Transcript Lateral prefrontal cortex: architectonic and functional organization

Lateral prefrontal cortex:
architectonic and functional
organization
Michael Petrides
In Brief..
Subdivision of the cerebral cortex according to..
differences in the arrangement of the cellular
elements into layers,
such as, differences in:
•
•
•
•
cell packing density across layers,
cell size or type in one or more layers,
the relative thickness of the layers,
or even in overall cortical thickness
Led to the brain mapping of the
primates……
1786
Vick d’Azyr
Regional differences in the
structure of the cerebral
cortex such as white stripe
in the visual cortex of
primates
1840
Baillarger
Outer and inner stripes of
Baillarger
(white stripes)
Meynert /
1867-85 Betz / Lewis
& Clarke
Cerebral cortex is not a
homogeneous sheet of
grey matter, but it consists
of several different areas
Campbell
The first complete
cytoarchitectonic
map of the human brain
based on 8 hemispheres
1905
Brodmann
Published his architectonic
map of the monkey
cerebral cortex
1907
Elliot Smith
Other major maps of the
human cerebral cortex
1908
Brodmann
Architectonic map of the
human cerebral cortex
1925
Economo &
Koskinas
Architectonic map of the
human cerebral cortex
1951
Bailey &
Bonin
Two more atlases of the
human cerebral cortex
1955
Sarkissov et
al
Other maps based on
Brodmann’s
1905
Cytoarchitectonic maps of the lateral and
orbital prefrontal cortex of the monkey
a) By Brodmann
b) By Walker
Cytoarchitectonic maps of the lateral
surface of the human cerebral cortex
a) By Brodmann
b) By Sarkissov et al
Cytoarchitectonic map of the lateral surface of
the prefrontal cortex by Petrides & Pandya
a) Of human brain
b) Of macaque monkey brain
Dorsal
Rostral
Caudal
Ventral
BASIC
DIFFERENCES
Classic cytoarchitectonic
maps (Brodmann,
Sarkissov et al)
Monkey Brain
Human Brain
• Area 10  part of orbital an ventrolateral
frontal region
• Area 12  frontopolar region
• Area 46 adjacent to area 9, No common
border with area 8
• Area 10  frontopolar region
• No area 46, 45
• Granular frontal area 9
• Area 46  large granular, adjacent to area
8, not homogeneous
Walker et al
• Area 12  ventrolateral part of the prfrontal
• Area 45 might correspond to Brodmann’s
area 45 of the human cortex
No human brain maps
• Area 10  frontopolar region
Petrides & Pandya
Dorsolateral Prefrontal Cortex
• Area 9  lying on the supirior frontal gyrus, a poorly developed layer IV and large pyramidal
cells in the deeper part of layer III
• Area 46
• Area 9/46
Ventrolateral Prefrontal Cortex
• Area 44
• Area 45
• Area 47/12
FUNCTIONAL ORGANIZATION OF
THE PREFRONTAL CORTEX
 major role in high-order control processes that exercise a top-down
regulation of cognition and behaviour
In particular, there is ..
•
a rostral - caudal axis of functional organization within the lateral frontal
cortex  cognitive control
and
• a dorso - ventral axis in the mid-lateral part of the prefrontal  executive
control
The rostral–caudal axis of frontal cortex
organization
I.
Lesion of caudal
dorsolateral region- PA
(periarcuate) lesions
(area 8 & rostral 6 )
Problem on tasks that
require the selection
between alternative
competing responses
based on
conditional operations.
II.
Lesion of the middorsolateral prefrontal
cortex-MDL (area 46 &
rostral 9/46
Yield a severe
deficit on tasks
designed to measure
the monitoring of
information in
working memory
A dorsal–ventral axis of organization
a)
b)
c)
d)
An example of a pair of abstract designs
At familiarity/novelty decision condition relative to the control
condition  Increased activity in the right mid-ventrolateral
prefrontal cortex (area 47/12)
an additional increase of activity in the right mid-dorsolateral
prefrontal cortex (areas 46 and 9/46) in the monitoring
condition minus control condition comparison
only the mid-dorsolateral prefrontal cortex (areas 46 and
9/46) showed increased activity at the familiarity/novelty
decision condition relative to monitoring condition
To summarize..
The lateral frontal cortex is functionally organized both along a
rostral–caudal axis and a dorsal– ventral axis
Caudally,
 The most caudal frontal region, the motor region on the
precentral gyrus, is involved in fine motor control and direct
sensorimotor mappings
 The caudal lateral frontal region is involved in higher order
control processes  conditional operations
Rostrally,
 the mid-lateral prefrontal region  cognitive control
 is itself organized along a dorsal–ventral axis of organization
 the mid-dorsolateral prefrontal cortex  monitoring of
information in working memory
 the mid-ventrolateral prefrontal region  in active judgments
on information held in posterior cortical association regions
that are necessary for active retrieval and encoding of
information
Thank you …