Search results for "Stimulus"
showing 10 items of 555 documents
Reward Unpredictability inside and outside of a Task Context as a Determinant of the Responses of Tonically Active Neurons in the Monkey Striatum
2001
Tonically active neurons (TANs) in the monkey striatum are involved in detecting motivationally relevant stimuli. We recently provided evidence that the timing of conditioned stimuli strongly influences the responsiveness of TANs, the source of which is likely to be the monkey's previous experience with particular temporal regularities in sequential task events. To extend these findings, we investigated the relationship of TAN responses to a primary liquid reward, the timing of which is more or less predictable to the monkey either outside of a task or during instrumental task performance. Reward predictability was indexed by the timing characteristics of the mouth movements. The responsive…
Hippocampal ripple-contingent training accelerates trace eyeblink conditioning and retards extinction in rabbits.
2010
There are at least two distinct oscillatory states of the hippocampus that are related to distinct behavioral patterns. Theta (4–12 Hz) oscillation has been suggested to indicate selective attention during which the animal concentrates on some features of the environment while suppressing reactivity to others. In contrast, sharp-wave ripples (∼200 Hz) can be seen in a state in which the hippocampus is at its most responsive to any kind of afferent stimulation. In addition, external stimulation tends to evoke and reset theta oscillation, the phase of which has been shown to modulate synaptic plasticity in the hippocampus. Theoretically, training on a hippocampus-dependent learning task conti…
RESOLVING AMBIGUITIES IN ORIENTATION, MOTION, AND DEPTH DOMAINS
1992
Three different perceptual systems—orientation, motion, and depth—can recover a global perceptual organization from spatially correlated random multielement patterns. In all three cases the global structure composed of random elements is evaluated by mechanisms performing measurements in the energy domain within appropriately defined local space—time areas. The selective increase in energy of one fraction of the elements may dramatically change the whole perceptual organization of the stimulus. In specially devised patterns one and the same element can belong to two or more separate perceptual organizations, the perceptual salience of one of which can be reinforced by a luminance increment…
Refining the dual olfactory hypothesis: Pheromone reward and odour experience
2009
In rodents, sexual advertisement and gender recognition are mostly (if not exclusively) mediated by chemosignals. Specifically, there is ample evidence indicating that female mice are ‘innately’ attracted by male sexual pheromones that have critical non-volatile components and are detected by the vomeronasal organ. These pheromones can only get access to the vomeronasal organ by active pumping mechanisms that require close contact with the source of the stimulus (e.g. urine marks) during chemoinvestigation. We have hypothesised that male sexual pheromones are rewarding to female mice. Indeed, male-soiled bedding can be used as a reinforcer to induce conditioned place preference, provided co…
Temporal refinement of sensory-evoked activity across layers in developing mouse barrel cortex.
2019
Rhythmic whisking behavior in rodents fully develops during a critical period about 2 weeks after birth, in parallel with the maturation of other sensory modalities and the onset of exploratory locomotion. How whisker-related sensory processing develops during this period in the primary somatosensory cortex (S1) remains poorly understood. Here, we characterized neuronal activity evoked by single- or dual-whisker stimulation patterns in developing S1, before, during and after the occurrence of active whisking. Employing multi-electrode recordings in all layers of barrel cortex in urethane-anesthetized mice, we find layer-specific changes in multi-unit activity for principal and neighboring b…
Cortisol reactivity in social anxiety disorder: A highly standardized and controlled study.
2020
Abstract In order to understand the psychopathology of the social anxiety disorder (SAD) at the neuroendocrine level, standardized experimental studies on endocrine and physiological markers are necessary, especially since empirical data are still ambiguous. Hence, differences in both, the autonomic nervous system (ANS) and the endocrine stress responses (ACTH, salivary and plasma cortisol) were investigated in a particularly homogenous sample after a standardized stressor (Trier Social Stress Test). The sample consisted of n = 35 patients with SAD, age, and gender matched to n = 35 healthy controls (HC). In terms of the heart rate, the response pattern was comparable in both groups. Conc…
Coupling between simultaneously recorded BOLD response and neuronal activity in the rat somatosensory cortex
2007
Abstract Understanding the link between the hemodynamic response and the underlying neuronal activity is important for interpreting functional magnetic resonance (fMRI) signals in human and animal studies. Simultaneous electrophysiological and functional imaging measurements provide a knowledge of information processing and communication in the brain with high spatial and temporal resolution. In this study, a range of neural and blood oxygenation level-dependent (BOLD) responses were elicited in the rat somatosensory cortex by changing the type of anesthesia (urethane or alpha-chloralose) and the electrical forepaw stimulus frequency (1–15 Hz). Duration of the stimulus was 30 s. Electrical …
State-dependent changes in auditory sensory gating in different cortical areas in rats.
2015
Sensory gating is a process in which the brain's response to a repetitive stimulus is attenuated; it is thought to contribute to information processing by enabling organisms to filter extraneous sensory inputs from the environment. To date, sensory gating has typically been used to determine whether brain function is impaired, such as in individuals with schizophrenia or addiction. In healthy subjects, sensory gating is sensitive to a subject's behavioral state, such as acute stress and attention. The cortical response to sensory stimulation significantly decreases during sleep; however, information processing continues throughout sleep, and an auditory evoked potential (AEP) can be elicite…
Stimulus Evaluation, Event Preparation, and Motor Action Planning in Young Patients With Mild Spastic Cerebral Palsy: An Event-Related Brain Potentia…
2012
The study investigated stimulus evaluation time, event preparation, and motor action planning of patients with mild spastic cerebral palsy and a peer control group in the age range of 9 to 18 years. To this end, participants were carrying out a stimulus recognition task. Findings indicated an overall slowness and inaccurate reaction time performance of the patient group. An event-related potential analysis revealed that the stimulus evaluation processing, indexed by the parietal P300, was intact in the group of patients. Also event preparation and action planning, indexed by respectively the frontal late contingent negative variation and the frontal P2, were intact in the group of patients…
Event-related potentials in newborns with and without familial risk for dyslexia: principal component analysis reveals differences between the groups
2003
Differences revealed by factor scores extracted by principal component analysis (PCA) from event-related potential (ERP) data of newborns with and without familial risk for dyslexia were examined and compared to results obtained by using original averaged ERPs. ERPs to consonant-vowel syllables (synthetic /ba/, /da/, /ga/; and natural /paa/, /taa/, /kaa/) were recorded from 26 at-risk and 23 control 1-7 day-old infants. The stimuli were presented equiprobably and with interstimulus intervals varying at random from 3,910 to 7,285 ms. Statistically significant between-group differences were found to be relatively similar irrespective of the methods of analysis (original ERPs vs. factor scores…