Transcript Neurochemistry of prefrontal function

Law of Initial Values
(Wilder, 1962)
50
40
30
20
Overexcited
Normal
Underexcited
10
0
ru
g
– placebo controls
80
70
60
D
• Intensity and duration of
drug effect depends on the
baseline
• Methylphenidate reduces
hyperactivity in persons
with high levels of basal
activity but increases it in
those with low levels
• Regression-to-the mean
effects?
What Determines Baseline?
• Cognitive demands
• Individual differences
– Genetics
– Gender
– Age
Yerkes-Dodson Law 1908
• As arousal increases
performance increases. At
some point increased
arousal leads to decreased
performance.
• As arousal increases there
is a reduction of cues to
regulate performance
(narrowing of attentional
focus).
• There is also increased
distractibility (increased
attentional shifts)
Arousal, Complexity, and Learning
State and Trait Anxiety
• State anxiety varies from second to second and
from task to task.
• Trait anxiety characterizes an individual’s general
tendency to worry.
Neurochemistry of prefrontal function
- effects on attention, memory
Cools and Robbins, 2004
Seamans and Yang, 2004
NA-Behavior Relationship
Are the extremes functional?
• Delayed response task
– Requires focused attention
– Is affected when distractibility increases
• Attentional set-shifting
– Requires flexible attention
– Improves when distractibility increases
Neuromodulation
- signal-to-noise
- switching
- burst/single spike
- oscillations
Neuromodulators alter intrinsic properties
of networks
Marder and Thilumalai, 2002
Modulation of spinal locomotor circuit
Le Beau et al., 2005