Conditional Visuomotor Learning Task
SAMPLE
DELAY
CHOICE
1st Reversal 2nd Reversal
A
A
A
B
B
B
etc….
0
500
1500
Trial Time (ms)
Asaad, W.F., Rainer, G. and Miller, E.K. (1998) Neuron, 21:1399-1407.
Object and Direction selective PF neuron
(nonlinear interaction)
SAMPLE
DELAY
Spikes per second
50
A - go left
A - go right
B - go left
B - go right
40
50
30
40
20
30
0
200
400
600
800
1000
Time (ms)
1200
1400
Movement Direction
Left
Right
Stimulus
Left
Mapping
Right
Left
Right
Prefrontal cortex :
May mediate learning of arbitrary associations. Many PF neurons
coded both an object and a currently-associated directional response.
During learning, information about the cue object and the action it
instructed gradually merged together in PF activity.
This may reflect the role of the PF cortex in acquiring and representing
behavior-guiding rules, a function crucial for intelligent, adaptive
behavior.
Asaad, W.F., Rainer, G. and Miller, E.K. (1998) Neuron, 21:1399-1407.
We trained monkeys to switch between two
abstract rules: “match” and “nonmatch”
Match (bar release)
Match Rule
(DMS)
Sample
Delay
Test
Nonmatch rule
(DNMS)
Four samples were used.
New objects every day.
Nonmatch (bar release)
Wallis, J.D., Anderson, K.C., and Miller, E.K. (2000) Soc. Neurosci. Abstr.
Condition
Sample
Rule
Example Trial
Cue
Lever release
+ reward
Match
+ low tone
+ no reward
Nonmatch
+ high tone
Lever release
A Prefrontal Neuron Tuned to the Match Rule
2D Graph 1
Firing rate (Hz)
20
Sample
Delay
MATCH - reward
MATCH - low tone
15
10
NONMATCH - no reward
NONMATCH - high tone
5
500
1000
1500
Time (milliseconds)
2000
A Prefrontal Neuron Tuned to the Nonmatch Rule
2D Graph 1
20
Firing rate (Hz)
Sample
Delay
NONMATCH - no reward
NONMATCH - high tone
15
10
MATCH - reward
MATCH - low tone
5
0
500
1000
1500
Time (milliseconds)
2000
The prefrontal cortex:
Selectively represents goal-relevant information (focal
attention, recall).
Synthesizes information from diverse sources to serve a common
behavioral goal (sensory inputs, stored knowledge).
Is plastic: it neural activity changes to meet behavioral demands.
Knits together arbitrary associations between diverse, but
behaviorally-related information.
Conveys information about the behavioral context in which the
animals are engaged and the rules used to guide behavior.
This may reflect the role of the PF cortex in acquiring and
representing the formal demands of behavior, rules or models of tasks
that provide a foundation for complex, intelligent behavior.
(Cohen and Servan-Schreiber, 1992; Passingham, 1993; Grafman, 1994;Wise et al., 1996;
Dehaene et al., 1998; Miller, 1999, Miller, 2000, Miller and Cohen, 2001).
The PF cortex and cognitive control
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Reward signals
(VTA neurons?)
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Reward signals
(VTA neurons?)
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The PF cortex and cognitive control
PF cortex
At home
Guest
Phone rings
Answer
Don’t
answer
Active
Inactive
The prefrontal cortex may be like a switch operator
in a system of railroad tracks:
Its integrative anatomy allows it to rapidly acquire a
“map” that specifies which pattern of “tracks” (neural
pathways) are needed to solve a given task.
PF cortex
The prefrontal cortex may be like a switch operator
in a system of railroad tracks:
Its integrative anatomy allows it to rapidly acquire a
“map” that specifies which pattern of “tracks” (neural
pathways) are needed to solve a given task.
PF cortex
The PF cortex actively maintains this
pattern during task performance,
allowing feedback signals to bias the
flow of activity in other brain areas
along those tracks.
The prefrontal cortex may be like a switch operator
in a system of railroad tracks:
Its integrative anatomy allows it to rapidly acquire a
“map” that specifies which pattern of “tracks” (neural
pathways) are needed to solve a given task.
PF cortex
The PF cortex actively maintains this
pattern during task performance,
allowing feedback signals to bias the
flow of activity in other brain areas
along those tracks.
Attention, retrieval, representation of
rules and goals, response selection,
inhibitory control, etc. can be
explained by PF bias signals acting
on different brain structures.