Prefrontal unit activity during associative learning in the monkey

Summary Single unit activity was recorded from the dorsolateral prefrontal cortex of two monkeys which were trained on a stimulus-reward association task. The monkeys were trained on a reaction time task overlapped with a classical conditioning paradigm. The sequential events of the task were as follows: (1) lever pressing to start the trial; (2) presentation of a visual cue for 1 s; (3) delay period of 1 s; (4) imperative stimulus presentation; and (5) release of the lever by the animal. The visual cue signaled whether or not a drop of fruit juice would be given (its associative significance) for the animal's release response instead of signaling what response the animal should perform (its behavioral significance). In this task, the animal had to release the lever even on the trial where no juice was given in order to advance to the next trial. A total of 423 units showed activity changes in relation to one or more of the task events, such as the cue presentation, delay, release response and reward delivery. Among 313 units which showed cue-related activity changes, 179 units showed differential activity in relation to the different cues. A majority of them (Type M; n = 120) showed activity changes in relation to whether the cue indicated juice delivery or not, independent of its physical properties. The activity of 13 units (Type P) was related to the physical properties of the stimulus, and the activity of the remaining 46 units (Type MP) appeared to be related to both aspects of the stimulus. Sustained activity changes during the delay period were observed in 68 Type M, in 3 Type P and in 24 Type MP units. The results suggest that the prefrontal cortex plays important roles in the stimulus-reward association and that prefrontal units are involved in higher order information processing, extracting and retaining the associative significance of the stimulus independent of its physical properties.     

Orexin A mediation of time spent moving in rats: Neural mechanisms

The brain regulates energy balance and spontaneous physical activity, including both small- and large-motor activities. Neural mediators of spontaneous physical activity are currently undefined, although the amount of time spent in sedentary positions versus standing and ambulating may be important in the energetics of human obesity. Orexin A, a neuropeptide produced in caudal hypothalamic areas and projecting throughout the neuraxis, enhances arousal and spontaneous physical activity. To test the hypothesis that orexin A affects the amount of time spent moving, we injected orexin A (0–1000 pmol) into three orexin projection sites in male Sprague–Dawley rats: hypothalamic paraventricular nucleus, rostral lateral hypothalamic area and substantia nigra pars compacta, and measured spontaneous physical activity. Orexin A affects local GABA release and we co-injected orexin A with a GABA agonist, muscimol, in each brain site. Dopamine signaling is important to substantia nigra function and so we also co-injected a dopamine 1 receptor antagonist (SCH 23390) in the substantia nigra pars compacta. In all brain sites orexin A significantly increased time spent vertical and ambulating. Muscimol significantly and dose-dependently inhibited orexin A effects on time spent moving only when administered to the rostral lateral hypothalamic area. In the substantia nigra pars compacta, SCH 23390 completely blocked orexin A–induced ambulation. These data indicate that orexin A influences time spent moving, in three brain sites utilizing separate signaling mechanisms. That orexin A modulation of spontaneous physical activity occurs in brain areas with multiple roles indicates generalization across brain site, and may reflect a fundamental mechanism for enhancing activity levels. This potential for conferring physical activity stimulation may be useful for inducing shifts in time spent moving, which has important implications for obesity.     

化合物构效关系的模糊极小极大神经网络识别研究

应用模糊极小极大神经网络研究了化合物复杂结构和性能（QSAR）之间的关系，用该法进行几组化合物致癌的识别，结果优于线性回归的方法，对此作出一些分析。     

Genetic and light intensity effects on the activity and emigratory behavior of the house fly,Musca domestica (L.)

The emigratory behavior and locomotor activity of yellow-eyed (y/y), wildtype (+/+), and heterozygous (+/y) house flies was examined at 8 fc (86 lx) and 1600 fc (17,223 lx) light intenstities. At 8 fc, emigration rate and activity of the y/y flies was similar to that of the +/+ and +/y flies. However, at 1600 fc, the y/y flies emigrated at twice the rate and showed an activity of about one-third that of the other genotypes. The behavior of the +/+ and +/y flies remained similar regardless of the experimental design or light intensity. The excessive neural stimulation by high-intensity light resulting from reduced shielding pigments led to behavioral modifications in the visual and tactile responses of the y/y flies.This research was supported in part by grants from the CUNY Faculty Research Award Program (No. 1103) and NIH Biomedical Research Support Grant 5-S05-R-07064.     

Effect of leucine-enkephalin on cerebral cortical unit activity

Experiments on unanesthetized rats immobilized with flaxedil showed that leucineenkephalin (150 g), if injected into the lateral cerebral ventricle, caused heterogeneous changes in the activity of 21 sensomotor cortical units tested. Spike discharges of five neurons were reduced and those of 11 neurons increased. Naloxone (2 mg/kg, intravenously) prevented both the inhibitor and the activating effect of leucine-enkephalin in the case of repeated injections of this pentapeptide. Leucine-enkephalin did not change the activity of five units.Department of Pharmacology, Faculties of Internal Medicine and Hygiene, I. M. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 42–44, July, 1979.     

Lateral Differences in the Latency Between Finger Tapping and the Heart Beat

Based upon suggestions that the two cerebral hemispheres may be differentially involved in the perception and regulation of autonomic activity, three studies were designed to explore differences in the relationship between left versus right hand finger tapping and the heartbeat. In each study, right-handed subjects were asked to tap with either their left versus right forefingers regularly at the rate of approximately once per second. When the time from the R-spike immediately preceding their tap to the tap was examined, a significant difference between the two hands was obtained in two of the studies, with the left hand tapping closer to the last R-spike compared with the right. A variety of additional conditions in the experiments suggest that this effect may depend upon tapping rhythmically. The implications of these findings for the differential role of the left and right hemispheres in the perception and regulation of cardiac activity are considered.     

Exploratory activity: genetic analysis of its modification by scopolamine and amphetamine

Short-term exploratory activity was found to be significantly higher in C57BL/6By than in BALB/cBy inbred mice. Scopolamine reversed the activity levels in these strains. Basal exploratory activity levels and the effects of scopolamine on this behavioral measure assessed in these two strains, their reciprocal F₁ hybrids, their recombinant inbred strains and three C57BL/6 congenic lines permitted characterization of a gene exerting a major effect on short-term exploratory activity [Exa, linked to H(w26), chromosome 4 (LG VIII)] and of a gene modulating the effects of scopolamine in this behavior, [Sco, linked to H-2, chromosome 17 (LG IX)]. Amphetamine exerted opposite effects in relation to those exerted by scopolamine on activity and its action was found to be determined by a polygenic system.