Lab Meetings 2001

Meeting Contents

January 9

Computational approaches to sensorimotor transformations
Alexandre Pouget & Lawrence Snyder
November 2000 Volume 3 Number Supp pp 1160 - 1211

~sabes/LabMeeting/PougetSnyder2000.pdf

Computational principles of movement neuroscience
Daniel Wolpert & Zoubin Ghahramani
November 2000 Volume 3 Number Supp pp 1212 - 1217

~sabes/LabMeeting/WolpertGhahramani2000.pdf

January 16

The plan is to work through a bunch of papers on reaching movement variability. There are four sets of papers: Soechting and Flanders, Gordon and Ghez, McIntyre and Lacquaniti, and Messier and Kalaska. Three people will each summarize (in 10 min or less) the data from one group. The rest of the meeting will be devoted to trying to understand the results. The meeting will be greatly improved if people who come have read most of the papers. Sam and I will each take one group. I'm looking for a volunteer to take the other two.

First come, first served.

Groups 1 & 2 are available on line and at ~sabes/LabMeeting.
Groups 3 & 4 are available on my door.

1)Soechting JF, Flanders M.
Sensorimotor representations for pointing to targets in
three-dimensional space.
J Neurophysiol. 1989 Aug;62(2):582-94.

http://jn.physiology.org/cgi/mjgca?SEARCHID=1041273519088_495&
VOLUME=62&FIRSTPAGE=582&JOURNALCODE=&FIRSTINDEX
=0&hits=10&RESULTFORMAT=&gca=jn%3B62%2F2%2F582&send
it=Get+All+Checked+Abstract%28s%29

2) Gordon J, Ghilardi MF, Ghez C.
Accuracy of planar reaching movements. I. Independence of direction
and extent variability.
Exp Brain Res. 1994;99(1):97-111.

3) This group is a bit more complicated, and may take more than 10 minutes (but no more than 15!)

McIntyre J, Stratta F, Droulez J, Lacquaniti F.
Analysis of pointing errors reveals properties of data representations
and coordinate transformations within the central nervous system.
Neural Comput. 2000 Dec;12(12):2823-55.

McIntyre J, Stratta F, Lacquaniti F.
Short-term memory for reaching to visual targets: psychophysical
evidence for body-centered reference frames.
J Neurosci. 1998 Oct 15;18(20):8423-35.

http://www.jneurosci.org/cgi/content/full/18/20/8423?maxtoshow=&HI
TS=10&hits=10&RESULTFORMAT=&searchid=1041273925617_218
9&stored_search=&FIRSTINDEX=0&volume=18&firstpage=8423&jou
rnalcode=jneuro

McIntyre J, Stratta F, Lacquaniti F.
Viewer-centered frame of reference for pointing to memorized targets
in three-dimensional space.
J Neurophysiol. 1997 Sep;78(3):1601-18.

http://www.jneurosci.org/cgi/content/full/18/20/8423?maxtoshow=&HIT
S=10&hits=10&RESULTFORMAT=&author1=mcintyre%2C+J&titleab
stract=viewercentered+frame+of+reference&searchid=1041274037200_2
203&stored_search=&FIRSTINDEX=0&journalcode=jneuro

4) Messier J, Kalaska JF.
Comparison of variability of initial kinematics and endpoints of
reaching movements.
Exp Brain Res. 1999 Mar;125(2):139-52 .

http://link.springerny.com/link/service/journals/00221/bibs/9125002/
91250139.htm

Messier J, Kalaska JF.
Differential effect of task conditions on errors of direction and
extent of reaching movements.
Exp Brain Res. 1997 Jul;115(3):469-78.

http://link.springerny.com/link/service/journals/00221/bibs/7115003/
71150469.htm

January 23

After yesterday's brutal meeting, we'll take it light for next week. We'll read the Nature paper on the Minimum Variance model by Harris and Wolpert:

Signal-dependent noise determines motor planning
Christopher M. Harris* & Daniel M. Wolpert
NATURE | VOL 394 | 20 AUGUST 1998 | pp.780-784

http://www.nature.com/cgitaf/DynaPage.taf?file=/nature/journal/v394/
n6695/full/394780a0_fs.html

January 30

This Tuesday we'll go back to cortex. We all know that parietal cortex does the visual work, sending a reach target to the frontal movement areas (PMd, M1, etc). But... here are two papers on sensory responses in frontal cortex:

Shen L, Alexander GE
Neural correlates of a spatial sensory-to-motor transformation in
primary motor cortex. J Neurophysiol 1997 Mar;77(3):1171-94

* ~sabes/LabMeeting/ShenAlexander1997.pdf

http://jn.physiology.org/cgi/content/full/77/3/1171

Boussaoud D, Wise SP
Primate frontal cortex: effects of stimulus and movement.
Exp Brain Res 1993;95(1):28-40

* On my door

Kurata, K; Hoshi, E. Reacquisition deficits in prism adaptation after
muscimol microinjection into the ventral premotor cortex of monkeys.
Journal of Neurophysiology, 1999 Apr, 81(4):1927-38.

http://jn.physiology.org/cgi/content/full/81/4/1927?maxtoshow=&HI
TS=10&hits=10&RESULTFORMAT=&searchid=1041534053563_9
82&stored_search=&FIRSTINDEX=0&volume=81&firstpage=1927&
journalcode=jn

Coding the Locations of Objects in the Dark
Michael S. A. Graziano, Xin Tian Hu, and Charles G. Gross
Science 1997 July 11; 277: 239-241

http://www.sciencemag.org/cgi/content/full/277/5323/239

February 6

Two papers on PMv, presented by Sam and Rob:

Kurata, K; Hoshi, E. Reacquisition deficits in prism adaptation after
muscimol microinjection into the ventral premotor cortex of monkeys.
Journal of Neurophysiology, 1999 Apr, 81(4):1927-38.

http://jn.physiology.org/cgi/content/full/81/4/1927?maxtoshow=&HI
TS=10&hits=10&RESULTFORMAT=&searchid=1041534053563_9
82&stored_search=&FIRSTINDEX=0&volume=81&firstpage=1927&
journalcode=jn

Coding the Location of the Arm by Sight
Michael S. A. Graziano, Dylan F. Cooke, and Charlotte S. R. Taylor
Science 2000 December 1; 290: 1782-1786

http://www.sciencemag.org/cgi/content/full/290/5497/1782

February 13

1) Kalaska JF.
Parietal cortex area 5 and visuomotor behavior.
Can J Physiol Pharmacol. 1996 Apr;74(4):483-98. Review.

http://ginkgo.cisti.nrc.ca/ppv/RPViewDoc?_handler_=HandleInitial
Get&journal=cjpp&volume=74&articleFile=y96-040.pdf

A review which includes most of the data from Crammond and Kalaska Cerebral Cortex 5(5) 410 (1995).

2) Read this abstract. The paper might be good too, and I encourage you to read it ;-). But the abstract may provide fuel for discussion of above.

Exp Brain Res 1992;90(1):229-32
Control of arm movement after bilateral lesions of area 5 in the monkey
(Macaca mulatta). Nixon PD, Burbaud P, Passingham RE

The effect of bilateral area 5 lesions on the analysis of proprioceptive information and the guidance of reaching movements was studied in three rhesus monkeys. In the first paradigm (Proprioceptive discrimination test) the monkeys were trained to discriminate between movements of a joystick to the right or left without visual control; they reported the direction of movement by touching or not touching a screen (go/no-go task). After area 5 had been removed, the monkeys were only mildly impaired on this test. It is concluded that such simple joint movement could be analysed in area 2, area 5 being concerned with more complex arm movements. In the second paradigm (Searching test) the monkey had to find a peanut on a board in the dark using proprioceptive information stored in memory during previous trials. After area 5 lesions, the number of correct reaches was not modified but the number of errors after an incorrect trial (correcting movement) was significantly increased. The data suggests that when visual input is not available, area 5 is involved in the guidance of arm movements on the basis of proprioceptive inputs.

February 27

Continuing on with Area 5, a somewhat painful but influential paper on Area 5 (does the work "spherangular" ring a bell?):

Representing Spatial Information For Limb Movement –
Role Of Area 5 In The Monkey
Lacquaniti F, Guigon E, Bianchi L, Ferraina S, Caminiti R
Cerebral Cortex 5: (5) 391-409 Sep-Oct 1995

March 6

As discussed last week, we'll continue with parietal cortex and reaching.

Three papers:

1) Desmurget et al, 1999: The TMS paper we keep referring to. A good paper despite a few suspect authors. I believe Rob has agreed to present...

Desmurget M, Epstein CM, Turner RS, Prablanc C, Alexander GE,
Grafton ST.
Role of the posterior parietal cortex in updating reaching movements
to a visual target. Nat Neurosci. 1999 Jun;2(6):563-7.

~sabes/LabMeeting/DesmurgetEtAl1999.pdf

2/3) The two Passingham papers on Parietal Lesions.

M. F. S. Rushworth, P. D. Nixon, R. E. Passingham:
Parietal cortex and movement
I. Movement selection and reaching
Exp Brain Res 117 (1997) 2, 292-310

http://link.springer-ny.com/link/service/journals/00221/bibs/7117002/71170292.htm

M. F. S. Rushworth, P. D. Nixon, R. E. Passingham:
Parietal cortex and movement
II. Spatial representation
Exp Brain Res 117 (1997) 2, 311-323

http://link.springer-ny.com./link/service/journals/00221/tocs/t7117002.htm

March 20

This week's lab meeting will be taking place, but it's going to be a "Real Lab Meeting". All are welcome, but it might be boring for those who don't consider themselves part of the lab and have no intention of considering themselves so in the future.

We'll cover the following topics:

1) Short and medium term plans for the lab.

I'll run through the main topics (Specific Aims) of the NIH grant
I'm preparing on the psychophyisical work.

We'll talk a little about the physiology plans. We'll talk about who wants to do what in the short/medium term (i.e. between now and end-of-summer?)

2) The lab meetings

Future reading topics
Better organization of food/drink providing

3) A few administrative items regarding the two lab spaces.

March 27

Caminiti et al
Early coding of reaching: frontal and parietal association connections
of parieto-occipital cortex
European Journal of Neuroscience 1999; 11(9):3339-3345

http://www.blackwellsynergy.com/servlet/useragent?func=synergy&
synergyAction=showFullText&doi=10.1046/j.1460-9568.1999.00801.x

Galletti et al
Brain location and visual topography of cortical area V6A in the
macaque monkey
European Journal of Neuroscience 1999; 11(2):575-582

http://www.blackwellsynergy.com/servlet/useragent?func=synergy&
synergyAction=showFullText&doi=10.1046/j.1460-9568.1999.00467.x

April 10

Next Tuesday (4/10), we'll begin our overview of cortical sensorimotor areas. Sam, Katrin, and I will begin with Parietal Cortex, including: V6, V6a, MIP, PEa, VIP, LIP, AIP, 7a, 7b, 7m, and MDP.

April 17

* Somatosensory Areas -- Dave
* Frontal Cortex (except M1) -- Rob and Steve
* M1 and all Spinal Connections -- Steph and Clint

Largely segregated parietofrontal connections linking rostral
intraparietal cortex (areas AIP and VIP) and the ventral premotor cortex
(areas F5 and F4).
Luppino G, Murata A, Govoni P, Matelli M

http://link.springer-ny.com./link/service/journals/00221/bibs/9128001/91280181.htm

Also, I highly recommend looking at PubMed with a search like: "parietal[TW] AND 7b[TW]" for your brain area. The search above yielded an excellent list of all the old papers.

(in case you care, [TW] is text word, i.e. works for title or abstract)

Schenk on the Medial wall
Sabes on the rostral tip of the IPS (AIP, 7t)
McGonigle on SI and SI
and a special guest appearance of Moore on 3a, if such a thing exists.

Here are the motor papers to read in preparation for Friday.

1) Meyer, Abrams, Kornblum, Wright, and Smith, "Optimality in Human Motor
Performance: Ideal Control of Rapid Aimed Movements", Psychological
Review 95(3):340 (1988)

2) TTodorov, "Cosine Tuning Minimizes Motor Errors".

http://www.gatsby.ucl.ac.uk/~emo/index.html

April 24

We'll continue this Tuesday, 3pm, wrapping up parietal cortex

May 5

Finally finishing Parietal Cortex, Chris Moore and I will present.

Presented by Sabes, Sober and Schenk:
Areas MIP/area 5, VIP, LIP, AIP, MDP, PO/V6/V6a in the Intraparietal sulcus

Presented by McGonigle and Moore :
Areas 1,2,3a and 3b in the primary somatosensory cortex
Somatosensory areas SII/PV in the lateral sulcus

Presented by Rob and Steve:
Premotor areas PMv(F4, F5ab, and F5c) and PMd(F2 and F7)

May 15

The next Sabes Lab Meeting will take place tomorrow, 3pm. Rob will cover the supplementary motor areas, and Stephanie and Clint will start in on M1.

May 22

1) Developmental time course (critical period) of prism-adaptation plasticity:

Knudsen, EI; Knudsen, PF. Sensitive and critical periods for
visual calibration of sound localization by barn owls.
Journal of Neuroscience, 1990 Jan, 10(1):222-32.

2) Early paper on an underlying neural mechanism:

~sam/Lab_Meeting_Papers/Brainard_Knudsen_91.pdf

Knudsen, EI; Brainard, MS. Visual instruction of the neural map
of auditory space in the developing optic tectum.
Science, 1991 Jul 5, 253(5015):85-7

May 29

Contrary to last week's plans, we will meet tomorrow 3pm for a summer organizational meeting. Topics include summer research priorities, plans for the two labs, and introducing our summer undergrad RA, who will be arriving tomorrow morning.

We will return to the Knudsen Owl work for one more meeting next week.

Zheng, W; Knudsen, EI. Functional selection of adaptive auditory space
map by GABAA-mediated inhibition [see comments]
Science, 1999 May 7, 284(5416):962-5.

http://www.sciencemag.org/cgi/content/full/284/5416/962

review for background:

Knudsen, EI; Zheng, W; DeBello, WM. Traces of learning in the auditory
localization pathway.
Proceedings of the National Academy of Sciences of the United States of
America, 2000 Oct 24, 97(22):11815-20.

June 5

Paper for lab meeting this week:

Zheng, W; Knudsen, EI. Functional selection of adaptive auditory space
map by GABAA-mediated inhibition [see comments]
Science, 1999 May 7, 284(5416):962-5.

http://www.sciencemag.org/cgi/content/full/284/5416/962

review for background:

Knudsen, EI; Zheng, W; DeBello, WM. Traces of learning in the auditory
localization pathway.
Proceedings of the National Academy of Sciences of the United States of
America, 2000 Oct 24, 97(22):11815-20.

June 12

A pair of new papers from Caminiti explores areas V6a and PEc/MDP/medial-SPL-wall, their connectivity with PMd, and their role in Eye Hand coordination. A potentially nice pair of anatomy and physiology papers.

Eye-Hand Coordination during Reaching. I. Anatomical Relationships between Parietal and Frontal Cortex.
Marconi B, Genovesio A, Battaglia-Mayer A, Ferraina S, Squatrito S, Molinari M, Lacquaniti F, Caminiti R.
Cereb Cortex. 2001 Jun;11(6):513-527.

http://cercor.oupjournals.org/cgi/content/full/11/6/513

Eye-Hand Coordination during Reaching. II. An Analysis of the Relationships between Visuomanual Signals in Parietal Cortex and Parieto-frontal Association Projections.
Battaglia-Mayer A, Ferraina S, Genovesio A, Marconi B, Squatrito S, Molinari M, Lacquaniti F, Caminiti R.
Cereb Cortex. 2001 Jun;11(6):528-544.

http://cercor.oupjournals.org/cgi/content/full/11/6/528

June 19

Clower DM, Hoffman JM, Votaw JR, Faber TL, Woods RP, Alexander GE.
Role of posterior parietal cortex in the recalibration of visually
guided reaching.
Nature. 1996 Oct 17;383(6601):618-21.

"Neuronal Correlates of Sensorimotor Adaptation", Chp 4 of Dottie's thesis

June 26

1) The recent Bizzi paper, looking at M1:

Neuron 2001 May;30(2):593-607
Neuronal Correlates of Motor Performance and Motor Learning in the
Primary Motor Cortex of Monkeys Adapting to an External Force Field.
Li CR, Padoa-Schioppa C, Bizzi E

2) Supplementary to (1) (i.e. not required reading), an older paper on the same topic:

Proc Natl Acad Sci U S A 2000 Feb 29;97(5):2259-63
Cortical correlates of learning in monkeys adapting to a new dynamical
environment.
Gandolfo F, Li C, Benda BJ, Schioppa CP, Bizzi E

http://www.pnas.org/cgi/content/full/97/5/2259

3) An odd Shadmehr looking at EMG "correlates":

J Neurosci 1999 Oct 1;19(19):8573-88
Electromyographic correlates of learning an internal model of reaching
movements.
Thoroughman KA, Shadmehr R.

http://www.jneurosci.org/cgi/content/full/19/19/8573

July 3

We'll read the three van Donkelaar papers on Eye-Hand coordination. Katrin agreed to present (1), and Tory and Dan agreed to take (2) and (3). I've given the URL's for the two which are freely available, but all three can be found at

http://keck.ucsf.edu/~sabes/LabMeeting/

1) Transcranial Magnetic Stimulation Disrupts Eye-Hand Interactions in the
Posterior Parietal Cortex
Paul Van Donkelaar, Ji-Hang Lee, and Anthony S. Drew
J Neurophysiol 2000 Sep;84(3):1677-80

http://jn.physiology.org/cgi/reprint/84/3/1677.pdf

2) Eye-hand coordination to visual versus remembered targets.
van Donkelaar P, Staub J.
Exp Brain Res 2000 Aug;133(3):414-8

http://link.springer-ny.com/link/service/journals/00221/papers/0133003/01330414.pdf

3) Saccade amplitude influences pointing movement kinematics.
van Donkelaar P.
Neuroreport 1998 Jun 22;9(9):2015-8

July 10

The next lab meeting will be Tues at 3pm. We are going to have a mini-symposium on the Superior Colliculus with an emphasis on its role in integrating sensory and motor modalities. The following week, we'll be reading newer (less well established) work which explores the role of SC in arm movements (arm saccades?!).

1) Katrin will discuss an older, classic review by Sparks, which focuses on saccadic eye movements:

Sparks DL.
Translation of sensory signals into commands for control of
saccadic eye movements: role of primate superior colliculus.
Physiol Rev. 1986 Jan;66(1):118-71. Review.

Available on my door.

2) I'll have few words to say about the book "The Merging of the Senses" by Stein and Meredith, which (as the name implies) emphasises sensory integration aspects of SC function. Maybe available in the library.

3) We'll also hear about some recent work from Sparks' lab showing the saccadic eye movement activity in the SC is probably better thought of as gaze saccade activity, i.e. for coordinated movement of the eye and head. Sam, Tory, Dan, and/or Yigal will present two or three of the following, in any order or combination which they agree upon:

a) behavior:

Edward G. Freedman and David L. Sparks
Eye-Head Coordination During Head-Unrestrained Gaze Shifts in
Rhesus Monkeys
J. Neurophysiol. 1997 77: 2328-2348

http://jn.physiology.org/cgi/reprint/77/5/2328.pdf

b) physiology:

Edward G. Freedman and David L. Sparks
Activity of Cells in the Deeper Layers of the Superior
Colliculus of the Rhesus Monkey: Evidence for a Gaze
Displacement Command
J. Neurophysiol. 1997 78: 1669-1690.

http://jn.physiology.org/cgi/reprint/78/3/1669.pdf

c) more recent review:

Sparks DL.
Conceptual issues related to the role of the superior colliculus
in the control of gaze.
Curr Opin Neurobiol. 1999 Dec;9(6):698-707.

http://keck.ucsf.edu/~sabes/LabMeeting/Sparks1999.pdf

July 17

Superior Colliculus and Reaching, some new(ish) results. And Sam was right, reticular formation lies beneath SC.

Exp Brain Res. 1997 Jun;115(2):191-205.
Arm-movement-related neurons in the primate superior colliculus and
underlying reticular formation: comparison of neuronal activity with
EMGs of muscles of the shoulder, arm and trunk during reaching.
Werner W, Dannenberg S, Hoffmann KP.

http://link.springerny.com/link/service/journals/00221/papers/7115
002/71150191.pdf

Exp Brain Res 1997 Jun;115(2):206-16
Anatomical distribution of arm-movement-related neurons in the primate
superior colliculus and underlying reticular formation in comparison
with visual and saccadic cells.
Werner W, Hoffmann KP, Dannenberg S.

http://link.springerny.com/link/service/journals/00221/papers/7115
002/71150206.pdf

A short paper showing some nice temporal correlation between SC and EMG, suggesting a fairly tight linkage.

J Neurophysiol 1999 Apr;81(4):1978-82
Correlation of primate superior colliculus and reticular formation
discharge with proximal limb muscle activity.
Stuphorn V, Hoffmann KP, Miller LE.

http://jn.physiology.org/cgi/reprint/81/4/1978.pdf

Additional food for thought (not required reading, won't be presented)

A) An earlier paper suggesting where the above signal might come from:

Behav Brain Res 1985 Nov-Dec;18(2):95-105
Inputs from motor and premotor cortex to the superior colliculus of
the macaque monkey.
Fries W.

In retrograde studies of corticotectal projections in the monkey using horseradish peroxidase (HRP), projections of the frontal lobes were found to originate not only from the frontal eye fields and prefrontal association cortex but also from both motor and premotor cortex. Even small HRP injections into the superficial layers of the superior colliculus yielded labelled cells in the agranular cortex (area 6) of the anterior bank of the arcuate sulcus. After large collicular injections affecting all layers, labelled cells were found in both motor and premotor cortex. This projection appeared to be topographically organized. Injections into the anterolateral parts of the superior colliculus labelled cells that were distributed within the presumed finger-hand--arm-shoulder representation, whereas after more caudal injections labelled cells occurred more in the presumed arm-trunk representation. The supplementary motor cortex was not found to contain labelled cells. The corticotectal cells in the motor cortex differed from those in the premotor cortex in their size distribution; the former being small, the latter both small and large. The functional significance of the motor and premotor input into the superior colliculus for sensory, and particularly visual, guidance of movements is discussed in view of a collicular role in the extrapersonal space representation and of its possible participation in steering arm and hand movements.

B) A recent paper on coding -- some cells look like motor only, some show strong gaze dependent effects.

J Neurophysiol 2000 Mar;83(3):1283-99
Neurons in the primate superior colliculus coding for arm movements in
gaze-related coordinates.
Stuphorn V, Bauswein E, Hoffmann KP.

http://jn.physiology.org/cgi/reprint/83/3/1283.pdf

July 24

1) E. E. Fetz and P. D. Cheney,
"Postspike Facilitation of Forelimb Muscle Activity by Primate
Corticomotoneuronal Cells", J. Neurophys. 44 (4),751-772, 1980.

2) D. Flament, P. A. Fortier and E. E. Fetz,
"Response Patterns and Postspike Effects of Peripheral Afferents in Dorsal
Root Ganglia of Behaving Monkeys", J. Neurophys. 67 (4), 875-889, 1992.

3) Matsumura et. al.
"Synaptic Interactions Between Primate Precentral Cortex Nuerons REvealed
by Spike-Triggered Averageing of Intracellular Membrane Potentials in
vivo.", J. Neuroscience, Dec. 1996, 16(23),7757-7767.

Available on Fetz's web page

http://depts.washington.edu/pbiopage/faculty/fetz.html

And one Lemon paper,

4) K. M. Bennett and R. N. Lemon,
"The influence of Single Monkey Cortico-Motoneuronal Cells at Different
Levels of Activity in Target Muscles.", J. Physiol., 1994, Jun, 477 (pt2),
291-307.

October 2

Let's meet this coming Tuesday at 3:30 (the new lab meeting time for this term) to talk over plans for the fall. I'll bring refreshments.

November 27

We'll begin with a review of highlights from the Neuroscience Meeting. Then we'll focus on one of them: Emanuel Todorov's new ideas on optimal feedback control. He's got two papers on the topic, a methods paper, which I'm trying to get hold of, and results paper.

The two Todorov papers can be downloaded at:

http://www-rcf.usc.edu/~etodorov/papers/coordination.pdf

http://www-rcf.usc.edu/~etodorov/papers/method.pdf

December 18

Ojakangas, CL; Ebner, TJ. Purkinje cell complex spike activity
during voluntary motor learning: relationship to kinematics.
Journal of Neurophysiology 1994 Dec, 72(6):2617-30

European Journal of Neuroscience 10 (1) 86-94
Role of the cerebellum in reaching movements in humans. I. Distributed
inverse dynamics control
Nicolas Schweighofer,1,2 Michael A. Arbib1 and Mitsuo Kawato2

http://www.blackwellsynergy.com/Journals/member/institutions/
processfree2.asp?contentid=ejn.1998.1&filetype=abstracts&article=13197

European Journal of Neuroscience 10 (1) 95-105
Role of the cerebellum in reaching movements in humans. II. A neural
model of the intermediate cerebellum
Nicolas Schweighofer,1,2 Jacob Spoelstra,1 Michael A. Arbib1 and
Mitsuo Kawato2

http://www.blackwellsynergy.com/Journals/member/institutions/
processfree2.asp?contentid=ejn.1998.1&filetype=abstracts&article=13198

Another modeling paper by people I'm even more suspect of is below...

Another model for the future possibly....

http://www.learnmem.org/content/vol3/issue6/
Learning & Memory, Vol 3, 475-502, 1997

RESEARCH PAPERS

A Neural Model of Cerebellar Learning for Arm Movement Control:
Cortico-Spino- Cerebellar Dynamics

JL Contreras-Vidal, S Grossberg and D Bullock
Department of Cognitive and Neural Systems and Center for Adaptive
Systems Boston University. Boston, Massachusetts 02215

A neural network model of opponent cerebellar learning for arm movement control is proposed. The model illustrates how a central pattern generator in cortex and basal ganglia, a neuromuscular force controller in spinal cord, and an adaptive cerebellum cooperate to reduce motor variability during multijoint arm movements using mono-and bi-articular muscles. Cerebellar learning modifies velocity commands to produce phasic antagonist bursts at interpositus nucleus cells whose feed-forward action overcomes inherent limitations of spinal feedback control of tracking. Excitation of alpha motoneuron pools, combined with inhibition of their Renshaw cells by the cerebellum, facilitate movement initiation and optimal execution. Transcerebellar pathways are opened by learning through long-term depression (LTD) of parallel fiber-Purkinje cell synapses in response to conjunctive stimulation of parallel fibers and climbing fiber discharges that signal muscle stretch errors. The cerebellar circuitry also learns to control opponent muscles pairs, allowing cocontraction and reciprocal inhibition of muscles. Learning is stable, exhibits load compensation properties, and generalizes better across movement speeds if motoneuron pools obey the size principle. The intermittency of climbing fiber discharges maintains stable learning. Long-term potentiation (LTP) in response to uncorrelated parallel fiber signals enables previously weakened synapses to recover. Loss of climbing fibers, in the presence of LTP, can erode normal opponent signal processing. Simulated lesions of the cerebellar network reproduce symptoms of cerebellar disease, including sluggish movement onsets, poor execution of multijoint plans, and abnormally prolonged endpoint oscillations. Received February 14,1997; accepted in revised form April 14, 1997.

From sabes@phy.ucsf.edu Wed Oct 16 14:55:45 2002
X-Coding-System: undecided-unix

*********AND WERE THEY TERRIBLE OR WERE THEY PRESENTED?

Sam,
Were these the papers you read? If they are really awful, we should skip them, but sometimes even bad models have a nice way of provding structure (and bias) to a lit review. And yes, I'll present them.
-Flip

European Journal of Neuroscience 10 (1) 86-94
Role of the cerebellum in reaching movements in humans. I. Distributed
inverse dynamics control
Nicolas Schweighofer,1,2 Michael A. Arbib1 and Mitsuo Kawato2

European Journal of Neuroscience 10 (1) 95-105
Role of the cerebellum in reaching movements in humans. II. A neural
model of the intermediate cerebellum
Nicolas Schweighofer,1,2 Jacob Spoelstra,1 Michael A. Arbib1 and
Mitsuo Kawato2