Biology subjects

Ball, F.

Publications and source records attributed to Ball, F..

4 recordsLinked to original sources

bioRxiv2021

Minimal interplay between explicit knowledge, dynamics of learning and temporal expectations in different, complex uni- and multisensory contexts

While temporal expectations (TE) generally improve reactions to temporally predictable events, it remains unknown how temporal rule learning and explicit knowledge about temporal rules contribute to performance improvements and whether any contributions generalise across modalities. Here, participants discriminated the frequency of diverging auditory, visual or audiovisual targets embedded in auditory, visual or audiovisual distractor sequences. Temporal regularities were manipulated run-wise (early vs. late target within sequence). Behavioural performance (accuracy, RT) plus measures from a computational learning model all suggest that temporal rule learning occurred but did not generalise across modalities, that dynamics of learning (size of TE effect across runs) and explicit knowledge have little to no effect on the strength of TE, and that explicit knowledge affects performance - if at all - in a context dependent manner: only under complex task regimes (unknown target modality) might it partially help to resolve response conflict while it is lowering performance in less complex environments..

neuroscience↗

bioRxiv2021

Cross-modal perceptual enhancement of unisensory targets is uni-directional and does not affect temporal expectations

Previous studies demonstrated that redundant target stimuli can enhance performance due to multisensory interplay and interactively facilitate performance enhancements due to temporal expectations (TE; faster and accurate reactions to temporally expected targets). Here we tested whether other types of multisensory interactions - i.e. interactions evoked by temporally flanking irrelevant stimuli - can result in similar performance patterns and boost not only unisensory target perception (multi-vs. unisensory sequences) but also unisensory temporal expectations (expected vs. unexpected). To test our hypothesis, we presented sequences of 12 stimuli (10 Hz) which either consisted of auditory (A), visual (V) or alternating auditory-visual stimuli (e.g. A-V-A-V-...) with either auditory (AV(A)) or visual (AV(V)) targets. Participants had to discriminate target frequency which was unpredictable by temporal regularities (expected vs. unexpected target positions) and by stimulation sequence (A, V, AV(A), AV(V)). Moreover, we ran two experiments in which we presented redundant multisensory targets and manipulated the speed of the stimulation sequence (10 vs. 15 Hz stimulus trains) to control whether the results of Experiment 1 depended on sequence speed. Performance for unisensory targets was affected by temporally flanking distractors, with multisensory interactions selectively improving unisensory visual target perception. Yet, only redundant multisensory targets reliably affected TEs. Together, these results indicate that cross-modal facilitation of unisensory target perception in fast stimulus streams is uni-directional, but also differs from multisensory interactions evoked by redundant targets; more specifically, it appears to be context-dependent (task, design etc.) whether unisensory stimulation (unlike redundant target stimulation) allows for the generation of temporal expectations.

neuroscience↗

bioRxiv2021

Context dependency of time-based event-related expectations for different modalities

Expectations about the temporal occurrence of events (when) are often tied with the expectations about certain event-related properties (what and where) happening at these time points. For instance, slowly waking up in the morning we expect our alarm clock to go off; however, the longer we do not hear it the more likely we already missed it. However, most current evidence for complex time-based event-related expectations (TBEEs) is based on the visual modality. Here we tested whether TBEEs can also act cross-modally. To this end, visual and auditory stimulus streams were presented which contained early and late targets embedded among distractors (to maximise temporal target uncertainty). Foreperiod-modality-contingencies were manipulated run-wise so that visual targets either occurred early in 80% of trials and auditory targets occurred late in 80 % of trials or vice versa. Participants showed increased sensitivity for expected auditory early/visual late targets which increased over time while the opposite pattern was observed for visual early/auditory late targets. A benefit in reaction times was only found for auditory early trials. Together, this pattern of results suggests that context-dependent TBEEs for auditory targets after short foreperiods (be they correct or not) dominated and determined which modality became more expected at the late position irrespective of the veridical statistical regularity. Hence, TBEEs in cross-modal and uncertain environments are context-dependent, shaped by the dominant modality in temporal tasks (i.e. auditory) and only boost performance cross-modally when expectations about the event after the short foreperiod match with the run-wise context (i.e. auditory early/visual late).

neuroscience↗

bioRxiv2019

Information-based taste maps in insular cortex are shaped by stimulus concentration

Taste processing is an essential ability in all animals signaling potential harm or benefit of ingestive behavior. Although the peripheral taste coding is well understood, current evidence for central taste processing remains contradictory. To address this issue, human participants judged pleasantness and intensity of low and high-concentration tastes (salty, sweet, sour, bitter) in two fMRI-experiments. High-resolution fMRI and multivariate pattern analysis were used to characterize taste-related informational content in human gustatory cortex (GC). Clusters within GC were narrowly tuned to specific tastants consistently across tasks. Importantly, taste concentrations completely altered the spatial layout of putative taste-specific maps with distinct, non-overlapping patterns for each taste category at different concentration levels. Together, our results point at population-level representations in human GC as a complex function of taste category and concentration.

neuroscience↗