discrimination in rats.

Rats were trained to lever-press for food reinforcers on a multiple schedule that had a fixed-interval (FI) and a differential reinforcement of low rate (DRL) component. Illumination of a stimulus light above the right-hand lever indicated that responses on this lever would be reinforced according to a FI 60-s schedule while responses on the left-hand lever were without programmed consequences. However, when the light above the left-hand lever was illuminated only responses on this lever were reinforced according to a DRL 15-s schedule. When the behaviour of the subjects had been brought under schedule control so that characteristic patterns of FI and DRL responding were emitted and there were relatively few responses on the incorrect levers, the effects of several doses of d-amphetamine (0.25, 0.5, 1.0, and 2.0 mg/kg) were assessed. The drug increased preference for responding on the right-hand lever. Thus, as dosage increased performance tended towards a constant high rate of responding on the right-hand lever throughout a session, with a much lower response rate on the left-hand lever. This result emphasises that the behavioural effects of drugs depend not only on patterns of ongoing behaviour but also on the context in which this behaviour occurs.

Animals↗
PubMed1977

Spatial and temporal processing in patients with Turner's syndrome.

Thirteen females with Turner's syndrome were examined for spatial abilitles and serial processing, and their performance was compared with that of normal females matched by age, intellignece, and socioeconomic class. Patients with Turners's syndrome performed significantly poorer on tests of spatial ability than controls, but only on spatial tests requiring the integration of isolated elements as synthetic wholes or the remembering of spatial configurations which could not be verbally mediated. Patients also performed less well than controls on tasks of serial processing when the tasks could not be mediated verbally. 2t was concluded that patients with Turner's syndrome may have a selective deficit in cortical functions that are lateralized to the right cerebral hemisphere.

Adolescent↗