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Jillian H Fecteau

Publications and source records attributed to Jillian H Fecteau.

10 recordsLinked to original sources
PubMed2006

Warning signals influence motor processing.

When observers initiate responses to visual targets, they do so sooner when a preceding stimulus indicates that the target will appear shortly. This consequence of a warning signal may change neural activity in one of four ways. On the sensory side, the warning signal may speed up the rate at which the target is registered by the brain or enhance the magnitude of its signal. On the motor end, the warning signal may lower the threshold required to initiate a response or speed up the rate at which activity accumulates to reach threshold. Here, we describe which explanation is better supported. To accomplish this end, monkeys performed different versions of a cue-target task while we monitored the activity of visuomotor and motor neurons in the superior colliculus. Although the cue target task was designed to measure the properties of reflexive spatial attention, there are two events in this task that produce nonspecific warning effects: a central reorienting event (brightening of central fixation marker) that is used to direct attention away from the cue, and the presentation of the cue itself. Monopolizing on these tendencies, we show that warning effects are associated with several changes in neural activity: the target-related response is enhanced, the threshold for initiating a saccade is lowered, and the rate at which activity accumulates toward threshold rises faster. Ultimately, the accumulation of activity toward threshold predicted behavior most closely. In the discussion, we describe the implications and limitations of these data for theories of warning effects and potential avenues for future research.

Animals↗
PubMed2006

Salience, relevance, and firing: a priority map for target selection.

The salience map is a crucial concept for many theories of visual attention. On this map, each object in the scene competes for selection - the more conspicuous the object, the greater its representation, and the more likely it will be chosen. In recent years, the firing patterns of single neurons have been interpreted using this framework. Here, we review evidence showing that the expression of salience is remarkably similar across structures, remarkably different across tasks, and modified in important ways when the salient object is consistent with the goals of the participant. These observations have important ramifications for theories of attention. We conclude that priority--the combined representation of salience and relevance--best describes the firing properties of neurons.

Action Potentials↗
PubMed2005

Visual letter matching: hemispheric functioning or scanning biases?

Finding two mixed-case letters that share the same name is easier to do when the letters are presented in opposite visual fields than when they are both in the same field. By contrast, finding a match between two same-case letters is easier when they are in the same field. These visual field effects have been attributed to the ability of the corpus callosum to coordinate the work of the cerebral hemispheres [Banich, M. T. (1998). The missing link: The role of interhemispheric interaction in attentional processing. Brain and Cognition, 36, 128-157; Weissman, D. H., & Banich, M. T. (2000). The cerebral hemispheres cooperate to perform complex but not simple tasks. Neuropsychology, 14, 41-59]. The present study considers the alternative hypothesis that attentional scanning biases may be at work. Experiment 1 examined the effects of explicit instructions to scan items in a specific order; Experiment 2 examined influences of implicit location biasing; Experiment 3 considered the possibility that same-case letter matching is different because a perceptual grouping mechanism can be used in that task. In each experiment, we first interpreted the results within the hemispheric framework before considering the alternative accounts. We concluded that two scanning biases may be in effect: (1) an automatic bias favoring items in locations relatively distant from the current focus of attention and (2) a learned bias to scan letters in a left-to-right direction.

Analysis of Variance↗
PubMed2005

Correlates of capture of attention and inhibition of return across stages of visual processing.

How do visual signals evolve from early to late stages in sensory processing? We explored this question by examining two neural correlates of spatial attention. The capture of attention and inhibition of return refer to the initial advantage and subsequent disadvantage to respond to a visual target that follows an irrelevant visual cue at the same location. In the intermediate layers of the superior colliculus (a region that receives input from late stages in visual processing), both behavioral effects link to changes in the neural representation of the target: strong target-related activity correlates with the capture of attention and weak target-related activity correlates with inhibition of return. Contrasting these correlates with those obtained in the superficial layers (a functionally distinct region that receives input from early stages in visual processing), we show that the target-related activity of neurons in the intermediate layers was the best predictor of orienting behavior, although dramatic changes in the target-related response were observed in both subregions. We describe the important consequences of these findings for understanding the neural basis of the capture of attention and inhibition of return and interpreting changes in neural activity more generally.

Action Potentials↗
PubMed2004

Sensory biases produce alternation advantage found in sequential saccadic eye movement tasks.

In two-choice reaction time tasks, participants respond faster when the correct decision switches across consecutive trials. This alternation advantage has been interpreted as the guessing strategies of participants. Because the participants expect that the correct decision will switch across consecutive trials, they respond faster when this expectation is confirmed and they respond more slowly when it is disconfirmed. In this study, we evaluated the veracity of this expectancy interpretation. After replicating a long-lasting alternation advantage in saccadic reaction times (Experiment 1), we show that reducing the participants' ability to guess with a challenging mental rotation task does not change the alternation advantage, which suggests that expectancy is not responsible for the effect (Experiment 2). Next, we used prosaccade and antisaccade responses to dissociate between the sensory and motor contributions of the alternation advantage (Experiment 3) and we found that the alternation advantage originates from sensory processing. The implications of these findings are discussed with regard to guessing strategies, sensory processing, and how these findings may relate to inhibition of return.

Analysis of Variance↗
PubMed2004

Neural correlates of the automatic and goal-driven biases in orienting spatial attention.

How do stimuli in the environment interact with the goals of observers? We addressed this question by showing that the relevance of an abruptly appearing visual object (cue) changes how observers orient attention toward a subsequent object (target) and how this target is represented in the activity of neurons in the superior colliculus. Initially after the appearance of the cue, attention is driven to its locus. This capture of attention is followed by a second bias in orienting attention, where observers preferentially orient to new locations in the visual scene-an effect called inhibition of return. In the superior colliculus, these two automatic biases in orienting attention were associated with changes in neural activity linked to the appearance of the target-relatively stronger activity linked to the capture of attention and weaker activity linked to inhibition of return. This behavioral pattern changes when the cue predicts the upcoming location of the target-the benefit associated with the capture of attention is enhanced and inhibition of return is reduced. These goal-driven changes in behavior were associated with an increase in pretarget- and target-related activity. Taken together, the goals of observers modify stimulus-driven changes in neural activity with both signals represented in the salience maps of the superior colliculi.

Action Potentials↗
PubMed2004

Hemisphere differences in conscious and unconscious word reading.

Hemisphere differences in word reading were examined using explicit and implicit processing measures. In an inclusion task, which indexes both conscious (explicit) and unconscious (implicit) word reading processes, participants were briefly presented with a word in either the right or the left visual field and were asked to use this word to complete a three-letter word stem. In an exclusion task, which estimates unconscious word reading, participants completed the word stem with any word other than the prime word. Experiment 1 showed that words presented to either visual field were processed in very similar ways in both tasks, with the exception that words in the right visual field (left hemisphere) were more readily accessible for conscious report. Experiment 2 indicated that unconsciously processed words are shared between the hemispheres, as similar results were obtained when either the same or the opposite visual field received the word stem. Experiment 3 demonstrated that this sharing between hemispheres is cortically mediated by testing a split-brain patient. These results suggest that the left hemisphere advantage for word reading holds only for explicit measures; unconscious word reading is much more balanced between the hemispheres.

Adult↗
PubMed2003

Using auditory and visual stimuli to investigate the behavioral and neuronal consequences of reflexive covert orienting.

Reflexively orienting toward a peripheral cue can influence subsequent responses to a target, depending on when and where the cue and target appear relative to each other. At short delays between the cue and target [cue-target onset asynchrony (CTOA)], subjects are faster to respond when they appear at the same location, an effect referred to as reflexive attentional capture. At longer CTOAs, subjects are slower to respond when the two appear at the same location, an effect referred to as inhibition of return (IOR). Recent evidence suggests that these phenomena originate from sensory interactions between the cue- and target-related responses. The capture of attention originates from a strong target-related response, derived from the overlap of the cue- and target-related activities, whereas IOR corresponds to a weaker target-aligned response. If such interactions are responsible, then modifying their nature should impact the neuronal and behavioral outcome. Monkeys performed a cue-target saccade task featuring visual and auditory cues while neural activity was recorded from the superior colliculus (SC). Compared with visual stimuli, auditory responses are weaker and occur earlier, thereby decreasing the likelihood of interactions between these signals. Similar to previous studies, visual stimuli evoked reflexive attentional capture at a short CTOA (60 ms) and IOR at longer CTOAs (160 and 610 ms) with corresponding changes in the target-aligned activity in the SC. Auditory cues used in this study failed to elicit either a behavioral effect or modification of SC activity at any CTOA, supporting the hypothesis that reflexive orienting is mediated by sensory interactions between the cue and target stimuli.

Acoustic Stimulation↗
PubMed2002

Vying for dominance: dynamic interactions control visual fixation and saccadic initiation in the superior colliculus.

By the time you have reached this point, your daily count of alternating saccades and fixations will have increased considerably. So too will have your understanding of the dynamic interactions model. In the superior colliculi, visual fixation and saccadic initiation may be viewed as independent motor plans that compete for dominance across the intermediate layers. Extrinsic input modifies a point location on the retinotopic motor map that is shaped into a motor plan through the intrinsic circuitry of the superior colliculi. Independent motor plans compete for selection in a push-pull fashion and when a saccadic plan ultimately reaches threshold, it produces a strong burst of action potentials that shuts down the remaining regions of the intermediate layers. Modifying the activity of the intermediate layers changes these dynamic interactions in predictable ways. Enhancing the activity of one region facilitates nearby locations and inhibits distant locations. Diminishing the activity of one region inhibits nearby locations and facilitates distant locations. Such effects have been demonstrated in the neurophysiological activity of single cells (Munoz and Istvan, 1998; Olivier et al., 1999) and in behavior (Hikosaka and Wurtz, 1985; Munoz and Wurtz, 1993b). In addition to explaining visual fixation and saccadic initiation during basic saccadic tasks, the dynamic interactions model can explain changes in the timing of saccadic initiation that are observed when this task is modified. Namely, the gap effect, or decreased saccadic reaction times as a consequence of a gap period, occurs because removing fixation decreases the activity of fixation regions and, correspondingly, increases the excitability of saccadic regions. Express saccades, are a special instance of such dynamic interactions, in which decreased fixation activity and heightened motor preparation signals cause the target-related activity to be translated into a saccadic signal immediately. Finally, the slowing of saccadic initiation for antisaccades, can be interpreted as the consequence of multiple competing signals across the intermediate layers. It should be emphasized that the dynamic interactions that we have described in this chapter are not limited to the superior colliculi. On the contrary, similar interactions take place at many levels of the neuraxis (Moschovakis et al., 1996; Leigh and Zee, 1999; Schall and Thompson, 1999; Hikosaka et al., 2000; Munoz et al., 2000; Glimcher, 2001; Scudder et al., 2002). At this juncture, however, the dynamic interactions involved in producing visual fixation and saccadic initiation are better understood in the superior colliculi because of its well-organized motor map and its well-characterized neuronal elements. Although we are a long way from understanding how the brain controls visual fixation and saccadic initiation, we have made substantial progress in understanding these behaviors in the superior colliculi.

Fixation, Ocular↗