scholarly journals Constraints on the Source of Short-Term Motion Adaptation in Macaque Area MT. I. The Role of Input and Intrinsic Mechanisms

2002 ◽  
Vol 88 (1) ◽  
pp. 354-369 ◽  
Author(s):  
Nicholas J. Priebe ◽  
Mark M. Churchland ◽  
Stephen G. Lisberger
Keyword(s):  
Firing Rate ◽  
Time Course ◽  
Receptive Fields ◽  
Visual Space ◽  
Extrastriate Cortex ◽  
Target Velocity ◽  
Short Term ◽  
Cellular Mechanisms ◽  
Area Mt ◽  
Short Term Adaptation

Neurons in area MT, a motion-sensitive area of extrastriate cortex, respond to a step of target velocity with a transient-sustained firing pattern. The transition from a high initial firing rate to a lower sustained rate occurs over a time course of 20–80 ms and is considered a form of short-term adaptation. The present paper asks whether adaptation is due to input-specific mechanisms such as short-term synaptic depression or if it results from intrinsic cellular mechanisms such as spike-rate adaptation. We assessed the contribution of input-specific mechanisms by using a condition/test paradigm to measure the spatial scale of adaptation. Conditioning and test stimuli were placed within MT receptive fields but were spatially segregated so that the two stimuli would activate different populations of inputs from the primary visual cortex (V1). Conditioning motion at one visual location caused a reduction of the transient firing to subsequent test motion at a second location. The adaptation field, estimated as the region of visual space where conditioning motion caused adaptation, was always larger than the MT receptive field. Use of the same stimulus configuration while recording from direction-selective neurons in V1 failed to demonstrate either adaptation or the transient-sustained response pattern that is the signature of short-term adaptation in MT. We conclude that the shift from transient to sustained firing in MT cells does not result from an input-specific mechanism applied to inputs from V1 because it operates over a wider range of the visual field than is covered by receptive fields of V1 neurons. We used a direct analysis of MT neuron spike trains for many repetitions of the same motion stimulus to assess the contribution to adaptation of intrinsic cellular mechanisms related to spiking. On a trial-by-trial basis, there was no correlation between number of spikes in the transient interval and the interval immediately after the transient period. This is opposite the prediction that there should be a correlation if spikes cause adaptation directly. Further, the transient was suppressed or extinguished, not delayed, in trials in which the neuron emitted zero spikes during the interval that showed a transient in average firing rate. We conclude that the transition from transient to sustained firing in neurons in area MT is caused by mechanisms that are neither input-specific nor controlled by the spiking of the adapting neuron. We propose that the short-term adaptation observed in area MT emerges from the intracortical circuit within MT.

scholarly journals Constraints on the Source of Short-Term Motion Adaptation in Macaque Area MT. II. Tuning of Neural Circuit Mechanisms

2002 ◽  
Vol 88 (1) ◽  
pp. 370-382 ◽  
Author(s):  
Nicholas J. Priebe ◽  
Stephen G. Lisberger
Keyword(s):  
Time Course ◽  
Neural Circuit ◽  
Extrastriate Cortex ◽  
Target Velocity ◽  
Short Term ◽  
Motion Adaptation ◽  
Area Mt ◽  
Mt Neurons ◽  
Preferred Direction ◽  
Direction Tuning

Neurons in area MT, a motion-sensitive area of extrastriate cortex, respond to a step of target velocity with a transient-sustained firing pattern. The transition from a high initial firing rate to a lower sustained rate occurs over a time course of 20–80 ms and is considered a form of short-term adaptation. In the present paper, we compared the tuning of the adaptation to the neuron's tuning to direction and speed. The tuning of adaptation was measured with a condition/test paradigm in which a testing motion of the preferred direction and speed of the neuron under study was preceded by a conditioning motion: the direction and speed of the conditioning motion were varied systematically. The response to the test motion depended strongly on the direction of the conditioning motion. It was suppressed in almost all neurons by conditioning motion in the same direction and could be either suppressed or enhanced by conditioning motion in the opposite direction. Even in neurons that showed suppression for target motion in the nonpreferred direction, the adaptation and response direction tuning were the same. The speed tuning of adaptation was linked much less tightly to the speed tuning of the response of the neuron under study. For just more than 50% of neurons, the preferred speed of adaptation was more than 1 log unit different from the preferred response speed. Many neurons responded best when slow motions were followed by faster motions (acceleration) or vice versa (deceleration), suggesting that MT neurons may encode information about the change of target velocity over time. Finally, adaptation by conditioning motions of different directions, but not different speeds, altered the latency of the response to the test motion. The adaptation of latency recovered with shorter intervals between the conditioning and test motions than did the adaptation of response size, suggesting that latency and amplitude adaptation are mediated by separate mechanisms. Taken together with the companion paper, our data suggest that short-term motion adaptation in MT is a consequence of the neural circuit in MT and is not mediated by either input-specific mechanisms or intrinsic mechanisms related to the spiking of individual neurons. The circuit responsible for adaptation is tuned for both speed and direction and has the same direction tuning as the circuit responsible for the initial response of MT neurons.

Short-Term Adaptation of Auditory Receptive Fields to Dynamic Stimuli

2004 ◽  
Vol 91 (2) ◽  
pp. 604-612 ◽  
Author(s):  
Mark N. Kvale ◽  
Christoph E. Schreiner
Keyword(s):  
Time Course ◽  
Modulation Depth ◽  
Receptive Fields ◽  
Amplitude Distribution ◽  
Strong Impact ◽  
Temporal Response ◽  
Stimulus Amplitude ◽  
Short Term ◽  
Dynamic Stimuli ◽  
Short Term Adaptation

Short-term adaptation and recovery from adaptation have a strong impact on the processing of dynamic stimuli. Adaptive effects on neuronal activity have been studied most commonly for changes in first-order statistics of stimuli such as stepwise increments or decrements in stimulus amplitude. However, changes in higher moment statistics, such as the variance of the amplitude distribution in visual stimuli, also can invoke pronounced adaptation behavior. We demonstrate here that neurons in the inferior colliculus (ICC) of the cat show adaptation to dynamic auditory stimuli that differ in the variance of their modulation depth distribution. In addition, it is shown that neurons show adaptation to other higher moment statistics (e.g., kurtosis) of the modulation envelope. The time course of adaptation is specific for the altered stimulus property and the direction of parameter change. The use of dynamic stimuli allows an estimate of the effects of the adaptation on the temporal response properties of the neurons. We demonstrate that temporal receptive fields of neurons undergo change during the course of adaptation. We show that adaptation to variance in the ICC has many similarities to that in the retina and suggest that adaptation to variance is a general property of sensory systems that allows them to effectively deal with a nonstationary environment.

Recovery from Adaptation to Moving Gratings

Perception ◽  
1977 ◽  
Vol 6 (6) ◽  
pp. 719-725 ◽  
Author(s):  
Max J Keck ◽  
Benjamin Pentz
Keyword(s):  
Time Course ◽  
Spontaneous Recovery ◽  
Motion Aftereffect ◽  
Time Decay ◽  
Short Term ◽  
Test Grating ◽  
Test Conditions ◽  
Sinusoidal Gratings ◽  
Short Term Adaptation

Short-term adaptation to moving sinusoidal gratings results in a motion aftereffect which decays in time. The time decay of the motion aftereffect has been measured psychophysically, and it is found to depend on (i) the spontaneous recovery from the adapted state, and (ii) the contrast of the test grating. We have measured the decays for various test conditions. An extrapolation of the measurements allows us to obtain a decay which represents the time course of the spontaneous recovery of the direction-sensitive mechanisms.

Area MT Neurons Respond to Visual Motion Distant From Their Receptive Fields

2005 ◽  
Vol 94 (6) ◽  
pp. 4156-4167 ◽  
Author(s):  
Daniel Zaksas ◽  
Tatiana Pasternak
Keyword(s):  
Time Course ◽  
Visual Motion ◽  
Cognitive Task ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Task Demands ◽  
Visual Signals ◽  
Area Mt ◽  
Mt Neurons ◽  
Stimulus Offset

Neurons in cortical area MT have localized receptive fields (RF) representing the contralateral hemifield and play an important role in processing visual motion. We recorded the activity of these neurons during a behavioral task in which two monkeys were required to discriminate and remember visual motion presented in the ipsilateral hemifield. During the task, the monkeys viewed two stimuli, sample and test, separated by a brief delay and reported whether they contained motion in the same or in opposite directions. Fifty to 70% of MT neurons were activated by the motion stimuli presented in the ipsilateral hemifield at locations far removed from their classical receptive fields. These responses were in the form of excitation or suppression and were delayed relative to conventional MT responses. Both excitatory and suppressive responses were direction selective, but the nature and the time course of their directionality differed from the conventional excitatory responses recorded with stimuli in the RF. Direction selectivity of the excitatory remote response was transient and early, whereas the suppressive response developed later and persisted after stimulus offset. The presence or absence of these unusual responses on error trials, as well as their magnitude, was affected by the behavioral significance of stimuli used in the task. We hypothesize that these responses represent top-down signals from brain region(s) accessing information about stimuli in the entire visual field and about the behavioral state of the animal. The recruitment of neurons in the opposite hemisphere during processing of behaviorally relevant visual signals reveals a mechanism by which sensory processing can be affected by cognitive task demands.

Time course on short-term adaptation in cochlear nucleus neurons of the cat

1986 ◽  
Vol 3 ◽  
pp. S4
Author(s):  
Teiji Tanahashi ◽  
Shigeisa Matsumuro ◽  
Shinji Kunishima
Keyword(s):  
Cochlear Nucleus ◽  
Time Course ◽  
Short Term ◽  
Short Term Adaptation

scholarly journals Differences in the Time Course of Short-Term Depression Across Receptive Fields Are Correlated With Directional Selectivity in Electrosensory Neurons

2009 ◽  
Vol 102 (6) ◽  
pp. 3270-3279 ◽  
Author(s):  
Maurice J. Chacron ◽  
Natalia Toporikova ◽  
Eric S. Fortune
Keyword(s):  
Time Course ◽  
Moving Objects ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Weakly Electric Fish ◽  
Common Mechanism ◽  
Directional Selectivity ◽  
Short Term ◽  
Nervous Systems ◽  
Time Courses

Directional selectivity, in which neurons respond preferentially to one direction of movement (“preferred”) over the opposite direction (“null”), is a critical computation that is found in the nervous systems of many animals. Here we show the first experimental evidence for a correlation between differences in short-term depression and direction-selective responses to moving objects. As predicted by quantitative models, the observed differences in the time courses of short-term depression at different locations within receptive fields were correlated with measures of direction selectivity in awake, behaving weakly electric fish ( Apteronotus leptorhynchus ). Because short-term depression is ubiquitous in the central nervous systems of vertebrate animals, it may be a common mechanism used for the generation of directional selectivity and other spatiotemporal computations.

Short-term adaptation of electrically induced saccades in monkey superior colliculus

1996 ◽  
Vol 76 (3) ◽  
pp. 1744-1758 ◽  
Author(s):  
B. J. Melis ◽  
J. A. van Gisbergen
Keyword(s):  
Superior Colliculus ◽  
Time Course ◽  
Visual Target ◽  
Target Selection ◽  
Movement Planning ◽  
Error Signal ◽  
Short Term ◽  
End Point ◽  
Gradual Process ◽  
Short Term Adaptation

1. This study focuses on the neural mechanisms underlying short-term adaptation of saccadic eye movements in the rhesus monkey. Involuntary saccades of various amplitudes and directions (E-saccades) were elicited in complete darkness by electrical stimulation (< or = 50 microA) in the deeper layers of the superior colliculus (SC) at 30 different sites in two monkeys. E-saccades at a given site could be adapted by presenting a visual target at a small distance from the expected end point immediately after their occurrence. The monkeys were trained to null the ensuing error signal by making the appropriate correction saccade to the visual target in many successive trials (E-adap paradigm). By properly adjusting the location of the visual target relative to the end point of the E-saccade, the latter could be modified in amplitude as well as in direction. 2. E-saccade modifications were highly significant, always in the intended direction, and occurred only if a postsaccadic visual error signal was created. These changes were plastic and required a subsequent E-adap series with an opposite error signal to cancel them. Their time course, both during the adaptation and the readaptation period, indicated that the modification was a slow and gradual process, as has been observed earlier in classical visual adaptation experiments. 3. Postadaptation tests, assessing whether the adaptation of E-saccades was also noticeable in normal visually guided saccades (V-saccades), showed incomplete adaptation transfer that was significant in most cases. A similar result, significant in all cases, was obtained with an extended version of the E-adap paradigm in which movement planning on the basis of target selection was possible. In this case, a presaccadic visual target was presented at the expected end point of the E-saccade, which was evoked just before the monkey would make a voluntary saccade itself (VE-adap). 4. In another series of experiments, V-saccades, which were matched to the optimal saccade vector of the particular collicular site under investigation, were adapted with the classical intrasaccadic target shift paradigm (V-adap). In agreement with earlier findings, this V-adaptation showed no transfer to the E-saccades. This result was obtained even in trials in which movement planning on the basis of target selection was possible (VE-test). 5. Our experiments have shown that saccades of collicular origin can be adapted and that presaccadic target selection is not crucial for this process. Both results are nicely in line with an existing model featuring a downstream adaptive corrector with access to SC inputs. This scheme, however, does not explain why the degree of saccadic adaptation, achieved by applying any of the three adaptation paradigms (E-adap, EV-adap, or V-adap), was never equally expressed in V- and E-saccades. Arguments for extending the model by adding a cortical input from the frontal eye fields to the adaptive corrector are discussed.

Response Adaptation of Medial Olivocochlear Neurons Is Minimal

2001 ◽  
Vol 86 (5) ◽  
pp. 2381-2392 ◽  
Author(s):  
M. C. Brown
Keyword(s):  
Firing Rate ◽  
Auditory Nerve ◽  
General Characteristic ◽  
Nerve Fibers ◽  
Short Term ◽  
Percentage Decrease ◽  
Short Term Adaptation ◽  
Auditory Nerve Fibers ◽  
Medial Olivocochlear

Response adaptation is a general characteristic of neurons. A number of studies have investigated the adaptation characteristics of auditory-nerve fibers, which send information to the brain about sound stimuli. However, there have been no previous adaptation studies of olivocochlear neurons, which provide efferent fibers to hair cells and auditory nerve dendrites in the auditory periphery. To study adaptation in efferent fibers, responses of single olivocochlear neurons were recorded to characteristic-frequency tones and noise, using anesthetized guinea pigs. To measure short-term adaptation, stimuli of 500 ms duration were presented, and the responses were displayed as peristimulus time histograms. These histograms showed regular peaks, indicating a “chopping” pattern of response. The rate during each chopping period as well as the general trend of the histogram could be well fit by an equation that expresses the firing rate as a sum of 1) a short-term adaptive rate that decays exponentially with time and 2) a constant steady-state rate. For the adaptation in medial olivocochlear (MOC) neurons, the average exponential time constant was 47 ms, which is roughly similar to that for short-term adaptation in auditory-nerve fibers. The amount of adaptation (expressed as a percentage decrease of onset firing rate), however, was substantially less in MOC neurons (average 31%) than in auditory-nerve fibers (average 63%). To test for adaptation over longer periods, we used noise and tones of 10 s duration. After the short-term adaptation, the responses of MOC neurons were almost completely sustained (average long-term adaptation 3%). However, in the same preparations, significant long-term adaptation was present in auditory-nerve fibers. These results indicate that the MOC response adaptation is minimal compared with that of auditory-nerve fibers. Such sustained responses may enable the MOC system to produce sustained effects in the periphery, supporting a role for this efferent system during ongoing stimuli of long duration.

17-β-Estradiol Modulation of Area Postrema Potassium Currents

2000 ◽  
Vol 84 (3) ◽  
pp. 1385-1391 ◽  
Author(s):  
Zhicheng Li ◽  
Meredith Hay
Keyword(s):  
Firing Rate ◽  
Neuronal Activity ◽  
Potassium Current ◽  
Time Course ◽  
Area Postrema ◽  
Potassium Currents ◽  
Inhibitory Effects ◽  
Cellular Mechanisms

The purpose of this study was to determine the effects of 17-β-estradiol on area postrema neuronal activity in vivo and on area postrema potassium currents (IK) in vitro. In anesthetized rats, intravenous injection of 17-β-estradiol (10 ng/kg bw) -inhibited area postrema neuronal activity in 8/8 neurons tested. The averaged firing rate decreased from 2.9 ± 1.1 to 1.1 ± 0.3 Hz. The inhibitory effects of 17-β-estradiol on area postrema neuronal activity were rapid in onset (within 1 min) and long-lasting (>8 min). To study the cellular mechanisms involved in this response, the effects of 17-β-estradiol were examined in dissociated area postrema neurons. In these cells, 17-β-estradiol (0.5 nM) increased the averaged peak IK 27 ± 8%. The time course for the potentiation was observed within ∼0.5–1 min after the application of 17-β-estradiol. Full recovery from the potentiation usually occurred within ∼3–4 min after the washout of 17-β-estradiol. The biologically inactive 17-α-estradiol had no effect on area postrema IK and the 17-β-estradiol antagonist, ICI 182,780 blocked the effects of 17-β-estradiol on area postrema IK. Finally, big conductance calcium-activated potassium current (MaxiK+) was identified in area postrema neurons ( n = 12/12). Blockade of MaxiK+ with 100 nM iberiotoxin blocked the effects of 17-β-estradiol on IK. These results suggested 17-β-estradiol might modulate area postrema neuronal activity by increasing MaxiK+ current.

scholarly journals Effect of feature-selective attention on neuronal responses in macaque area MT

2012 ◽  
Vol 107 (5) ◽  
pp. 1530-1543 ◽  
Author(s):  
X. Chen ◽  
K.-P. Hoffmann ◽  
T. D. Albright ◽  
A. Thiele
Keyword(s):  
Selective Attention ◽  
Firing Rate ◽  
Visual Processing ◽  
Sine Wave ◽  
Stimulus Dimension ◽  
Extrastriate Cortex ◽  
Motion Direction ◽  
Area Mt ◽  
Mt Neurons ◽  
Feature Based

Attention influences visual processing in striate and extrastriate cortex, which has been extensively studied for spatial-, object-, and feature-based attention. Most studies exploring neural signatures of feature-based attention have trained animals to attend to an object identified by a certain feature and ignore objects/displays identified by a different feature. Little is known about the effects of feature-selective attention, where subjects attend to one stimulus feature domain (e.g., color) of an object while features from different domains (e.g., direction of motion) of the same object are ignored. To study this type of feature-selective attention in area MT in the middle temporal sulcus, we trained macaque monkeys to either attend to and report the direction of motion of a moving sine wave grating (a feature for which MT neurons display strong selectivity) or attend to and report its color (a feature for which MT neurons have very limited selectivity). We hypothesized that neurons would upregulate their firing rate during attend-direction conditions compared with attend-color conditions. We found that feature-selective attention significantly affected 22% of MT neurons. Contrary to our hypothesis, these neurons did not necessarily increase firing rate when animals attended to direction of motion but fell into one of two classes. In one class, attention to color increased the gain of stimulus-induced responses compared with attend-direction conditions. The other class displayed the opposite effects. Feature-selective activity modulations occurred earlier in neurons modulated by attention to color compared with neurons modulated by attention to motion direction. Thus feature-selective attention influences neuronal processing in macaque area MT but often exhibited a mismatch between the preferred stimulus dimension (direction of motion) and the preferred attention dimension (attention to color).

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