Specific Stimulus Features Research Articles

Adult Learning and Mate Choice: Possibilities and Experimental Evidence

A critical issue in the study of mate choice is the analysis of the stimuli that elicit and regulate sexual behavior. Studies with Japanese quail, several mammalian species, and a fish species (the blue gourami) indicate that the stimulus control of sexual behavior is determined in part by what animals learn as a result of sexual interactions in adulthood.Species specific stimuli provided by a sexual partner can become conditioned by sexual reinforcement and thereby come to elicit more vigorous social behavior. Discrete localized stimuli as well as spatial contextual cues of the environment in which social interactions occur can also become conditioned. Sexually conditioned localized stimuli may elicit approach and?/or courtship conditioned responses and may increase responding to species specific eliciting stimuli provided by a sexual partner. Sexually conditioned contextual stimuli also may increase responding to species specific stimulus features of a sexual partner. These findings indicate that the features of a conspecific to which an animal responds sometimes may be determined by what that animal has learned as a result of sexual experience. The findings also suggest that a complete account of the stimulus control of sexual behavior requires consideration of not only stimulus aspects of conspecifics that elicit sexual responses but also discrete and contextual environmental stimuli that may become associated with sexual experience.

Cross-modality transfer effects in conditioning-enhanced neophobia in chicks (Gallus domesticus): Evidence for the separability of novelty from specific stimulus characteristics

In this study, we investigated the separability of novelty from specific stimulus characteristics (e.g., color or taste quality) in the transfer of aversion effects. Ninety-six chicks (Gallus domesticus) received a novel visual (red water) or taste (3.0% vinegar) CS paired with an injection of lithium chloride or saline. The chicks were then tested for aversion to the CS or for conditioning-enhanced neophobia in response to a different novel visual cue (green water) or taste cue (1.0% saline). Aversions to the CSs were reliable and similar to each other. Reliable evidence of conditioning-enhanced neophobia occurred with respect to each test stimulus, irrespective of the type of CS, but conditioning with the vinegar CS produced reliably greater enhancement of neophobia than did conditioning with red water. For each CS, postconditioning neophobia was more persistent in testing with saline than with green water. The results for postconditioning neophobia suggested that novelty is a general stimulus property that is separable from specific stimulus characteristics.

Properties of the evoked potential generators: current source-density analysis of visually evoked potentials in the cat cortex.

The depth profiles of visually evoked field potentials were recorded in areas 17 and 18 of the cat visual cortex. For comparison, potential profiles evoked by electrical stimulation of the primary afferents and of the nonspecific reticular system were also recorded. From these profiles the current source-density (CSD) distributions were calculated using the one-dimensional CSD method. CSD distributions evoked by the different types of stimuli differ in their amplitudes and time courses by approximately one and two orders of magnitude. Qualitatively, however, they are very similar. Thus, the CSDs can be interpreted as reflecting the same basic pattern of excitatory synaptic activations. This pattern consists of early activation components in the input layers, followed by excitatory synaptic activations in layer III, then in layer II, and in layer V. The basic pattern of cortical activation was found to be modulated by specific features of the visual stimuli. Modulations reflecting contour-versus contrast-contents as well as those reflecting characteristic features of moving patterns have been identified. Most of the CSD components of the cortical activation sequence were obtained from regions extending well beyond the cellular receptive fields in visual cortex. Thus, they reflect nonretinotopic activities. Parameters other than specific features of the visual stimuli have profound influence on cortical CSDs. Nonspecific parameters which have been considered are the general state of cortical excitability, the temporal interactions of successive activities (which are predominantly facilitatory), and the lateral interactions of simultaneous activations from different regions of the visual field (predominantly inhibitory).

The electric sense of weakly electric fish.

Recent studies of electroreception have been particularly successful in three different areas: Electroreceptors are tuned to the dominant frequency of the animal's EOD, and their tuning follows natural and experimentally induced shifts in EOD frequency. Steroid hormones influence the electric organ pacemaker frequency in the genus Sternopygus, and the tuning of electroreceptors will follow hormone-induced frequency shifts only if the receptors experience the animal's EOD. The frequency tuning of electroreceptors reveals properties similar to those of cochlear hair cells, and electroreceptors may be suitable model systems for in vitro studies of cellular and molecular aspects of electrical filter mechanisms in hair cells. In contrast to the South American or gymnotoid electric fish, the African or mormyrid electric fish evaluate electroreceptive information with the help of corollary discharges of their electric-organ pacemaker. The corollary discharge inhibits input from knollenorgan receptors so that, in the context of social communication, the animal only perceives EODs of neighbors but not its own. The corollary discharge at the same time enhances input from most mormyromasts so that the animal, in the context of electrolocation, selectively receives feedback from its own EODs. Finally, responses of ampullary electroreceptors to the animal's own EODs are centrally nulled by an elaborate and modifiable efference copy so that the animal is only informed about "nontrivial", low-frequency events in its environment. Laminated and topographically organized structures in the hindbrain and midbrain of gymnotoid fish are being studied with regard to neuroanatomical fine structure and functional organization. Different laminae and cell types in the hindbrain are specialized for the extraction of specific stimulus features, such as modulations of phase or amplitude in a sinusoidal stimulus regime. This information is passed on to the midbrain for the computation of more complex stimulus variables, such as the difference in phase modulations reported from different parts of the body surface. The torus semicircularis of the midbrain is designed for parallel processing of information from different parts of the body surface and for parallel computation of different stimulus variables for the control of behavioral responses. Electrical and visual information converge in the tectum opticum, which harbors a multimodal representation of sensory space.

Textural segmentation, second-order statistics, and textural elements.

Beck (1972, 1973) hypothesized that textural segmentation occurs strongly on the basis of simple properties such as brightness, color, size, and the slopes of contours and lines of the elemental descriptors of a texture or textural elements. The experiment reported supports the hypothesis that specific stimulus features, rather than second-order statistics, account for textural segmentation. The results agree with Julesz (1981a,b) who has reported evidence disproving his original conjecture of the importance of second-order statistics. Julesz (1981a,b) now hypothesizes textural segmentation to be a function of local features which he called textons. Textons are features that give textural segmentation when textures have identical second-order statistics. The two hypotheses are to date in complete agreement on the stimulus features producing textural segmentation, and the experiment reported is consistent with both.

Stimulus-response profile analysis: a comprehensive, quantitative approach to the study of sensory coding and information processing

In order to understand the coding and information processing capabilities of mechanosensory neurons, it is necessary to examine stimulus-response relationships under a wide variety of stimulus conditions, using a comprehensive set of quantitative analytic procedures. We employ the methodology of stimulus-response profile analysis, which is based on 4 principles: (1) the use of a broad-based battery of quantitatively controlled mechanical stimuli; (2) maintenance of comprehensive records of experiments; (3) detailed, quantitative analysis of single-unit responses; and (4) the application of these principles uniformly and consistently to all units studied. In addition to conventional graphical portrayals of single-unit activity, we employ a set of quantitative response indices, each of which represents a particular aspect of a unit's overall responsiveness. The distribution of a response index for the entire sample of neurons examined in a particular population offers insight into the manner in which a specific stimulus feature is represented within that population. The distributions of response indices obtained from different neural populations can be compared statistically in order to evaluate interpopulation differences in stimulus-response relationships. This comprehensive, quantitative approach is capable of demonstrating significant, although subtle, interpopulation differences which are not revealed by more cursory, qualitative methods.

Responses of high-frequency movement detector neurons in dragonfly larvae to motion of single objects

Neurons of the class described respond by a discharge with a frequency of 150–250/sec to motion of single objects in a large receptive field. The response depends directly on the size of the object. The neurons are selectively sensitive to motion of dark objects. Widening a dark border (bringing a black disc closer) evokes a stronger response than narrowing a dark border (moving a white disc further away). The response to uniform movement consists of high-frequency volleys of discharges separated by pauses. Repeated movements along the same trajectory induce habituation; after cessation of the movements sensitivity is restored with a time constant of about 30 sec. The role of lateral inhibition and local habituation in the identification of the specific features of optical stimuli is discussed.

Visual properties of neurons in inferotemporal cortex of the Macaque.

IN THE LAST DEC,ADE, considerable progress has been made in understanding the physiology of one of the most fundamental aspects of human experience: perception of the visual world. It is now clear that the retina and visual pathways do not simply transmit a mosaic of Iight and dark to some central sensorium. Rather, even at the retinal level, specific features of visual stimuli are detected and their presence communicated to the next level. In cats and monkeys, the geniculostriate visual system consists of a series of converging and diverging connections such that at each successive tier of processing mechanism, single neurons respond to increasingly more specific visual stimuli falling on an increasingly wider area of the retina (19-Z). How far does this analytical-synthetic process continue whereby individual cells have more and more specific trigger features? Are there regions of the brain beyond striate and prestriatel cortex where this processing of visual information is carrie,d further? If so, how far and in what way? Are there cells that are concerned with the storage of visual information as well as its analysis? There are several lines of evidence suggesting that a possible site for further processing of visual information and perhaps even for storage of such information might, in the monkey, be inferotemporal cortexthe cortex on the inferior convexity of the temporal lobe. First, this area receives afferents from prestriate cortex which itself processes visual information received from

Development of self-control using Premack's differential rate hypothesis: A case study

Premack in his theory of reinforcement (1959) focuses on the frequency of occurrence of responses rather than upon specific stimulus characteristics. Simply stated, for any pair of responses, the more probable one will reinforce the less probable one. One clinical implication of the Premackian hypothesis is in terms of “self-control” : using one type of behavior to control other types of behavior (Holland and Skinner, 1961). In this conceptualization of “self-control”, if the emission of a high-frequency reinforcing response is made contingent upon the emission of a low-frequency appropriate response, then the latter should increase in its frequency of occurrence; concurrently, the non-reinforced inappropriate response should decrease in its frequency of occurrence. In a clinical situation, developing procedures within this framework could maximize the efficiency of therapist-patient contacts; particularly, when the purpose is one of the patient learning to control and/or eliminate inappropriate behavior (Homme. DeBaca, Devine, Steinhorst, and Ricken. 1963; Goldiamond, 1965; Greenspoon and Brownstein, 1967). The programming of such a technique necessitates two considerations: selection and measurement of the responses involved. In terms of response-selection, an ideal low frequency response would be one incompatible with the inappropriate response to be conttolled. The high frequency, reinforcing response, for purposes of long-term effects and generalization from the specific learning situation, should be one already existing in the individual's behavioral repertoire (Ferster, 1967). Three operations are implied in the measurement process (Premack. 1959; McIntire, 1963): independent measurements of the respective frequencies of the selected responses, programming a situation which would insure the two responses occurring repeatedly in a contingent order, and some measure of the first response which would reflect an increment in frequency as a result of such pairing.

Effective stimuli for pattern discrimination in monkeys

Rhesus monkeys were trained and tested for pattern equivalence in an operant situation and in a Wisconsin General Test Apparatus (WGTA), In the operant situation, Ss’ utilization of specific stimulus features varied, while in the WGTA cue utilization was more consistent between Ss. These differences in cue utilization were attributed to stimulus-response relationships.