Lingual and biting responses to prey chemicals by ingestively naive scincid lizards: discrimination from control chemicals, time course, and effect of method of stimulus presentation

Chemoecology ◽  
2000 ◽  
Vol 10 (2) ◽  
pp. 51-58 ◽  
Author(s):  
William E. Cooper Jr. ◽  
Ruston Hartdegen
Keyword(s):  
Time Course ◽  
Stimulus Presentation ◽  
Prey Chemicals

Modulation of medial temporal lobe activity in epilepsy patients with hippocampal sclerosis during verbal working memory

2009 ◽  
Vol 15 (4) ◽  
pp. 536-546 ◽  
Author(s):  
PABLO CAMPO ◽  
FERNANDO MAESTÚ ◽  
IRENE GARCÍA-MORALES ◽  
ANTONIO GIL-NAGEL ◽  
BRYAN STRANGE ◽  
...  
Keyword(s):  
Working Memory ◽  
Episodic Memory ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Time Course ◽  
Hippocampal Sclerosis ◽  
Stimulus Presentation ◽  
Verbal Working Memory ◽  
Compelling Evidence ◽  
Electrophysiological Studies

AbstractIt has been traditionally assumed that medial temporal lobe (MTL) is not required for working memory (WM). However, animal lesion and electrophysiological studies and human neuropsychological and neuroimaging studies have provided increasing evidences of a critical involvement of MTL in WM. Based on previous findings, the central aim of this study was to investigate the contribution of the MTL to verbal WM encoding. Here, we used magnetoencephalography (MEG) to compare the patterns of MTL activation of 9 epilepsy patients suffering from left hippocampal sclerosis with those of 10 healthy matched controls while they performed a verbal WM task. MEG recordings allow detailed tracking of the time course of MTL activation. We observed impaired WM performance associated with changes in the dynamics of MTL activity in epilepsy patients. Specifically, whereas patients showed decreased activity in damaged MTL, activity in the contralateral MTL was enhanced, an effect that became significant in the 600- to 700-ms interval after stimulus presentation. These findings strongly support the crucial contribution of MTL to verbal WM encoding and provide compelling evidence for the proposal that MTL contributes to both episodic memory and WM. Whether this pattern is signaling reorganization or a normal use of a damaged structure is discussed. (JINS, 2009, 15, 536–546.)

Time Course of Attentional Modulation in the Frontal Eye Field During Curve Tracing

2009 ◽  
Vol 101 (4) ◽  
pp. 1813-1822 ◽  
Author(s):  
P. S. Khayat ◽  
A. Pooresmaeili ◽  
P. R. Roelfsema
Keyword(s):  
Visual Information ◽  
Time Course ◽  
Stimulus Presentation ◽  
Frontal Eye Field ◽  
Stimulus Selection ◽  
Visual Response ◽  
Visual Responses ◽  
Cortical Regions ◽  
Visual Cortical ◽  
Curve Tracing

Neurons in the frontal eye fields (FEFs) register incoming visual information and select visual stimuli that are relevant for behavior. Here we investigated the timing of the visual response and the timing of selection by recording from single FEF neurons in a curve-tracing task that requires shifts of attention followed by an oculomotor response. We found that the behavioral selection signal in area FEF had a latency of 147 ms and that it was delayed substantially relative to the visual response, which occurred 50 ms after stimulus presentation. We compared the FEF responses to activity previously recorded in the primary visual cortex (area V1) during the same task. Visual responses in area V1 preceded the FEF responses, but the latencies of selection signals in areas V1 and FEF were similar. The similarity of timing of selection signals in structures at opposite ends of the visual cortical processing hierarchy supports the view that stimulus selection occurs in an interaction between widely separated cortical regions.

Rapid prediction of biomechanical costs during action decisions

2014 ◽  
Vol 112 (6) ◽  
pp. 1256-1266 ◽  
Author(s):  
Ignasi Cos ◽  
Julie Duque ◽  
Paul Cisek
Keyword(s):  
Time Course ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
Single Pulse ◽  
Stimulus Presentation ◽  
Biomechanical Properties ◽  
Time Interval ◽  
Decision Task ◽  
Rapid Prediction ◽  
The One

When given a choice between actions that yield the same reward, we tend to prefer the one that requires the least effort. Recent studies have shown that humans are remarkably accurate at evaluating the effort of potential reaching actions and can predict the subtle energetic demand caused by the nonisotropic biomechanical properties of the arm. In the present study, we investigated the time course over which such information is computed and comes to influence decisions. Two independent approaches were used. First, subjects performed a reach decision task in which the time interval for deciding between two candidate reaching actions was varied from 200 to 800 ms. Second, we measured motor-evoked potential (MEPs) to single-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) to probe the evolving decision at different times after stimulus presentation. Both studies yielded a consistent conclusion: that a prediction of the effort associated with candidate movements is computed very quickly and influences decisions within 200 ms after presentation of the candidate actions. Furthermore, whereas the MEPs measured 150 ms after stimulus presentation were well correlated with the choices that subjects ultimately made, later in the trial the MEP amplitudes were primarily related to the muscular requirements of the chosen movement. This suggests that corticospinal excitability (CSE) initially reflects a competition between candidate actions and later changes to reflect the processes of preparing to implement the winning action choice.

scholarly journals The functional properties of human magnitude integration

2020 ◽  
Author(s):  
IRENE TOGOLI ◽  
Michele Fornaciai ◽  
Domenica Bueti
Keyword(s):  
Sensory Processing ◽  
Time Course ◽  
External Environment ◽  
Stimulus Presentation ◽  
Neural Processing ◽  
Behavioral Experiments ◽  
Asymmetric Effects ◽  
Static Versus Dynamic ◽  
Over Time

Magnitude information is essential to create a representation of the external environment and successfully interact with it. Duration and numerosity, for example, can shape our predictions and bias each other (i.e., the greater the number of people queuing, the longer we expect to wait). While these biases suggest the existence of a generalized magnitude system, asymmetric effects (i.e., numerosity affecting duration but not vice versa) challenged this idea. Here we propose that such asymmetric integration depends on the stimuli used and the neural processing dynamics they entail. Across multiple behavioral experiments employing different stimulus presentation displays (static versus dynamic), we show that the integration between numerosity and time can be symmetrical if the stimuli entail a similar neural time-course and numerosity unfolds over time. Overall, these findings support the idea of a generalized magnitude system, but also highlight the role of early sensory processing in magnitude representation and integration.

scholarly journals Time-dependent competition between habitual and goal-directed response preparation

2017 ◽  
Author(s):  
Robert M Hardwick ◽  
Alexander D Forrence ◽  
John W Krakauer ◽  
Adrian M Haith
Keyword(s):  
Time Course ◽  
Stimulus Presentation ◽  
Time Dependent ◽  
Response Preparation ◽  
Movement Initiation ◽  
Control Behavior ◽  
Association Task ◽  
Habitual Behavior ◽  
Human Participants ◽  
Habitual Responses

AbstractConverging evidence indicates that separate goal-directed and habitual systems compete to control behavior1. However, it has proven difficult to reliably induce habitual behavior in human participants2–4. We reasoned that habits may be present in the form of habitually prepared responses, but are overridden by goal-directed processes, preventing their overt expression. Here we show that latent habits can be unmasked by limiting the time participants have to respond to a stimulus. Participants trained for 4 days on a visuomotor association task. By continuously varying the time allowed to prepare responses, we found that the probability of expressing a learned habit followed a stereotyped time course, peaking 300-600ms after stimulus presentation. This time course was captured by a computational model of response preparation in which habitual responses are automatically prepared at short latency, but are replaced by goal-directed responses at longer latency. A more extensive period of practice (20 days) led to increased habit expression by reducing the average time of movement initiation. These findings refine our understanding of habits, and show that practice can influence habitual behavior in distinct ways: by promoting habit formation, and by modulating the likelihood of habit expression.

Cortical mapping of gamma oscillations in areas V1 and V4 of the macaque monkey

2001 ◽  
Vol 18 (4) ◽  
pp. 527-540 ◽  
Author(s):  
GABRIEL ROLS ◽  
CATHERINE TALLON-BAUDRY ◽  
PASCAL GIRARD ◽  
OLIVIER BERTRAND ◽  
JEAN BULLIER
Keyword(s):  
Time Course ◽  
Stimulus Presentation ◽  
Gamma Oscillations ◽  
Macaque Monkey ◽  
Stimulus Onset ◽  
Gamma Activity ◽  
Cortical Mapping ◽  
Time Frequency ◽  
Area V4 ◽  
Retinotopic Organization

To characterize the temporal and spatial parameters of gamma activity evoked by visual stimuli in areas V1 and V4 of the monkey cortex, we recorded the electrocorticogram (ECoG) with an implanted array of 28 and 31 subdural electrodes placed over the surface of the operculum in two anesthetized monkeys. This intermediate level of recordings should help to bridge the gap between multiunit and scalp recordings. Both averaged and single-trial responses to small flashed stimuli, for which we varied the retinotopic position, the luminance and the color, were analyzed in the time-frequency domain using a wavelet-based decomposition of the signal. Large gamma oscillations (40–55 Hz), not phase locked to stimulus onset, were observed during the whole stimulus presentation, whereas visual evoked potentials (VEPs) were present mainly at stimulus onset and offset. Cortical mapping showed that both activities were restricted in spatial extent and followed the retinotopic organization of area V1 on the operculum, thus strongly suggesting they were generated in the underlying cortex. Oscillatory burst detection in single trials showed that one to two bursts lasting from 100 ms to 500 ms occurred in the first 500 ms following stimulus onset, and that bursts occurring during the subsequent phases of the response had a smaller amplitude and duration. Finally, we showed that gamma activity was stronger with higher luminances and for red than for green, yellow, or white stimuli of same luminance. In one animal we recorded gamma activity over area V4. This was of lower magnitude than the activity recorded over V1 and was delayed by 40 ms with respect to the beginning of gamma activity in V1, in contrast with the VEPs that were delayed by 20 ms only. Both gamma oscillations and early VEP followed the retinotopic organization of V4 over the prelunate gyrus. The results show that gamma oscillations are dependent upon the same parameters as the VEPs (retinotopic position, luminance, and color). However, the differences in the time course of VEPs and gamma activity (transient vs. sustained) suggests that these two responses may reflect different cell populations, different networks, or different firing modes.

scholarly journals The specious interaction of time and numerosity perception

2021 ◽  
Vol 288 (1959) ◽  
pp. 20211577
Author(s):  
Irene Togoli ◽  
Michele Fornaciai ◽  
Domenica Bueti
Keyword(s):  
Sensory Processing ◽  
Time Course ◽  
External Environment ◽  
Stimulus Presentation ◽  
Asymmetric Effects ◽  
Behavioural Experiments ◽  
Static Versus Dynamic ◽  
Numerosity Perception ◽  
Over Time

Magnitude information is essential to create a representation of the external environment and successfully interact with it. Duration and numerosity, for example, can shape our predictions and bias each other (i.e. the greater the number of people queuing, the longer we expect to wait). While these biases suggest the existence of a generalized magnitude system, asymmetric effects (i.e. numerosity affecting duration but not vice versa) challenged this idea. Here, we propose that such asymmetric integration depends on the stimuli used and the neural processing dynamics they entail. Across multiple behavioural experiments employing different stimulus presentation displays (static versus dynamic) and experimental manipulations known to bias numerosity and duration perceptions (i.e. connectedness and multisensory integration), we show that the integration between numerosity and time can be symmetrical if the stimuli entail a similar neural time-course and numerosity unfolds over time. Overall, these findings support the idea of a generalized magnitude system, but also highlight the role of early sensory processing in magnitude representation and integration.

scholarly journals A comparison of visuomotor cue integration strategies for object placement and prehension

2009 ◽  
Vol 26 (1) ◽  
pp. 63-72 ◽  
Author(s):  
HAL S. GREENWALD ◽  
DAVID C. KNILL
Keyword(s):  
Motor Control ◽  
Visual Cues ◽  
Time Course ◽  
Three Dimensional ◽  
Stimulus Presentation ◽  
Task Demands ◽  
Cue Integration ◽  
Movement Initiation ◽  
Initial Stimulus ◽  
Integration Strategies

AbstractVisual cue integration strategies are known to depend on cue reliability and how rapidly the visual system processes incoming information. We investigated whether these strategies also depend on differences in the information demands for different natural tasks. Using two common goal-oriented tasks, prehension and object placement, we determined whether monocular and binocular information influence estimates of three-dimensional (3D) orientation differently depending on task demands. Both tasks rely on accurate 3D orientation estimates, but 3D position is potentially more important for grasping. Subjects placed an object on or picked up a disc in a virtual environment. On some trials, the monocular cues (aspect ratio and texture compression) and binocular cues (e.g., binocular disparity) suggested slightly different 3D orientations for the disc; these conflicts either were present upon initial stimulus presentation or were introduced after movement initiation, which allowed us to quantify how information from the cues accumulated over time. We analyzed the time-varying orientations of subjects’ fingers in the grasping task and those of the object in the object placement task to quantify how different visual cues influenced motor control. In the first experiment, different subjects performed each task, and those performing the grasping task relied on binocular information more when orienting their hands than those performing the object placement task. When subjects in the second experiment performed both tasks in interleaved sessions, binocular cues were still more influential during grasping than object placement, and the different cue integration strategies observed for each task in isolation were maintained. In both experiments, the temporal analyses showed that subjects processed binocular information faster than monocular information, but task demands did not affect the time course of cue processing. How one uses visual cues for motor control depends on the task being performed, although how quickly the information is processed appears to be task invariant.

Shifting Attention in a Rapid Visual Search Paradigm

1994 ◽  
Vol 79 (1) ◽  
pp. 315-335 ◽  
Author(s):  
Shulan Hsieh ◽  
Alan Allport
Keyword(s):  
Time Course ◽  
Stimulus Presentation ◽  
Semantic Space ◽  
Attention Shift ◽  
Direct Function ◽  
Monitoring Task ◽  
Attentional System ◽  
Semantic Shift ◽  
The Difference ◽  
Criterion Shifts

A method is introduced for studying shifts of attention in semantic space, testing 56 subjects in four experiments on a semantic monitoring task based on rapid, serial, visually presented (RSVP) word-sequences. Following a cue to shift attention, accuracy of semantic monitoring drops abruptly to a low level, then gradually recovers to reach preshift levels over successive stimuli in the RSVP sequence. Using this method, we compared two kinds of criterion-shifts, one requiring a set-reversal (‘reversal shifts’), the other involving a shift between orthogonally defined categories (‘orthogonal shifts’); no differences were found. We have also examined the difference in a shift between two different processing domains (semantic vs typographic) compared with a shift of criterion within the same processing domain. The results showed no differences for within- vs between-domain shifts. Finally, we studied the time-course of a semantic attention shift. Execution of a semantic shift did not follow an internally controlled time-course but was a direct function of the rate of stimulus presentation. No evidence was found for the operation of a ‘supervisory attentional system’ independent of external stimulus triggering.

Ultrastructural Changes of the Symbiotic Chlorella-Like Alga Isolated from Hydra Viridis

1982 ◽  
Vol 40 ◽  
pp. 320-321
Author(s):  
K.W. Lee ◽  
R.H. Meints ◽  
D. Kuczmarski ◽  
J.L. Van Etten
Keyword(s):  
Time Course ◽  
Reciprocal Cross ◽  
Ultrastructural Level ◽  
Ultrastructural Changes ◽  
Symbiotic Relationship ◽  
Cell Recognition ◽  
Green Hydra ◽  
Different Strains ◽  
Hydra Viridis

The physiological, biochemical, and ultrastructural aspects of the symbiotic relationship between the Chlorella-like algae and the hydra have been intensively investigated. Reciprocal cross-transfer of the Chlorellalike algae between different strains of green hydra provide a system for the study of cell recognition. However, our attempts to culture the algae free of the host hydra of the Florida strain, Hydra viridis, have been consistently unsuccessful. We were, therefore, prompted to examine the isolated algae at the ultrastructural level on a time course.

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