Biological Network underlying fast task-specific reactions.

A proposal on the respective roles of Parietal and Premotor Cortex, Frontal Cortex and Cerebellum

Guido Bugmann
Centre for Neural and Adaptive Systems
School of Computing
University of Plymouth


1. What is the fastest route from the visual system to the motor output?
 

V1 -> PO -> MIP -> Pre-Motor -> Motor Cortex

(for arm movements)

V1 -> PO -> LIP -> FEF -> Superior Colliculus

(for eye movements)

Areas (from 1) v1 PO  PPC (MIP) PM M1
Latencies (from 2) 65 ms 70 ms (values for MT used) 72 ms (values of FEF/MST used) ? ?

2. Role of MIP ? (Kalaska & Crammond, 1995)
 

Proposal based on (3):
"MIP knows WHAT action is to be performed as indicated by the visual stimulus and the current task"
No decisions as to the execution of the response, only sensory-motor mapping.

PPC lesions: Inability to set-up a response rule.

3. Role of PM ?
 
Proposal based on (3):
"PM acts as a relay between PPC and M1, and acts upon PFC signals telling WHEN to perform the action"
4. How does PM know when to enable actions ?
 
Pre-frontal cortex exerts general inhibitory control. (Braun et al., 1992) , possibly using object-specific information from IT (slow visual pathway).
5. How does MIP know which mapping to apply?
 
Many inputs to MIP:  - M1 and PM
- PFC (46)
- Cerebellum
- Visual areas (IT)

Imaging studies: The cerebellum sends sensory – motor maps to the PPC (Le et all, 1998)

Lesion studies: Cerebellar lesions cause deficits in applying motor response rules.

-> Proposal: Role of Lateral Cerebellum is setting up task-specific
sensory-motor associations in PPC


6. How does the cerebellum know which is the current task?
 

Many inputs to the Cerebellum :  - PPC
- Motor cortices
- PFC

Imaging studies: Fronto-Polar Prefrontal Cortex (area 10) (Koechlin et al, 1999, Nature) is active when switching between two tasks is required. Area 10 projects to cerebellum (exact target sub-area  unknown). Could be the source of task specification signals.

Lesion of FPPFC has similar effects as PPC lesions.

7. Computational implications.

            Download: "Planning Behaviours" extendend abstract of presentation at the Emernet Workshop, Edinburgh 15 Sept. 1999

 "Role of the cerebellum in time-critical goal-oriented behaviour: Anatomical basis and control principle." ps.zip (250.872)  PDF (111.833)
Bugmann G.
 

References:
 

1. Johnson P.B., Ferraina S., Bianchi L. & Caminiti R. (1996) "Cortical networks for visual reaching: Physiological and anatomical organization of frontal and parietal lobe arm regions", Cerebral Cortex, 6, pp. 102-119.

2. Schmolesky M.T., Wang Y., Hanes D.P., Thompson K.G., Leutgeb S., Schall J.D. and Leventhal A.G. (1998) "Signal timing  across the visual system", J. of Neurophysiology, 79:6, pp.3272-3278

3. Kalaska J.F. & Crammond D.J. (1995) "Deciding not to GO: Neuronal Correlates of Response Selection in a GO/NOGO Task in Primate Premotor and Parietal Cortex", Cerebral Cortex, 5:5, pp.410-428.

4. Braun D., Weber H., Mergner TH. and Schulte-Mönting J. (1992) "Saccadic reaction times in patients with frontal and parietal lesions", Brain, 115, pp. 1359-1386.

5. Le T.H., Pardo J.V., and Hu X. (1998) “4 T-fMRI Study of Nonspatial Shifting of Selective Attention: Cerebellar and Parietal Contributions”,  J Neurophysiology, 79, pp 1535-1548.

6. Koechlin E., Basso G., Pietrini P., Panzer S. & Grafman J. (1999) "The role of the anterior prefrontal cortex in human cognition", Nature, 399:6732, pp. 148-151.
 



Guido Bugmann, 15 September 1999