scholarly journals Modeling Contextual Modulation of Memory Associations in the Hippocampus

Author(s):  
Praveen K. Pilly ◽  
Michael D. Howard ◽  
Rajan Bhattacharyya
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fazilet Zeynep Yildirim ◽  
Daniel R. Coates ◽  
Bilge Sayim

AbstractThe perception of a target depends on other stimuli surrounding it in time and space. This contextual modulation is ubiquitous in visual perception, and is usually quantified by measuring performance on sets of highly similar stimuli. Implicit or explicit comparisons among the stimuli may, however, inadvertently bias responses and conceal strong variability of target appearance. Here, we investigated the influence of contextual stimuli on the perception of a repeating pattern (a line triplet), presented in the visual periphery. In the neutral condition, the triplet was presented a single time to capture its minimally biased perception. In the similar and dissimilar conditions, it was presented within stimulus sets composed of lines similar to the triplet, and distinct shapes, respectively. The majority of observers reported perceiving a line pair in the neutral and dissimilar conditions, revealing ‘redundancy masking’, the reduction of the perceived number of repeating items. In the similar condition, by contrast, the number of lines was overestimated. Our results show that the similar context did not reveal redundancy masking which was only observed in the neutral and dissimilar context. We suggest that the influence of contextual stimuli has inadvertently concealed this crucial aspect of peripheral appearance.


2017 ◽  
Vol 114 (38) ◽  
pp. 10244-10249 ◽  
Author(s):  
Xue-Xin Wei ◽  
Alan A. Stocker

Perception of a stimulus can be characterized by two fundamental psychophysical measures: how well the stimulus can be discriminated from similar ones (discrimination threshold) and how strongly the perceived stimulus value deviates on average from the true stimulus value (perceptual bias). We demonstrate that perceptual bias and discriminability, as functions of the stimulus value, follow a surprisingly simple mathematical relation. The relation, which is derived from a theory combining optimal encoding and decoding, is well supported by a wide range of reported psychophysical data including perceptual changes induced by contextual modulation. The large empirical support indicates that the proposed relation may represent a psychophysical law in human perception. Our results imply that the computational processes of sensory encoding and perceptual decoding are matched and optimized based on identical assumptions about the statistical structure of the sensory environment.


2004 ◽  
Vol 91 (6) ◽  
pp. 2628-2648 ◽  
Author(s):  
Melanie T. Wyder ◽  
Dino P. Massoglia ◽  
Terrence R. Stanford

This study examines the influence of behavioral context on the activity of visuomotor neurons in primate central thalamus. Neurons that combine information about sensory stimuli and their behavioral relevance are thought to contribute to the decision mechanisms that link specific stimuli to specific responses. We reported in a previous study that neurons in central thalamus carry spatial information throughout the instructed delay period of a visually guided delayed saccade task. The goal of the current study was to determine whether the delay-period activity of thalamic neurons is modulated by behavioral context. Single neurons were evaluated during performance of visually guided and memory-guided variants of a saccadic choice task in which a cue designated the response field stimulus as the target of a rewarded saccade or as an irrelevant distracter. The relative influence of the physical stimulus and context on delay-period activity suggested a minimum of 3 neural groups. Some neurons signaled the locations of visible stimuli regardless of behavioral relevance. Other neurons preferentially signaled the locations of current saccadic goals and did so even in the absence of the physical stimulus. A third group signaled only the locations of currently visible saccadic goals. For the latter 2 groups, activity was the product of both stimulus and context, suggesting that central thalamic neurons play a role in the context-dependent linkage of sensory signals and saccadic commands. More generally, these data suggest that the anatomical substrate of sensorimotor decision making may include the cortico-subcortical loops for which central thalamus serves as the penultimate synapse.


2010 ◽  
Vol 9 (8) ◽  
pp. 456-456
Author(s):  
M. Meng ◽  
T. Cherian ◽  
P. Sinha

2021 ◽  
Vol 12 ◽  
Author(s):  
Emily Rose Hurwitz ◽  
Carol Lynne Krumhansl

The term “listening niche” refers to the contexts in which people listen to music including what music they are listening to, with whom, when, where, and with what media. The first experiment investigates undergraduate students’ music listening niches in the initial COVID-19 lockdown period, 4 weeks immediately after the campus shut down abruptly. The second experiment explores how returning to a hybrid semester, the “new normal,” further affected these listening habits. In both experiments, the participants provided a list of their most frequently listened-to songs during the respective period of time. From these, they identified one song that seemed most associated with this period, their “signature song,” and stated why this song seemed relevant. These reasons were coded on nine underlying themes. Three clusters were found to underlie the themes: (1) emotional responses (2) memory associations, and (3) discovery of new music. We identified songs and reasons for selecting them that represented the three clusters and related these to the lyrical content. Compared to before the pandemic, participants in both experiments report listening more in general and on Spotify, but there were no differences in listening between lockdown and the new normal. Whom they were listening with shifted overtime from family members to significant others and finally to other friends and roommates. These results demonstrate how students listen to and find new music that is meaningful to them during this unprecedented pandemic.


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