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1.
Karen Van Ooteghem James S. Frank Fay B. Horak 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2009,199(2):185-193
Healthy older adults were repeatedly exposed to continuous, variable amplitude oscillations of the support surface to determine
(1) whether age affects the capacity for postural motor learning under continuous perturbation conditions with limited predictability
and (2) whether practice leads to modifications in the control strategy used to maintain balance in older adults. During training,
a translating platform underwent 45-s trials of constant frequency (0.5 Hz) and seemingly random amplitude oscillations (range
±2 to 15 cm). The middle 15 s of each trial contained the same sequence of oscillation amplitudes. This repeated middle segment
was the same as the repeated segment used in Van Ooteghem et al. (Exp Brain Res 187(4): 603–611, 2008) and was therefore used
for analyses. To examine learning, participants performed a retention test following a 24-h delay. Kinematic data were used
to derive spatial and temporal measures of whole body centre of mass (COM), trunk, thigh, and shank segment orientation, and
ankle and knee angle from performance during the repeated middle segment. Results showed that with training, older adults
maintained the capacity to learn adaptive postural responses in the form of improved temporal control of the COM and minimization
of trunk instability at a rate comparable to young adults. With practice, however, older adults maintained a more rigid, ‘platform-fixed’
control strategy which differed from young adults who shifted towards ‘gravity-fixed’ control and decreased COM motion. This
study provides important insight into the ability of older adults to demonstrate longer-term improvements in postural regulation. 相似文献
2.
Wilmut K Barnett AL 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,210(2):185-194
During everyday locomotion, we encounter a range of obstacles requiring specific motor responses; a narrow aperture which
forces us to rotate our shoulders in order to pass through is one example. In adults, the decision to rotate their shoulders
is body scaled (Warren and Whang in J Exp Psychol Hum Percept Perform 13:371–383, 1987), and the movement through is temporally and spatially tailored to the aperture size (Higuchi et al. in Exp Brain Res 175:50–59,
2006; Wilmut and Barnett in Hum Mov Sci 29:289–298, 2010). The aim of the current study was to determine how 8-to 10-year-old children make action judgements and movement adaptations
while passing through a series of five aperture sizes which were scaled to body size (0.9, 1.1, 1.3, 1.5 and 1.7 times shoulder
width). Spatial and temporal characteristics of movement speed and shoulder rotation were collected over the initial approach
phase and while crossing the doorway threshold. In terms of making action judgements, results suggest that the decision to
rotate the shoulders is not scaled in the same way as adults, with children showing a critical ratio of 1.61. Shoulder angle
at the door could be predicted, for larger aperture ratios, by both shoulder angle variability and lateral trunk variability.
This finding supports the dynamical scaling model (Snapp-Childs and Bingham in Exp Brain Res 198:527–533, 2009). In terms of movement adaptations, we have shown that children, like adults, spatially and temporally tailor their movements
to aperture size. 相似文献
3.
Cressman EK Carlsen AN Chua R Franks IM 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2006,171(2):278-282
Previous research has shown that a startle ‘go’ stimulus, presented at a constant latency with respect to a warning stimulus, is capable of eliciting an intended voluntary movement in a simple reaction time (RT) task at very short latencies without involvement of the cerebral cortex (Carlsen et al. in Exp Brain Res 152:510–518, 2003; J Motor Behav 36:253–264, 2004a; Exp Brain Res 159:301–309 2004b; Valls-Solé et al. in J Physiol 516:931–938, 1999). The purpose of the present experiment was to determine the effect of temporal uncertainty on response latency during an RT task that comprised a startle stimulus. Participants were required to perform an active 20° wrist extension movement in response to an auditory tone that was presented 2,500 to 5,500 ms after a warning stimulus, in 1,000 ms increments. On certain trials the control auditory stimulus (80 dB) was unexpectedly replaced by the startle stimulus (124 dB). When participants were startled the intended voluntary movement was initiated at approximately 70 ms, regardless of foreperiod duration. The magnitude and invariance of response latencies to the startle stimulus suggest that the intended movement had indeed been prepared prior to the arrival of the imperative go stimulus, within 2.5 s of the warning stimulus. Furthermore, there was no evidence that the prepared movement decayed over a period of at least 3 s. 相似文献
4.
Bonnie M. Lawrence 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2010,204(1):115-118
Previously, we have shown that the reaction times (RTs) of exogenously generated saccadic eye movements decrease with an increase
in the number of response alternatives (Lawrence et al. in J Vis 8(26):1–7, 2008; Lawrence and Gardella in Exp Brain Res 195(3):413–418, 2009). Because this pattern of RTs is in the direction opposite that predicted by Hick (Q J Exp Psychol 4:11–26, 1952), we termed the effect an “anti-Hick’s” effect. In the present study, we examined whether this effect characterizes saccades
in general, or only those saccades that are exogenously generated. An anti-Hick’s effect was found for exogenous, but not
for endogenous, saccades. These results demonstrate a clear dissociation between exogenously and endogenously generated saccades
and place an important constraint on the anti-Hick’s effect. 相似文献
5.
Welsh TN Pratt J 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2006,174(1):167-175
Inhibition of return (IOR), the term given for the slowing of a response to a target that appeared at the same location as a previously presented stimulus, has been studied with both target–target (TT; participants respond to each successive event) and cue–target (CT; participants only respond to the second of two events) tasks. Although both tasks have been used to examine the processes and characteristics of IOR, few studies have been conducted to understand if there are any differences in the processes that underlie the IOR that results from ignoring (CT paradigm) or responding to (TT paradigm) the first stimulus. The purpose of the present study was to examine the notion that IOR found in TT tasks represents “true” IOR whereas IOR found in CT tasks consist of both “true” IOR and response inhibition (Coward et al. in Exp Brain Res 155:124–128, 2004). Consistent with the pattern of effects found by Coward et al. (Exp Brain Res 155:124–128, 2004), IOR was larger in the CT task than in the TT task when a single detection response was required (Experiment 1). However, when participants completed one of two spatially-directed responses (rapid aiming movement to the location of the target stimulus), IOR effects from the CT and TT tasks were equal in magnitude (Experiment 2). Rather than CT tasks having an additional response inhibition component, these results suggest that TT tasks may show less of an inhibitory effect because of a facilitatory response repetition effect. 相似文献
6.
Our recent work has revealed that visuospatial working memory (VSWM) relates to the rate of explicit motor sequence learning (Bo and Seidler in J Neurophysiol 101:3116–3125, 2009) and implicit sequence performance (Bo et al. in Exp Brain Res 214:73–81, 2011a) in young adults (YA). Although aging has a detrimental impact on many cognitive functions, including working memory, older adults (OA) still rely on their declining working memory resources in an effort to optimize explicit motor sequence learning. Here, we evaluated whether age-related differences in VSWM and/or verbal working memory (VWM) performance relates to implicit performance change in the serial reaction time (SRT) sequence task in OA. Participants performed two computerized working memory tasks adapted from change detection working memory assessments (Luck and Vogel in Nature 390:279–281, 1997), an implicit SRT task and several neuropsychological tests. We found that, although OA exhibited an overall reduction in both VSWM and VWM, both OA and YA showed similar performance in the implicit SRT task. Interestingly, while VSWM and VWM were significantly correlated with each other in YA, there was no correlation between these two working memory scores in OA. In YA, the rate of SRT performance change (exponential fit to the performance curve) was significantly correlated with both VSWM and VWM, while in contrast, OA’s performance was only correlated with VWM, and not VSWM. These results demonstrate differential reliance on VSWM and VWM for SRT performance between YA and OA. OA may utilize VWM to maintain optimized performance of second-order conditional sequences. 相似文献
7.
Pierre-Luc Tremblay Marc-Andre Bedard Dominic Langlois Pierre J. Blanchet Martin Lemay Maxime Parent 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2010,205(3):375-385
Chunking of single movements into integrated sequences has been described during motor learning, and we have recently demonstrated
that this process involves a dopamine-dependant mechanism in animal (Levesque et al. in Exp Brain Res 182:499–508, 2007; Tremblay et al. in Behav Brain Res 198:231–239, 2009). However, there is no such evidence in human. The aim of the present study was to assess this question in Parkinson’s disease
(PD), a neurological condition known for its dopamine depletion in the striatum. Eleven PD patients were tested under their
usual levodopa medication (ON state), and following a 12-h levodopa withdrawal (OFF state). Patients were compared with 12
healthy participants on a motor learning sequencing task, requiring pressing fourteen buttons in the correct order, which
was determined by visual stimuli presented on a computer screen. Learning was assessed from three blocks of 20 trials administered
successively. Chunks of movements were intrinsically created by each participant during this learning period. Then, the sequence
was shuffled according to the participant’s own chunks, generating two new sequences, with either preserved or broken chunks.
Those new motor sequences had to be performed separately in a fourth and fifth blocks of 20 trials. Results showed that execution
time improved in every group during the learning period (from blocks 1 to 3). However, while motor chunking occurred in healthy
controls and ON-PD patients, it did not in OFF-PD patients. In the shuffling conditions, a significant difference was seen
between the preserved and the broken chunks conditions for both healthy participants and ON-PD patients, but not for OFF-PD
patients. These results suggest that movement chunking during motor sequence learning is a dopamine-dependent process in human. 相似文献
8.
Forget J Lippé S Lassonde M 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2009,192(3):443-454
Acallosal participants usually do not display any disconnection signs in tasks requiring an explicit or declarative type of
response. They can accurately compare stimuli placed in each hand and they perform normally on lateralized recognition tasks.
They, however, show impairment in tasks assessing interdependent motor control, bilateral coordination and they are also unable
to intermanually transfer an implicit procedural motor skill. These deficits suggest that compensation might be limited when
a motor component is involved. Alternately, it is also possible that interhemispheric transmission in callosal agenesis might
be limited when implicit or unconscious processes are involved (Berlucchi et al. in Neuropsychologia 33:923–936, 1995; De Guise et al. in Brain 122:1049–1062, 1999). The aim of the present study was to assess interhemispheric transfer in two distinct nondeclarative tasks, namely visuoperceptual
skill learning and perceptual priming, with a lateralized version of the fragmented picture task developed by Snodgrass et
al. (Behav Res Methods Inst Comp 19:270–274, 1987) that did not involve any motor component. The performance of five acallosal and one early-callosotomized individuals was
compared to that of control participants divided into four groups (n = 10) according to which hemisphere was trained (left or right) and which response mode was used (manual or verbal). Visuoperceptual
skill learning was observed in all control groups except for the group submitted to training of the left hemisphere in the
manual modality of response. The acallosal and early-callosotomized participants did not show any implicit learning of the
visuoperceptual skill on any of the conditions. The evaluation of the perceptual priming effect in the second part of the
testing revealed that the priming effect was restricted to the trained hemisphere in participants without corpus callosum,
as opposed to all neurogically intact participants who presented interhemispheric transfer of the priming effect. These findings
indicate that the compensatory pathways, most probably subcortical commissures, are insufficient to allow interhemispheric
transfer of perceptual priming, confirming the limits of neural plasticity in the absence of the corpus callosum. They also
support the dissociation between declarative and nondeclarative memory in the split-brain and acallosal participants suggested
by Berlucchi et al. (1995) and observed by De Guise et al. (Brain 122:1049–1062, 1999). These results are further discussed within the context of neurobiological theories of memory systems. 相似文献
9.
de Boer-Schellekens L Vroomen J 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2012,216(2):243-248
We examined whether developmental dyslexic adults suffer from sluggish attentional shifting (SAS; Hari and Renvall in Trends
Cogn Sci 5:525–532, 2001) by measuring their shifting of attention in a visual search task with dynamic cluttered displays (Van der Burg et al. in
J Exp Psychol Human 34:1053–1065, 2008). Dyslexics were generally slower than normal readers in searching a horizontal or vertical target among oblique distracters.
However, the addition of a click sound presented in synchrony with a color change of the target drastically improved their
performance up to the level of the normal readers. These results are in line with the idea that developmental dyslexics have
specific problems in disengaging attention from the current fixation, and that the phasic alerting by a sound can compensate
for this deficit. 相似文献
10.
Feng Du Richard A. Abrams 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2010,205(1):115-121
We studied endogenous cuing during the attentional blink in order to examine its resistance to dual task interference. In
two experiments, we found a reduced impact of endogenous cuing during the “blink” time of the attentional blink. In a third
experiment endogenous cuing was intact when it was not influenced by demands imposed by an earlier target. Contrary to a recent
report (Zhang et al. in Exp Brain Res, 185, 287–295, 2008), the results indicate that endogenous orienting guided by semantic cues is susceptible to the attentional blink. 相似文献
11.
Ehresman C Saucier D Heath M Binsted G 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2008,188(3):371-378
This experiment examined whether the impact of pictorial illusions during the execution of goal-directed reaching movements
is attributable to ocular motor signaling. We analyzed eye and hand movements directed toward both the vertex of the Müller–Lyer
(ML) figure in a closed-loop procedure. Participants pointed to the right vertex of a visual stimulus in two conditions: a
control condition wherein the figure (in-ML, neutral, out-ML) presented at response planning remained unchanged throughout
the movement, and an experimental condition wherein a neutral figure presented at response planning was perturbed to an illusory
figure (in-ML, out-ML) at movement onset. Consistent with previous work from our group (Heath et al. in Exp Brain Res 158:378–384,
2004; Heath et al. in J Mot Behav 37:179–185, 2005b), action-bias present in both conditions; thus illusory bias was introduced into during online control. Although primary
saccades were influenced by illusory configurations (control conditions; see Binsted and Elliott in Hum Mov Sci 18:103–117,
1999a), illusory bias developed within the secondary “corrective” saccades during experimental trials (i.e., following a veridical
primary saccade). These results support the position that a unitary spatial representation underlies both action and perception
and this representation is common to both the manual and oculomotor systems. 相似文献
12.
Alen Hajnal Michael J. Richardson Steven J. Harrison R. C. Schmidt 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2009,199(1):89-93
The current study examined whether the amount and location of available movement information influenced the stability of visuo-motor
coordination. Participants coordinated a hand-held pendulum with an oscillating visual stimulus in an inphase and antiphase
manner. The effects of occluding different amounts of phase at different phase locations were examined. Occluding the 0°/180°
phase locations (end-points) significantly increased the variability of the visuo-motor coordination. The amount of occlusion
had little or no affect on the stability of the coordination. We concluded that the end-points of a visual rhythm are privileged
and provide access to movement information that ensures stable coordination. The results are discussed with respect to the
proposal of Bingham and colleagues (e.g., Bingham GP. Ecol Psychol 16:45–53, 2004a; Wilson AD, Collins DR, Bingham GP. Exp Brain Res 165:351–361, 2005a) that the relevant information for rhythmic visual coordination is relative direction information. 相似文献
13.
Lucy M. McGarry Frank A. Russo Matt D. Schalles Jaime A. Pineda 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2012,218(4):527-538
Previous studies demonstrate that perception of action presented audio-visually facilitates greater mirror neuron system (MNS)
activity in humans (Kaplan and Iacoboni in Cogn Process 8(2):103–113, 2007) and non-human primates (Keysers et al. in Exp Brain Res 153(4):628–636, 2003) than perception of action presented unimodally. In the current study, we examined whether audio-visual facilitation of the
MNS can be indexed using electroencephalography (EEG) measurement of the mu rhythm. The mu rhythm is an EEG oscillation with
peaks at 10 and 20 Hz that is suppressed during the execution and perception of action and is speculated to reflect activity
in the premotor and inferior parietal cortices as a result of MNS activation (Pineda in Behav Brain Funct 4(1):47, 2008). Participants observed experimental stimuli unimodally (visual-alone or audio-alone) or bimodally during randomized presentations
of two hands ripping a sheet of paper, and a control video depicting a box moving up and down. Audio-visual perception of
action stimuli led to greater event-related desynchrony (ERD) of the 8–13 Hz mu rhythm compared to unimodal perception of
the same stimuli over the C3 electrode, as well as in a left central cluster when data were examined in source space. These
results are consistent with Kaplan and Iacoboni’s (in Cogn Process 8(2):103–113, 2007), findings that indicate audio-visual facilitation of the MNS; our left central cluster was localized approximately 13.89 mm
away from the ventral premotor cluster identified in their fMRI study, suggesting that these clusters originate from similar
sources. Consistency of results in electrode space and component space support the use of ICA as a valid source localization
tool. 相似文献
14.
Steele-Russell I Russell MI Castiglioni JA Setlow B Werka T 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2008,188(2):199-213
In an earlier experiment we showed that selective attention plays a critical role in rabbit eye blink conditioning (Steele-Russell
et al. in Exp Brain Res 173:587–602, 2006). The present experiments are concerned to examine the extent to which visual recognition processes are a separate component
from the motor learning that is also involved in conditioning. This was achieved by midline section of the optic chiasma which
disconnected the direct retinal projections via the brainstem to the cerebellar oculomotor control system. By comparing both
normal and chiasma-sectioned rabbits it was possible to determine the dependence or independence of conditioning on the motor
expression of the eye blink response during training. Both normal and chiasma-sectioned animals were tested using a multiple
test battery to determine the effect of this redirection of the visual input pathways on conditioning. All animals were first
tested for any impairment in visual capability following section of the optic chiasma. Despite the loss of 90% of retinal
ganglion cell fibres, no visual impairment for either intensity or pattern vision was seen in the chiasma animals. Also no
difference was seen in nictitating membrane (NM) conditioning to an auditory signal between normal and chiasma animals. Testing
for motor learning to a visual signal, the chiasma rabbits showed a complete lack of any NM conditioning. However the sensory
tests of visual conditioning showed that chiasma-sectioned animals had completely normal sensory recognition learning. These
results show that NM Pavlovian conditioning involves anatomically separate and independent sensory recognition and motor output
components of the learning.
This research was supported by S&W research grants ID# 1810 to ISR and ID# 7985 to JAC. 相似文献
15.
Elaine J. Anderson S. K. Mannan G. Rees P. Sumner C. Kennard 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2010,200(1):91-107
Recent behavioural findings using dual-task paradigms demonstrate the importance of both spatial and non-spatial working memory
processes in inefficient visual search (Anderson et al. in Exp Psychol 55:301–312, 2008). Here, using functional magnetic resonance imaging (fMRI), we sought to determine whether brain areas recruited during visual
search are also involved in working memory. Using visually matched spatial and non-spatial working memory tasks, we confirmed
previous behavioural findings that show significant dual-task interference effects occur when inefficient visual search is
performed concurrently with either working memory task. Furthermore, we find considerable overlap in the cortical network
activated by inefficient search and both working memory tasks. Our findings suggest that the interference effects observed
behaviourally may have arisen from competition for cortical processes subserved by these overlapping regions. Drawing on previous
findings (Anderson et al. in Exp Brain Res 180:289–302, 2007), we propose that the most likely anatomical locus for these interference effects is the inferior and middle frontal cortex
of the right hemisphere. These areas are associated with attentional selection from memory as well as manipulation of information
in memory, and we propose that the visual search and working memory tasks used here compete for common processing resources
underlying these mechanisms. 相似文献
16.
Snapp-Childs W Wilson AD Bingham GP 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,215(2):89-100
Following many studies showing that the coupling in bimanual coordination can be perceptual, Bingham (Ecol Psychol in 16:45–53,
2001; 2004a, b) proposed a dynamical model of such movements. The model contains three key hypotheses: (1) Being able to produce stable
coordinative movements is a function of the ability to perceive relative phase, (2) the information to perceive relative phase
is relative direction of motion, and (3) the ability to resolve this information is conditioned by relative speed. The first
two hypotheses have been well supported (Wilson and Bingham in Percept Psychophys 70:465–476, 2008; Wilson et al. in J Exp Psychol Hum 36:1508–1514, 2010a), but the third was not supported when tested by de Rugy et al. (Exp Brain Res 184:269–273, 2008) using a visual coordination task that required simultaneous control of both the amplitude and relative phase of movement.
The purposes of the current study were to replicate this task with additional measures and to modify the original model to
apply it to the new task. To do this, we conducted two experiments. First, we tested the ability to produce 180° visual coordination
at different frequencies to determine frequencies suitable for testing in the de Rugy et al. task. Second, we tested the de
Rugy et al. task but included additional measures that yielded results different from those reported by de Rugy et al. These
results were used to elaborate the original model. First, one of the phase-driven oscillators was replaced with a harmonic
oscillator, so the resulting coupling was unidirectional. This change resulted in the model producing less stable 180° coordination
behavior beyond 1.5 Hz consistent with the results obtained in Experiment 1. Next, amplitude control and phase correction
elements were added to the model. With these changes, the model reproduced behaviors observed in Experiment 2. The central
finding was that the stability of rhythmic movement coordination does depend on relative speed and, thus, all three of the
hypotheses contained in the original Bingham model are supported. 相似文献
17.
Vallis LA McFadyen BJ 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2005,167(1):119-127
Carrying out the daily activities of work and play requires the ability to integrate available sensory information in order to navigate complex, potentially cluttered, environments. The expression of locomotor adjustment behaviour is still maturing during mid- to late-childhood (Grasso et al. in Neurosci Biobehav Rev 22(4): 533–539, 1998a; McFadyen et al. in Gait Posture 13:7–16, 2001), which raises the question, do children coordinate their body segments differently than adults when circumventing an obstacle in their travel path? Healthy young children (n=5; age 10.3±1.5 years) and adults (n=6; age 26.3±2.9 years) were asked to walk at their natural pace during unobstructed walking, as well as during the avoidance to the right or left of a cylindrical obstacle located in the travel path 3 m from the initial starting position. Fourteen infrared markers were fixed to participants and tracked using the Optotrak motion analysis system (60 Hz; Northern Digital Inc, Canada). Data analyses included center of mass (COM) clearance from the obstacle, gait speed, angular movement of the head and trunk (yaw, pitch and roll) and medial–lateral (M-L) COM displacement. Onset of change in these variables from unobstructed walking was also calculated as the time from OBS crossing. Although there were no differences in when adults or children altered their M-L COM trajectory, adults reoriented their head and trunk segments at the same time as their COM while children reoriented their head and trunk prior to changing COM direction. A comparison of foot placement data for this task indicated that while adults changed their gait patterns well in advance of obstacle crossing, children initiated M-L adjustments to gait patterns just prior to OBS crossing. Vallis and McFadyen (Exp Brain Res 152 (3):409–414, 2003) indicated that during circumvention of an obstacle, adults coordinate body segments for a single transient change in COM trajectory while maintaining the underlying travel direction. The present data suggest, however, that children partition obstacle avoidance into two tasks, initially steering with proactive movement of the head and trunk segments and finally making adjustments to their gait trajectory, via stride and step width changes, to ensure adequate obstacle clearance just prior to obstacle crossing. This study demonstrates different anticipatory control strategies used by children as compared to adults to circumvent obstacles in the travel path. The different head and trunk anticipatory segmental coordination suggests that children gather visual information differently when circumventing an obstacle in their travel path and are more dependent on visual input to guide their circumvention strategy. 相似文献
18.
Akao T Kumakura Y Kurkin S Fukushima J Fukushima K 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2007,182(4):469-478
Young primates exhibit asymmetric eye movements during vertical smooth-pursuit across a textured background such that upward
pursuit has low velocity and requires many catch-up saccades. The asymmetric eye movements cannot be explained by the un-suppressed
optokinetic reflex resulting from background visual motion across the retina during pursuit, suggesting that the asymmetry
reflects most probably, a low gain in upward eye commands (Kasahara et al. in Exp Brain Res 171:306–321, 2006). In this study, we examined (1) whether there are intrinsic differences in the upward and downward pursuit capabilities
and (2) how the difficulty in upward pursuit is correlated with the ability of vertical VOR cancellation. Three juvenile macaques
that had initially been trained only for horizontal (but not vertical) pursuit were trained for sinusoidal pursuit in the
absence of a textured background. In 2 of the 3 macaques, there was a clear asymmetry between upward and downward pursuit
gains and in the time course of initial gain increase. In the third macaque, downward pursuit gain was also low. It did not
show consistent asymmetry during the initial 2 weeks of training. However, it also exhibited a significant asymmetry after
4 months of training, similar to the other two monkeys. After 6 months of training, these two monkeys (but not the third)
still exhibited asymmetry. As target frequency increased in these two monkeys, mean upward eye velocity saturated at ∼15°/s,
whereas horizontal and downward eye velocity increased up to ∼40°/s. During cancellation of the VOR induced by upward whole
body rotation, downward eye velocity of the residual VOR increased as the stimulus frequency increased. Gain of the residual
VOR during upward rotation was significantly higher than that during horizontal and downward rotation. The time course of
residual VOR induced by vertical whole body step-rotation during VOR cancellation was predicted by addition of eye velocity
during pursuit and VOR x1. These results support our view that the directional asymmetry reflects the difference in the organization
of the cerebellar floccular region for upward and downward directions and the preeminent role of pursuit in VOR cancellation. 相似文献
19.
Saccades and reaches,behaving differently 总被引:1,自引:1,他引:0
Bonnie M. Lawrence Andrew L. Gardella 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2009,195(3):413-418
Previously, we have shown, both in humans and monkeys, that the latencies of exogenously generated saccades decrease with
an increase in the number of response alternatives (Lawrence et al. in J Vis 8:26, 1–7, 2008). Because this pattern of latencies was in the direction opposite that predicted by Hick (Q J Exp Psychol 4:11–26, 1952), we termed the effect an “anti-Hick’s” effect. In contrast, previous research has shown that reach latencies increase with
an increase in response alternatives (e.g., Wright et al. in Exp Brain Res 179:475–496, 2007). Given that there are known interactions between the saccade and reach systems, we examined whether the direction of the
relationship between latencies and response alternatives differed when saccades and reaches are concomitantly executed. Interestingly,
we found that the pattern of latencies nevertheless persisted in a visually guided saccade and reach task. These results place
an important constraint on the anti-Hick’s effect, suggesting not only that the effect is localized within the saccade system,
but also that it is localized in the saccade system at a level in which saccade and reach signals do not interact.
相似文献
Bonnie M. LawrenceEmail: Email: |
20.
Kristina A. Neely Matthew Heath 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2010,201(3):593-598
In the visuomotor mental rotation (VMR) paradigm, participants execute a center-out reaching movement to a location that deviates
from a visual cue by a predetermined instruction angle. Previous work has demonstrated a linear increase in reaction time
(RT) as a function of the amplitude of the instruction angle (Georgopoulos and Massey in Exp Brain Res 65:361–370, 1987). In contrast, we recently reported a RT advantage for an instruction angle of 180° relative to a 90° angle (Neely and Heath
in Neurosci Lett 463:194–198, 2009). It is possible, however, that perceptual expertise with the cardinal axes, which are perceptually familiar reference frames,
influenced the results of our previous investigation. To address this issue, we employed a VMR paradigm identical to that
of our previous work, with the exception that the stimulus array was shifted 45° from the horizontal and vertical meridians.
Our results demonstrated that RTs were fastest and least variable when the instruction angle was 0°, followed by 180°, which
in turn, was faster than 90°. Such findings establish that the RT advantage for the 180° instruction angle is not influenced
by perceptual expertise with the cardinal axes. Moreover, the present results provide convergent evidence that RT is not determined
by the angle of rotation; instead, they indicate that response latencies reflect computational differences in the complexity
of response remapping. 相似文献