ABSTRACT
Emoticons have been considered pragmatic cues that enhance emotional expressivity during computer-mediated communication. Yet, it is unclear how emoticons are processed in ambiguous text-based communication due to incongruences between the emoticon's emotional valence and its context. In this study, we investigated the electrophysiological correlates of contextual influence on the early emotional processing of emoticons, during an emotional congruence judgment task. Participants were instructed to judge the congruence between a text message expressing an emotional situation (positive or negative), and a subsequent emoticon expressing positive or negative emotions. We analyzed early event-related potentials elicited by emoticons related to face processing (N170) and emotional salience in visual perception processing (Early Posterior Negativity, EPN). Our results show that accuracy and Reaction Times depend on the interaction between the emotional valence of the context and the emoticon. Negative emoticons elicited a larger N170, suggesting that the emotional information of the emoticon is integrated at the early stages of the perceptual process. During emoticon processing, a valence effect was observed with enhanced EPN amplitudes in occipital areas for emoticons representing negative valences. Moreover, we observed a congruence effect in parieto-temporal sites within the same time-window, with larger amplitudes for the congruent condition. We conclude that, similar to face processing, emoticons are processed differently according to their emotional content and the context in which they are embedded. A congruent context might enhance the emotional salience of the emoticon (and therefore, its emotional expression) during the early stages of their processing.
Subject(s)
Electroencephalography , Emotions , Evoked Potentials , Reaction Time , Text Messaging , Humans , Emotions/physiology , Female , Male , Evoked Potentials/physiology , Young Adult , Adult , Reaction Time/physiology , Brain/physiology , Judgment/physiology , Visual Perception/physiologyABSTRACT
The Continuous Visual Attention Test (CVAT) is a test that detects visuomotor reaction time (RT, alertness), variability of reaction time (VRT, sustained attention), omission errors (OE, focused attention), and commission errors (CE, response inhibition). The standard test takes 15 min, while the ultrafast version only 90 s. Besides overall task length, the two versions differ by target probability (20% and 80% in the 15-min vs. only 80% in the 90-s test) and stimulus-onset asynchrony (SOA) (1, 2, and 4 s in the 15-min vs. only 1 s in the 90-s test. We aimed to analyze the effect of target probability, SOA, and time length on the CVAT variables across the 15-min task and to verify correlations and agreements between the 15-min and the 90-s CVATs. 205 healthy participants performed the two CVATs on the same day. Considering the 15-min task, RT and CE were strongly affected by target probability. Conversely, VRT was not affected. When the 15-min task was compared to the 90-s task, we found no significant difference in the VRT variable. Additionally, a significant agreement between the two tasks was found for the VRT variable. We concluded that sustained attention can be measured with the 90-s CVAT.
Subject(s)
Attention , Reaction Time , Humans , Attention/physiology , Reaction Time/physiology , Male , Female , Adult , Young Adult , Psychomotor Performance/physiology , Neuropsychological Tests , Adolescent , Middle Aged , Visual Perception/physiology , Photic StimulationABSTRACT
INTRODUCTION: Attention and working memory are key cognitive functions that allow us to select and maintain information in our mind for a short time, being essential for our daily life and, in particular, for learning and academic performance. It has been shown that musical training can improve working memory performance, but it is still unclear if and how the neural mechanisms of working memory and particularly attention are implicated in this process. In this work, we aimed to identify the oscillatory signature of bimodal attention and working memory that contributes to improved working memory in musically trained children. MATERIALS AND METHODS: We recruited children with and without musical training and asked them to complete a bimodal (auditory/visual) attention and working memory task, whereas their brain activity was measured using electroencephalography. Behavioral, time-frequency, and source reconstruction analyses were made. RESULTS: Results showed that, overall, musically trained children performed better on the task than children without musical training. When comparing musically trained children with children without musical training, we found modulations in the alpha band pre-stimuli onset and the beginning of stimuli onset in the frontal and parietal regions. These correlated with correct responses to the attended modality. Moreover, during the end phase of stimuli presentation, we found modulations correlating with correct responses independent of attention condition in the theta and alpha bands, in the left frontal and right parietal regions. CONCLUSIONS: These results suggest that musically trained children have improved neuronal mechanisms for both attention allocation and memory encoding. Our results can be important for developing interventions for people with attention and working memory difficulties.
Subject(s)
Alpha Rhythm , Attention , Memory, Short-Term , Music , Theta Rhythm , Humans , Memory, Short-Term/physiology , Attention/physiology , Male , Female , Child , Theta Rhythm/physiology , Alpha Rhythm/physiology , Auditory Perception/physiology , Electroencephalography , Visual Perception/physiology , Brain/physiologyABSTRACT
In the animal kingdom, threat information is perceived mainly through vision. The subcortical visual pathway plays a critical role in the rapid processing of visual information-induced fear, and triggers a response. Looming-evoked behavior in rodents, mimicking response to aerial predators, allowed identify the neural circuitry underlying instinctive defensive behaviors; however, the influence of disk/background contrast on the looming-induced behavioral response has not been examined, either in rats or mice. We studied the influence of the dark disk/gray background contrast in the type of rat and mouse defensive behavior in the looming arena, and we showed that rat and mouse response as a function of disk/background contrast adjusted to a sigmoid-like relationship. Both sex and age biased the contrast-dependent response, which was dampened in rats submitted to retinal unilateral or bilateral ischemia. Moreover, using genetically manipulated mice, we showed that the three type of photoresponsive retinal cells (i.e., cones, rods, and intrinsically photoresponsive retinal ganglion cells (ipRGCs)), participate in the contrast-dependent response, following this hierarchy: cones > > rods > > > ipRGCs. The cone and rod involvement was confirmed using a mouse model of unilateral non-exudative age-related macular degeneration, which only damages canonical photoreceptors and significantly decreased the contrast sensitivity in the looming arena.
Subject(s)
Photic Stimulation , Retinal Ganglion Cells , Animals , Rats , Mice , Male , Retinal Ganglion Cells/physiology , Female , Contrast Sensitivity/physiology , Behavior, Animal/physiology , Retinal Cone Photoreceptor Cells/physiology , Mice, Inbred C57BL , Visual Perception/physiology , Fear/physiology , Retina/physiology , Visual Pathways/physiologyABSTRACT
Tasks we often perform in our everyday lives, such as reading or looking for a friend in the crowd, are seemingly straightforward but they actually require the orchestrated activity of several cognitive processes. Free-viewing visual search requires a plan to move our gaze on the different items, identifying them, and deciding on whether to continue with the search. Little is known about the electrophysiological signatures of these processes in free-viewing because there are technical challenges associated with eye movement artefacts. Here, we aimed to study how category information, as well as ecologically relevant variables such as the task performed, influence brain activity in a free-viewing paradigm. Participants were asked to observe/search from an array of faces and objects embedded in random noise. We concurrently recorded electroencephalogram and eye movements and applied a deconvolution analysis approach to estimate the contribution of the different elements embedded in the task. Consistent with classical fixed-gaze experiments and a handful of free-viewing studies, we found a robust categorical effect around 150 ms in occipital and occipitotemporal electrodes. We also report a task effect, more negative in posterior central electrodes in visual search compared with exploration, starting at around 80 ms. We also found significant effects of trial progression and an interaction with the task effect. Overall, these results generalise the characterisation of early visual face processing to a wider range of experiments and show how a suitable analysis approach allows to discern among multiple neural contributions to the signal, preserving key attributes of real-world tasks.
Subject(s)
Eye Movements , Facial Recognition , Humans , Electroencephalography , Visual Perception/physiology , Fixation, OcularABSTRACT
Visual perception is the product of serial hierarchical processing, parallel processing, and remapping on a dynamic network involving several topographically organized cortical visual areas. Here, we will focus on the topographical organization of cortical areas and the different kinds of visual maps found in the primate brain. We will interpret our findings in light of a broader representational framework for perception. Based on neurophysiological data, our results do not support the notion that vision can be explained by a strict representational model, where the objective visual world is faithfully represented in our brain. On the contrary, we find strong evidence that vision is an active and constructive process from the very initial stages taking place in the eye and from the very initial stages of our development. A constructive interplay between perceptual and motor systems (e.g., during saccadic eye movements) is actively learnt from early infancy and ultimately provides our fluid stable visual perception of the world.
Subject(s)
Saccades , Visual Perception , Animals , Visual Perception/physiology , Brain , Primates , Brain MappingABSTRACT
Understanding the neural basis of consciousness is a fundamental goal of neuroscience, and sensory perception is often used as a proxy for consciousness in empirical studies. However, most studies rely on reported perception of visual stimuli. Here we present behavior, high density scalp EEG and eye metric recordings collected simultaneously during a novel tactile threshold perception task. We found significant N80, N140 and P300 event related potentials in perceived trials and in perceived versus not perceived trials. Significance was limited to a P100 and P300 in not perceived trials. We also found an increase in pupil diameter and blink rate and a decrease in microsaccade rate following perceived relative to not perceived tactile stimuli. These findings support the use of eye metrics as a measure of physiological arousal associated with conscious perception. Eye metrics may also represent a novel path toward the creation of tactile no-report tasks in the future.
Subject(s)
Consciousness , Touch Perception , Consciousness/physiology , Electroencephalography , Humans , Scalp , Touch/physiology , Visual Perception/physiologyABSTRACT
Fast and accurate threat detection is critical for animal survival. Reducing perceptual ambiguity by integrating multiple sources of sensory information can enhance perception and reduce response latency. However, studies addressing the link between behavioral correlates of multisensory integration and its underlying neural basis are rare. Fish that detect an urgent threat escape with an explosive behavior known as C-start. The C-start is driven by an identified neural circuit centered on the Mauthner cell, an identified neuron capable of triggering escapes in response to visual and auditory stimuli. Here we demonstrate that goldfish can integrate visual looms and brief auditory stimuli to increase C-start probability. This multisensory enhancement is inversely correlated to the salience of the stimuli, with weaker auditory cues producing a proportionally stronger multisensory effect. We also show that multisensory stimuli reduced C-start response latency, with most escapes locked to the presentation of the auditory cue. We make a direct link between behavioral data and its underlying neural mechanism by reproducing the behavioral data with an integrate-and-fire computational model of the Mauthner cell. This model of the Mauthner cell circuit suggests that excitatory inputs integrated at the soma are key elements in multisensory decision making during fast C-start escapes. This provides a simple but powerful mechanism to enhance threat detection and survival.
Subject(s)
Escape Reaction/physiology , Reaction Time/physiology , Rhombencephalon/physiology , Acoustic Stimulation , Animals , Auditory Perception/physiology , Cues , Female , Goldfish/physiology , Male , Neurons/physiology , Visual Perception/physiologyABSTRACT
Visuospatial working memory (VSWM) deficits have been demonstrated to occur during the development of type-1-diabetes (T1D). Despite confirming the early appearance of distinct task-related brain activation patterns in T1D patients compared to healthy controls, the effect of VSWM load on functional brain connectivity during task performance is still unknown. Using electroencephalographic methods, the present study evaluated this topic in clinically well-controlled T1D young patients and healthy individuals, while they performed a VSWM task with different memory load levels during two main VSWM processing phases: encoding and maintenance. The results showed a significantly lower number of correct responses and longer reaction times in T1D while performing the task. Besides, higher and progressively increasing functional connectivity indices were found for T1D patients in response to cumulative degrees of VSWM load, from the beginning of the VSWM encoding phase, without notably affecting the VSWM maintenance phase. In contrast, healthy controls managed to solve the task, showing lower functional brain connectivity during the initial VSWM processing steps with more gradual task-related adjustments. Present results suggest that T1D patients anticipate high VSWM load demands by early recruiting supplementary processing resources as the probable expression of a more inefficient, though paradoxically better adjusted to task demands cognitive strategy.
Subject(s)
Cognitive Dysfunction/physiopathology , Connectome , Diabetes Complications/physiopathology , Diabetes Mellitus, Type 1/physiopathology , Memory, Short-Term/physiology , Psychomotor Performance/physiology , Adolescent , Adult , Cognitive Dysfunction/etiology , Diabetes Mellitus, Type 1/complications , Electroencephalography , Female , Humans , Male , Space Perception/physiology , Visual Perception/physiology , Young AdultABSTRACT
A pesquisa sobre percepção de cenas é um esforço da comunidade científica em superar as dificuldades apresentadas ao estudo de estímulos complexos. As consistentes descobertas provaram a viabilidade do tema e encorajam uma abordagem mais holística e integrada nas investigações em percepção visual. Esse esforço e seus achados são, entretanto, pouco conhecidos pelos leitores em língua portuguesa e, até mesmo, entre alguns especialistas que se interessam pelo tema. O objetivo deste trabalho é fazer uma apresentação do campo, esboçar seu desenvolvimento, identificar suas principais questões e demonstrar sua pertinência e importância. Para isso, uma revisão seletiva de textos foi executada entre os autores que construíram os fundamentos da percepção de cenas. Ao concluir a leitura, espera-se que o leitor constate o papel relevante dos processos mnemônicos e do sujeito que observa no processo de captação visual do ambiente natural.
Scene perception research is a scientific community effort to overcome difficulties presented to the study of complex stimuli. Consistent findings support feasibility of the theme and encourage a more holistic and integrated approach to visual perception research. This effort and its findings are, however, poorly known by readers in Portuguese language, even among experts interested in the subject. The purpose of this paper is to introduce this field of research, outline its development, identify its main issues and demonstrate its relevance and importance. This task was accomplished by a selective review of papers from authors who built the foundations of scene perception. Upon completion of the reading, it is expected that the reader understands the relevant role of mnemonic processes and of the observer in the process of visual capture of natural environments.
Subject(s)
Humans , Space Perception/physiology , Visual Perception/physiology , Visual Fields/physiologyABSTRACT
Human behavior is biased by past experience. For example, when intercepting a moving target, the speed of previous targets will bias responses in future trials. Neural mechanisms underlying this so-called serial dependence are still under debate. Here, we tested the hypothesis that the previous trial leaves a neural trace in brain regions associated with encoding task-relevant information in visual and/or motor regions. We reasoned that injecting noise by means of transcranial magnetic stimulation (TMS) over premotor and visual areas would degrade such memory traces and hence reduce serial dependence. To test this hypothesis, we applied bursts of TMS pulses to right visual motion processing region hV5/MT+ and to left dorsal premotor cortex (PMd) during intertrial intervals of a coincident timing task performed by twenty healthy human participants (15 female). Without TMS, participants presented a bias toward the speed of the previous trial when intercepting moving targets. TMS over PMd decreased serial dependence in comparison to the control Vertex stimulation, whereas TMS applied over hV5/MT+ did not. In addition, TMS seems to have specifically affected the memory trace that leads to serial dependence, as we found no evidence that participants' behavior worsened after applying TMS. These results provide causal evidence that an implicit short-term memory mechanism in premotor cortex keeps information from one trial to the next, and that this information is blended with current trial information so that it biases behavior in a visuomotor integration task with moving objects.SIGNIFICANCE STATEMENT Human perception and action are biased by the recent past. The origin of such serial bias is still not fully understood, but a few components seem to be fundamental for its emergence: the brain needs to keep previous trial information in short-term memory and blend it with incoming information. Here, we present evidence that a premotor area has a potential role in storing previous trial information in short-term memory in a visuomotor task and that this information is responsible for biasing ongoing behavior. These results corroborate the perspective that areas associated with processing information of a stimulus or task also participate in maintaining that information in short-term memory even when this information is no longer relevant for current behavior.
Subject(s)
Attentional Bias/physiology , Memory, Short-Term/physiology , Motor Cortex/physiology , Psychomotor Performance/physiology , Visual Perception/physiology , Adult , Female , Humans , Male , Photic Stimulation , Transcranial Magnetic StimulationABSTRACT
Top-down modulation of sensory responses to distracting stimuli by selective attention has been proposed as an important mechanism by which our brain can maintain relevant information during working memory tasks. Previous works in visual working memory (VWM) have reported modulation of neural responses to distracting sounds at different levels of the central auditory pathways. Whether these modulations occur also at the level of the auditory receptor is unknown. Here, we hypothesize that cochlear responses to irrelevant auditory stimuli can be modulated by the medial olivocochlear system during VWM. Twenty-one subjects (13 males, mean age 25.3 yr) with normal hearing performed a visual change detection task with different VWM load conditions (high load = 4 visual objects; low load = 2 visual objects). Auditory stimuli were presented as distractors and allowed the measurement of distortion product otoacoustic emissions (DPOAEs) and scalp auditory evoked potentials. In addition, the medial olivocochlear reflex strength was evaluated by adding contralateral acoustic stimulation. We found larger contralateral acoustic suppression of DPOAEs during the visual working memory period (n = 21) compared with control experiments (n = 10), in which individuals were passively exposed to the same experimental conditions. These results show that during the visual working memory period there is a modulation of the medial olivocochlear reflex strength, suggesting a possible common mechanism for top-down filtering of auditory responses during cognitive processes.NEW & NOTEWORTHY The auditory efferent system has been proposed to function as a biological filter of cochlear responses during selective attention. Here, we recorded electroencephalographic activity and otoacoustic emissions in response to auditory distractors during a visual working memory task in humans. We found that the olivocochlear efferent activity is modulated during the visual working memory period suggesting a common mechanism for suppressing cochlear responses during selective attention and working memory.
Subject(s)
Auditory Perception/physiology , Cochlea/physiology , Cochlear Nucleus/physiology , Hearing/physiology , Memory, Short-Term/physiology , Reflex/physiology , Superior Olivary Complex/physiology , Visual Perception/physiology , Acoustic Stimulation , Adult , Efferent Pathways/physiology , Electroencephalography , Evoked Potentials, Auditory/physiology , Female , Humans , Male , Young AdultABSTRACT
The goal of this study was to examine the visual preference towards socially salient stimuli, using a low-cost eye-tracking device in a group of typically developing (TD) Ecuadorian preschoolers aged 11 to 60 months, from rural and urban areas, and from families with low to high socioeconomic status (SES). Series of original stimuli inspired by those used in Western experiments on the early detection of Autism Spectrum Disorder (ASD) were proposed in two eye-tracking tasks. Two types of movements (human vs. object) were presented in task 1, and dynamic speaking faces in task 2. Parental perceptions of the adaptability of the low-cost eye-tracking device used here were also investigated through a questionnaire. The analyses of mean fixation times showed a visual preference for human movements compared to moving objects whatever age, residency location or SES. In task 2, visual preference for the mouth's area compared to the eyes' area was observed in specific conditions, modulated by residency location and SES but not by age. The analyses of the parental perception indicated that the eye-tracking technique is well accepted. The findings suggest that these stimuli, along with the experimental procedure and low-cost eye-tracking device used in the present study may be a relevant tool that can be used in clinical settings as a contribution to the early identification of at-risk factors of ASD in low- and middle-income contexts.
Subject(s)
Attention/physiology , Autism Spectrum Disorder/physiopathology , Eye Movements/physiology , Fixation, Ocular/physiology , Social Behavior , Visual Perception/physiology , Autism Spectrum Disorder/epidemiology , Child, Preschool , Ecuador/epidemiology , Feasibility Studies , Female , Humans , Infant , Male , Motivation , Risk FactorsABSTRACT
Threatening stimuli seem to capture attention more swiftly than neutral stimuli. This attention bias has been observed under different experimental conditions and with different types of stimuli. It remains unclear whether this adaptive behaviour reflects the function of automatic or controlled attention mechanisms. Additionally, the spatiotemporal dynamics of its neural correlates are largely unknown. The present study investigates these issues using an Emotional Flanker Task synchronized with EEG recordings. A group of 32 healthy participants saw response-relevant images (emotional scenes from IAPS or line drawings of objects) flanked by response-irrelevant distracters (i.e., emotional scenes flanked by line drawings or vice versa). We assessed behavioural and ERP responses drawn from four task conditions (Threat-Central, Neutral-Central, Threat-Peripheral, and Neutral-Peripheral) and subjected these responses to repeated-measures ANOVA models. When presented as response-relevant targets, threatening images attracted faster and more accurate responses. They did not affect response accuracy to targets when presented as response-irrelevant flankers. However, response times were significantly slower when threatening images flanked objects than when neutral images were shown as flankers. This result replicated the well-known Emotional Flanker Effect. Behavioural responses to response-relevant threatening targets were accompanied by significant modulations of ERP activity across all time-windows and regions of interest and displayed some meaningful correlations. The Emotional Flanker Effect was accompanied by a modulation over parietal and central-parietal regions within a time-window between 550-690ms. Such a modulation suggests that the attentional disruption to targets caused by response-irrelevant threatening flankers appears to reflect less neural resources available, which are seemingly drawn away by distracting threatening flankers. The observed spatiotemporal dynamics seem to concur with understanding of the important adaptive role attributed to threat-related attention bias.
Subject(s)
Attentional Bias/physiology , Electrophysiological Phenomena , Emotions/physiology , Adult , Female , Humans , Male , Photic Stimulation , Reaction Time , Visual Perception/physiology , Young AdultABSTRACT
The mdx52 mouse model of Duchenne muscular dystrophy (DMD) is lacking exon 52 of the DMD gene that is located in a hotspot mutation region causing cognitive deficits and retinal anomalies in DMD patients. This deletion leads to the loss of the dystrophin proteins, Dp427, Dp260 and Dp140, while Dp71 is preserved. The flash electroretinogram (ERG) in mdx52 mice was previously characterized by delayed dark-adapted b-waves. A detailed description of functional ERG changes and visual performances in mdx52 mice is, however, lacking. Here an extensive full-field ERG repertoire was applied in mdx52 mice and WT littermates to analyze retinal physiology in scotopic, mesopic and photopic conditions in response to flash, sawtooth and/or sinusoidal stimuli. Behavioral contrast sensitivity was assessed using quantitative optomotor response (OMR) to sinusoidally modulated luminance gratings at 100% or 50% contrast. The mdx52 mice exhibited reduced amplitudes and delayed implicit times in dark-adapted ERG flash responses, particularly in their b-wave and oscillatory potentials, and diminished amplitudes of light-adapted flash ERGs. ERG responses to sawtooth stimuli were also diminished and delayed for both mesopic and photopic conditions in mdx52 mice and the first harmonic amplitudes to photopic sine-wave stimuli were smaller at all temporal frequencies. OMR indices were comparable between genotypes at 100% contrast but significantly reduced in mdx52 mice at 50% contrast. The complex ERG alterations and disturbed contrast vision in mdx52 mice include features observed in DMD patients and suggest altered photoreceptor-to-bipolar cell transmission possibly affecting contrast sensitivity. The mdx52 mouse is a relevant model to appraise the roles of retinal dystrophins and for preclinical studies related to DMD.
Subject(s)
Muscular Dystrophy, Duchenne/physiopathology , Visual Perception/physiology , Animals , Electroretinography , Mice , Mice, Inbred mdx , Synaptic Transmission/physiologyABSTRACT
In this study, we compared visual pictorial size perception between healthy volunteers (CG) and an experimental group (EG) of people diagnosed with schizophrenia. We have been using paintings by Salvador Dalí and Rorschach plates to estimate visual pictorial size perception. In this transversal, ex post facto, and quasi-experimental study, we observed differences between EG and CG. Schizophrenic in-patients perceived sizes about 1.3-fold greater than healthy volunteers (p=0.006), implying that pictorial size perception is altered in some way in schizophrenia. Considering the present and previous results, this measurement of diameter size of first pictorial perception may be a useful estimate of some aspects of perceptual alterations that may be associated with psychotic symptoms in prodromal and acute schizophrenic episodes and other related mental states. Eventually, this may help in preventing people from evolving to acute episodes.
Subject(s)
Humans , Male , Female , Adult , Paintings/psychology , Schizophrenia , Schizophrenic Psychology , Visual Perception/physiology , Size Perception/physiologyABSTRACT
AIM: To evaluate whether children with cerebral palsy (CP) are able to engage in a motor imagery task. Possible associations between motor imagery and functional performance, working memory, age, and intelligence were also investigated. METHOD: This is a case-control study that assessed 57 children (25 females, 32 males) with unilateral CP, aged 6 to 14 years (mean age: 10y 4mo; SD 2y 8mo) and 175 typically developing (control) children, aged 6 to 13 years (87 females, 88 males; mean age: 9y 4mo; SD 1y 11mo). The hand laterality judgment task was used to measure motor imagery ability. Reaction time, accuracy, and the effect of the biomechanical constraints were assessed in this task. RESULTS: Performance in both groups followed the biomechanical constraints of the task, that is, longer reaction times to recognize stimuli rotated laterally when compared to medial stimuli. Reaction time means did not differ significantly between groups (p>0.05). Significant differences between the unilateral CP and control groups were observed for accuracy (p<0.05). Functional performance and working memory were correlates of motor imagery tasks. INTERPRETATION: Results suggest that children with unilateral CP can engage in motor imagery; however, they commit more errors than typically developing controls. In addition, their performance in tasks of motor imagery is influenced by functional performance and working memory.
Subject(s)
Cerebral Palsy/physiopathology , Imagination/physiology , Memory, Short-Term/physiology , Motor Activity/physiology , Psychomotor Performance/physiology , Space Perception/physiology , Visual Perception/physiology , Adolescent , Case-Control Studies , Child , Female , Humans , MaleABSTRACT
We studied the multiunit responses to moving and static stimuli from 585 cell clusters in area MT using multi-electrode arrays. Our aim was to explore if MT columns exhibit any larger-scale tangential organization or clustering based on their response properties. Neurons showing both motion and orientation selectivity were classified into four categories: 1- Type I (orientation selectivity orthogonal to the axis of motion); 2- Type II (orientation selectivity coaxial to the axis of motion); 3- Type DS (significant response to moving stimuli, but non-significant response to static stimuli); and 4- Type OS (significant orientation selectivity, but non-significant direction selectivity). Type I (34%), Type II (24%) and Type DS (32%) clusters were the most predominant and may be associated with different stages of motion processing in MT. On the other hand, the rarer Type OS (9%) may be integrating motion and form processing. Type I and unidirectional sites were the only classes to exhibit significant clustering. Type OS sites showed a trend for clustering, which did not reach statistical significance. We also found a trend for unidirectional sites to have bidirectional sites as neighbors. In conclusion, neuronal clustering associated with these four categories may be related to distinct MT functional circuits.
Subject(s)
Neurons/physiology , Orientation/physiology , Sapajus apella/physiology , Temporal Lobe/physiology , Visual Pathways/physiology , Visual Perception/physiology , AnimalsABSTRACT
Flower cues serve as information that improves foraging by flower visitors. These cues may act in a synergic, redundant or complementary way. We examined how the integration of visual cues affects foraging in the southern monarch butterfly, and whether these combined cues can be learned. Artificial flowers having two flower cues, colouration pattern (uniform or radial) and dimension (2D or 3D), were employed in laboratory experiments. We assumed that uniform flowers are less informative than radial ones, and that bi-dimensionality is less informative than tri-dimensionality. These cues resulted in four floral types (uniform 2D, radial 2D, uniform 3D and radial 3D). Two- and multiple choice tests were run to investigate whether butterflies show more attraction to more informative flowers than less informative ones. Flower cues acted in a complementary way, as more informative flowers were preferred by southern monarchs than less informative ones. In a multiple-choice scenario, uniform 2D flowers received less visits than radial flowers of both dimensions. In a second experiment, butterflies were conditioned to the four flower types. No conditioning occurred, as radial flowers were visited consistently more than uniform flowers. Our results show that southern monarchs take integrated flower information into account for foraging decisions, and that learning does not occur when highly informative flowers are present.
Subject(s)
Behavior, Animal/physiology , Butterflies/physiology , Conditioning, Psychological/physiology , Cues , Flowers , Visual Perception/physiology , AnimalsABSTRACT
BACKGROUND: Visual search abilities are essential to everyday life activities and are known to be affected in Alzheimer's disease (AD). However, little is known about visual search efficiency in mild cognitive impairment (MCI), a transitive state between normal aging and dementia. Eye movement studies and machine learning methods have been recently used to detect oculomotor impairments in individuals with dementia. OBJECTIVE: The aim of the present study is to investigate the association between eye movement metrics and visual search impairment in MCI and AD. METHODS: 127 participants were tested: 43 healthy controls, 51 with MCI, and 33 with AD. They completed an eyetracking visual search task where they had to find a previously seen target stimulus among distractors. RESULTS: Both patient groups made more fixations on the screen when searching for a target, with longer duration than controls. MCI and AD fixated the distractors more often and for a longer period of time than the target. Healthy controls were quicker and made less fixations when scanning the stimuli for the first time. Machine-learning methods were able to distinguish between controls and AD subjects and to identify MCI subjects with a similar oculomotor profile to AD with a good accuracy. CONCLUSION: Results showed that eye movement metrics are useful for identifying visual search impairments in MCI and AD, with possible implications in the early identification of individuals with high-risk of developing AD.