scholarly journals When Left Is One and Right Is Double: An Experimental Investigation of Visual Allesthesia after Right Parietal Damage

Vision ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 16
Author(s):  
Denise Baumeler ◽  
Sabine Born ◽  
Nicolas Burra ◽  
Radek Ptak
Keyword(s):  
Visual Processing ◽  
Posterior Parietal Cortex ◽  
Experimental Studies ◽  
Physiological Processes ◽  
Unilateral Stimulation ◽  
Original Stimulus ◽  
Stationary Objects ◽  
Visual Phenomena ◽  
Posterior Parietal ◽  
Automatic Activation

Illusory visual phenomena, such as palinopsia, polyopsia or allesthesia, are rare manifestations of posterior cortical damage. Symptoms are characterized by illusory perceptions, ranging from isolated stationary objects to scenes and moving persons. Such illusions may appear while the original object is still in view, or become manifest with a delay and last for minutes, hours or even days. Some authors have suggested a disinhibited cortical response underlying visual illusions, but experimental studies supporting this hypothesis are lacking. Here, we examined a rare patient who after focal right parietal injury consistently reported a second stimulus on the left when briefly shown a target in his right hemifield. The patient perceived the illusory stimulus as less intense, and therefore concluded that it must have a different shape than the original stimulus. A masking experiment revealed that the frequency of the illusion was inversely related to the visibility of the original stimulus, suggesting that it depended on early, feedforward visual processing. We propose that illusory perceptions reflect the interplay of two physiological processes: a fast and automatic activation of contralateral, homotopic visual cortex after unilateral stimulation, and the lack of top-down inhibition following damage to the posterior parietal cortex.

Comparison of subcortical connections of inferior temporal and posterior parietal cortex in monkeys

1993 ◽  
Vol 10 (1) ◽  
pp. 59-72 ◽  
Author(s):  
Joan S. Baizer ◽  
Robert Desimone ◽  
Leslie G. Ungerleider
Keyword(s):  
Parietal Cortex ◽  
Visual Processing ◽  
Posterior Parietal Cortex ◽  
Temporal Cortex ◽  
Spatial Vision ◽  
Nucleus Basalis ◽  
Basal Nuclei ◽  
Processing Pathways ◽  
Posterior Parietal ◽  
Area Te

AbstractTo investigate the subcortical connections of the object vision and spatial vision cortical processing pathways, we injected the inferior temporal and posterior parietal cortex of six Rhesus monkeys with retrograde or anterograde tracers. The temporal injections included area TE on the lateral surface of the hemisphere and adjacent portions of area TEO. The parietal injections covered the posterior bank of the intraparietal sulcus, including areas VIP and LIP. Our results indicate that several structures project to both the temporal and parietal cortex, including the medial and lateral pulvinar, claustrum, and nucleus basalis. However, the cells in both the pulvinar and claustrum that project to the two systems are mainly located in different parts of those structures, as are the terminals which arise from the temporal and parietal cortex. Likewise, the projections from the temporal and parietal cortex to the caudate nucleus and putamen are largely segregated. Finally, we found projections to the pons and superior colliculus from parietal but not temporal cortex, whereas we found the lateral basal and medial basal nuclei of the amygdala to be reciprocally connected with temporal but not parietal cortex. Thus, the results show that, like the cortical connections of the two visual processing systems, the subcortical connections are remarkably segregated.

scholarly journals Human posterior parietal cortex responds to visual stimuli as early as peristriate occipital cortex

2018 ◽  
Author(s):  
Tamar I. Regev ◽  
Jonathan Winawer ◽  
Edden M. Gerber ◽  
Robert T. Knight ◽  
Leon Y. Deouell
Keyword(s):  
Visual Processing ◽  
Posterior Parietal Cortex ◽  
Right Hemisphere ◽  
Intractable Epilepsy ◽  
Event Related Potentials ◽  
Visual Responses ◽  
Baseline Activity ◽  
Visual Areas ◽  
Related Potentials ◽  
Posterior Parietal

AbstractMuch of what is known about the timing of visual processing in the brain is inferred from intracranial studies in monkeys, with human data limited to mainly non-invasive methods with lower spatial resolution. Here, we estimated visual onset latencies from electrocorticographic (ECoG) recordings in a patient who was implanted with 112 sub-dural electrodes, distributed across the posterior cortex of the right hemisphere, for pre-surgical evaluation of intractable epilepsy. Functional MRI prior to surgery was used to determine boundaries of visual areas. The patient was presented with images of objects from several categories. Event Related Potentials (ERPs) were calculated across all categories excluding targets, and statistically reliable onset latencies were determined using a bootstrapping procedure over the single trial baseline activity in individual electrodes. The distribution of onset latencies broadly reflected the known hierarchy of visual areas, with the earliest cortical responses in primary visual cortex, and higher areas showing later responses. A clear exception to this pattern was robust, statistically reliable and spatially localized, very early responses on the bank of the posterior intra-parietal sulcus (IPS). The response in the IPS started nearly simultaneously with responses detected in peristriate visual areas, around 60 milliseconds post-stimulus onset. Our results support the notion of early visual processing in the posterior parietal lobe, not respecting traditional hierarchies, and give direct evidence for the upper limit of onset times of visual responses across the human cortex.

scholarly journals Arousal dependent modulation of thalamo-cortical functional interaction

2017 ◽  
Author(s):  
Iain Stitt ◽  
Zhe Charles Zhou ◽  
Susanne Radtke-Schuller ◽  
Flavio Fröhlich
Keyword(s):  
Visual Processing ◽  
Posterior Parietal Cortex ◽  
Active Vision ◽  
Saccadic Eye Movements ◽  
Dynamic Interaction ◽  
Visual Exploration ◽  
Functional Interaction ◽  
Lateral Posterior ◽  
Posterior Parietal ◽  
And Behavior

Summary paragraphCognition and behavior emerge from the dynamic interaction of widely distributed, but functionally specialized brain networks. However, it remains unclear how network-level interactions dynamically reorganize to support ever-shifting cognitive and behavioral demands. Here, we investigate how the interaction between posterior parietal cortex (PPC) and lateral posterior (LP) / Pulvinar is shaped by ongoing fluctuations in pupil-linked arousal, which is a non-invasive measure related to neuromodulatory tone in the brain. We found that fluctuations in pupil-linked arousal tracked the dynamic interaction between PPC and LP/Pulvinar characterized by changes in the direction and carrier frequency of oscillatory interaction. Active visual exploration by saccadic eye movements elicited similar transitions in thalamo-cortical interaction. These findings suggest a common network substrate of both spontaneous activity and active vision. Thus, neuromodulators may play a role in dynamically sculpting the patterns of thalamo-cortical functional interaction that underlie visual processing.

Posterior parietal cortex mediates encoding processes in change blindness

2009 ◽  
Author(s):  
Philip Tseng ◽  
Cassidy Sterling ◽  
Adam Cooper ◽  
Bruce Bridgeman ◽  
Neil G. Muggleton ◽  
...  
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Change Blindness ◽  
Posterior Parietal

The Grasp Cell Hypothesis: Near-miss effect points to common neurological machinery in posterior parietal cortex for controllable objects and concepts

2018 ◽  
Author(s):  
Imogen M Kruse
Keyword(s):  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Near Miss ◽  
Illusion Of Control ◽  
Gambling Behaviour ◽  
Drug Seeking ◽  
Spatial Influence ◽  
Reward Probability ◽  
Posterior Parietal ◽  
Action Value

The near-miss effect in gambling behaviour occurs when an outcome which is close to a win outcome invigorates gambling behaviour notwithstanding lack of associated reward. In this paper I postulate that the processing of concepts which are deemed controllable is rooted in neurological machinery located in the posterior parietal cortex specialised for the processing of objects which are immediately actionable or controllable because they are within reach. I theorise that the use of a common machinery facilitates spatial influence on the perception of concepts such that the win outcome which is 'almost complete' is perceived as being 'almost within reach'. The perceived realisability of the win increases subjective reward probability and the associated expected action value which impacts decision-making and behaviour. This novel hypothesis is the first to offer a neurological model which can comprehensively explain many empirical findings associated with the near-miss effect as well as other gambling phenomena such as the ‘illusion of control’. Furthermore, when extended to other compulsive behaviours such as drug addiction, the model can offer an explanation for continued drug-seeking following devaluation and for the increase in cravings in response to perceived opportunity to self-administer, neither of which can be explained by simple reinforcement models alone. This paper therefore provides an innovative and unifying perspective for the study and treatment of behavioural and substance addictions.

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