|Brodman '09||Vogt & Vogt '19||von Bonin & Bailey '47||Barbas & Pandya '87||Matelli et al. '91|
||From Picard and Strick, 2001: Motor areas of
the frontal lobe in monkeys (a) and homologous areas in
the human (b). In humans, the border between areas 6
and 4 on the lateral surface is located in the anterior bank of the
central sulcus .
For illustration, the border is drawn on the surface of the hemisphere
along the central sulcus (bottom, white dotted line). Except for the
most medial portion, M1 does not occupy the precentral gyrus. Pictures
of the monkey brain courtesy of Richard P Dum; pictures of the human
brain reproduced with permission from .
1. Posterior -to- Anterior Gradient
- "Simple" -to- "Complex"
- Non-controversial - many lines of evidence support this view.
- Posterior areas are active w/ "Simple" movement (basic or overlearned spatial and/or temporal coordination. E.g., when task is routine).
- More anterior areas become active w/ "Complex" tasks (tasks with additional or new motor/cognitive demands. E.g., when task is not routine).
2. Ventrolateral -to- Dorsomedial Gradient
R. E. Passingham ('93), G. Rizzolatti ('98), Geyer et al ('00)
- "Exteroceptive guidance" -to- "internal guidance"
- Ventrolateral areas are used when movement is guided by exteroceptive cues (vision or audition)
- Dorsomedial areas are used when movement is guided by "internal cues" - which may mean internal feedback loops (e.g., basal ganglia) and/or proprioception.
- May be governed by the "predominant" posterior parietal inputs to each of the areas
- Different premotor areas are good at different jobs, but are not so easily categorized as Passingham et al propose.
- There are more similarities than differences between the premotor areas.
Problem: What do we do with all of these areas?
- Network models can solve visuomotor transforms with one hidden layer.
- What do premotor areas do that the parietal areas cannot?
Meanwhile, explore the specific areas: