Attention: Spatial, featural, temporal, divided

Talk Session: Wednesday, May 24, 2023, 10:45 am – 12:30 pm, Talk Room 1
Moderator: Alex White, Barnard College

Talk 1, 10:45 am, 62.11

Spatial attention effects dominate over temporal attention

Helena Palmieri1 (), Marisa Carrasco12; 1Department of Psychology, New York University, New York, NY, 10003, USA, 2Center for Neural Science, New York University, New York, NY, 10003, USA

Rationale: Spatial attention increases contrast sensitivity and spatial resolution at attended locations and decreases them at unattended locations. Temporal attention improves performance at a specific given moment and decreases it at unattended moments. Most psychophysical experiments study attentional mechanisms in isolation, but in everyday life, they work together to optimize behavior. Here we investigate whether and how spatial and temporal attention benefit performance together while maximizing their independent effects and measuring their combined effect all in the same task. Here we investigate how spatial and temporal attention interact. Methods: In a 2AFC task, observers (n = 12) reported the orientation of a tilted Gabor. We manipulated observers’ spatial and temporal attention with precues (valid, neutral, or invalid) that indicated the most likely side (lower left or right) and timing (time one or two) of the tested target. We measured performance (d′) and reaction times for every combination of spatial and temporal cue. We measured the isolated effects of temporal and spatial attention to establish a baseline for comparison with the conjoint effect. Results: Spatial attention has clear benefit and cost effects across temporal attention conditions. Temporal attention benefits on accuracy are small across spatial attention conditions, but decreases reaction times across all spatial attention conditions. We also fit a computational model to these data, which models attentional encoding of the stimulus and late noise on the perceptual decision. Conclusions: These results suggest that people rely more on spatial attention than on temporal attention.

Acknowledgements: NIH R01-EY019693 to MC, NIH R01-EY019693-08S1 to HP

Talk 2, 11:00 am, 62.12

Expectation modulates the reflexive allocation of covert spatial attention

Michael Grubb1 (), Nick Crotty1, Nicole Massa1, Dagoberto Tellez1, Alex White2; 1Trinity College, 2Barnard College

Predictive coding theories of perception posit that visual stimuli are processed differently when they are expected than when they are unexpected. In this study, we extend that investigation into a new domain: covert exogenous spatial attention. It has long been known that the onsets of task-irrelevant stimuli (“cues”) cause reflexive shifts of attention towards their locations. We asked, do implicit expectations about the likelihood of task-irrelevant cues modulate how strongly they capture attention? Participants discriminated the orientation of a simple line that was preceded, on some trials, by a task-irrelevant disk (the exogenous cue). The color of the fixation dot (red or green) implicitly signaled the probability that a disk would appear (0.8, “expected”, or 0.2, “unexpected”). When presented, this disk flashed briefly, either near the target line (valid cue) or near a distractor line (invalid cue, equally likely). Across several experiments, we varied how much time participants were given to process the stimuli before responding. In short, we found that unexpected disks generated significantly larger cueing effects (discrimination accuracy, valid–invalid) than expected disks, but only when participants responded during the initial phase of visual processing (within 500 ms). Intriguingly, in post-experiment surveys, we found that participants were unable to report what the color of the fixation dot signaled about the likelihood of the cues. Therefore, our data demonstrate that implicitly learned contingencies between irrelevant visual events form expectations that modulate the deployment of attention.

Acknowledgements: NSF CAREER #2141860 to MAG, NIH NEI R00EY029366 to ALW

Talk 3, 11:15 am, 62.13

Feature-based attention has a spatial gradient

Nika Adamian1 (), Søren Krogh Andersen1,2; 1University of Aberdeen, 2University of Southern Denmark

Selective attention to a particular feature is known to be spatially global, with processing of that feature enhanced throughout the visual field. Theoretical accounts of feature-based attention assume that this spread of attentional enhancement is uniform across space. However, underlying empirical studies of spatial profile of feature-based attention have almost exclusively used isoeccentric locations to control for variability in visual processing across retinal eccentricities. Here we used EEG and frequency-tagged stimuli to measure the spread of feature-based attention across a wide range of eccentricities. Participants (n=29) were presented with a stimulus comprised of one central and two peripheral apertures filled with superimposed sets of red and blue randomly moving dots. On each trial they were cued to attend to either red or blue color. Their task was to detect brief episodes of coherent motion in the dots of the cued color in the central aperture. Peripheral apertures were presented simultaneously to the central one in one of three eccentricity conditions: close (spanning 5° to 9° degrees of visual angle), mid (12° to 21°) or far (22° to 38°) with the size of the dots progressively increasing. Attentional selection was measured through steady-state visual evoked potentials (SSVEPs) elicited by the flickering stimuli at each of the locations. The estimates of attentional modulation were then individually adjusted to account for signal-to-noise ratio (SNR) decline of SSVEPs between fovea and periphery. By magnifying stimuli sizes with eccentricity and by using SNR-corrected SSVEP amplitudes we were able to control for variations in visual processing across non-isoeccentric locations. SSVEP modulations analysed as a function of stimulus location showed robust attentional enhancement which, however, decreased with increasing eccentricity. These results suggest that the spread of feature-based attention across the visual field is not uniform and instead has a spatial gradient.

Acknowledgements: This work was supported by the Leverhulme Early Career Fellowship ECF-2020-488 to N.A.

Talk 4, 11:30 am, 62.14

Attraction of population receptive fields is determined by precision of attention

Sumiya A. Sheikh Abdirashid1,2,3 (), Tomas Knapen1,2,3, Serge O. Dumoulin1,2,3,4; 1Spinoza Centre for Neuroimaging, Amsterdam, Netherlands, 2Netherlands Institute for Neuroscience, Amsterdam, Netherlands, 3Experimental and Applied Psychology, Vrije Universiteit, Amsterdam, Netherlands, 4Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, Netherlands

Spatial attention enhances perception at attended locations. Population receptive fields (pRFs) are attracted to the position of the attentional locus, yet how the precision of attention influences pRF properties remains to be investigated. The attention field model, often used to summarize the locus of attention by a Gaussian field, predicts that attentional precision (Gaussian standard deviation) should influence pRF properties. Here, we investigated the effect of spatial precision of attention on pRF properties while keeping the attended location constant. We measured pRFs using ultra-high field 7T MRI while participants performed a color discrimination task. Two attention conditions were compared: attention narrowed on fixation (0.1 deg) and attention maximally distributed across the entire screen (>5 deg). In both conditions the same visual stimulus was presented and only the spatial extent of attention varied. The stimulus contained a standard pRF mapping contrast-defined bar. The narrow attention and distributed attention conditions did not differ in task difficulty and participants successfully modulated their spatial distribution of attention. The task elicited eccentricity-dependent changes in BOLD baseline in early visual areas. In particular, higher foveal BOLD responses to the narrow attention task and higher peripheral BOLD responses to the distributed attention task were observed. As predicted by the attention field model, pRF positions were altered as a function of attentional precision, with stronger attraction of pRF position towards the attended locus in the narrow attention condition. Moreover, larger pRF position changes were observed with increasing pRF size up the visual hierarchy. In addition to pRF position changes, attentional precision also influenced pRF size, with increased pRF size differences in higher visual areas. These results indicate that the size of spatial attention dynamically alters pRF properties in a manner consistent with the predictions of the attention field model.

Talk 5, 11:45 am, 62.15

Dissociable neuronal substrates of visual feature attention and working memory in the primate brain

Diego Mendoza-Halliday1 (), Haoran Xu1, Robert Desimone1; 1Massachusetts Institute of Technology

Visual attention and working memory (WM) are two different cognitive functions. However, because of their close relationship, it is often claimed that they share the same neuronal substrates. Here we examined whether the brain areas and neurons that are modulated by selective attention to a visual feature are the same as or different from those encoding WM representations of the same feature. Two macaque monkeys performed a WM-guided feature attention task that required maintaining a visual motion direction representation in WM and then selectively attending to stimuli with that motion direction. We recorded activity of motion direction-selective neurons in areas MT, MST, LIP, and LPFC-p, a posterior prefrontal subregion. We found that the percentage of neurons exclusively showing either attentional modulation or WM coding far exceeded the percentage showing both signals. This dissociation was most striking in LPFC-p, a region proposed as a source for feature attentional signals that modulate activity in visual cortex. To examine whether LPFC-p plays a causal role in feature attention and WM, we developed a method for large-scale bilateral inactivation of LPFC-p during either the WM period or the sustained attention period. LPFC-p inactivation during the sustained attention period reduced the strength of feature attentional effects not only locally but also in MST and LIP. In contrast, inactivation during the WM period reduced the strength of WM coding only in MST neurons and did not affect the strength of feature attentional effects in any area. Interestingly, LPFC-p inactivation during the sustained attention period impaired task performance, whereas inactivation during the WM period did not, suggesting that LPFC-p plays a critical role in feature attention but not in WM. Together, our results indicate that across multiple visual processing stages, the neuronal substrates underlying feature attention and WM are largely dissociable.

Acknowledgements: NIH Grant EY017921

Talk 6, 12:00 pm, 62.16

Simultaneous changes in acetylcholine (ACh) levels and neural activity during goal-directed behavior in non-human primates.

Fabian Munoz Silva1,2 (), Maria Bompolaki3,4, Alex Dranovsky3,4, Vincent Ferrera1,2; 1Department of Neuroscience, Columbia University, 2Zuckerman Mind Brain Behavior Institute, Columbia University, 3Department of Psychiatry, Columbia University, 4New York State Psychiatric Institute, New York

The cholinergic system is thought to orchestrate task engagement. However, we lack a detailed understanding of how transient shifts in performance may be influenced by rapid changes in acetylcholine (ACh) levels. Neurotransmitter-specific fluorescent genetically encoded sensor recordings using fiber photometry provide a method for overcoming these limitations. This approach allows monitoring of variations in local neurotransmitter release and can provide important details about neuromodulation without the need to target reporter expression to particular cells of interest or demand single-cell precision for signal analysis. It has proven technically difficult to examine circuit function in non-human primates (NHP) using genetic methods because transgene expression is frequently low and transient. Here, we describe the use of GRAB-ACh3.0 to examine the effect of cholinergic modulation on signal detection in V1 of a rhesus macaque. We used fiber photometry to measure GRAB-ACh3.0 activity with simultaneous single-cell electrophysiology, pupillometry, and eye tracking while the animal was engaged in a smooth pursuit task. Our results indicate that global ACh fluorescence in V1 correlates with performance in the task supporting the notion that momentary lapses of attention occur during periods of low ACh. Both ACh and LFP in V1 present a power peak between the frequencies 2 and 4 Hz. Global ACh fluorescence in V1 correlates with the firing rate of local neurons. These results highlight the role of cholinergic signaling in moment-to-moment fluctuations in behavioral output as well as neuronal activity, reinforcing the potential of cholinergic compensation to improve performance. To our knowledge, this is the first evidence of rapid neurotransmitter changes correlating with moment-to-moment fluctuations in behavioral output in primates. These results have important implications for understanding the neurochemical underpinnings of sustained attention and goal-directed performance and define a pharmaceutically targetable substrate to manage conditions like attention deficit disorder.

Acknowledgements: MH091844, MH115215, MH111703

Talk 7, 12:15 pm, 62.17

The attentionally-modulated posterior parietal area V6A in macaques and humans

Patrizia Fattori1 (), Marina De Vitis1, Matteo Filippini1, Kostas Hadjidimitrakis1, Claudio Galletti1; 1University of Bologna, Italy

Area V6A occupies the caudalmost part of the superior parietal lobule in both human and non-human primates. In macaques, V6A is a visuomotor area that represents large part of the visual field and the upper limbs. V6A cells are modulated by the direction and amplitude of arm movement, by wrist orientation and by grip type, indicating that this area is involved in the control of all phases of reach-to-grasp actions. V6A may act as a ‘state estimator’ whose output is used to adjust the motor plan in order to maintain consistency between the ongoing movement and the desired one. In humans, neuroimaging studies have revealed strong homologies with macaque showing that hV6A is involved in the visuomotor control of goal-directed hand movements. Since goal-directed behaviors crucially depend on the ability to flexibly adapt the motor plan in response to unexpected changes in target location, which in turn depends on the ability to shift attention to a new location, we checked whether shifts of spatial attention modulate V6A activity. Indeed, 1) some V6A cells discharged whenever the animal covertly directed its spotlight of attention towards particular parts of its field of view, 2) hV6A was activated by covert attentional shifts in attentional reorienting and 3) TMS over the hV6A did affect these attentional shifts. In addition, it was observed that a small lesion matching hV6A resulted in a shifting attention deficit, particularly intense when repeated shifts of spatial attention were required. Notably, a small cortical region that likely includes hV6A was found to be implicated in coding visual information in terms of egocentric coordinates, that is the same coordinates used to direct the spotlight of attention. We suggest that hV6A hosts an egocentric spatial map useful to direct the limbs in reach-to-grasp movements, particularly towards moving objects and during self-motion.

Acknowledgements: PRIN 2020: 20208RB4N9 and H2020-951910-FET.PROACT – MAIA