Auditory and Visual Spatial Localization Deficits Following Bilateral Parietal Lobe Lesions in a Patient with Balint's Syndrome

2000 ◽  
Vol 12 (4) ◽  
pp. 583-600 ◽  
Author(s):  
M. L. Phan ◽  
K. L. Schendel ◽  
G. H. Recanzone ◽  
L. C. Robertson
Keyword(s):  
Parietal Lobe ◽  
Auditory Localization ◽  
Spatial Processing ◽  
Visual Localization ◽  
Opposite Pattern ◽  
Sensory Stimuli ◽  
Parietal Lobes ◽  
Visual Spatial ◽  
Electrophysiological Studies ◽  
Localization Ability

Lesion and electrophysiological studies indicate that the parietal lobes play a role in visual spatial attention and in computing the spatial coordinates of visual input. Fewer studies have investigated the role of the parietal lobe in auditory spatial processing, and an extensive comparison of visual and auditory spatial processing in humans with parietal lobe lesions has yet to be conducted. We have studied such localization abilities in a Balint's syndrome patient (RM) who has bilateral parietal lobe lesions. The results indicated that this patient had a significant deficit in both visual and auditory localization relative to age-matched controls. Unlike the controls, however, RM's auditory localization ability either matched or exceeded his visual localization ability depending on the task. Accordingly, RM exhibited “auditory capture”, but not “visual capture” under conditions where control subjects showed the opposite pattern. These results are consistent with hypotheses that the parietal lobes are involved in creating multiple spatial representations and in shifting from one spatial reference point to another, but suggest that these parietal structures are not necessary for the integration of multiple sensory stimuli resulting in capture effects.

scholarly journals Evaluation of two infants with myotonic dystrophy by the McFie's diagram from the results of WISC

1998 ◽  
Vol 56 (3B) ◽  
pp. 633-638 ◽  
Author(s):  
CRISTINA MARIA DUARTE WIGG ◽  
LUIZ ANTONIO ALVES DURO
Keyword(s):  
Myotonic Dystrophy ◽  
Left Hemisphere ◽  
Parietal Lobe ◽  
Psychological Test ◽  
Intelligence Scale ◽  
Verbal Skills ◽  
Parietal Lobes ◽  
Visual Spatial ◽  
The Right ◽  
Impairment Severity

In this paper the authors disclose the result of a research carried out on two brothers whose parents were first cousins, being the gene transmitted by the father. The psychological test Wechsler Intelligence Scale of Children (WISC) was used in two occasions in order to assess the verbal and non-verbal skills. FRM and IRM were nine and eleven-year-old respectively, in the first examination, being the former thirteen and the latter fifteen-year-old on the second one. A comparison between the McFie's diagram and the WISC scores was made: the McFie's diagram showed the impairment severity in each cortical lobe when the left hemisphere was compared with the right one. The McFie's diagram was made from WISC's scores: the McFie's diagram showed the impairment severity in each cortical lobe when the left hemisphere was compared with the right one. On the second examination the performance was worse than in the first, mainly in the non-verbal aspects. The IRM's diagram showed a reduction in the right frontal and parietal lobes. In the FRM's diagram a reduction in the left frontal, temporal and parietal lobes, and also, in the right parietal lobe was found. The visual-spatial constructive aspects showed greatest impairment in this result.

Occipitoparietal alpha-band responses to the graded allocation of top-down spatial attention

2014 ◽  
Vol 112 (6) ◽  
pp. 1307-1316 ◽  
Author(s):  
Isabel Dombrowe ◽  
Claus C. Hilgetag
Keyword(s):  
Visual Field ◽  
Spatial Attention ◽  
Brain Regions ◽  
Alpha Band ◽  
Top Down ◽  
Attentional Resources ◽  
Parietal Lobes ◽  
Visual Spatial ◽  
Entire Visual Field ◽  
Band Activity

The voluntary, top-down allocation of visual spatial attention has been linked to changes in the alpha-band of the electroencephalogram (EEG) signal measured over occipital and parietal lobes. In the present study, we investigated how occipitoparietal alpha-band activity changes when people allocate their attentional resources in a graded fashion across the visual field. We asked participants to either completely shift their attention into one hemifield, to balance their attention equally across the entire visual field, or to attribute more attention to one-half of the visual field than to the other. As expected, we found that alpha-band amplitudes decreased stronger contralaterally than ipsilaterally to the attended side when attention was shifted completely. Alpha-band amplitudes decreased bilaterally when attention was balanced equally across the visual field. However, when participants allocated more attentional resources to one-half of the visual field, this was not reflected in the alpha-band amplitudes, which just decreased bilaterally. We found that the performance of the participants was more strongly reflected in the coherence between frontal and occipitoparietal brain regions. We conclude that low alpha-band amplitudes seem to be necessary for stimulus detection. Furthermore, complete shifts of attention are directly reflected in the lateralization of alpha-band amplitudes. In the present study, a gradual allocation of visual attention across the visual field was only indirectly reflected in the alpha-band activity over occipital and parietal cortexes.

scholarly journals Reversibility of Multimodal Shift: Zebrafish Shift to Olfactory Cues When the Visual Environment Changes

2020 ◽  
Vol 60 (1) ◽  
pp. 33-42
Author(s):  
Piyumika S Suriyampola ◽  
Melissa Lopez ◽  
Brontë E Ellsworth ◽  
Emília P Martins
Keyword(s):  
Bright Light ◽  
Activity Level ◽  
Sensory Response ◽  
Opposite Pattern ◽  
Sensory Stimuli ◽  
Olfactory Responses ◽  
Lighting Conditions ◽  
Sensory Modalities ◽  
Complex Forms ◽  
Olfactory Cue

Synopsis Animals can shift their reliance on different sensory modalities in response to environmental conditions, and knowing the degree to which traits are reversible may help us to predict their chances of survival in a changing environment. Here, using adult zebrafish (Danio rerio), we found that 6 weeks in different light environments alone were sufficient to shift whether fish approached visual or chemical cues first, and that a subsequent reversal of lighting conditions also reversed their sensory preferences. In addition, we measured simple behavioral responses to sensory stimuli presented alone, and found that zebrafish housed in dim light for 6 weeks responded weakly to an optomotor assay, but strongly to an olfactory cue, whereas fish experiencing bright light for 6 weeks responded strongly to the visual optomotor stimulus and weakly in an olfactory assay. Visual and olfactory responses were equally reversible, and shifted to the opposite pattern when we reversed lighting conditions for 6 weeks. In contrast, we did not find a change in activity level, suggesting that changes in multiple sensory modalities can buffer animals from changes in more complex forms of behavior. This reversal of sensory response provides insight into how animals may use sensory shifts to keep up with environmental change.

Unit study of monkey frontal cortex: active localization of auditory and of visual stimuli

1986 ◽  
Vol 56 (4) ◽  
pp. 934-952 ◽  
Author(s):  
E. Vaadia ◽  
D. A. Benson ◽  
R. D. Hienz ◽  
M. H. Goldstein
Keyword(s):  
Auditory Cortex ◽  
Frontal Cortex ◽  
Broad Band ◽  
Primary Auditory Cortex ◽  
Auditory Localization ◽  
Visual Localization ◽  
Spatial Tuning ◽  
Active Localization ◽  
Localization Conditions ◽  
Localization Behavior

The influence of sound localization behavior on unit activity in the frontal cortex of awake rhesus monkeys was examined by comparing responses under three behavioral conditions: auditory localization, during which a response was required to the location of a sound (broad-band noise) source; auditory detect, during which a response was required to indicate the occurrence of the sound regardless of location; visual localization, during which no sounds were presented and a response was required to the location of a visual stimulus; and nonperform, presentation of auditory stimuli as in the first two conditions, but with the animal sitting passively. Extracellular microelectrode recordings were made in the periarcuate region and dorsal and ventral prefrontal areas near the principal sulcus. Four monkeys were used with a total of 498 cells studied. Of the total population, only five cells were found to have characteristics similar to those of auditory units in the primary auditory cortex and the surrounding belt area. More typically, units were found that had strong short-latency responses specific to the auditory and/or visual localization tasks. These units had no or weak responses when the same sound stimuli were presented in the auditory detect task or when a monkey received the sound stimuli in a nonperforming condition. Two regions were identified, one medial and/or posterior to the arcuate sulcus, in Brodmann's area 6; the second included parts of areas 8 and 9 within the genu of the arcuate sulcus. Units from these regions are referred to, respectively, as the postarcuate and the prearcuate populations. Both populations responded predominantly during active localization behavior. Sixty-two percent of the postarcuate population responded during auditory localization, 32% responded during auditory detect, and only 18% responded to acoustic stimuli presented in the nonperforming condition. In the prearcuate population percentages in these three conditions were 35, 25, and 12%, respectively. For visual localization, 54% in the postarcuate population responded, whereas 42% in the prearcuate responded. Spatial tuning of units during auditory localization was similar to that seen in units of the primary auditory cortex, with the greatest percentages of units responding to stimuli contralateral to the recording site. Similar tuning was observed for the visual localization task as well. Similarities in spatial tuning between the auditory and visual localization conditions were examined to assess the "bimodal" nature of the units.(ABSTRACT TRUNCATED AT 400 WORDS)

Functional MRI neuroanatomic correlates of the Hooper Visual Organization Test

2004 ◽  
Vol 10 (7) ◽  
pp. 939-947 ◽  
Author(s):  
CHAD H. MORITZ ◽  
STERLING C. JOHNSON ◽  
KATHRYN M. MCMILLAN ◽  
VICTOR M. HAUGHTON ◽  
M. ELIZABETH MEYERAND
Keyword(s):  
Right Hemisphere ◽  
Parietal Lobe ◽  
Neuropsychological Test ◽  
Occipital Cortex ◽  
Normal Subjects ◽  
Object Identification ◽  
Visual Spatial ◽  
Dorsolateral Prefrontal ◽  
Fmri Analysis ◽  
Visual Organization

The Hooper Visual Organization Test (VOT), a commonly applied neuropsychological test of visual spatial ability, is used for assessing patients with suspected right hemisphere, or parietal lobe involvement. A controversy has developed over whether the inferences of this test metric can be assumed to involve global, lateralized, or regional functionality. In this study, the characteristic visual organization and object naming aspects of the VOT task presentation were adapted to a functional MR imaging (fMRI) paradigm to probe the neuroanatomic correlates of this neuropsychological test. Whole brain fMRI mapping results are reported on a cohort of normal subjects. Bilateral fMRI responses were found predominantly in the posterior brain, in regions of superior parietal lobules, ventral temporal-occipital cortex, and posterior visual association areas, and to a lesser extent, the frontal eye fields bilaterally, and left dorsolateral prefrontal cortex. The results indicate a general brain region or network in which VOT impairment, due to its visuospatial and object identification demands, is possible to be detected. Discussion is made of interpretive limitations when adapting neuropsychological tests to fMRI analysis. (JINS, 2004, 10, 939–947.)

Behavioral Time Course of Microstimulation in Cortical Area MT

2010 ◽  
Vol 103 (1) ◽  
pp. 334-345 ◽  
Author(s):  
Nicolas Y. Masse ◽  
Erik P. Cook
Keyword(s):  
Electrical Stimulation ◽  
Time Course ◽  
Behavioral Effects ◽  
Sensory Stimuli ◽  
Temporal Properties ◽  
Behavioral Studies ◽  
Electrophysiological Studies ◽  
Excitatory Component ◽  
Sensory Neural

Electrical stimulation of the brain is a valuable research tool and has shown therapeutic promise in the development of new sensory neural prosthetics. Despite its widespread use, we still do not fully understand how current passed through a microelectrode interacts with functioning neural circuits. Past behavioral studies have suggested that weak electrical stimulation (referred to as microstimulation) of sensory areas of cortex produces percepts that are similar to those generated by normal sensory stimuli. In contrast, electrophysiological studies using in vitro or anesthetized preparations have shown that neural activity produced by brief microstimulation is radically different and longer lasting than normal responses. To help reconcile these two aspects of microstimulation, we examined the temporal properties that microstimulation has on visual perception. We found that brief application of subthreshold microstimulation in the middle temporal (MT) area of visual cortex produced smaller and longer-lasting effects on motion perception compared with an equivalent visual stimulus. In agreement with past electrophysiological studies, a computer simulation reproduced our behavioral effects when the time course of a single microstimulation pulse was modeled with three components: an immediate fast strong excitatory component, followed by a weaker inhibitory component, and then followed by a long duration weak excitatory component. Overall, these results suggest the behavioral effects of microstimulation in our experiments were caused by the unique and long-lasting temporal effects microstimulation has on functioning cortical circuits.

scholarly journals Frontal and Parietal Components of a Cerebral Network Mediating Voluntary Attention to Novel Events

2003 ◽  
Vol 15 (2) ◽  
pp. 294-313 ◽  
Author(s):  
K. R. Daffner ◽  
L. F. M. Scinto ◽  
A. M. Weitzman ◽  
R. Faust ◽  
D. M. Rentz ◽  
...  
Keyword(s):  
Parietal Lobe ◽  
Substantial Reduction ◽  
Event Related Potentials ◽  
Button Press ◽  
Voluntary Attention ◽  
Parietal Lobes ◽  
Novelty P3 ◽  
Related Potentials ◽  
Posterior Parietal ◽  
P3 Amplitude

Despite the important role that attending to novel events plays in human behavior, there is limited information about the neuroanatomical underpinnings of this vital activity. This study investigated the relative contributions of the frontal and posterior parietal lobes to the differential processing of novel and target stimuli under an experimental condition in which subjects actively directed attention to novel events. Event-related potentials were recorded from well-matched frontal patients, parietal patients, and non-brain-injured subjects who controlled their viewing duration (by button press) of line drawings that included a frequent, repetitive background stimulus, an infrequent target stimulus, and infrequent, novel visual stimuli. Subjects also responded to target stimuli by pressing a foot pedal. Damage to the frontal cortex resulted in a much greater disruption of response to novel stimuli than to designated targets. Frontal patients exhibited a widely distributed, profound reduction of the novelty P3 response and a marked diminution of the viewing duration of novel events. In contrast, damage to posterior parietal lobes was associated with a substantial reduction of both target P3 and novelty P3 amplitude; however, there was less disruption of the processing of novel than of target stimuli. We conclude that two nodes of the neuroanatomical network for responding to and processing novelty are the prefrontal and posterior parietal regions, which participate in the voluntary allocation of attention to novel events. Injury to this network is indexed by reduced novelty P3 amplitude, which is tightly associated with diminished attention to novel stimuli. The prefrontal cortex may serve as the central node in determining the allocation of attentional resources to novel events, whereas the posterior parietal lobe may provide the neural substrate for the dynamic process of updating one's internal model of the environment to take into account a novel event.

Auditory localization in the northern saw-whet owl, Aegolius acadicus

1989 ◽  
Vol 67 (8) ◽  
pp. 1955-1959 ◽  
Author(s):  
B. J. Frost ◽  
P. J. Baldwin ◽  
M. Csizy
Keyword(s):  
Great Accuracy ◽  
Auditory Localization ◽  
Head Orientation ◽  
Sound Sources ◽  
Slight Tendency ◽  
Search Coil ◽  
Aegolius Acadicus ◽  
Localization Ability ◽  
Search Coil Technique ◽  
Vertical Localization

Although there are several anecdotal reports in the literature that northern saw-whet owls (Aegolius acadicus) have extremely accurate auditory localization abilities, there have been no attempts to quantify these observations. In this study we used the search coil technique to obtain precise measurements of the northern saw-whet owl's head orientation toward either cricket chirps or mouse squeaks presented through speakers at various azimuthal positions. The results indicate owls of this species can orient their heads toward sound sources with great accuracy in the azimuthal plane, yielding mean errors of <1.0°, but show a slight tendency to undershoot more peripherally located sounds. Vertical localization is somewhat less precise, but still very accurate. Subsequent studies will be aimed at elucidating the physiological and anatomical substrates of this extreme accuracy in auditory localization ability.

Neuropathological basis for drawing disability (constructional apraxia) in Alzheimer's disease

1993 ◽  
Vol 23 (3) ◽  
pp. 623-629 ◽  
Author(s):  
H. Förstl ◽  
A. Burns ◽  
R. Levy ◽  
N. Cairns
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Parietal Lobe ◽  
Three Dimensional ◽  
Parahippocampal Gyrus ◽  
Parietal Lobes ◽  
Duration Of Illness ◽  
Constructional Apraxia ◽  
Drawing Tasks ◽  
Relationship Of

SynopsisThe performance on four drawing tasks was studied in a sample of patients with verified Alzheimer's disease in order to examine the relationship of ‘constructional apraxia’ to neuropathological changes in the parietal lobe and in other brain areas. Twenty-three patients were able to attempt to copy pentagons, a spiral and a three-dimensional drawing of a house, 22 patients were able to draw a clock-face spontaneously. The results were rank-ordered by two independent raters. The values obtained in the different drawing tasks were correlated significantly with each other, with global estimates of cognitive performance (CAMCOG, Mini-Mental State), with a shorter duration of illness, higher brain weight (in the subsample of female patients), higher counts of large neurons in the parahippocampal gyrus and hippocampus, but not in the parietal lobe. This suggests that there is no specific relationship between ‘constructional apraxia’ and neuropathological changes in the parietal lobes of patients with advanced Alzheimer's disease, but that there is a correlation between widespread brain changes and several neuropsychological deficits, one of them being drawing disability.

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