Who Needs Emotions? The Brain Meets the Robot

eware the passionate robot 367
awake, behaving monkey show dopamine neurons which fire to predicted
rewards and track expected and unexpected environmental events, thereby
encoding prediction errors (Schultz, 2000; Fellous & Suri, 2003). Moreover,
prefrontal networks are equipped with the ability to hold neural representations
in memory and to use them to guide adaptive behavior; dopamine
receptors are essential for this ability. Thus, dopamine plays essential roles all
the way from basic motivational systems to the working memory systems seen
to be essential to the linkage of emotion and consciousness (see below for a
critique).
Next, consider serotonin, aggression and depression. Kelley (Chapter 3)
shows that serotonin has been widely implicated in many behavioral functions,
including behavioral state regulation and arousal, motor pattern generation,
sleep, learning and plasticity, food intake, mood, and social behavior.
The cell bodies of serotonergic systems are found in midbrain and pontine
regions in the mammalian brain and have extensive descending and ascending
projections. Serotonin plays a critical role in the modulation of aggression
and agonistic social interactions in many animals—in crustaceans,
serotonin plays a specific role in social status and aggression; in primates,
with the system’s expansive development and innervation of the cerebral
cortex, serotonin has come to play a much broader role in cognitive and
emotional regulation, particularly control of negative mood or affect.
Finally, we look at opioid peptides and their role in pain and pleasure.
Kelley shows that opioids, which include the endorphins, enkephalins, and
dynorphins, are found particularly within regions involved in emotional regulation,
responses to pain and stress, endocrine regulation, and food intake.
Increased opioid function is clearly associated with positive affective states
such as relief of pain and feelings of euphoria, well-being, and relaxation.
Activation of opioid receptors promotes maternal behavior in mothers and
attachment behavior and social play in juveniles. Separation distress, exhibited
by archetypal behaviors and calls in most mammals and birds, is reduced
by opiate agonists and increased by opiate antagonists in many species
(Panksepp, 1998). Opiates can also effect the reduction or elimination of
the physical sensation induced by a painful stimulus as well as the negative
emotional state it induces.
What is striking here is the way in which these three great neuromodulatory
systems seem to be distinct from each other in their overall functionalities,
while exhibiting immense diversity of behavioral consequences
within each family. The different effects depend on both molecular details
(the receptors which determine how a cell will respond to the presence of
the neuromodulator) and global arrangements (the circuitry within the
modulated brain region and the connections of that region within the brain).
Kelley notes that much of the investigation of central opioids has been fueled