scholarly journals Discharge Properties of MST Neurons That Project to the Frontal Pursuit Area in Macaque Monkeys

2005 ◽  
Vol 94 (2) ◽  
pp. 1084-1090 ◽  
Author(s):  
Anne K. Churchland ◽  
Stephen G. Lisberger
Keyword(s):  
Optic Flow ◽  
Action Potentials ◽  
Rhesus Monkeys ◽  
Statistical Significance ◽  
Image Motion ◽  
Antidromic Activation ◽  
Medial Superior Temporal ◽  
Mst Neurons ◽  
Direction Tuning ◽  
And Control

We have used antidromic activation to determine the functional discharge properties of neurons that project to the frontal pursuit area (FPA) from the medial-superior temporal visual area (MST). In awake rhesus monkeys, MST neurons were considered to be activated antidromically if they emitted action potentials at fixed, short latencies after stimulation in the FPA and if the activation passed the collision test. Antidromically activated neurons ( n = 37) and a sample of the overall population of MST neurons ( n = 110) then were studied during pursuit eye movements across a dark background and during laminar motion of a large random-dot texture and optic flow expansion and contraction during fixation. Antidromically activated neurons showed direction tuning during pursuit (25/37), during laminar image motion (21/37), or both (16/37). Of 27 neurons tested with optic flow stimuli, 14 showed tuning for optic flow expansion ( n = 10) or contraction ( n = 4). There were no statistically significant differences in the response properties of the antidromically activated and control samples. Preferred directions for pursuit and laminar image motion did not show any statistically significant biases, and the preferred directions for eye versus image motion in each sample tended to be equally divided between aligned and opposed. There were small differences between the control and antidromically activated populations in preferred speeds for laminar motion and optic flow; these might have reached statistical significance with larger samples of antidromically activated neurons. We conclude that the population of MST neurons projecting to the FPA is highly diverse and quite similar to the general population of neurons in MST.

scholarly journals Direction and Contrast Tuning of Macaque MSTd Neurons During Saccades

2009 ◽  
Vol 101 (6) ◽  
pp. 3100-3107 ◽  
Author(s):  
Nathan A. Crowder ◽  
Nicholas S. C. Price ◽  
Michael J. Mustari ◽  
Michael R. Ibbotson
Keyword(s):  
Visual Stimulation ◽  
Large Cell ◽  
Saccadic Suppression ◽  
Image Motion ◽  
Active Motion ◽  
Temporal Area ◽  
Full Field ◽  
Medial Superior Temporal ◽  
Preferred Direction ◽  
Direction Tuning

Saccades are rapid eye movements that change the direction of gaze, although the full-field image motion associated with these movements is rarely perceived. The attenuation of visual perception during saccades is referred to as saccadic suppression. The mechanisms that produce saccadic suppression are not well understood. We recorded from neurons in the dorsal medial superior temporal area (MSTd) of alert macaque monkeys and compared the neural responses produced by the retinal slip associated with saccades (active motion) to responses evoked by identical motion presented during fixation (passive motion). We provide evidence for a neural correlate of saccadic suppression and expand on two contentious results from previous studies. First, we confirm the finding that some neurons in MSTd reverse their preferred direction during saccades. We quantify this effect by calculating changes in direction tuning index for a large cell population. Second, it has been noted that neural activity associated with saccades can arrive in the parietal cortex ≤30 ms earlier than activity produced by similar visual stimulation during fixation. This led to the question of whether the saccade-related responses were visual in origin or were motor signals arising from saccade-planning areas of the brain. By comparing the responses to saccades made over textured backgrounds of different contrasts, we provide strong evidence that saccade-related responses were visual in origin. Refinements of the possible models of saccadic suppression are discussed.

Simulated Optic Flow and Extrastriate Cortex. II. Responses to Bar Versus Large-Field Stimuli

1997 ◽  
Vol 77 (2) ◽  
pp. 562-570 ◽  
Author(s):  
Kathleen Mulligan ◽  
Jong-Nam Kim ◽  
Helen Sherk
Keyword(s):  
Optic Flow ◽  
Preceding Paper ◽  
Forward Direction ◽  
Direction Selectivity ◽  
Image Motion ◽  
Extrastriate Cortex ◽  
Large Field ◽  
Response Properties ◽  
Tuning Curves ◽  
Direction Tuning

Mulligan, Kathleen, Jong-Nam Kim, and Helen Sherk. Simulated optic flow and extrastriate cortex. II. Responses to bar versus large-field stimuli. J. Neurophysiol. 77: 562–570, 1997. In the preceding paper we described the responses of cells in the cat's lateral suprasylvian visual area (LS) to large-field optic flow and texture movies. To assess response properties such as direction selectivity, cells were also tested with moving bar stimuli. We expected that there would be good agreement between response properties elicited with optic flow movies and those revealed with bar stimuli. We first asked how well bar response properties predicted responsiveness to optic flow movies. There was no correlation between responsiveness to movies and the degree of end-stopping, length summation, or preference for bars that accelerated and expanded. We then considered only the 322 cells that responded to both bars and optic flow or texture movies and asked how well the strength of their response to movies could be predicted from the direction-tuning curves generated with bar stimuli. One-third of these cells responded much more strongly to movies than could be predicted from their direction-tuning curves. Generally, such cells were rather well tuned for the direction of bar motion and preferred a direction substantially different from what they saw in optic flow movies. Optic flow movies shown in the forward direction were the most effective variety of movie for two-thirds of these cells. To see whether this outcome stemmed from differential direction tuning for bars and large multielement displays, in a second series of experiments we compared direction tuning for bars and large-field texture movies. Many cells showed substantially different direction tuning for the two kinds of stimulus: almost [Formula: see text] of 409 cells had tuning curves that overlapped each other by <50%. But only a small number of cells (<10%) responded much better to texture movies than to bars in the predominant direction of image motion in optic flow movies. This result, like that reported in the preceding paper, suggests that cells in LS respond differently to optic flow than to texture displays lacking optic flow motion cues.

Responses in ventral intraparietal area of awake macaque monkey to optic flow patterns corresponding to rotation of planes in depth can be explained by translation and expansion effects

1997 ◽  
Vol 14 (4) ◽  
pp. 633-646 ◽  
Author(s):  
S.J. Schaafsma ◽  
J. Duysens ◽  
C.C.A.M. Gielen
Keyword(s):  
Optic Flow ◽  
Macaque Monkey ◽  
Induced Responses ◽  
Temporal Area ◽  
Medial Superior Temporal ◽  
Preferred Direction ◽  
Optimal Direction ◽  
Mst Neurons ◽  
Ventral Intraparietal Area ◽  
Parallel Axis

AbstractThere is evidence that neurons in medial superior temporal area (MST) respond to rotation in depth of textured planes. MST neurons project to the ventral intraparietal area (VIP) and the question arises whether VIP neurons are responsive to rotation in depth as well. In the present study on awake monkeys, we have simulated movement of a flat board, covered with dots, by a computer. The two-dimensional images corresponded to the projection of structured planes rotating around a fronto-parallel axis. In the literature this stimulus is called fanning. Fanning effectively induced responses in VIP neurons. Most often the responses were nearly as strong as for translation, expansion/contraction, or rotation, indicating that there was no special sensitivity for rotation in depth. For neurons, sensitive to expansion, the response to fanning could often be explained by the positioning of the expanding part of the fanning stimulus over the area which was most responsive to expansion. For neurons which were direction selective to translation, the optimal direction of fanning was usually the same as the preferred direction for translation. It is concluded that VIP neurons may be sensitive to movement of structured planes but they are not specialized for the detection of such movement.

MST Responses to Pursuit Across Optic Flow With Motion Parallax

2000 ◽  
Vol 84 (2) ◽  
pp. 818-826 ◽  
Author(s):  
Urmen D. Upadhyay ◽  
William K. Page ◽  
Charles J. Duffy
Keyword(s):  
Flow Field ◽  
Optic Flow ◽  
Visual Motion ◽  
Motion Parallax ◽  
Depth Plane ◽  
Relative Depth ◽  
Depth Cues ◽  
Medial Superior Temporal ◽  
Heading Direction ◽  
Mst Neurons

Self-movement creates the patterned visual motion of optic flow with a focus of expansion (FOE) that indicates heading direction. During pursuit eye movements, depth cues create a retinal flow field that contains multiple FOEs, potentially complicating heading perception. Paradoxically, human heading perception during pursuit is improved by depth cues. We have studied medial superior temporal (MST) neurons to see whether their heading selectivity is also improved under these conditions. The responses of 134 MST neurons were recorded during the presentation of optic flow stimuli containing one or three speed-defined depth planes. During pursuit, multiple depth-plane stimuli evoked larger responses (71% of neurons) and stronger heading selectivity (70% of neurons). Responses to the three speed-defined depth-planes presented separately showed that most neurons (54%) preferred one of the planes. Responses to multiple depth-plane stimuli were larger than the averaged responses to the three component planes, suggesting enhancing interactions between depth-planes. Thus speed preferences create selective responses to one of many depth-planes in the retinal flow field. The presence of multiple depth-planes enhances those responses. These properties might improve heading perception during pursuit and contribute to relative depth perception.

MST Neurons Respond to Optic Flow and Translational Movement

1998 ◽  
Vol 80 (4) ◽  
pp. 1816-1827 ◽  
Author(s):  
Charles J. Duffy
Keyword(s):  
Optic Flow ◽  
Direction Selectivity ◽  
Movement Detection ◽  
Temporal Area ◽  
Medial Superior Temporal ◽  
Preferred Direction ◽  
Translational Movement ◽  
Mst Neurons ◽  
Best Responses ◽  
Stimulus Direction

Duffy, Charles J. MST neurons respond to optic flow and translational movement . J. Neurophysiol. 80: 1816–1827, 1998. We recorded the responses of 189 medial superior temporal area (MST) neurons by using optic flow, real translational movement, and combined stimuli in which matching directions of optic flow and real translational movement were presented together. One-half of the neurons (48%) showed strong responses to optic flow simulating self-movement in the horizontal plane, and 24% showed strong responses to translational movement. Combining optic flow stimuli with matching directions of translational movement caused substantial changes in both the amplitude of the best responses (44% of neurons) and the strength of direction selectivity (71% of neurons), with little effect on which stimulus direction was preferred. However, combining optic flow and translational movement such that opposite directions were presented together changed the preferred direction in 45% of the neurons with substantial changes in the strength of direction selectivity. These studies suggest that MST neurons combine visual and vestibular signals to enhance self-movement detection and disambiguate optic flow that results from either self-movement or the movement of large objects near the observer.

scholarly journals Extrastriate Area MST and Parietal Area VIP Similarly Represent Forward Headings

2010 ◽  
Vol 104 (1) ◽  
pp. 239-247 ◽  
Author(s):  
James B. Maciokas ◽  
Kenneth H. Britten
Keyword(s):  
Eye Movements ◽  
Optic Flow ◽  
Posterior Parietal Cortex ◽  
Three Dimensional ◽  
Quantitative Comparison ◽  
Medial Superior Temporal ◽  
Flow Information ◽  
Mst Neurons ◽  
Optic Flow Information ◽  
Cloud Of Points

Many studies have documented the involvement of medial superior temporal extrastriate area (MST) in the perception of heading based on optic flow information. Furthermore, both heading perception and the responses of MST neurons are relatively stable in the presence of eye movements that distort the retinal flow information on which perception is based. Area VIP in the posterior parietal cortex also contains a robust representation of optic flow cues for heading. However, the studies in the two areas were frequently conducted using different stimuli, making quantitative comparison difficult. To remedy this, we studied MST using a family of random dot heading stimuli that we have previously used in the study of VIP. These stimuli simulate observer translation through a three-dimensional cloud of points, and a range of forward headings was presented both with and without horizontal smooth pursuit eye movements. We found that MST neurons, like VIP neurons, respond robustly to these stimuli and partially compensate for the presence of pursuit. Quantitative comparison of the responses revealed no substantial difference between the heading responses of MST and VIP neurons or in their degree of pursuit tolerance.

Sensitivity of MST neurons to optic flow stimuli. I. A continuum of response selectivity to large-field stimuli

1991 ◽  
Vol 65 (6) ◽  
pp. 1329-1345 ◽  
Author(s):  
C. J. Duffy ◽  
R. H. Wurtz
Keyword(s):  
Optic Flow ◽  
Receptive Fields ◽  
Flow Fields ◽  
Direction Selectivity ◽  
Single Component ◽  
Large Field ◽  
Temporal Area ◽  
Response Characteristics ◽  
Medial Superior Temporal ◽  
Mst Neurons

1. Neurons in the dorsomedial region of the medial superior temporal area (MSTd) have large receptive fields that include the fovea, are directionally selective for moving visual stimuli, prefer the motion of large fields to small spots, and respond to rotating and expanding patterns of motion as well as frontal parallel planar motion. These characteristics suggested that these neurons might contribute to the analysis of the large-field optic flow stimulation generated as an observer moves through the visual environment. 2. We tested the response of MSTd neurons in two awake monkeys by systematically presenting a set of translational and rotational stimuli to each neuron. These 100 X 100 degrees stimuli were the motion components from which all optic flow fields are derived. 3. In 220 single neurons we found 23% that responded primarily to one component of motion (planar, circular, or radial), 34% that responded to two components (planocircular or planoradial, but never circuloradial), and 29% that responded to all three components. 4. The number of stimulus components to which a neuron responded was unrelated to the size or eccentricity of its receptive field. 5. Triple-, double-, and single-component neurons varied widely in the strength of their responses to the preferred components. Grouping these neurons together revealed that they did not form discrete classes but rather a continuum of response selectivity. 6. This continuum was apparent in other response characteristics. Direction selectivity was weakest in triple-component neurons, strongest in single-component neurons. Significant inhibitory responses were less frequent in triple-component neurons than in single-component neurons. 7. There was some indication that the neurons of similar component classes occupied adjacent regions within MSTd, but all combinations of component and direction selectivity were occasionally found in immediate juxtaposition. 8. Experiments on a subset of neurons showed that the speed of motion, the dot density, and the number of different speed planes in the display had little influence on these responses. 9. We conclude that the selective responses of many MSTd neurons to the rotational and translational components of optic flow make these neurons reasonable candidates for contributing to the analysis of optic flow fields.

Individuality, self and sociality of vascular plants

2021 ◽  
Vol 376 (1821) ◽  
pp. 20190760 ◽  
Author(s):  
František Baluška ◽  
Stefano Mancuso
Keyword(s):  
Action Potentials ◽  
Vascular Plants ◽  
Kin Recognition ◽  
Flowering Plants ◽  
Theme Issue ◽  
Long Distance ◽  
Self Recognition ◽  
Seed Dispersers ◽  
And Control

Vascular plants are integrated into coherent bodies via plant-specific synaptic adhesion domains, action potentials (APs) and other means of long-distance signalling running throughout the plant bodies. Plant-specific synapses and APs are proposed to allow plants to generate their self identities having unique ways of sensing and acting as agents with their own goals guiding their future activities. Plants move their organs with a purpose and with obvious awareness of their surroundings and require APs to perform and control these movements. Self-identities allow vascular plants to act as individuals enjoying sociality via their self/non-self-recognition and kin recognition. Flowering plants emerge as cognitive and intelligent organisms when the major strategy is to attract and control their animal pollinators as well as seed dispersers by providing them with food enriched with nutritive and manipulative/addictive compounds. Their goal in interactions with animals is manipulation for reproduction, dispersal and defence. This article is part of the theme issue ‘Basal cognition: multicellularity, neurons and the cognitive lens’.

scholarly journals Effects of two different deep digital flexor tenotomy techniques on distal articular angles of equine cadaver forelimbs

2012 ◽  
Vol 42 (11) ◽  
pp. 2005-2010
Author(s):  
Antonio Cezar de Oliveira Dearo ◽  
Vitor Bruno Bianconi Rosa ◽  
Peter Reichmann ◽  
Milton Luis Ribeiro de Oliveira
Keyword(s):  
Quantitative Data ◽  
Statistical Significance ◽  
Surgical Approaches ◽  
Control Groups ◽  
Before And After ◽  
Distal Interphalangeal ◽  
The Difference ◽  
And Control ◽  
Flexor Tenotomy

Deep digital flexor (DDF) tenotomy is a technique employed for years to treat selected disorders of the musculoskeletal system in horses. Although two different surgical approaches (i.e. mid-metacarpal and pastern) have been described for performing the procedure, in vitro quantitative data regarding the modifications induced by either technique on the distal articular angles is lacking. Therefore, the purpose of the study reported here was to investigate the viability of a proposed biomechanical system of induced-traction used to compare the two DDF tenotomy techniques by measuring the distal articular angles of equine cadaver forelimbs. Ten pairs of forelimbs were collected and mounted to a biomechanical system developed to apply traction at the toe level. Dorsal articular angles of the metacarpophalangeal (MP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints were determined by geometric lines on radiographs taken before and after performing each technique. Comparisons between each tenotomy group and its own control, for each joint, and between the two tenotomy groups using as variable the difference between the tenotomy and control groups were tested. Despite the lack of statistical significance, the DDF tenotomy technique at the pastern level produced extension, to a lesser and greater extent, of the PIP and DIP joints, respectively when compared to the mid-metacarpal level. No remarkable differences could be observed for the MP joint. The developed traction-induced biomechanical construct seemed to be effective in producing valuable quantitative estimations of the distal articular angles of equine cadaver forelimbs subjected to different DDF tenotomy techniques.

scholarly journals THE IMPORTANCE OF EDUCATION TO REDUCE SELF-DESTRUCTIVE NAIL HABITS

2021 ◽  
Vol 4 ◽  
pp. 491-499
Author(s):  
Ilze Upeniece ◽  
Monta Beltiņa
Keyword(s):  
Clinical Practice ◽  
General Education ◽  
Statistical Significance ◽  
Target Population ◽  
Control Group ◽  
Age Related ◽  
Nail Changes ◽  
Group 2 ◽  
And Control ◽  
Traumatic Damage

Onychophagia and onychotillomania are rarely seen in clinical practice and are considered undervalued. The study aims were to determine the prevalence of onychophagia and onychotillomania habit in the patient group with hand nail damage and control group, to determine which would be the target population to educate. Patients were interviewed about self-destructive habits. Excel and SPSS were used for data analysis. In the nail damage group, 28.6% of the respondents showed self-destructive habits and past habits – 31.4%. In the control group, the result was 22.9% and 31.4%. For 74.3% of patients the cause of nail damage was skin disease (including 61.54% of respondents with nail damage who have psoriasis), for 5.7% it was age-related nail changes, for 20% traumatic damage and for 57.14% of them it was a result of self-destructive habit. In the nail damage group both – present and past self-destructive habits are higher than in the control group, but it has no statistical significance (p=0.785). 1)The prevalence of onychophagia and onychotillomania does not differ between patients and control group. 2)General education of the population is necessary to actualize this problem, which can worsen nail changes.

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