scholarly journals Stimulus repetition affects both strength and synchrony of macaque inferior temporal cortical activity

2012 ◽  
Vol 107 (12) ◽  
pp. 3509-3527 ◽  
Author(s):  
Dzmitry A. Kaliukhovich ◽  
Rufin Vogels
Keyword(s):  
Firing Rate ◽  
Response Strength ◽  
Visual Images ◽  
Stimulus Repetition ◽  
Short Term ◽  
Know How ◽  
Repetition Suppression ◽  
Deep Layers ◽  
Fixation Task ◽  
Passive Fixation

Repetition of a visual stimulus reduces the firing rate of macaque inferior temporal (IT) neurons. The neural mechanisms underlying this adaptation or repetition suppression are still unclear. In particular, we do not know how the IT circuit is affected by stimulus repetition. To address this, we measured local field potentials (LFPs) and multiunit spiking activity (MUA) simultaneously at 16 sites with a laminar electrode in IT while repeating visual images. Stimulus exposures and interstimulus intervals were each 500 ms. The rhesus monkeys were performing a passive fixation task during the recordings. Induced LFP power decreased with repetition for spectral frequencies above 60 Hz but increased with repetition for lower frequencies, the latter because of a delayed decrease in power when repeating a stimulus. LFP-LFP and MUA-LFP coherences decreased with repetition for frequencies above 60 Hz. This repetition suppression of the MUA-LFP coherence was not due to differences in firing rate since it was present when spike counts were equated for the adapter and repeated stimuli. For frequencies between 15 and 40 Hz, the effect of repetition on synchronization depended on the electrode depth: For the putative superficial layers synchronization was enhanced with repetition, while the LFPs of the putative deep layers decreased their synchrony across layers. The between-site, trial-to-trial covariations in MUA (“noise correlations”) decreased with repetition, but this might have reflected repetition suppression of the firing rate. This work demonstrates that short-term stimulus repetition affects the synchronized activity, in addition to response strength, in IT cortex.

scholarly journals Functional ultrasound imaging of deep visual cortex in awake nonhuman primates

2020 ◽  
Vol 117 (25) ◽  
pp. 14453-14463 ◽  
Author(s):  
Kévin Blaize ◽  
Fabrice Arcizet ◽  
Marc Gesnik ◽  
Harry Ahnine ◽  
Ulisse Ferrari ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Nonhuman Primates ◽  
Brain Activity ◽  
Ocular Dominance ◽  
Spatiotemporal Resolution ◽  
Retinotopic Maps ◽  
Visual Tasks ◽  
Deep Layers ◽  
Fixation Task ◽  
Passive Fixation

Deep regions of the brain are not easily accessible to investigation at the mesoscale level in awake animals or humans. We have recently developed a functional ultrasound (fUS) technique that enables imaging hemodynamic responses to visual tasks. Using fUS imaging on two awake nonhuman primates performing a passive fixation task, we constructed retinotopic maps at depth in the visual cortex (V1, V2, and V3) in the calcarine and lunate sulci. The maps could be acquired in a single-hour session with relatively few presentations of the stimuli. The spatial resolution of the technology is illustrated by mapping patterns similar to ocular dominance (OD) columns within superficial and deep layers of the primary visual cortex. These acquisitions using fUS suggested that OD selectivity is mostly present in layer IV but with extensions into layers II/III and V. This imaging technology provides a new mesoscale approach to the mapping of brain activity at high spatiotemporal resolution in awake subjects within the whole depth of the cortex.

scholarly journals Functional ultrasound imaging of deep visual cortex in awake non-human primates

2019 ◽  
Author(s):  
Blaize Kévin ◽  
Gesnik Marc ◽  
Arcizet Fabrice ◽  
Ahnine Harry ◽  
Ferrari Ulisse ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Ocular Dominance ◽  
Functional Responses ◽  
Spatiotemporal Resolution ◽  
Retinotopic Maps ◽  
Visual Areas ◽  
Deep Layers ◽  
Fixation Task ◽  
Passive Fixation ◽  
The Brain

SummaryDeep regions of the brain are not easily accessible to investigation at the mesoscale level in awake animals or humans. We have recently developed functional Ultrasound (fUS) imaging fUS imaging technique to uncover deep hemodynamic functional responses. Applying fUS imaging on two awake non-human primates performing a passive fixation task, we reconstructed their retinotopic maps down to the deep calcarine and lunate sulci on visual areas (V1, V2 and V3). These maps were acquired in a single hour session with very few stimuli presentation. The spatial resolution of the technology is illustrated by mapping of Ocular Dominance (OD) columns within superficial and deep layers of the primary visual cortex. These acquisitions showed that OD selectivity is mostly present in layer IV but with evidence also in layers II/III and V. The fUS imaging technology therefore provides a new mesoscale approach to map brain activities at high spatiotemporal resolution in awake subjects within the whole depth of the cortex.

Time Window from Visual Images to Visual Short-Term Memory: Consolidation or Integration?

2004 ◽  
Vol 51 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Yuhong Jiang
Keyword(s):  
Short Term Memory ◽  
Time Window ◽  
Short Interval ◽  
Visual Images ◽  
Short Term ◽  
Temporal Window ◽  
Term Memory ◽  
Visual Short Term Memory ◽  
Probe Task ◽  
Long Time

Abstract. When two dot arrays are briefly presented, separated by a short interval of time, visual short-term memory of the first array is disrupted if the interval between arrays is shorter than 1300-1500 ms ( Brockmole, Wang, & Irwin, 2002 ). Here we investigated whether such a time window was triggered by the necessity to integrate arrays. Using a probe task we removed the need for integration but retained the requirement to represent the images. We found that a long time window was needed for performance to reach asymptote even when integration across images was not required. Furthermore, such window was lengthened if subjects had to remember the locations of the second array, but not if they only conducted a visual search among it. We suggest that a temporal window is required for consolidation of the first array, which is vulnerable to disruption by subsequent images that also need to be memorized.

scholarly journals The steady-state visual evoked potential (SSVEP) reflects the activation of cortical object representations: evidence from semantic stimulus repetition

2020 ◽  
Author(s):  
Elise L. Radtke ◽  
Ulla Martens ◽  
Thomas Gruber
Keyword(s):  
Steady State ◽  
Object Representation ◽  
Sensory Information ◽  
Familiar Object ◽  
Object Representations ◽  
Stimulus Repetition ◽  
Experimental Conditions ◽  
Repetition Suppression ◽  
Task Irrelevant ◽  
Visual Evoked

AbstractWe applied high-density EEG to examine steady-state visual evoked potentials (SSVEPs) during a perceptual/semantic stimulus repetition design. SSVEPs are evoked oscillatory cortical responses at the same frequency as visual stimuli flickered at this frequency. In repetition designs, stimuli are presented twice with the repetition being task irrelevant. The cortical processing of the second stimulus is commonly characterized by decreased neuronal activity (repetition suppression). The behavioral consequences of stimulus repetition were examined in a companion reaction time pre-study using the same experimental design as the EEG study. During the first presentation of a stimulus, we confronted participants with drawings of familiar object images or object words, respectively. The second stimulus was either a repetition of the same object image (perceptual repetition; PR) or an image depicting the word presented during the first presentation (semantic repetition; SR)—all flickered at 15 Hz to elicit SSVEPs. The behavioral study revealed priming effects in both experimental conditions (PR and SR). In the EEG, PR was associated with repetition suppression of SSVEP amplitudes at left occipital and repetition enhancement at left temporal electrodes. In contrast, SR was associated with SSVEP suppression at left occipital and central electrodes originating in bilateral postcentral and occipital gyri, right middle frontal and right temporal gyrus. The conclusion of the presented study is twofold. First, SSVEP amplitudes do not only index perceptual aspects of incoming sensory information but also semantic aspects of cortical object representation. Second, our electrophysiological findings can be interpreted as neuronal underpinnings of perceptual and semantic priming.

scholarly journals Decline in Marriage Associated with the COVID-19 Pandemic in the United States

2020 ◽  
Vol 6 ◽  
pp. 237802312098032
Author(s):  
Brandon G. Wagner ◽  
Kate H. Choi ◽  
Philip N. Cohen
Keyword(s):  
United States ◽  
The United States ◽  
Cumulative Number ◽  
Short Term ◽  
Know How ◽  
The Social ◽  
Reporting Delays ◽  
Social Upheaval ◽  
Near Future ◽  
Do So

In the social upheaval arising from the coronavirus disease 2019 (COVID-19) pandemic, we do not yet know how union formation, particularly marriage, has been affected. Using administration records—marriage certificates and applications—gathered from settings representing a variety of COVID-19 experiences in the United States, the authors compare counts of recorded marriages in 2020 against those from the same period in 2019. There is a dramatic decrease in year-to-date cumulative marriages in 2020 compared with 2019 in each case. Similar patterns are observed for the Seattle metropolitan area when analyzing the cumulative number of marriage applications, a leading indicator of marriages in the near future. Year-to-date declines in marriage are unlikely to be due solely to closure of government agencies that administer marriage certification or reporting delays. Together, these findings suggest that marriage has declined during the COVID-19 outbreak and may continue to do so, at least in the short term.

scholarly journals Blink-Perturbed Saccades in Monkey. II. Superior Colliculus Activity

2000 ◽  
Vol 83 (6) ◽  
pp. 3430-3452 ◽  
Author(s):  
H.H.L.M. Goossens ◽  
A. J. Van Opstal
Keyword(s):  
Superior Colliculus ◽  
Firing Rate ◽  
High Frequency ◽  
Displacement Vector ◽  
Neural Mechanism ◽  
Fixed Number ◽  
Deep Layers ◽  
The Mean ◽  
Reflex Blinks ◽  
Frequency Burst

Trigeminal reflex blinks evoked near the onset of a saccade cause profound spatial-temporal perturbations of the saccade that are typically compensated in mid-flight. This paper investigates the influence of reflex blinks on the discharge properties of saccade-related burst neurons (SRBNs) in intermediate and deep layers of the monkey superior colliculus (SC). Twenty-nine SRBNs, recorded in three monkeys, were tested in the blink-perturbation paradigm. We report that the air puff stimuli, used to elicit blinks, resulted in a short-latency (∼10 ms) transient suppression of saccade-related SRBN activity. Shortly after this suppression (within 10–30 ms), all neurons resumed their activity, and their burst discharge then continued until the perturbed saccade ended near the extinguished target. This was found regardless whether the compensatory movement was into the cell's movement field or not. In the limited number of trials where no compensation occurred, the neurons typically stopped firing well before the end of the eye movement. Several aspects of the saccade-related activity could be further quantified for 25 SRBNs. It appeared that 1) the increase in duration of the high-frequency burst was well correlated with the (two- to threefold) increase in duration of the perturbed movement. 2) The number of spikes in the burst for control and perturbed saccades was quite similar. On average, the number of spikes increased only 14%, whereas the mean firing rate in the burst decreased by 52%. 3) An identical number of spikes were obtained between control and perturbed responses when burst and postsaccadic activity were both included in the spike count. 4) The decrease of the mean firing rate in the burst was well correlated with the decrease in the velocity of perturbed saccades. 5) Monotonic relations between instantaneous firing rate and dynamic motor error were obtained for control responses but not for perturbed responses. And 6) the high-frequency burst of SRBNs with short-lead and long-lead presaccadic activity (also referred to as burst and buildup neurons, respectively) showed very similar features. Our findings show that blinking interacts with the saccade premotor system already at the level of the SC. The data also indicate that a neural mechanism, rather than passive elastic restoring forces within the oculomotor plant, underlies the compensation for blink-related perturbations. We propose that these interactions occur downstream from the motor SC and that the latter may encode the desired displacement vector of the eyes by sending an approximately fixed number of spikes to the brainstem saccadic burst generator.

Sparseness of the neuronal representation of stimuli in the primate temporal visual cortex

1995 ◽  
Vol 73 (2) ◽  
pp. 713-726 ◽  
Author(s):  
E. T. Rolls ◽  
M. J. Tovee
Keyword(s):  
Multidimensional Scaling ◽  
Firing Rate ◽  
Visual Stimuli ◽  
Natural Scenes ◽  
Information Theoretic ◽  
Network Operation ◽  
Face Selectivity ◽  
Fixation Task ◽  
Neuronal Representation ◽  
Face Stimuli

1. To analyze the selectivity and the sparseness of firing to visual stimuli of single neurons in the primate temporal cortical visual area, neuronal responses were measured to a set of 68 visual stimuli in macaques performing a visual fixation task. The population of neurons analyzed had responses that occurred primarily to faces. The stimuli included 23 faces, and 45 nonface images of real-world scenes, so that the function of this brain region could be analyzed when it was processing natural scenes. 2. The neurons were selected to meet the previously used criteria of face selectivity by responding more than twice as much to the optimal face as to the optimal nonface stimulus in the set. Application of information theoretic analyses to the responses of these neurons confirmed that their responses contained much more information about which of 20 face stimuli had been seen (on average 0.4 bits) than about which (of 20) nonface stimuli had been seen (on average 0.07 bits). 3. The sparseness of the representation of a scene or object provided by each of these neurons (which can be thought of as the proportion of stimuli to which the neuron responds, and which is fundamental to understanding the network operation of the system) can be defined as [formula: see text] where ri is the firing rate to the ith stimulus in the set of n stimuli. The sparseness has a maximal value of 1.0. It was found that the sparseness of the representation of the 68 stimuli by each neuron had an average across all neurons of 0.65. This indicates a rather distributed representation. 4. If the spontaneous firing rate was subtracted from the firing rate of the neuron to each stimulus, so that the changes of firing rate, i.e., the responses of the neurons, were used in the sparseness calculation, then the "response sparseness" had a lower value, with a mean of 0.33 for the population of neurons, or 0.60 if calculated over the set of faces. 5. Multidimensional scaling to produce a stimulus space represented by this population of neurons showed that the different faces were well separated in the space created, whereas the different nonface stimuli were grouped together in the space. 6. The information analyses and multidimensional scaling provided evidence that what was made explicit in the responses of these neurons was information about which face had been seen.(ABSTRACT TRUNCATED AT 400 WORDS)

Russia's economy will benefit from thaw with Trump

2017 ◽  
Keyword(s):  
Emerging Economies ◽  
Investor Sentiment ◽  
Short Term ◽  
Similar Action ◽  
Content Type ◽  
Oil Companies ◽  
Know How ◽  
Russian Economy ◽  
President Elect ◽  
The Eu

Subject Russia-US relations and its impact on the Russian economy. Significance Cautious hopes of improvement in US-Russian relations have boosted investor sentiment towards the Russian economy. Improved relations have the potential to spur Russian economic recovery, backed by stabilising global oil prices and reviving domestic demand. US President-elect Donald Trump's more favourable stance give Russian assets a perceived comparative advantage over other emerging economies, encouraging short-term speculative investment. Impacts A complete or partial lifting of US sanctions would encourage the EU to take similar action. Improved relations will divert funds to Russia from other emerging markets. A renewed flow of US technology and know-how would benefit Russian financial institutions and corporates. Russian oil companies will exploit US technologies to develop Arctic deposits.

scholarly journals Spontaneous Motion on Two-Dimensional Continuous Attractors

2015 ◽  
Vol 27 (3) ◽  
pp. 507-547 ◽  
Author(s):  
C. C. Alan Fung ◽  
S.-i. Amari
Keyword(s):  
Firing Rate ◽  
Synaptic Depression ◽  
Object Motion ◽  
Spike Frequency ◽  
Two Dimensional ◽  
Spike Frequency Adaptation ◽  
Short Term ◽  
Perturbative Approach ◽  
Frequency Adaptation ◽  
Spontaneous Motion

Attractor models are simplified models used to describe the dynamics of firing rate profiles of a pool of neurons. The firing rate profile, or the neuronal activity, is thought to carry information. Continuous attractor neural networks (CANNs) describe the neural processing of continuous information such as object position, object orientation, and direction of object motion. Recently it was found that in one-dimensional CANNs, short-term synaptic depression can destabilize bump-shaped neuronal attractor activity profiles. In this article, we study two-dimensional CANNs with short-term synaptic depression and spike frequency adaptation. We found that the dynamics of CANNs with short-term synaptic depression and CANNs with spike frequency adaptation are qualitatively similar. We also found that in both kinds of CANNs, the perturbative approach can be used to predict phase diagrams, dynamical variables, and speed of spontaneous motion.

Sign in / Sign up

Export Citation Format

Share Document