Abstract:
:Regional blood oxygenation in the cerebellum and posterior cerebral cortices was monitored with functional magnetic resonance imaging (fMRI) at four Tesla while 16 normal subjects performed three tasks with identical visual stimulation: fixation; attention focused upon either stimulus shape or color and sustained during blocks of trials (sustained attention); and rapid, serial shifts in attention between stimulus shape or color within blocks of trials (shifting attention). The stimuli were displayed centrally for 100 ms followed by a central fixation mark for 900 ms. Each stimulus was either a circle or a square displayed in either red or green. Attention shifting required switching between color and shape information after each target detection and occurred on average once every three seconds. Subjects pressed a response key upon detecting the target; reaction time and response accuracy were recorded. Two protocols for T2*-weighted echo-planar imaging were optimized, one with a surface coil for the cerebellum alone and the other with a volume coil for imaging both cerebellum and posterior brain structures (parietal, occipital, and part of temporal cortices). Because fMRI of the cerebellum is particularly susceptible to cardiac and respiratory fluctuations, novel techniques were applied to isolate brain activation signals from physiological noise. Functional activation maps were generated for contrasts of 1) sustained attention to color minus fixation; 2) sustained attention to shape minus fixation; and 3) shifting attention minus sustained attention (to color and shape; i.e., summed across blocks of trials). Consistent with the ease of these tasks, subjects performed with >80% accuracy during both sustained attention and shifting attention. Analysis of variance did not show significant differences in false alarms or true hits across either attentional condition. A subgroup of subjects whose performance data were recorded during ten minutes of continuous practice did not show significant changes over time. Both contrasts between the conditions of sustained attention to color or to shape as compared with the fixation condition showed significant bilateral activation in occipital and inferior temporal regions (Brodmann areas 18, 19, and 37). The anterior medial cerebellum was also significantly activated ipsilateral to the finger used for responding. The principal comparison of interest, the contrast between the condition of shifting attention and the condition of sustained attention produced significant and reproducible activation: lateral cerebellar hemisphere (ansiform lobule: Crus I Anterior and Crus I Posterior; left Crus I Posterior); cerebellar folium; posterior superior parietal lobule (R and L); and cuneus and precuneus (R and L).
journal_name
J Neurophysioljournal_title
Journal of neurophysiologyauthors
Le TH,Pardo JV,Hu Xdoi
10.1152/jn.1998.79.3.1535subject
Has Abstractpub_date
1998-03-01 00:00:00pages
1535-48issue
3eissn
0022-3077issn
1522-1598journal_volume
79pub_type
杂志文章abstract::Responses of low characteristic-frequency (CF) neurons in the inferior colliculus were obtained to amplitude-modulated (AM) high-frequency tones in which the modulation rate was equal to the neuron's CF. Despite all spectral components lying outside the pure tone-evoked response areas, discharge rates were modulated b...
journal_title:Journal of neurophysiology
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doi:10.1152/jn.00034.2004
更新日期:2004-09-01 00:00:00
abstract::Experiments were performed on human elbow flexor and extensor muscles and jaw-opening and -closing muscles to observe the effect on rhythmic movements of sudden loading. The load was provided by an electromagnetic device, which simulated the appearance of a smoothly increasing spring-like load. The responses to this l...
journal_title:Journal of neurophysiology
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doi:10.1152/jn.1999.82.3.1209
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abstract::1. The synaptic connections of 44 single identified muscle spindle Ia afferents and of 21 Golgi tendon organ (Ib) afferents from medial gastrocnemius (MG) were studied in 46 cats by the spike-triggered averaging of synaptic noise in 803 motoneurons of various types. 2. The well-known monosynaptic Ia excitatory connect...
journal_title:Journal of neurophysiology
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abstract::1. The preceding study described a corrective response in cats when one hind leg steps into a hole. In this investigation we examine the extent to which this behavior is organized at the spinal level by comparing the responses elicited in intact and chronic spinal cats. 2. Adult cats were trained to step bipedally wit...
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abstract::Motor behavior often occurs in environments with multiple goal options that can vary during the ongoing action. We explored this situation by requiring subjects to select between different target options during an ongoing reach. During split trials the original target was replaced with a left and a right flanking targ...
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pub_type: 杂志文章
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abstract::1. The electrical responses of nociceptive (N) lateral and N medial neurons of the leech segmental ganglion to mechanical, chemical, and thermal stimulation of the skin were studied in a superfused ganglion-body wall preparation. 2. Mechanical indentation of the skin > 10 mN evoked in both types of cells a sustained d...
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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doi:10.1152/jn.1980.43.1.69
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pub_type: 杂志文章
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更新日期:2008-03-01 00:00:00
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pub_type: 杂志文章
doi:10.1152/jn.1999.82.5.2476
更新日期:1999-11-01 00:00:00
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journal_title:Journal of neurophysiology
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1995.74.3.1271
更新日期:1995-09-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00197.2004
更新日期:2004-09-01 00:00:00
abstract::Responses of cat striate cortical cells to a drifting sinusoidal grating were modified by the superimposition of a second, perturbing grating (PG) that did not excite the cell when presented alone. One consequence of the presence of a PG was a shift in the tuning curves. The orientation tuning of all 41 cells exposed ...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.2001.86.6.2703
更新日期:2001-12-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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journal_title:Journal of neurophysiology
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journal_title:Journal of neurophysiology
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journal_title:Journal of neurophysiology
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更新日期:1994-02-01 00:00:00
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journal_title:Journal of neurophysiology
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更新日期:1998-11-01 00:00:00
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journal_title:Journal of neurophysiology
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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