Mislocalization of visual stimuli: independent effects of static and dynamic attention

Shifts of visual attention cause systematic distortions of the perceived locations of visual objects around the focus of attention. In the attention repulsion effect, the perceived location of a visual target is shifted away from an attention-attracting cue when the cue is presented before the target. Recently it has been found that, if the visual cue is presented after the target, the perceived location of the target shifts toward the location of the following cue. One unanswered question is whether a single mechanism underlies both attentional repulsion and attraction effects. We presented participants with two disks at diagonal locations as visual cues and two vertical lines as targets. Participants were asked to perform a forced-choice task to judge targets' positions. The present study examined whether the magnitude of the repulsion effect and the attraction effect would differ (Experiment 1), whether the two effects would interact (Experiment 2), and whether the location or the dynamic shift of attentional focus would determine the distortions effects (Experiment 3). The results showed that the effect size of the attraction effect was slightly larger than the repulsion effect and the preceding and following cues have independent influences on the perceived positions. The repulsion effect was caused by the location of attnetion and the attraction effect was due to the dynamic shift of attentional focus, suggesting that the underlying mechanisms for the retrospective attraction effect might be different from those for the repulsion effect.     

Peeping and attachment to visual and auditory stimuli in day-old chicks

The usefulness of peeping in indexing attachment to visual and auditory stimuli was confirmed in chicks between 18 and 30 h post-hatch. Greater attractiveness of the auditory stimulus was associated with a more marked initial reduction in peeping after auditory stimulus presentation, suggesting a greater attentional impact, and with greater effectiveness in reducing peeping during repeated stimulus presentations. There was no difference between the two stimuli in effects on peeping before or shortly after the initial approach to the stimuli. Of additional interest was the observation of a sharp rise in peeping immediately preceding the increased activity associated with initial approach. The possible relationship between peeping and arousal was considered.     

Selective attention and memory: evoked potentials in visual and auditory verbal competition

The brain mechanisms of the selective verbal attention were studied using evoked potential (EP) technique. It was shown that the late "cognitive" EP components (400-800 ms) related to memory function were more positive to the words presented via a relevant sensory channel and more negative to irrelevant words. The hypothesis is advanced that words delivered via two competing sensory channels, such as visual and auditory, are perceived, i.e., the subject sees and hears them. However, irrelevant signals are not stored in episodic memory due to the active inhibition of the information transmission to the hippocampal structures.     

Convergence of visual and auditory stimuli on the neurons of the visual cortex in the conscious rabbit

We investigated the visual-cortex neurons of the conscious rabbit during simultaneous stimulation with a clicking sound and a light flash (complex) and during separate application of these stimuli. We tested the development of the reflex with time and of the sound-light association during prolonged rhythmic application of the sound and light. Fifty visual-cortex neurons were studied; 20% of the cells responded with a specific phased reaction and 16% exhibited a specific response to the complex different from the responses to each of its components. Development of a sound-light association was observed in 18% of the cells and a temporal reflex was induced in 25%. In most cases, the conditioned reaction evoked was similar to some informational element in the neuronal response to the complex.M. V. Lomonosov Moscow State University. Institute of Cybernetics, Academy of Sciences of the GruzSSR. Translated from Neirofiziologiya, Vol. 2, No. 4, pp. 391–398, July–August, 1970.     

EEG correlates of the states of visual and auditory attention in healthy subjects

In order to determine more accurately the EEG markers of different types of attention (AT) of a healthy adult, 14 young healthy subjects (aged 18–30 years) were subjected to spectral coherent analysis of the electrical activity of the brain in the baseline state and during activation of different forms of AT (the orienting response to the sound tone and opening of the eyes, involuntary and voluntary visual AT). In the last two cases, specially developed computer-aided techniques were used. The quantitative differences in the states were assessed on the basis of nonparametric (the Mann-Whitney test) and parametric (Student’s t test) statistics. In three subjects, EEG and fMRI comparisons of the brain response to opening of the eyes were made. It was shown that the activation of different forms of AT in healthy subjects is accompanied by considerable diffuse nonspecific changes in the EEG spectral coherent characteristics (a decrease in the average spectral frequency and power, as well as in coherence) in combination with more local, more often oppositely directed shifts in the region of the cortical representation of the working analyzer. Complex systemic rearrangements of the brain activity involving all components of the activating system, as well as the specifics of different forms of AT connected with the rearrangement of activity between its divisions, are reflected in the diffuse changes of intercentral interaction. For example, marked reactivity of the symmetrical frontopolar (F _p1-F _p2) and the anterotemporal (F ₇-F ₈) cortical areas with unidirectional maximum shifts during voluntary AT is likely to reflect the responses of the frontothalamic component of the activating system. The reciprocity of the behavior of interhemispheric frontopolar and temporal relationships seems to be determined by the activity of its different components: frontothalamic and hippocampal. The local component of the EEG response to opening of the eyes in the form of increased α coherence in the occipital areas is coupled with increased oxygenation of blood in the cortical representation of the visual analyzer (the +BOLD effect of the fMRI response).     

Topography of alpha and theta oscillatory responses upon auditory and visual stimuli in humans

Brain resonance phenomena and induced rhythms in the brain recently gained importance in electroencephalographic, magnetoencephalographic and cellular studies (Ba\c sar and Bullock 1992). It was hypothesized that evoked potentials are superpositions of induced rhythms caused by resonance phenomena in neural populations (Ba\c sar et al. 1992). According to Ba\c sar (1972), such resonance phenomena are reflected in the main peaks of the amplitude frequency characteristics computed from EEG responses. The present study is based on a frequency domain approach for the evaluation of topography- and modality-dependent properties of oscillatory brain responses. EEG and evoked potentials were recorded from vertex, parietal and occipital scalp locations in 24 volunteers. Two combined methods were applied: (1) amplitude frequency characteristics were computed from the transient evoked responses, and (2) frequency components of the transient responses were obtained by adaptive digital filtering. Our main goal was to investigate theta (4--7 Hz) and alpha (8--15 Hz) response components. (1) Amplitude frequency characteristics. Auditory stimuli elicited theta-alpha compound responses in the 4--11 Hz frequency band (e.g. typical peaking frequency around 7 Hz for vertex recordings). Visual stimuli elicited alpha responses (e.g. typical peaking frequency for vertex recordings around 9--12 Hz). Frequency maxima for visual stimuli thus had main peaks at higher frequency values than frequency maxima for auditory stimuli. (2) Digital filtering confirmed these results: for vertex recordings, theta vs. alpha response amplitudes were 9 vs 6 for auditory stimuli and 5 vs 5 for visual stimuli, thus confirming a shift towards higher frequencies, i.e. a more prominent contribution of the alpha range, in the case of visual stimulation. We hypothesize that these properties might reflect site- and modality-specific features of stimulus encoding in the brain in which resonance properties of neuron populations are involved. Furthermore we emphasize the utility of the systems theory approach for a better understanding of brain function by means of EPs. Received: 25 February 1994 / Accepted in revised form: 5 August 1994     

A naturalistic analysis of autobiographical memories triggered by olfactory visual and auditory stimuli

The emotional and content qualities of autobiographical memories evoked by three memory cue items (campfire, fresh-cut grass, popcorn) presented in olfactory, visual and auditory form were examined using a new repeated measures paradigm. Results revealed that memories recalled by odors were significantly more emotional and evocative than those recalled by the same cue presented visually or auditorily. However, there were no differences in the content features (vividness, specificity) of memories as a function of cue-form. These findings support previous research in both laboratory and naturalistic settings and is the first comparative sensory memory study to include auditory variants of memory cues. The present data contribute to a growing body of evidence indicating that there is a privileged relationship between olfaction and emotion during recollection. Various subject factors such as age, sex and region of residence were also examined and some were found to affect the quality of memories in interaction with the specific memory cue items, indicating that prior experience is a primary influence in autobiographical memory. Questions for future investigation regarding how odor-evoked memories may be different from other memory experiences are suggested.     

Rhythmic processing in children with developmental dyslexia: auditory and motor rhythms link to reading and spelling.

Potential links between the language and motor systems in the brain have long attracted the interest of developmental psychologists. In this paper, we investigate a link often observed (e.g., [Wolff, P.H., 2002. Timing precision and rhythm in developmental dyslexia. Reading and Writing, 15 (1), 179-206.] between motor tapping and written language skills. We measure rhythmic finger tapping (paced by a metronome beat versus unpaced) and motor dexterity, phonological and auditory processing in 10-year old children, some of whom had a diagnosis of developmental dyslexia. We report links between paced motor tapping, auditory rhythmic processing and written language development. Motor dexterity does not explain these relationships. In regression analyses, paced finger tapping explained unique variance in reading and spelling. An interpretation based on the importance of rhythmic timing for both motor skills and language development is proposed.     

Mismatch negativity (MMN) for sequences of auditory and visual stimuli: evidence for a mechanism specific to the auditory modality

ERPs to sequences of standard and deviant sinusoidal 100 msec tone pips, high-contrast sinusoidal gratings and to their simultaneously presented combinations were recorded. Mismatch negativity (MMN), an ERP component elicited by deviant stimuli, was estimated for the different stimulus sequences in order to find out whether it reflects modality-specific processes or non-specific attentive phenomena. In addition to the auditory modality, we studied whether the mismatch response could be evoked by a deviant visual stimulus in a visual sequence or by a deviant stimulus in either modality. The results show that only auditory stimuli produced the mismatch response, suggesting that MMN is not a manifestation of a general attentional mechanism but is probably specific to the auditory modality.     

Adaptive allocation of attention: effects of sex and sociosexuality on visual attention to attractive opposite-sex faces

We tested the hypothesis that, compared with sociosexually restricted individuals, those with an unrestricted approach to mating would selectively allocate visual attention to attractive opposite-sex others. We also tested for sex differences in this effect. Seventy-four participants completed the Sociosexual Orientation Inventory and performed a computer-based task that assessed the speed with which they detected changes in attractive and unattractive male and female faces. Differences in reaction times served as indicators of selective attention. Results revealed a Sex×Sociosexuality interaction: Compared with sociosexually restricted men, unrestricted men selectively allocated attention to attractive opposite-sex others; no such effect emerged among women. This finding was specific to opposite-sex targets and did not occur in attention to same-sex others. These results contribute to a growing literature on the adaptive allocation of attention in social environments.     

Interhemisphere differences of extrastriate cortical activation during attention and selection of lateralized visual stimuli in humans

The cortical activation was estimated by event-related potentials (ERPs) methods during selection tasks of lateralized visual stimuli in right and left hemi-fields requiring different forms of attention: 1. Attention of a stimuli form, 2. Attention of a stimuli position, 3. Combined attention of form and position. ERPs were recorded in 15 young healthy adults in 6 leads: P3, P4, T3, T4, T5, T6 and endogenous ERPs components: CNV (contingent negative variation), N1, P3 and complex [N1--P3]. The differences between ERPs at contra- and ipsilateral stimuli in the right and left hemispheres were considered as indices of asymmetry. The asymmetry was revealed in right hemisphere in all kinds of attention forms. The level (amplitude) of right-side asymmetry was depended on the level of attention: The significant relation between the right-side asymmetry and subjects' reaction time was also revealed. It is proposed that such an asymmetry is the evidence of better spatial differentiation of visual stimuli in right hemisphere in humans.     

Children with reading disability show brain differences in effective connectivity for visual, but not auditory word comprehension

Background

Previous literature suggests that those with reading disability (RD) have more pronounced deficits during semantic processing in reading as compared to listening comprehension. This discrepancy has been supported by recent neuroimaging studies showing abnormal activity in RD during semantic processing in the visual but not in the auditory modality. Whether effective connectivity between brain regions in RD could also show this pattern of discrepancy has not been investigated.

Methodology/Principal Findings

Children (8- to 14-year-olds) were given a semantic task in the visual and auditory modality that required an association judgment as to whether two sequentially presented words were associated. Effective connectivity was investigated using Dynamic Causal Modeling (DCM) on functional magnetic resonance imaging (fMRI) data. Bayesian Model Selection (BMS) was used separately for each modality to find a winning family of DCM models separately for typically developing (TD) and RD children. BMS yielded the same winning family with modulatory effects on bottom-up connections from the input regions to middle temporal gyrus (MTG) and inferior frontal gyrus(IFG) with inconclusive evidence regarding top-down modulations. Bayesian Model Averaging (BMA) was thus conducted across models in this winning family and compared across groups. The bottom-up effect from the fusiform gyrus (FG) to MTG rather than the top-down effect from IFG to MTG was stronger in TD compared to RD for the visual modality. The stronger bottom-up influence in TD was only evident for related word pairs but not for unrelated pairs. No group differences were noted in the auditory modality.

Conclusions/Significance

This study revealed a modality-specific deficit for children with RD in bottom-up effective connectivity from orthographic to semantic processing regions. There were no group differences in connectivity from frontal regions, suggesting that the core deficit in RD is not in top-down modulation.     

The effects of neck flexion on cerebral potentials evoked by visual,auditory and somatosensory stimuli and focal brain blood flow in related sensory cortices

Background

A flexed neck posture leads to non-specific activation of the brain. Sensory evoked cerebral potentials and focal brain blood flow have been used to evaluate the activation of the sensory cortex. We investigated the effects of a flexed neck posture on the cerebral potentials evoked by visual, auditory and somatosensory stimuli and focal brain blood flow in the related sensory cortices.

Methods

Twelve healthy young adults received right visual hemi-field, binaural auditory and left median nerve stimuli while sitting with the neck in a resting and flexed (20° flexion) position. Sensory evoked potentials were recorded from the right occipital region, Cz in accordance with the international 10–20 system, and 2 cm posterior from C4, during visual, auditory and somatosensory stimulations. The oxidative-hemoglobin concentration was measured in the respective sensory cortex using near-infrared spectroscopy.

Results

Latencies of the late component of all sensory evoked potentials significantly shortened, and the amplitude of auditory evoked potentials increased when the neck was in a flexed position. Oxidative-hemoglobin concentrations in the left and right visual cortices were higher during visual stimulation in the flexed neck position. The left visual cortex is responsible for receiving the visual information. In addition, oxidative-hemoglobin concentrations in the bilateral auditory cortex during auditory stimulation, and in the right somatosensory cortex during somatosensory stimulation, were higher in the flexed neck position.

Conclusions

Visual, auditory and somatosensory pathways were activated by neck flexion. The sensory cortices were selectively activated, reflecting the modalities in sensory projection to the cerebral cortex and inter-hemispheric connections.     

Mechanisms of selective attention in adults and children as reflected by evoked potentials to warning stimuli

Components of evoked potentials to stimuli differing in size and warning about the necessity of subsequent recognition of an image at the global or local level were analyzed to identify the specific features of selective attention in adults and seven-year-old children. In both age groups, components were found that were related to selective attention aimed at processing a warning stimulus (the P1, N1, and P2 components) and producing a response to the subsequent test stimulus. Both age groups exhibited similar dependences of changes in the P1 component (40–110 and 110–220 ms in the adults and children, respectively) on the type of the warning stimulus. The children displayed a greater increase in the amplitude of the P1 component of the response to the global versus the local key than the adults did. The P1 component is suggested to reflect not only the sensory features of the stimulus but also the selective attention associated with its sensory processing. The amplitude of the P2 component of the response to the global key (190–240 and 330–410 ms in the adults and children, respectively) was higher in both age groups. This component is believed to indicate evaluation of the signal importance of the warning stimulus. In the adults, late components of event-related potentials (ERPs), i.e., P3-N3 (300–450 ms), were associated with the global or local level of recognition of a test hierarchical stimulus that was presented after the key, with the greatest differences in the central and posterior associative areas of the right hemisphere and in the frontocentral areas of the left hemisphere. In the children, the N3 component (530–600 ms) in the left parietal area, as well as the late ERP phases, i.e., Ps (680–950 ms) and Ns (1030–1130 ms), during which the frontal cortical areas are involved in preparing the subsequent response, was shown to depend on the type of the warning stimulus.     

AIM: A network model of attention in auditory cortex

Attentional modulation of cortical networks is critical for the cognitive flexibility required to process complex scenes. Current theoretical frameworks for attention are based almost exclusively on studies in visual cortex, where attentional effects are typically modest and excitatory. In contrast, attentional effects in auditory cortex can be large and suppressive. A theoretical framework for explaining attentional effects in auditory cortex is lacking, preventing a broader understanding of cortical mechanisms underlying attention. Here, we present a cortical network model of attention in primary auditory cortex (A1). A key mechanism in our network is attentional inhibitory modulation (AIM) of cortical inhibitory neurons. In this mechanism, top-down inhibitory neurons disinhibit bottom-up cortical circuits, a prominent circuit motif observed in sensory cortex. Our results reveal that the same underlying mechanisms in the AIM network can explain diverse attentional effects on both spatial and frequency tuning in A1. We find that a dominant effect of disinhibition on cortical tuning is suppressive, consistent with experimental observations. Functionally, the AIM network may play a key role in solving the cocktail party problem. We demonstrate how attention can guide the AIM network to monitor an acoustic scene, select a specific target, or switch to a different target, providing flexible outputs for solving the cocktail party problem.