大脑的复杂性研究

The evolution of the neural system



对称放射形神经系统(水母)，受到刺激后 向任意方向运动。 线状的神经系统(头尾结构)，具有精确的 头部和尾部可以限制选择同时也减少混 淆外界信息。 在头部形成膨大的脑，对信息的快速收 集和处理具有帮助
人脑适应性调整的三个阶段


Behaviorism assumes that all behavior can be reduced to simple building blocks of SR (stimulus- response) and that complex behavior is a series of S-R chains Biopsychology - Explanations for the cause of mental illnesses are often reductionist. Genetics, and neurochemical imbalances are frequently highlighted, as being the main cause of these disorders. In the case of schizophrenia for example excess production of the neurotransmitter dopamine is seen as a possible cause. This view clearly has implications for treatment. Gender can also be reduced to biological factors (e.g. hormones). Also, language can be reduced to structures in the brain, e.g. Broca’s area, Wernicke’s area (but holism could state: influence of family, education, social class on language). Another example of biological reductionism is aggression – e.g. testosterone levels. Structuralism – One of the first approaches in psychology. Wundt tried to break conscious experiences down into its constituent (i.e. basic) parts: images, sensations and feelings



基因，形成大脑和神经系统的蓝图，是 生物对生存环境的响应以及将来环境的 预测。 生物诞生后，遗传物质根据经验作精细 的调整，学会对付威胁和利用机会生存 的技能 对某些瞬间的过程的适应，对瞬间发生 的状况作出最佳的响应。
Building blocks of the brain
Macaque unfolded visual cortex

Speed of tennis: 200~225Km/h=56~63m/s Tennis court size: length~23.77m,width~8.23m Signal from retina to cortex ~50-100ms Signal from cortex to foot ~20 ms the computation of cortex: longer time ~500ms The intensive training, habitual learning (basal ganglia) shortens the reaction time to 200 ms It is necessary that brain anticipates the future.
Decision making
Roitman and Shadlen (2002),Gold and Shadlen (2007)
The simulation model
Xiaojing Wang(2002)
Mean field analysis
Kong-Fatt Wong and Xiao-Jing Wang(2006), Xiao-Jing Wang(2008)

Time compensation as an example of the holism.

The computational research on decision making and working memory


Working memory
Decision making
The primary response to and adaptation to the environment: the genetic DNA varies with the changes of environment. Very slow (years, hundred years), many generations Example: the origin of new species
360 0 360 360
cE I E , syn I E 1 exp[ g E (cE I E , syn I E )]
0
( )S NMDA ( , t ) d J E I E
360
0
S NMDA ( , t ) d I 0 ( )

A unifying account for the discrete-slot and shared-resource models of WM capacity

A continuous network maintains multiple objects of an analog
feature as slots in WM
The multiple choices decision making
Churchland, A.K., Kiani, R., and Shadlen, M.N. (2008). Moran Furman, Xiao-Jing Wang(2008)
Materials and Methods
S NMDA ( , t ) S ( , t ) NMDA [1 S NMDA ( , t )] rE ( , t ) dt NMDA rE ( , t ) ( I syn ( )) I syn ( ) J E E , NMDA
Wiring Diagram of the Visual System (Van Essen and Felleman)
Topographic Maps,: sensory system +somatarysome +motor system +basal ganglia
~80% of neurons in the cortex are excitatory “pyramidal cells”
[ J E E , NMDA ( ) J E I E ]S NMDA ( , t ) d I 0 ( ) W ( ) S NMDA ( , t ) d I 0 ( )
0
I 0 ( ) I back I t arg et I motion I noise
人体淋巴细胞
黄色中性粒细胞吞噬棕色炭疽热细胞
Response to the invasion of bacteria, toxin and other organism in environment: the immune system. Slow (hours, days, even months), in one generations Example: cold
2011年北京师范大学系统科学暑期学校
大脑的复杂性研究
王Байду номын сангаас辉
2011.07.22
Out line

Brain is the adaptive response to environment
Building blocks of the brain Different philosophy about how the brain works



Working memory
PATRICIA S. GOLDMAN-RAKIC 1996 PNAS
PATRICIA S. GOLDMAN-RAKIC 1995 Neuron
Paul M. Bays, Masud Husain 2008 Science
Weiwei Zhang, Steven J. Luck 2008 Nature
~20% of neurons in the cortex are inhibitory “interneurons”
Different philosophy about how brain works

Reductionism:

brain can be explained by breaking it down into smaller component parts

Holism: approaches that emphasizes the whole rather than their constituent parts, the whole is greater than the sum of its parts


Social Psychology looks at the behavior of individuals in a social context Perception – This is were the brain understands and interprets sensory information. Visual illusions show that humans perceive more than the sum of the sensations on the retina. Time compensation- how can players hit the fast moving tennis.
Unbiased decision making
Biased decision making
The noise plays an important role in the decision making

Two (fade-out and merging) dynamical phenomena underlie limited WM capacity

Recurrent excitation and normalization explain dynamically allocated
shared-resource
Detection and response to the fast variation of the environment: the neural system. Fast (milliseconds, second), in one generations

The neural system makes the animal detect and respond to the environment almost simultaneously. The occurs of the neural system is a tremendous progress of the evolution.