Neurologizing the Psychology of Affects: How Appraisal-Based Constructivism and Basic Emotion Theory Can Coexist

ABSTRACT— Abundant neurobehavioral data, not discussed by Lisa Feldman Barrett (2006) , support the existence of a variety of core emotional operating systems in ancient subneocortical regions of the brain ( Panksepp, 1998a, 2005a ). Such brain systems are the primary-process ancestral birthrights of all mammals. There may be as many genetically and neurochemically coded subcortical affect systems in emotionally rich medial regions of the brain as there are "natural" emotional action systems in the brain. When emotional primes are aroused directly, as with local electrical or chemical stimulation, the affective changes sustain conditioned place preferences and place aversions, which are the premier secondary-process indices of affective states in animals. Humans are not immune to such brain manipulations; they typically exhibit strong emotional feelings. Human emotion researchers should not ignore these systems and simply look at the complex and highly variable culturally molded manifestations of emotions in humans if they wish to determine what kinds of "natural" emotional processes exist within all mammalian brain. Basic emotion science has generated workable epistemological strategies for understanding the primal sources of human emotional feelings by detailed study of emotional circuits in our fellow animals.     

Perinatal leupeptin retards subsequent acquisition of a visual discrimination task in chicks

Recent discoveries that calcium sensitive proteases (calpains) may play an important role in memory led to investigation of the effects of leupeptin, a calpain inhibitor, on learning. Intracerebral injections of either 0.9% saline, 80 micrograms aprotinin, 306 micrograms glutamate, or 8 or 80 micrograms leupeptin were administered to 95 two-day-old chicks. On Day 10 posthatch, animals were then tested on a task requiring discriminations between pebbles and food pellets. Chicks receiving 8 or 80 micrograms leupeptin or 306 micrograms glutamate were found to be deficient in acquiring the task. Aprotinin, a control serine protease inhibitor, did not retard discrimination learning. None of the drugs tested altered body weight or gross visual skills. These results suggest that retardation produced by leupeptin is not due to nonspecific changes in protease activity, visual competency, or growth. The reported results confirm earlier reports of leupeptin-induced memory impairments in rats.     

AMPA/kainate, NMDA, and dopamine D1 receptor function in the nucleus accumbens core: a context-limited role in the encoding and consolidation of instrumental memory

Neural integration of glutamate- and dopamine-coded signals within the nucleus accumbens (NAc) is a fundamental process governing cellular plasticity underlying reward-related learning. Intra-NAc core blockade of NMDA or D1 receptors in rats impairs instrumental learning (lever-pressing for sugar pellets), but it is not known during which phase of learning (acquisition or consolidation) these receptors are recruited, nor is it known what role AMPA/kainate receptors have in these processes. Here we show that pre-trial intra-NAc core administration of the NMDA, AMPA/KA, and D1 receptor antagonists AP-5 (1 microg/0.5 microL), LY293558 (0.01 or 0.1 microg/0.5 microL), and SCH23390 (1 microg/0.5 microL), respectively, impaired acquisition of a lever-pressing response, whereas post-trial administration left memory consolidation unaffected. An analysis of the microstructure of behavior while rats were under the influence of these drugs revealed that glutamatergic and dopaminergic signals contribute differentially to critical aspects of the initial, randomly emitted behaviors that enable reinforcement learning. Thus, glutamate and dopamine receptors are activated in a time-limited fashion-only being required while the animals are actively engaged in the learning context.     

At the interface of the affective,behavioral, and cognitive neurosciences: decoding the emotional feelings of the brain

This article summarizes recent conceptual and empirical advances in understanding basic affective processes of hte mammalian brain and how we might distinguish affective from cognitive processes. Six reasons are advanced for distinguishing the two types of consciousness, including (i) the presence of experienced valence, (ii) cortical sub-cortical locus of control, (iii) different developmental trajectories, (iv) informational vs organic considerations, (v) differences in bodily expressions, (vi) differences in cerebral laterality. The position is advanced that to make progress on understanding the neurobiological nature of affect, we need to utilize experimental strategies different from those that are common in cognitive science.     

Opiates and homing

Beginning at 15 days of age. Long-Evans rat pups were trained to run toward their home cage in a T-maze task. Morphine (.5-1.0 mg/kg sc) slowed initial acquisition running times but did not change the number of trials required to learn the position habit. Morphine markedly impeded extinction of the homing behavior. Opiate-treated animals ran as accurately and as quickly toward home on the 12th day of extinction as on the first (10 trials given per day). Conversely, naloxone (1 mg/kg sc) reduced resistance to extinction. The morphine effect was not state-dependent since the drug also impeded extinction in animals that had acquired the task under saline. The morphine effect was blocked by naloxane, which indicates that the increased resistance to extinction was due to an opiate receptor effect. These results indicate that morphine has a strong capacity to sustain a social habit in the absence of reinforcement.     

Effects of fluoxetine on play dominance in juvenile rats

In a series of three studies, we investigated the influence of a selective serotonin re-uptake inhibitor (fluoxetine) on the rough-and-tumble play of juvenile rats. In Experiment 1, both members of eight pairs of solitary-housed juvenile rats received either vehicle, 2.5, 5, or 10 mg/kg fluoxetine in a counterbalanced within-subject design 20 min before being allowed to play for 5 min periods on four successive test days. The 5 and 10 mg/kg pretreatments significantly reduced incidence of pins during play without affecting dorsal contacts. In Experiment 2, one member of each of 19 established play pairs received 5 mg/kg fluoxetine 20 min before play, while the other member received vehicle. Dominant rats showed no reduction in pins as a result of fluoxetine treatment, but subordinate rats who received fluoxetine exhibited significant reductions in pins. Subsequent dyadic analyses indicated that in pairs where the subordinate animal received fluoxetine, dominant animals maintained their pinning advantage over the 10 days of testing, but in pairs where the dominant animals received fluoxetine, this pinning asymmetry diminished. In Experiment 3, we replicated the above procedure with inexperienced play pairs, to control for the effects of prior social learning. Fluoxetine treatment (5 mg/kg) significantly reduced both pins and dorsal contacts in all treated rats. The results indicate that fluoxetine can reduce the playful pins of juvenile rats, but that prior social learning mediates the strength of these effects. © 1996 Wiley-Liss, Inc.     

Nimodipine alters acquisition of a visual discrimination task in chicks

Chicks 5 days old received intraperitoneal injections of nimodipine 30 min before training on either a visual discrimination task (0, 0.5, 1.0, or 5.0 mg/kg) or a test of separation-induced distress vocalizations (0, 0.5, or 2.5 mg/kg). Chicks receiving 1.0 mg/kg nimodipine made significantly fewer visual discrimination errors than vehicle controls by trials 41-60, but did not differ from controls 24 h later. Chicks in the 5 mg/kg group made significantly more errors when compared to controls both during acquisition of the task and during retention. Nimodipine did not alter separation-induced distress vocalizations at any of the doses tested, suggesting that nimodipine's effects on learning cannot be attributed to a reduction in separation distress. These data indicate that nimodipine's facilitation of learning in young subjects is dose dependent, but nimodipine failed to enhance retention.     

Opioids: from physical pain to the pain of social isolation

The opioid systems play an important role in mediating both physical pain and negative affects (eg, the pain of social isolation). From an evolutionary perspective, it is not surprising that the neurocircuitry and neurochemistry of physical pain would overlap with that involved in complex social emotions. Exposure to trauma as well as a range of gene variants in the opioid system may be associated with alterations in opioid systems function, with changes in reward processing, and with vulnerability to substance abuse. A role for interventions with opioid agents in depression and anxiety disorders has been suggested.     

The trans-species concept of self and the subcortical-cortical midline system

The nature of the self has been one of the central problems in philosophy and most recently in neuroscience. Here, we suggest that animals and humans share a 'core self' represented in homologous underlying neural networks. We argue that the core self might be constituted by an integrative neuronal mechanism that enables self-related processing (SRP). Because mammalian organisms are capable of relating bodily states, intrinsic brain states (e.g. basic attentional, emotional and motivational systems) and environmental stimuli to various life-supporting goal-orientations, SRP appears to be a core ability preserved across numerous species. Recent data suggest that SRP is operating via a central integrative neural system made up of subcortical-cortical midline structures (SCMSs), that are homologous across mammalian species.