THE BRAIN FROM TOP TO BOTTOM
is provided by readers like you.
If someone's motor cortex is destroyed
(by a stroke, for example), he or she loses the ability to make precise movements,
especially of the hands and fingers. Learning of new movements is not strongly
affected by damage to the cerebral cortex. The memory of motor sequences learned
previously is also largely spared, though these movements will be executed more
clumsily. These observations show that it is the
rather than the cortex that plays an important role in learning and remembering
of movements, also known as .
Area 4 of the precentral gyrus is
not the only area in the cortex that contributes to the pyramidal system. But
is the one where movements can be successfully triggered by lower-intensity electrical
stimuli. In other words, electrical stimuli that are insufficient to produce movements
when applied to other areas of the cortex are sufficient to do so when applied
to Area&4.
THE MOTOR CORTEX
So many different structures
in the brain are involved in motor functions that some people even say that practically
the entire brain contributes to body movements. Though the motor cortex is usually
associated with , the control of voluntary movements actually involves almost all areas
of the neocortex.
primary motor cortex
is the anatomical region composed of Area 4 of the precentral
gyrus. Its location was confirmed in the mid-20th century in brain operations
performed by neurosurgeons such as Dr. Wilder Penfield, in Montreal. While performing
operations to alleviate patients' epileptic symptoms, Penfield stimulated various
areas of the cortex to identify vital ones that should not be removed. In this
process, he discovered that stimulations applied to the precentral gyrus triggered
highly localized muscle contractions on the
and that there was a somatotopic representation of the corresponding
parts of the body in Area 4 in the primary motor cortex (see box below) .
Penfield also showed that cortical Area 6, just
rostral to Area 4, has two other somatotopic representations that induce complex
movements when stimulated. The first is in the lateral portion of Area 6 and is
called the premotor area (PMA). It helps to guide body movements
by integrating sensory information, and it controls the muscles that are closest
to the body's main axis.
The second somatotropic representation is in
the supplementary motor area (SMA),
in the medial part
of Area 6. The SMA is involved in planning complex movements and in co-ordinating
movements involving both hands.
Note, however, that the primary motor
cortex, the PMA, and the SMA are not the only parts of the cortex that are involved
also play important roles
in this regard.
Dr. Penfield's experiments in stimulating
the cortex enabled him to develop a complete map of the motor cortex, known as
the motor homunculus (there are also other kinds, such as the
sensory homunculus). The most striking aspect of this map is that the areas assigned
to various body parts on the cortex are proportional not to their size, but rather
to the complexity of the movements that they can perform. Hence, the areas for
the hand and face are especially large compared with those for the rest of the
body. This is no surprise, because the speed and dexterity of human hand and mouth
movements are precisely what give us two of our most distinctly human faculties:
the ability to use tools and the ability to speak.
The functions of the basal ganglia
are complex and still largely unknown. People who have Parkinson's disease, characterized
by trembling and by difficulty in initiating movements, show a deficiency of
in their basal ganglia. Because these structures play an important role in determining
various aspects of movement, their malfunctioning results in the motor problems
associated with Parkinson's disease.
Some abnormalities also are found
in the basal ganglia of people who have Huntington's Disease or Tourette Syndrome.
These patients experience involuntary movements that cause all sorts of grimaces,
tics, and spasms.
THE BASAL GANGLIA
The term &basal ganglia&
refers to a group of several structures in the brain: the caudate nucleus, the
putamen, the globus pallidus, and the subthalamic nucleus. The substantia nigra,
a midbrain structure that has many interconnections with the basal ganglia, is
not actually part of this grouping but is often associated with it.
The basal ganglia are involved in a . The information from
the frontal, prefrontal, and parietal areas of the cortex passes through the basal
ganglia, then returns to the supplementary motor area via the thalamus. The basal
ganglia are thus thought to facilitate movement by channelling information from
various regions of the cortex to the SMA. The basal ganglia may also act as a
filter, blocking the execution of movements that are unsuited to the situation.
Not all of the circuits involving the basal ganglia are motor circuits, however.
Many are instead involved in memorizing and in cognitive and
processing. A great deal about the basal ganglia remains unknown. They seem to
play a far larger role than just their contribution to motor control.
The cerebellum also acts as a , thanks to its modifiable
neural connections that continuously compare everything they are programmed to
do with the results that they are actually achieving. When this comparison does
not allow the expected result to be achieved satisfactorily, the cerebellum's
activity modifies the sequence of movements in a compensatory manner to make them
more effective. This
thus develops automatically with practice, without the help
of any conscious control.
The cerebellum also appears to play
a major role in learning how to co-ordinate the various segments of the body.
The movement of each segment of your body affects the next, because of its mass.
The cerebellum therefore apparently learns how to calibrate its commands to the
muscles in terms of strength and duration in order to correct in advance for the
effects of these interactions along the path of motion.
THE CEREBELLUM
cerebellum appears to play several roles. It stores learned sequences of movements,
it participates in fine tuning and co-ordination of movements produced elsewhere
in the brain, and it integrates all of these things to produce movements so fluid
and harmonious that we are not even aware of them. To
do all this, the cerebellum maintains close communications with the cortex. The
motor, somatosensory, and posterior parietal areas of the cortex project massive
numbers of axons to the nuclei of the pons, located in the brainstem. The neurons
of the pons then project their axons into the cerebellum. This corticopontocerebellar
tract forms an extremely dense nerve bundle containing about 20 million axons,
just about 20 times more than the pyramidal bundle!
The two hemispheres
of the cerebellum then sends signals back to the motor cortex via interconnections
in the ventrolateral nucleus (VLc) of the thalamus. The cerebellar hemispheres
thus influence the muscles of the arms and legs via the cortex and the .&&
The two hemispheres of the cerebellum are not
divided neatly in two like the two hemispheres of the cerebrum. The medial portion
constitutes what is known as the cerebellar vermis. This vermis does not display
any lateralization. It projects axons to the brainstem which, via the , help to maintain posture.
More recently, the cerebellum
has also been discovered to play a .
&I move, therefore
I am a self, (I think).&
- Rodolfo Llinas
The brain mechanisms that go into
planning and executing a movement are far more complex than the motor cortex's
simply issuing a command and the motor neurons' executing it.
For example,
suppose that you go to pick up a glass of water that you think is cool and refreshing,
but is actually boiling hot. As soon as you touch the glass, you pull your hand
back immediately, by ,
without thinking about it.
But suppose that next, your child tries to
grab this glass, which you already know is hot. In this case, because your child's
safety is so important to you, you can consciously overcome the reflex to pull
your hand away. Instead, using your voluntary motor control, you grab the glass
yourself and put it where your child can't reach it.
Lastly, if someone
tells you that the glass is made of fine crystal and not ordinary glass, you will
probably handle it more carefully. In other words, your brain will take this information
into account and adapt your method of grasping the glass accordingly.
All of these facts demonstrate that the execution of a movement is not simply
a matter of the brain's sending a &Go!& command to some motor neurons
in the spinal cord, but rather the result of a highly elaborate construct. Moreover.
the remarkable adaptability of motor activity demonstrates the involvement of
powerful .
THE ACTIVATION SEQUENCE FOR THE MOTOR AREAS
The information processing
that the brain must perform to initiate a voluntary movement can be divided into
three steps. The first step is to select an appropriate response
to the current situation, out of a repertoire of possible responses. This response,
which corresponds to a particular behavioural objective, is determined in a global,
symbolic fashion.
The second step is to plan the movement in
physical terms. This step consists in defining the characteristics of
the selected response as the sequence of muscle contractions required to carry
The third step is to actually execute the movement.
It is in this step that the motor neurons are activated that trigger the observable
mechanics of the movement.
Consequently, the control
messages issued by the motor cortex are themselves triggered by messages from
. The motor cortex also communicates closely with subcortical
structures such as the
and the , through the thalamus,
which acts as a relay.In light of what we now know about the sequence in
which the motor areas of the cortex are activated, we can deconstruct the classic
sequence &Ready? Set. Go!& in terms of localized activity in the brain.
In the &Ready?& phase, the parietal and frontal lobes become active
first, with a contribution from the subcortical structures involved in vigilance
and attentiveness. The &Set& command then activates the supplementary
and premotor cortical areas, where the strategies for movement are developed and
maintained until the &Go!& signal is given. The &Go!& signal
may come from an outside source, as it does in an actual race, or it may come
from inside the person doing the running, who decides for himself or herself that
all the conditions are present to start running. The &Go!& command then
applies information from subcortical structures such as the basal ganglia that
will influence Area&6, and then eventually the primary cortex, which will
cause the action to be carried out.&&&&from top to bottom
的翻译结果:
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Mean while,there is still not a certain solution to develope collaboration graphics design system based on J2EE,in this paper,a development mode is brought forward,using Java API for holding out TCP/IP protocol to design from bottom to top,and using groupware technology of J2EE to cover from top to bottom,at the same time an instance about this mode is given.
但是,在J2EE架构之下开发协同化图形设计系统尚无可靠方案,本文提出一套以支持TCP/IP协议的Java API(套接字)自底向上进行设计、以J2EE的组件技术自顶向下进行包罗的协同CAD系统的开发模式,并给出了一个该模式的应用实例.
In this paper, the application of double port RAM to the technology of big screen LED display system is introduced briefly which is designed with the method of from top to bottom.
文中重点介绍采用以自顶向下方法设计的基于CPLD(复杂可编程逻辑器件)的大屏幕LED(发光二极管)显示系统中双口RAM的应用,并给出了系统设计方法及相关硬件电路。
Based on existing problems of sports team management,this paper makes analyze and design on problems by using the software engineering from top to bottom and finally use PB (7.0) to realize this system.
针对专业运动队的管理问题 ,运用软件工程自顶向下的开发方法对问题进行分析与设计 ,最后运用面向对象的开发工具 POWERBUIL DER7.0具体实现系统
On the development & research of the Central Tire Inflation/Deflation System (CTI/DS), the writer uses a new design concept of TOP-DOWN, which is based on the system of Pro/Engineer, and begins with the skeleton formation and completes the design of details from top to bottom.
在轮胎中央充排气系统的开发与研究的过程中 ,利用了Pro/Engineer系统中TOP DOWN设计理念 ,从造型轮廓开始 ,自顶向下完成了各个零部件的详细设计。
Making model from top to bottom is guiding idea of UG WAVE and is the key of realizing the Concurrent Engineering technology facing to product level.
自顶向下产品建模则是UG WAVE的的指导思想，它是实现产品级并行工程技术的关键。
WT5HX]Results:
With the exception of C7 and L5 of vertebral radius vector,other radius vectors become larger in turn from top to bottom;
结果：椎体矢径除C7和L5外，其他由上而下矢径依次增大；
For column with single feed, liquid sidestreams drawn at the rectifying section and vapor sidestreams at the stripping section, it has been proved the when light key concentrations in sidestreoams decrease ard heavy key concentrations increase from top to bottom, and "controlling minimum reflux" can be calculated only by applying the Underwood equations to feed sections.
对于一股进料,在精馏段开设液体侧线产品,提馏段开设汽体侧线产品的塔,证明了当在各侧线中轻关键组分的浓度由上而下递减,重关键组分的浓度递增时,只要将Underwood方程应用于进料级上、下两段,求出的即为控制最小回流比。
During the diffusion from top to bottom of the knowledge,such public cultural facilities as new-type medium,library and newspaper reading room and all kinds of popular literature and art forms such as novel and traditional Chinese opera were not only a means to open the wisdom of the people,but also a product of the changes of social culture.
在这个知识由上而下的传播过程中,新式传媒与藏书楼、阅报社等公共文化设施以及小说、戏曲等各种通俗文艺形式既是开启民智的手段,同时又是社会文化变迁的产物。
The hierarchical structure is decompose d from top to bottom according to system function,element relationship and compo nent structure.
依照功能、设备、元件的层次结构,由上而下进行功能分解;
The inscription on animal bones and carves on tortoise shells transmit the knife method,which becomes the direct reason of ancient Chinese character going from top to bottom,from right to left rows and columns.
作为中国书法篆刻的源头,甲骨文契刻隐藏有汉字行款成因的重要信息,“用刀乃右手”、“自右向左或由上而下执刀直冲”、“将甲骨旋转,以便取势”等刀法特点,是形成古代汉字下行左行行款的更为久远、也更为直接的成因。
E-SOD of the three layers from top to bottom of the control group and IDA group are ,5301 and 24 respectively (P<0.05, P0.05).
两组的E-SOD上中下三层分别为01和24(P<0.05,P0.05)。
Its indicator elements are Cu,Pb,Zn,Ag,Cd,Hg,As,Sb,Au,Ba,Sr and B.The sequence of axial zoning or vertical zoning(from top to bottom) is Zn-Hg-Pb-Ag-Cu
1-Ba-Sr-Sb-As-Cu
2, Ni,Co,Au.
指示元素有Cu、Pb、Zn、Ag、Cd、Hg、As、Sb、Au、Ba、Sr、B等，原生异常的轴向分带序列（从上到下）：Zn－Hg－Pb－Ag－Cu1－Ba－Sr－Sb－As－Cu2、Ni、Co、Au，具有明显多建造晕的特点。
Guide elements of the deposit are Cu, Mo,Au, Ag,Pb, Zn, As,Sb, Bi, W. The horizontal zoning, from ore belt to its outside, is Cu,Mo, Ag→Pb,Zn. And axialzoning, from top to bottom, is Sb→As→Zn→Pb→Ag→Cu→Au→Mo→Bi→W.
矿床元素组合为：Cu、Mo、Au、Ag、Pb、Zn、As、Sb、Bi、W，由矿带向外出现Cu、Mo、Ag→Pb、Zn的水平分带，由上向下出现Sb→AS→Zn→Pb→Ag→Cu→Au→Mo→Bi→W的轴向分带。
(3) The vertical variation curve of Fe2 + is differ from that of Fe3 +, the content of Fe2 + increase from top to bottom, but the content of Fe3 + is opposite.
剖面沉积物Fe~(2+)和Fe~(3+)的垂向变化特征分别是：Fe~(2+)的含量的自上而下递增、Fe~(3+)的含量自上而下递减。
The vertical zoning sequence of primary halos by single-stage is as follows(from top to bottom):Hg, B, Sb, As→Ag, Au→Bi, Mn→Ni.
单阶段形成的矿体 (晕 )的垂直分带序列是(从上→下 ) :Hg ,B ,Sb ,As→Ag ,As→Bi,Mn→Ni。
查询“from top to bottom”译词为用户自定义的双语例句&&&&我想查看译文中含有：的双语例句
为了更好的帮助您理解掌握查询词或其译词在地道英语中的实际用法，我们为您准备了出自英文原文的大量英语例句，供您参考。&&&&&&&&&&&&&&&&&&&& This paper describes 5 genera and 18 species of fusulinids from the Changxing limestone of Upper Permian in northern Zhejiang, among them are 5 new species and 1 subspecies. According to the vertical distribution of fusulinid faunas 3 zones and 2 subzones are established from top to bottom:3. P 2. S 1. Gallowayinella—Reichelina zone, and also 2 subzones: (2) R (1) Gallowayinella subzone. A new understanding has been raise... &&&&&&&&&&&&本文描述了浙江省北部地区晚二迭世晚期长兴组的(?)类5属18种,其中有5个新种和一个新亚种。建立地区性的三个(?)带和二个亚带,自上而下是:3.P2.S1.Gallowayinella-Reichelina zone,其中包括二个亚带,即(2)Reichelina subzone,(1)Gallowayinella subzone。并对长兴煤山地区的长兴组标准剖面提出新的认识,认为该区缺失了长兴组的中、下两段地层。&&&&&&&& The fossiliferous deposits at Choukoutien, Loc. 1, where Peking Man lived, are some 40 metres in thickness, and may be divided into 13 layers from top to bottom. Their dates are summarized in Table 1. According to the dates, Layer 3 would be correlated with Stage 8 in the record of deep-sea sediments and Layer 10 would correspond to Stage 12. Just as Kahlke and Chow Benshun (1961) said, "There in no real break in the continuity of the record as well as in the composition ... &&&&&&&&&&&&根据同位素年龄的测定,在距今46万年到23万年期间,北京人曾在周口店地区居住。这段时间相当于海洋的O~(18)的第12—8阶段。对周口店第一地点的第3—10层的各哺乳动物群,我们利用聚类分析等数理统计方法进行了分析和对比。第5层和第8—9层的哺乳动物群分别代表温暖期,它们相当于O~(18)的第9和第11阶段;而第3层、第6—7层和第10层的哺乳动物群则分别代表寒冷期,它们相当于第8、第10和第12阶段。&&&&&&&& In the paper chimney model test on the shaking table subjected to horizontal shock vibration is described with the purpose of reproducing the cracking pattern of the chimney occurred durring earthquake. The relation between the crack location in the chimney and the fundamental period of the shaking table and the relation between the location of the highest crack and the ratio of the chimney-table fundamental periods are given.The experimental results show that generally there are 2-4 cracks in the chi... &&&&&&&&&&&&本文介绍在振动台上的烟囱模型经受横向冲击后产生多道裂缝、再现地震震害现象的试验。文中给出了裂缝位置与振动台自振周期的关系以及最高裂缝的高度与烟囱和台面两者的基本周期之比的关系。 实验结果表明,在冲击振动下烟囱模型一般产生2—4条裂缝,它们是自上而下逐步出现的;在多次冲击作用下,烟囱裂而不倒;只有在更大冲击的作用下,烟囱才出现“掉头”现象,碎块散落在烟囱四周。这与震害现象极为相似。实验证明水平地震力完全可以解释烟囱的震害现象。&nbsp&&&&&&&&相关查询:
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2008 CNKI－中国知网
北京市公安局海淀分局 备案号：110 1081725
&2008中国知网(cnki) 中国学术期刊(光盘版)电子杂志社Creating Auto Layout constraints to topLayoutGuide and bottomLayoutGuide in code [创建自动布局约束topLayoutGuide和bottomLayoutGuide代码] - 问题-字节技术
Creating Auto Layout constraints to topLayoutGuide and bottomLayoutGuide in code
创建自动布局约束topLayoutGuide和bottomLayoutGuide代码
问题 (Question)
on creating Auto Layout constraints between a view and one of the layout guides only shows an example using .
Is there any way to create these constraints programmatically without VFL (using
or similar)?
(Note: I'm specifically asking about doing this in code, not in Interface Builder. And I don't want the calculated length of the guide set as a static constant on a constraint, I want a constraint where changes to the layout guide length would automatically cause the constrainted view to adjust position.)
苹果的创建一个视图之间的自动布局约束和布局指南之一只显示了一个示例使用.有什么办法可以以编程方式创建这些约束不VFL(使用吗或类似的)?(注:我特别询问在代码,这样做不是在界面构建器。我不想要计算length引导设置为静态常量的约束,我想要一个约束,改变布局指导长度将自动导致约束视图调整位置。)
最佳答案 (Best Answer)
You have to use NSLayoutAttributeBaseline as the attribute for the topLayoutGuide when using the constraintWithItem: method.
[NSLayoutConstraint constraintWithItem:self.button
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.topLayoutGuide
attribute:NSLayoutAttributeBaseline
multiplier:1.0
constant:0.0];
你必须使用NSLayoutAttributeBaseline topLayoutGuide的属性时使用constraintWithItem:方法。[NSLayoutConstraint constraintWithItem:self.button
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.topLayoutGuide
attribute:NSLayoutAttributeBaseline
multiplier:1.0
constant:0.0];
答案 (Answer) 2
I've created, you are supposed to embed all your subviews into a tank view(container view) added into a xib, it removes tank view-superview xib constraints and adds an upper constraints to topLayoutGuide giving an iOS6 look. It could be interesting for what you want to achieve.
//This should be added before the layout of the view
- (void) adaptToTopLayoutGuide {
//Check if we can get the top layoutguide
if (![self respondsToSelector:@selector(topLayoutGuide)]) {
//tankView is a contaner view
NSArray * array = [self.tankView referencingConstraintsInSuperviews]; //&--For this method get the Autolayout Demistified Book Sample made by Erica Sadun
[self.view removeConstraints:array];
NSArray * constraintsVertical = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[topLayoutGuide]-0-[tankView]|" options:0 metrics:nil views:@{@"tankView": self.tankView, @"topLayoutGuide":self.topLayoutGuide}];
[self.view addConstraints:constraintsVertical];
NSArray * constraintsHorizontal = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[tankView]|" options:0 metrics:nil views:@{@"tankView": self.tankView}];
[self.view addConstraints:constraintsHorizontal];
这是一个我已经创建了,你应该将你所有的中的嵌入槽视图(容器视图)添加到xib,它消除了坦克view-superview xib约束并将上层约束添加到topLayoutGuide iOS6看起来。这可能是有趣的你想实现什么。//This should be added before the layout of the view
- (void) adaptToTopLayoutGuide {
//Check if we can get the top layoutguide
if (![self respondsToSelector:@selector(topLayoutGuide)]) {
//tankView is a contaner view
NSArray * array = [self.tankView referencingConstraintsInSuperviews]; //&--For this method get the Autolayout Demistified Book Sample made by Erica Sadun
[self.view removeConstraints:array];
NSArray * constraintsVertical = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[topLayoutGuide]-0-[tankView]|" options:0 metrics:nil views:@{@"tankView": self.tankView, @"topLayoutGuide":self.topLayoutGuide}];
[self.view addConstraints:constraintsVertical];
NSArray * constraintsHorizontal = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[tankView]|" options:0 metrics:nil views:@{@"tankView": self.tankView}];
[self.view addConstraints:constraintsHorizontal];}