Sentences with phrase «own saccades»

Saccades and memory: Baseline associations of the King - Devick and SCAT2 SAC tests in professional ice hockey players.

Sommer says future experiments may inactivate more of the thalamus to see if monkeys have a harder time distinguishing their own saccades from changes in their environment.

«This is important because each saccade shifts the position of visible objects on the retina, and hence the brain needs to know the stable positions of objects in external space,» says Dr. Pack.

Vision is an extremely dynamic process — Even when we look at a fixed image, our eyes are making rapid movements, called «saccades» to explore the image that is sent to our brain.

By recording neuronal activity in monkeys as they performed tasks that caused saccades, Dr. Christopher Pack has shown that there are waves of activity that cross specific vision processing areas of the brain in defined patterns, and that these patterns are reorganized by saccadic eye movements.

You can become aware of, and even control, these large movements of the eyes, which scientists call saccades.

, real rat laughter doesn't tend to sound very much like the human variety, which normally involves pulsating sound bursts starting with a vocalized inhalation and consisting of a series of short distinct saccades separated by almost equal time intervals.

Moving your eyes smoothly enough to trace out words is hard because your eyes constantly make jerky motions known as saccades, unless you are tracking a moving object.

Subjects were tested for their rapid eye movement that allows focus to shift on multiple objects in the field of vision (aka saccade) and ability to follow objects moving across the visual field, known as smooth - pursuit.

Twenty - seven percent of Chinese participants responded with high proportions of express saccades, similar to 22 % of the British Chinese, but many more than the 10 % of white British participants.

He said: «Examining saccades from different populations is revealing a lot about underlying brain mechanisms and how we think.

These rapid eye movements, known as saccades, were timed in all of the participants to see which of them were capable of making high numbers of express saccades — particularly fast responses which begin a tenth of a second after a target appears.

The findings, published in the journal PLoS One, revealed that similar numbers of the British Chinese and mainland Chinese participants made high numbers express saccades, with the white British participants made far fewer.

«These finding suggest that assessing the ability of people to adapt saccade amplitudes is one way to determine whether this function of the cerebellum is altered in ASD,» said Edward Freedman, Ph.D. an associate professor in the URMC Department of Neuroscience and co-author of the study.

«If these deficits do turn out to be a consistent finding in a sub-group of children with ASD, this raises the possibility that saccade adaptation measures may have utility as a method that will allow early detection of this disorder.»

In healthy individuals, these saccades are rapid, precise, and accurate, redirecting the line of sight from one point of interest to another.

The rapid eye movements we make when we shift our attention from one object to another, known as saccades, are essential to navigating, understanding, and interacting with the world around us.

Research suggests that saccades and microsaccades are controlled by the same brain areas, so it seems likely to us that microsaccades also will be found to be abnormal in schizophrenia.

According to neurologists R. John Leigh and David Zee, authors of the comprehensive The Neurology of Eye Movements (Oxford University Press, 1999), schizophrenics show consistent abnormalities in the voluntary control of saccades, particularly in tasks requiring imagination, memory or prediction.

But there has been extensive work showing that people with schizophrenia do indeed have abnormal saccades, the fast eye movements that direct our gaze from object to object as we explore a visual scene.

Plots are aligned to two events in the trial: left, target onset; right, saccade onset.

The observation that activity is only correlated with the present interval implies that the correlations observed prior to central saccades to timing do not reflect past or future planning of peripheral saccades.

For example, if LIP activity were strongly modulated by both central and peripheral saccades, then a firing rate reconstruction based on only one of those saccades would poorly predict peri-saccadic activity for the other saccade.

Although the predominant feature of activity modulation during self - timed saccades is a near linear decline in firing rate over time, other modulations are clearly present.

Specifically, we looked at whether activity locked to a particular saccade could completely explain the peri-saccadic activity aligned to the other saccade by generating firing rate predictions of each saccadic alignment on the basis of the other (Figure 5A) and behavioral variability.

However, a study by Dickinson et al. [85] found that neurons in LIP can be activated by the instruction to perform a saccade, in the absence of any spatial information.

Brief increases in activity just prior to saccade onset are followed by short intervals of decreased activity at the time of saccades.

Overall correlations were significant for precentral and postperipheral saccade aligned activity and increased from 0.050 and 0.076 to 0.145 and 0.157, respectively.

In order to determine what factors are associated with firing rate changes, we generated a prediction of neural activity by convolving observed neural activity aligned with one saccade direction with the intersaccade distribution times aligned with the other saccade direction.

A similar response is also evident during the self - timed saccade activity (blue, left), although the cause is likely due to a central saccade bringing the RF to encompass the peripheral target instead of target onset since first saccades are not included in the rhythmic analysis (Figure 4C).

Around the time of saccade onset (± 100 ms), the activity displays distinct modulations.

Yet correlations were not significant for either saccade alignment as animals fixated on the central target in the high modulation cells.

A good fit between the predicted rates (green traces) and the observed firing rates (red and blue traces) would indicate that activity locked to a particular saccade can largely explain the firing rate changes seen in the cyclical task.

The 800 ms intervals were investigated as that is the minimum time for correctly made saccades as defined by the error window (1,000 ms ± 200 ms).

(A and B) Average combined population activity, grouped by interval length, aligned to central saccades (A) and peripheral saccades (B).

The same analysis is then repeated using activity aligned to central saccades.

The difference between this prediction and the observed firing rate for activity aligned to central saccades indicates how well activity associated with peripheral saccades can completely explain task - related modulations in activity.

(C and D) Binned correlations between firing rate and current interval lengths for all intervals of the combined population, aligned to central saccades (C) and peripheral saccades (D).

If LIP activity strictly reflected a broad timing system (like those described by centralized timing models), its activity would have a consistent relationship with time irrespective of saccade direction.

For central saccades (C), the p values from left to right are: 5.5e - 13; 0.0164, 0.0001, 0, 0, 0.0001, 0.0001, 0, 0, 0.0502, 0, 0.497, 0.0012, 0.0827, 0.958, 0.0126, 0.0004; 0.0163.

Zero time points and vertical black lines indicate saccade onset.

Therefore, LIP activity is likely related to motor planning rather than saccade metrics.

(E) Average memory - guided delayed - saccade activity for the same example cell shown in (C).

After this memory - guided task, we recorded from the same neurons while the animals performed the self - timed rhythmic - saccade task (Figure 1A, B).

For each saccade, the burst magnitude was quantified from the raw data by counting all spikes in the time window between the two tick marks (identifying saccade onset an offset with a 20 ms lead time), and the resulting spike counts are displayed in the adjacent panels as running averages.

This movement - field plot shows that the number of spikes in the burst (color code) varies systematically with saccade amplitude and direction.

This analysis shows that the peak firing rate occurs at about the same instant relative to saccade onset (see Table 1, for further quantification) while the burst duration increases systematically with the preferred amplitude of the cells (indexed by the gray - scaling).

We first examined the temporal discharge profiles of saccade - related neurons along the rostral - to - caudal extent of the SC for saccades of five particular amplitudes.

Nevertheless, the burst properties reported in this study strongly support the idea that the deeper layers of the SC act as an optimal controller: the systematic organization of peak firing rates and burst durations as function of saccade amplitude along the motor map, the synchronous change in firing rate of recruited cells in the population, and the shaping of the temporal burst profile of a given cell with the currently planned saccade, all contribute to the generation of straight eye - movement trajectories with optimal kinematics.

Moreover, all cells synchronize their bursts, thus maximizing the total instantaneous input to the brainstem, and ensuring that oblique saccades have straight trajectories.