Conditioning of skin conductance levels through a combined instrumental-classical conditioning procedure

A paucity of studies and inconsistent results characterize attempts to instrumentally condition tonic electrodermal activity. The present study was conducted to further explore the classical and instrumental conditioning of skin conductance levels (SCLs) through auditory analogue feedback. Fifty undergraduates were randomly assigned to one of five groups of equal size: instrumental conditioning alone, classical conditioning alone, instrumental and classical conditioning combined, and two control groups. The combined training group achieved significantly higher SCLs relative to the group receiving instrumental conditioning alone.This study was completed by the first author under the direction of the second author in partial fulfillment of the requirements for the Master of Arts degree.     

Effects of L-dopa during Auditory Instrumental Learning in Humans

The dopaminergic neurotransmitter system is critically involved in promoting plasticity in auditory cortex. We combined functional magnetic resonance imaging (fMRI) and a pharmacological manipulation to investigate dopaminergic modulation of neural activity in auditory cortex during instrumental learning. Volunteers either received 100 mg L-dopa (Madopar) or placebo in an appetitive, differential instrumental conditioning paradigm, which involved learning that a specific category of frequency modulated tones predicts a monetary reward when fast responses were made in a subsequent reaction time task. The other category of frequency modulated tones was not related to a reward. Our behavioral data provides evidence that dopaminergic stimulation differentially impacts on the speed of instrumental responding in rewarded and unrewarded trials. L-dopa increased neural BOLD activity in left auditory cortex to tones in rewarded and unrewarded trials. This increase was related to plasma L-dopa levels and learning rate. Our data thus provides evidence for dopaminergic modulation of neural activity in auditory cortex, which occurs for both auditory stimuli related to a later reward and those not related to a reward.     

Dependence of search activities on the probability of random execution of instrumental reaction

The increase in rat search activity was found to develop in early stages of the learning when probability of random performance of instrumental reaction to light was equal to 0.25. This phenomenon was not depended on duration of conditioned signal and/or/of intersignal period at the invariable probability. The probability of random performance of instrumental reaction is suggested to determine search activity and to be able to influence leaning rate.     

Conditioning of skin conductance levels through a combined instrumental-classical conditioning procedure

A paucity of studies and inconsistent results characterize attempts to instrumentally condition tonic electrodermal activity. The present study was conducted to further explore the classical and instrumental conditioning of skin conductance levels (SCLs) through auditory analogue feedback. Fifty undergraduates were randomly assigned to one of five groups of equal size: instrumental conditioning alone, classical conditioning alone, instrumental and classical conditioning combined, and two control groups. The combined training group achieved significantly higher SCLs relative to the group receiving instrumental conditioning alone.     

Searching activity under different reinforcement regimens and the process of information interaction with the environment]

When training rats in casual environmental conditions the search activity is determined by the regimen of unconditioned confirmation and the probability of a primary chance correct performance of instrumental reactions (PCCR). The value of PCCR determines what part of instrumental reactions will be realized due to a conditioned signal and confirmed appropriately. This, in its turn, influences the informational interaction of the animal with the environment in any regimen of confirmation (constant or probable). With the least favourable values of PCCR for learning a decreased number of confirmation lowers the search activity due to a sharp deterioration of the conditions for acquiring information--both factors (PCCR and low frequency of confirmation) cause single-directed changes (decrease) in informational significance of research reactions. The optimal PCCR values for learning promote informational significance of every search reaction, this leading to, weakening of the relationship between the intensity of the search activity and probability of unconditioned confirmation.     

Effect of an enkephalin-like tetrapeptide on the food instrumental behavior of rats

An enkephalin-like tetrapeptide (subcutaneous, intraperitoneal and intraventricular injections) disturbs the goal-oriented food instrumental behavior of rats by decreasing the number of adequately performed instrumental reactions. In addition to these disorders, intraventricular microinjections entail an increase in the number of inadequate, incomplete behavioral reactions. Besides, injection of the tetrapeptide evokes specific disorders of motor activity, which manifest in the occurrence in rats of stretches, "duck-like step", motor stereotypy, arching of the tail, changes in the tone of abdominal muscles, etc. The tetrapeptide effects described were not inhibited by narcan, remaining unchanged for 3.5-5 months following a single injection of the tetrapeptide.     

Mastication effort estimated by electromyography for cooked rice of differing water content

The objective of this study was to quantify the mastication effort for cooked rice. We analyzed mastication patterns while normal subjects ate a spoonful of cooked rice that had been prepared by cooking with different amounts of water (1.5, 2.0, 3.0, and 4.0 times the water to rice weight). The rice samples were served with the same weight, same volume and same solid content, and electromyography (EMG) of the masticatory muscles was measured. The texture of the four cooked rice samples was instrumentally analyzed by the two-bite method. The number of chews, masticatory time, and jaw-closing muscle activities per chew evaluated by EMG were higher in the rice sample cooked with least water, which exhibited a high firmness value in the instrumental test. Rice cooked with 4.0 times the amount of water exhibited the longest jaw-opening duration, which was related to the adhesiveness value in the instrumental test. The ratio of jaw-opening muscle activity to the preceding jaw-closing muscle activity was lower for the rice containing least water, this corresponding to the area ratio (balance degree) in the instrumental test. Softer rice containing more water reduced the total mastication effort until swallowing because it required a shorter mastication time. It was not difficult for the softer rice with high density to be ingested in greater weight, decreasing the mastication effort for a certain amount.     

Orchestration of metabolism by macrophages

Metabolic adaptation is a key component of macrophage plasticity and polarization, instrumental to their function in homeostasis, immunity, and inflammation. Macrophage products also impact metabolism, as illustrated by obesity-associated pathologies. Defining the mechanisms regulating macrophage metabolic activity and orchestration of metabolism by macrophages is crucial to pathology and therapeutic intervention.     

Emotional stress during conditioned reflex transformation of heterogeneous instrumental reflexes

The factors leading to pronounced emotional stress accompanied by changes in electrical activity of hippocampus were studied in four dogs during elaboration of conditioned switching-over of heterogeneous instrumental reflexes. Objectively recorded signs of emotional stress were observed in two cases: when the animal was not accurate enough in discerning defensive and alimentary situations and throughout the improvement of instrumental defensive reflex. Pronouncement of hippocampal theta-rhythm increased at those stages of switching-over elaboration where the probability of successful avoiding pain stimulation was relatively low. The data obtained permit the conclussion that theta-rhythm is the correlate of the degree of the emotional stress and not only a manifestation of general arousal reaction depending on the level of sensory input.     

Tonic component of the conditioned reflex process and its functional role

Tonic background activity of 266 neurones in the hippocampus and different neocortical areas was studied in freely moving rabbits in the process of defensive and food instrumental conditioned performance and during switching-over of instrumental and classical food and defensive reflexes. Associations of CS and reinforcement evoke background activity changes in most of recorded cortical neurones preceding the development of other conditioned manifestations. Conditioned reflex was performed only after reaching the background firing rate of almost every examined neurone optimal for its realization. The performance of different conditioned reflexes was associated with different background activity levels of cortical neurones. The above mentioned data form the experimental basis for the identification of the tonic component in conditioned process which reflects tonic character of temporary connection formation and function.     

Activity of neurons of the motor zone of the cortex during elaboration of a local instrumental defensive reflex in the rabbit

During instrumental defensive reaction of wrist extension in response to a sound (conditioned) stimulus, two types of neuronal responses in the rabbit motor cortex were discovered. The first type was recorded in cells with activity not connected with electromyographic activity of wrist extensors. The reaction consisted in the appearance of inhibitory response at the place of the cancelled electrocutaneous stimulation at animal's performance of conditioned reaction to sound. The second type of responses was shown for a neurone with the activity significantly related to electromyographic activity. In this case the conditioned motor response was accompanied by enhancement of the cellular activation reaction to sound and the increase of spike activity in interstimuli intervals.     

Role of Acetylcholine in the Modulation of Activity of Neocortical Neurons in Awake Animals Performing an Instrumental Conditioned Reflex

We studied modulatory effects of the cholinergic system on the activity of sensorimotor cortex neurons related to realization of an instrumental conditioned placing reflex. Experiments were carried out on awake cats; multibarrel glass microelectrodes were used for extracellular recording of impulse activity of neurons in the sensorimotor cortex and iontophoretic application of synaptically active agents within the recording region. The background and reflex-related activity was recorded in the course of realization of conditioned movements, and then changes of spiking induced by applications of the testing substances were examined. Applications of acetylcholine and carbachol resulted in increases in the intensity of impulse reactions of neocortical neurons evoked by presentation of an acoustic signal and in simultaneous shortening of the response latencies. An agonist of muscarinic receptors, pylocarpine, exerted a similar effect on the evoked activity of sensorimotor cortex neurons. Blockers of muscarinic receptors, atropine and scopolamine, vice versa, sharply suppressed impulse reactions of cortical neurons to afferent stimulation and simultaneously increased latencies of these responses. Applications of an agonist of nicotinic receptors, nicotine, was accompanied by suppression of impulse neuronal responses, an increase in the latency of spike reactions to presentation of a sound signal, and a corresponding increase in the latency of a conditioned motor reaction. In contrast, application of an antagonist of nicotinic receptors, tubocurarine, significantly intensified neuronal spike responses and shortened their latency. The mechanisms underlying the effects of antagonists of membrane muscarinic and nicotinic cholinoreceptors and the role of activation of these receptors in the modulation of activity of pyramidal and non-pyramidal neocortical neurons related to realization of the instrumental motor reflex are discussed.     

Reversal of signal significance of stimuli in the avoidance reflex]

The course of reversal learning in go -- no go avoidance reflex differentiation in both cats and dogs was analysed in terms of interrelations between drive and instrumental reflex activity. When signalling properties of the conditioned stimuli were reversed, marked changes in the drive state of experimental animals occurred. The increase of the fear drive influenced both the transfer of the instrumental response to the new positive conditioned stimulus and the extinction of the response to the previously positive stimulus. The quality of the conditioned stimuli and their reflexogenic strength exerted clear effects on the fear drive and on the course of reversal learning. Prefrontal lesions affected the drive state and the conditioned reflex activity of the animals during the reversal learning.     

The effect of the acute administration of ethanol on the realization of behavior and its neuronal support

In experiments on rabbits trained to instrumental food procuring behaviour it was cleared up, which changes of activity of neurones of the limbic cortical area corresponded to disturbances of this behaviour (increase in time of realization and in the number of errors) caused by intraperitoneal injection of 12% ethanol solution in a dose of 1 g/kg. In comparison with control (administration of isotonic solution), the number of active cells singled out in the microelectrode track was reduced by 1/3; the pattern of behavioural specialization of neurones involved in provision of the disturbed behaviour was changed. The content of neurones of the most recent systems formed during animals learning instrumental behaviour, decreased from 27 to 11%, and of neurones providing for realization of systems formed at previous stages of individual development increased from 18 to 36%.     

The interaction of mediators with protein synthesis processes in the visual cortex neurons in the goal-directed behavior of cats]

The chemical sensitivity was studied of the neurones of cats visual cortex at successive stages of food-procuring instrumental behaviour, formed in conditions of intraventricular administration of the blocker of protein synthesis the cyclohexamide. Animals with cyclohexamide had a low chemical sensitivity of the cortical neurones to microionophoretically applied solutions of acetylcholine and noradrenaline. In comparison with the intact animals, in animals with cyclohexamide the number of neurones reacting with change of the impulse activity at the stages of instrumental behaviour as well as the number of areactive cells, did not depend on the nature of the applied neurotransmitter.     

Effects of reorganization of the food-procuring behavior in the time deficit situation in primates

The organization of the food-procuring behavior inMacaca mulatto was studied under conditions of the time deficit. It has been shown that if the duration of performance of the alimentary behavior in the animals is restricted by 8 s, four ways of individual arrangement of their activity are observed: (1) stabilization of time intervals between the acts performed; (2) shift of the effectiveness of performance from the instrumental phase to the consumatory one of the reflex in the same animal in different experiments; (3) in the case of an individual experiment: an increased effectiveness of performance of one act (the instrumental or consumatory one) and a decreased effectiveness of the other; (4) an abrupt change in the tactics of motor responsiveness. All the behavioral phenomena revealed are believed to be connected with a voluntary and goal-oriented strive of the monkeys to obtain the maximal amount of food under the conditions of time deficit by way of the active (directly in the experiment) or latent (at the intersignal period) reorganization of their activity program. Deceased.     

Neuronal correlates of an alimentary instrumental conditioned reflex in rats

Elaboration of an instrumental reaction of getting the food from a narrow tube with a defnite forepaw (handedness) brings about a distinct re-distribution of cellular activity in the motor cortex and in the caudate nucleus, contralateral to the instrumental paw. The changes were observed at a 250 msec. interval before and 512 msec. interval after the beginning of the movement. Two types of cellular discharge changes were recorded: phasic and tonic. The phasic reactions (both inhibitory and activating) were grouped around the beginning of movement, with an average duration of about 100 msec. The tonic reactions lasted a few hundred milliseconds.     

Neuronal activity in the nucleus basalis magnocellularis during performance of an instrumental task

Spike activity of 95 neurons in the rabbit basal forebrain forebrain magnocellular nucleus was recorded during spontaneous behavior and instrumental conditioned performance. Almost half of the neurons (48.4%) displayed a significant (p > 0.05) negative correlation between their spontaneous discharge rate and the power of the delta rhythm in the EEG of the frontal cortex; most of these cells can be classified as projection cholinergic neurons. During instrumental conditioned performance, neurons of this subgroup responded with excitation to the conditioned stimulus, whereas presumably noncholinergic nonprojection neurons responded to the conditioned stimulus with inhibition. Excitatory response of cells in the basal forebrain magnocellular nucleus was significantly more intense as compared to trials without the conditioned reaction. On the whole, our data testify that the basal forebrain magnocellular nucleus maintains the level of arousal and attention required for the instrumental conditioned performance.     

Vibrational optical activity of oligopeptides

Vibrational optical activity (VOA) is a relatively newspectroscopic technique, which has two principal manifestations, ir vibrational CD and vibrational Raman optical activity. Progress in the study of oligopeptides using both of these forms of VOA is reviewed from the perspective of theoretical and instrumental techniques, spectral results, and structural interpretations. © 1994 John Wiley & Sons, Inc.     

Frequency of gamma activity is modulated by motivation in the auditory cortex of cat

Repetitive acoustic stimuli elicit steady-state response (SSR) in the gamma-band both in humans and in mammals. Our aim was to investigate changes of the spontaneous gamma activity and the SSR in the auditory cortex of cats in the background of an instrumental conditioning situation. Epidural electrodes were chronically implanted above the auditory neocortex. The presentation rate of the clicks varied between 20 and 65/s. Spontaneous EEG and SSR were collected in three behavioral states: in an indifferent environment, in the instrumental cage while the cat was waiting for the light CS, and when she stepped on the pedal and was waiting for the meat reward. Using different repetition rate clicks we determined which stimulus rate elicited the largest SSR in these three situations. In quiet animal the highest SSR appeared at 28-30/s. Before and during the CS the optimal stimulus rate shifted to 32-38/s. The frequency of the spontaneous gamma activity changed in parallel way depending on the situation. We conclude that both the SSR and the spontaneous gamma activity reflect resonant activity of the same neuronal circuit of the auditory cortex, and it is modulated by the motivational state of the animal.