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At least 235 records · Page 13Linked to original sources
PubMed1991

Neuropsychological probes of fronto-limbic system dysfunction in schizophrenia. Olfactory identification and Wisconsin Card Sorting performance.

Schizophrenic patients and normal control subjects took the University of Pennsylvania Smell Identification Test (UPSIT) and Wisconsin Card Sorting Test (WCST) as dual neuropsychological 'probes' of orbitofrontal (OF) and dorsolateral (DL) prefrontal function respectively. Patients were significantly impaired on both tasks compared to controls. UPSIT and WCST performance were uncorrelated in patients but were positively correlated in controls. The lack of correlation found in the patients suggests that the tasks may be tapping independent dysfunctions in schizophrenia reflecting differential impairment in fronto-limbic brain systems. Individual profiles of preserved and impaired performance on the UPSIT and WCST suggested that three schizophrenic patients had OF dysfunction, five had DL dysfunction and seven had a generalized (OF and DL) frontal system dysfunction. The reduced ability of schizophrenic patients to identify odors was largely independent of many deficits or confounds typically associated with schizophrenia and did not appear to be simply a function of generalized deficit. These data are preliminary and require replication with larger samples and validation with other measures of fronto-limbic system dysfunction.

Adolescent↗
PubMed2000

Functional role of the limbic system and basal ganglia in motivated behaviors.

It has been suggested that the cortico- and limbic-striatal systems are important in various motor functions such as motivated behaviors. In this paper we review our previous studies to investigate neuronal mechanisms of feeding behaviors. We recorded neuronal activity from the amygdala, caudate nucleus, globus pallidus, and substantia nigra during feeding behavior in monkeys, and compared neuronal responses recorded from these brain areas. First, of 710 amygdalar neurons tested, 129 (18.2%) responded to single sensory stimulation (48 to vision, 32 to audition, 49 to ingestion), 142 (20%) to multimodal stimulation, and 20 to only one item with affective significance. Eight food related amygdalar neurons were tested in reversal by salting food or introducing saline, and all responses were modulated by reversal. These results suggest that the amygdala might be important in ongoing recognition of the affective significance of complex stimuli (food-nonfood discrimination). Second, activity was recorded from 351 neurons in the head of the caudate nucleus of monkeys during an operant feeding task. The 16% of these neurons responded in the discrimination phase. Some of these neurons responded specifically to food. The magnitude of these food-specific neurons depended on the rewarding nature of the food (reward value), and was inversely related to the latency of the onset of bar press. Of the caudate neurons, 10% responded in the bar press phase. Activity of most neurons which responded in the bar press phase was not correlated to individual bar presses. Cooling of the dorsolateral prefrontal cortex abolished sustained responses during bar pressing, but did not abolish the feeding behavior. However, bar press speed tended to be delayed by prefrontal cooling. Third, activity of 358 neurons was recorded from the monkey globus pallidus, and 204 neurons responded during the feeding task. In the globus pallidus, few neurons responded to food in the discrimination phase. On the other hand, activity of most responsive neurons changed during bar press and/or ingestion phases. Activity of about half of these responsive neurons was directly related to specific feeding motor acts such as arm extension, flexion, bar pressing, grasping, chewing, etc. Some of these neurons showed motor-related responses with gradual and preparatory responses. These motor-related neurons were located mainly in the caudodorsal part of the globus pallidus. On the other hand, about one third, especially in the rostroventral part of the globus pallidus, showed dissociating responses in that they responded during bar pressing for food or during ingestion in an operant task, but not during bar pressing for nonfood or during forcible ingestion. The response magnitude of the neurons during arm extension and bar pressing depended on the nature of the food. Fourth, activity of 261 neurons was recorded from the substantia nigra pars reticulata. Most of responding neurons (more than two-thirds of the recorded neurons) responded during the bar press and/or ingestion phases. Activity of the one-third of neurons was related to specific motor execution such as arm extension, flexion and bar pressing, but not to motor preparation. These neurons were located mainly in the rostral part of the nucleus. More than one-third of the recorded neurons responded during feeding and/or drinking acts and intra- and perioral sensory stimuli, and were located mainly in the caudomedial part of the nucleus. Based upon these responses and known anatomical evidence, various information including that from the amygdala and prefrontal cortex is integrated in the basal ganglia, and converted to coordinated motivated behaviors such as feeding behavior.

Animals↗
PubMed1984

Effects of oxytocin and a derivative (Z-prolyl-D-leucine) on morphine tolerance/withdrawal are mediated by the limbic system.

Recent data indicate that the neurohypophyseal hormone oxytocin (OXT) and Z-prolyl-D-leucine (Z-Pro-D-Leu), a synthetic dipeptide derived from the C-terminal part of OXT, attenuate the development of tolerance to and dependence on morphine in the mouse. Biochemical and behavioral data raise the possibility that these effects of the peptides might be associated with their effects on the central nervous system and in particular on limbic brain structures. The present results confirm this hypothesis, since intracerebroventricular (i.c.v., 50 ng) and local (0.5 ng) injections of OXT and Z-Pro-D-Leu into the dorsal hippocampus and the mesolimbic nucleus accumbens attenuate morphine tolerance/dependence, similarly to systemic injections of these peptides in higher amounts (5-50 micrograms). Local injections of these peptides into other brain sites (e.g. the nucleus caudatus, ventral tegmental area and the external cortical surface) are without effect. Lesion of the nucleus accumbens by the catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) completely prevents the effects of Z-Pro-D-Leu and partially those of OXT on morphine tolerance/dependence. The data point to the role of limbic structures as mediators of the effects of neuropeptides on morphine addiction.

Animals↗