basal ganglia

The basal ganglia (or basal nuclei) comprise multiple subcortical nuclei, of varied origin, in the brains of vertebrates, which are situated at the base of the forebrain. Basal ganglia nuclei are strongly interconnected with the cerebral cortex, thalamus, andbrainstem, as well as several other brain areas. The basal ganglia are associated with a variety of […]

The basal ganglia (or basal nuclei) comprise multiple subcortical nuclei, of varied origin, in the brains of vertebrates, which are situated at the base of the forebrain. Basal ganglia nuclei are strongly interconnected with the cerebral cortex, thalamus, andbrainstem, as well as several other brain areas. The basal ganglia are associated with a variety of functions including: control of voluntary motor movements, procedural learning, routine behaviors or “habits” such as bruxism, eye movements, cognition[1] and emotion.[2]

The main components of the basal ganglia – as defined functionally – are the dorsal striatum (caudate nucleus and putamen),ventral striatum (nucleus accumbens and olfactory tubercle), globus pallidus, ventral pallidum, substantia nigra, and subthalamic nucleus.[3] It is important to note, however, that the dorsal striatum and globus pallidus may be considered anatomically distinct from the substantia nigra, nucleus accumbens, and subthalamic nucleus. Each of these components has a complex internal anatomical and neurochemical organization. The largest component, the striatum (dorsal and ventral), receives input from many brain areas beyond the basal ganglia, but only sends output to other components of the basal ganglia. The pallidum receives input from the striatum, and sends inhibitory output to a number of motor-related areas. The substantia nigra is the source of the striatal input of the neurotransmitter dopamine, which plays an important role in basal ganglia function. The subthalamic nucleus receives input mainly from the striatum and cerebral cortex, and projects to the globus pallidus.

Currently, popular theories implicate the basal ganglia primarily in action selection; that is, it helps determine the decision of which of several possible behaviors to execute at any given time. In more specific terms, the basal ganglia’s primary function is likely to control and regulate activities of the motor and premotor cortical areas so that voluntary movements can be performed smoothly.[1][4]Experimental studies show that the basal ganglia exert an inhibitory influence on a number of motor systems, and that a release of this inhibition permits a motor system to become active. The “behavior switching” that takes place within the basal ganglia is influenced by signals from many parts of the brain, including the prefrontal cortex, which plays a key role in executive functions.[2][5]

The importance of these subcortical nuclei for normal brain function and behavior is emphasized by the numerous and diverse neurological conditions associated with basal ganglia dysfunction, which include: disorders of behavior control such as Tourette syndrome, hemiballismus, and obsessive–compulsive disorder; dystonia; addiction; and movement disorders, the most notable of which are Parkinson’s disease, which involves degeneration of the dopamine-producing cells in the substantia nigra pars compacta, and Huntington’s disease, which primarily involves damage to the striatum.[1][3] The basal ganglia have a limbic sector whose components are assigned distinct names: the nucleus accumbens, ventral pallidum, and ventral tegmental area (VTA). There is considerable evidence that this limbic part plays a central role in reward learning, particularly a pathway from the VTA to the nucleus accumbens that uses the neurotransmitter dopamine. A number of highly addictive drugs, including cocaine, amphetamine, andnicotine, are thought to work by increasing the efficacy of this dopamine signal. There is also evidence implicating overactivity of the VTA dopaminergic projection in schizophrenia.[6]

Although the role of the basal ganglia in motor control is clear, there are also many indications that it is involved in the control of behavior in a more fundamental way, at the level of motivation. In Parkinson’s disease, the ability to execute the components of movement is not greatly affected, but motivational factors such as hunger fail to cause movements to be initiated or switched at the proper times. The immobility of Parkinsonian patients has sometimes been described as a “paralysis of the will”.[11] These patients have occasionally been observed to show a phenomenon called kinesia paradoxica, in which a person who is otherwise immobile responds to an emergency in a coordinated and energetic way, then lapses back into immobility once the emergency has passed.

The role in motivation of the “limbic” part of the basal ganglia—the nucleus accumbens (NA), ventral pallidum, and ventral tegmental area (VTA)—is particularly well established. Thousands of experimental studies combine to demonstrate that the dopaminergic projection from the VTA to the NA plays a central role in the brain’s reward system. Animals with stimulating electrodes implanted along this pathway will bar-press very energetically if each press is followed by a brief pulse of electric current. Numerous things that people find rewarding, including addictive drugs, good-tasting food, and sex, have been shown to elicit activation of the VTA dopamine system. Damage to the NA or VTA can produce a state of profound torpor.

Although it is not universally accepted, some theorists have proposed a distinction between “appetitive” behaviors, which are initiated by the basal ganglia, and “consummatory” behaviors, which are not. For example, an animal with severe basal ganglia damage will not move toward food even if it is placed a few inches away, but, if the food is placed directly in the mouth, the animal will chew it and swallow it.


The candle problem

Uploaded on Aug 25, 2009 http://www.ted.com Career analyst Dan Pink examines the puzzle of motivation, starting with a fact that social scientists know but most managers don’t: Traditional rewards aren’t always as effective as we think. Listen for illuminating stories — and maybe, a way forward. The candle problem or candle task, also known as […]

Uploaded on Aug 25, 2009

http://www.ted.com Career analyst Dan Pink examines the puzzle of motivation, starting with a fact that social scientists know but most managers don’t: Traditional rewards aren’t always as effective as we think. Listen for illuminating stories — and maybe, a way forward.

The candle problem or candle task, also known as Duncker’s candle problem, is a cognitive performance test, measuring the influence of functional fixedness on a participant’s problem solving capabilities. The test was created [1] by Gestalt psychologist Karl Duncker and published posthumously in 1945. Duncker originally presented this test in his thesis on problem solving tasks at Clark University.

The test presents the participant with the following task: how to fix a lit candle on a wall (a cork board) in a way so the candle wax won’t drip onto the table below.[3] To do so, one may only use the following along with the candle:

  • a book of matches
  • a box of thumbtacks

The solution is to empty the box of thumbtacks, put the candle into the box, use the thumbtacks to nail the box (with the candle in it) to the wall, and light the candle with the match.[3] The concept of functional fixedness predicts that the participant will only see the box as a device to hold the thumbtacks and not immediately perceive it as a separate and functional component available to be used in solving the task.

Response

Many of the people who attempted the test explored other creative, but less efficient, methods to achieve the goal. For example, some tried to tack the candle to the wall without using the thumbtack box,[4] and others attempted to melt some of the candle’s wax and use it as an adhesive to stick the candle to the wall.[1] Neither method works.[1] However, if the task is presented with the tacks piled next to the box (rather than inside it), virtually all of the participants were shown to achieve the optimal solution, which is self defined.[4]

The test has been given to numerous people, including M.B.A. students at the Kellogg School of Management in a study investigating whether living abroad and creativity are linked.[5]

Glucksberg

Glucksberg (1962)[6] used a 2 × 2 design manipulating whether the tacks and matches were inside or outside of their boxes and whether subjects were offered cash prizes for completing the task quickly. Subjects who were offered no prize, termed low-drive, were told “We are doing pilot work on various problems in order to decide which will be the best ones to use in an experiment we plan to do later. We would like to obtain norms on the time needed to solve.” The remaining subjects, termed high-drive, were told “Depending on how quickly you solve the problem you can win $5.00 or $20.00. The top 25% of the Ss [subjects] in your group will win $5.00 each; the best will receive $20.00. Time to solve will be the criterion used.” (As a note, adjusting for inflation since 1962, the study’s publish year, the amounts in today’s dollars would be approximately $39 and $154, respectively.[7]) The empty-boxes condition was found to be easier than the filled-boxes condition: more subjects solved the problem, and those who did solve the problem solved it faster. Within the filled-boxes condition, high-drive subjects performed worse than low-drive subjects. Glucksberg interpreted this result in terms of “neobehavioristic drive theory”: “high drive prolongs extinction of the dominant habit and thus retards the correct habit from gaining ascendancy”. An explanation in terms of the overjustification effect is made difficult by the lack of a main effect for drive and by a nonsignificant trend in the opposite direction within the empty-boxes condition.

Another way to explain the higher levels of failure during the high-drive condition is that the process of turning the task into a competition for limited resources can create mild levels of stress in the subject, which can lead to the Sympathetic nervous system, otherwise known as the Fight-or-flight response, taking over the brain and body. This stress response effectively shuts down the creative thinking and problem solving areas of the brain in the prefrontal cortex.

Linguistic implications

E. Tory Higgins and W. M. Chaires found that having subjects repeat the names of common pairs of objects in this test, but in a different and unaccustomed linguistic structure, such as “box and tacks” instead of “box of tacks”, facilitated performance on the candle problem.[3] This phrasing helps one to distinguish the two entities as different and more accessible.[3]

In a written version of the task given to people at Stanford University, Michael C. Frank and language acquisition researcher Michael Ramscar reported that simply underlining certain relevant materials (“on the table there is a candle, a box of tacks, and a book of matches…”) increases the number of candle-problem solvers from 25% to 50%.[4]

References

  1. ^ Jump up to: a b c “Dan Pink on the surprising science of motivation”. Retrieved 16 January 2010.
  2. Jump up ^ Daniel Biella and Wolfram Luther. “A Synthesis Model for the Replication of Historical Experiments in Virtual Environments”. 5th European Conference on e-Learning. Academic Conferences Limited. p. 23. ISBN 978-1-905305-30-8.
  3. ^ Jump up to: a b c d Richard E. Snow and Marshall J. Farr, ed. (1987). “Positive Affect and Organization”. Aptitude, Learning, and Instruction Volume 3: Conative and Affective Process Analysis. Routledge. ISBN 978-0-89859-721-9.
  4. ^ Jump up to: a b c Frank, Michael. “Against Informational Atomism”. Retrieved 15 January 2010.
  5. Jump up ^ “Living Outside the Box: Living abroad boosts creativity”. April 2009. Retrieved 16 January 2010.
  6. Jump up ^ Glucksberg, S. (1962). “The influence of strength of drive on functional fixedness and perceptual recognition”. Journal of Experimental Psychology 63: 36–41. doi:10.1037/h0044683. PMID 13899303. edit
  7. Jump up ^ Inflated values automatically calculated.

How to learn

Published on Nov 20, 2013 Chris Lonsdale is Managing Director of Chris Lonsdale & Associates, a company established to catalyse breakthrough performance for individuals and senior teams. In addition, he has also developed a unique and integrated approach to learning that gives people the means to acquire language or complex technical knowledge in short periods […]

Published on Nov 20, 2013

Chris Lonsdale is Managing Director of Chris Lonsdale & Associates, a company established to catalyse breakthrough performance for individuals and senior teams. In addition, he has also developed a unique and integrated approach to learning that gives people the means to acquire language or complex technical knowledge in short periods of time.

Jan-21-2014 Update. The video transcripts are now available via the following links:

English Only:
http://www.the-third-ear.com/files/TE…

English + Chinese Translation:
http://www.kungfuenglish.com/files/TE…