Midbrain-hypothalamic interrelationships in the control of aggressive behavior

Previous studies have suggested an involvement of the midbrain ventral tegmental area in the biting attack upon a rat elicited by electrical stimulation of the lateral hypothalamus in cats. In order assess further the relationship between these two regions, 12 cats were implanted with attack-eliciting electrodes in both the lateral hypothalamus and the midbrain ventral tegmental area. Following a lesion of the midbrain attack site, attack previously elicited from hypothalamic electrodes ipsilateral to the lesion was eliminated or significantly reduced in frequency. The attack elicited from electrodes in the hypothalamus contralateral to the lesion was unaffected. Midbrain lesions made at sites from which attack was never elicited had no effect on hypothalamically elicited attack. The midbrain lesion in some cases eliminated only certain components of the total attack pattern; for example, the approach of a cat to the rat frequently remained present while the bite was absent. Additionally, it was found that the attack elicited from rostral hypothalamic electrodes was disrupted to a greater degree by a single midbrain lesion than the attack elicited from more caudal hypothalamic electrodes. These finding are discussed in terms of the neural system mediating this form of aggressive behavior in cats.     

The neural pathways mediating quiet-biting attack behavior from the hypothalamus in the cat: A functional autoradiographic study

Electrical stimulation of the region of the lateral hypothalamus produced a consistent form of quiet-biting attack behavior in cats. In one series of experiments, cats, implanted with electrodes from which attack had been elicited, were anesthetized and then were injected with a bolus of ¹⁴C-2-deoxyglucose at the same time as electrical stimulation was delivered through the attack electrodes. Brains prepared for X-ray autoradiography revealed that lateral hypothalamic stimulation activated the classical medial forebrain bundle pathway supplying the septal region, diagonal band, lateral preoptic area, and ventral tegmental region. Stimulation of quiet-attack sites in perifornical hypothalamus resulted in the activation of a much more extensive projection system which included the central and lateral tegmental fields of the midbrain and pons, and central gray region, as well as the structures described above. In a second series of experiments, ³H-leucine was placed into the region of the electrode tip from which attack was elicited in order to identify more precisely the pathways arising from that site. In general, tritiated amino acid radioautography replicated the ¹⁴C-2-deoxyglucose findings. In addition, the amino acid radioautographic data revealed the presence of extensive projections from perifornical hypothalamus to such pontine structures as the nucleus locus coeruleus, motor nucleus of NV , and the lateral pontine tegmental field. The functional connections between the lateral hypothalamic “attack region” and lateral preoptic zone were also confirmed by electrophysiological methods.     

Transfer of an escape response from tail shock to brain-stimulated attack behavior

Nine cats, each with two hypothalamic electrodes in sites which when stimulated produced either quiet attack or attack accompanied by certain forms of vocalization, were trained to escape from tail shock by jumping onto a stool. They were then tested for transfer of the escape response to brain stimulation. Stimulation of the seven sites that yielded quiet biting attack did not elicit the learned response of jumping onto the stool. Stimulation of eight of the 11 sites that yielded attack accompanied by vocalization did elicit the learned response. It was concluded that attack behavior elicited by brain stimulation should not be considered a special case of the response to aversive stimulation, but that attack and response to aversive stimulation involve independent but overlapping systems.     

Centrally elicited aggressive behavior: A model system for the study of episodic neurobehavioral pathologies?

Studies in which the predatory-like attack of a cat upon a rat has been elicited by electrical brain stimulation have been briefly reviewed with an emphasis on the question of where within the central nervous system such brain stimulation is producing its behaviorally meaningful effects. Two opposing but by no means mutually exclusive views are considered. The first is that brain stimulation elicits this behavior pattern primarily because it affects a specific motivated behavior system that is organized discretely in the midbrain and pons. The second is that forebrain neural activity is modulated in behaviorally significant ways by brainstem stimulation, which elicits predatory-like aggressive behavior in the cat. The possibility that further research on the altered state of central nervous system activity, induced by brain stimulation which elicits aggressive behavior in the cat, may lead to a further understanding of the altered states of central nervous system activity that underlie the aggressive dyscontrol syndrome and other episodic state disorders is discussed.     

Predatory aggression: Midbrain-pontine junction rather than hypothalamus as the critical structure?

Electrical stimulation of sites in the region of the ventromedial periaqueductal gray substance at the level of the midbrain–pontine junction was found to elicit a predatory attack by a cat upon a rat. The intensity of stimulation required to elicit the attack was three to four times less than that required to elicit similar behavior by hypothalamic stimulation. The results suggest that anatomically distinct regions of the periaqueductal gray substance are concerned with the regulation of predatory and affective forms of aggressive behavior. The difficulty in reconciling these results with the preeminent role assigned the hypothalamus in the organization of predatory behavior is also discussed.     

Motivated behaviors elicited from hypothalamus, midbrain, and pons of the guinea pig (Cavia porcellus).

Eating, drinking, biting attack, male mating behavior, and gnawing were elicited by electrical stimulation through electrodes located predominantly in a region extending from the preoptic area through the lateral hypothalamus into the ventral midbrain. Escape and digging were elicited from a parallel but more medial region that overlapped the lateral zone only in the preoptic-anterior hypothalamic area. Several differentiable vocalizations were produced from sites distributed through most, although not all, areas explored. Sites yielding painlike responses were located principally in the vicinity of the presumed pain pathway traced after anterolateral cordotomy in other species. Reward was obtained from widespread sites that were generally congruent with catecholaminergic systems as described in the rat. Although there was considerable overlap of the effective zones for many responses, their underlying mechanisms were differentiated anatomically by localized differences in their distribution or functionally by the elicitation of pure responses from some electrodes. Response mechanisms localized in the brain stem of the guinea pig generally resembled those in the rat, although there were differences in details, especially in the posterior midbrain and pons.     

Effects of the cholinomimetic drug arecoline upon aggression: Intra- vs. inter-specific allocation of attack

Systemic injections of cholinomimetic drugs have been reported to induce both rage and predatory attack in several species. In order to assess the relative contribution of each of these two behavioral patterns in the control of cholinergically induced attack, a group of adult female cats was chemically stimulated in the simultaneous presence of both a prey object and a conspecific attack object. In this choice situation stimulated cats initially tended to engage in rage attack. When a second group of subjects was tested in a successive choice situation a significantly greater number of attacks occurred against conspecifics. The results suggest that cholmergic stimulation initially induces affective attack, with somewhat less frequent incidents of predation.     

Oscillatory brain dynamics, wavelet analysis, and cognition

On the basis of a systems theoretical approach it was hypothesized that event-related potentials (ERPs) are superpositions of stimulus-evoked and time-locked EEG rhythms reflecting resonance properties of the brain (Ba?ar, 1980). This approach led to frequency analysis of ERPs as a way of analyzing evoked rhythms. The present article outlines the basic features of ERP frequency analysis in comparison to ERP wavelet analysis, a recently introduced method of time-frequency analysis. Both methods were used in an investigation of the functional correlates of evoked rhythms where auditory and visual ERPs were recorded from the cat brain. Intracranial electrodes were located in the primary auditory cortex and in the primary visual cortex thus permitting "cross-modality" experiments. Responses to adequate stimulation (e.g., visual ERP recorded from the visual cortex) were characterized by high amplitude alpha (8-16 Hz) responses which were not observed for inadequate stimulation. This result is interpreted as a hint at a special role of alpha responses in primary sensory processing. The results of frequency analysis and of wavelet analysis were quite similar, with possible advantages of wavelet methods for single-trial analysis. The results of frequency analysis as performed earlier were thus confirmed by wavelet analysis. This supports the view that ERP frequency components correspond to evoked rhythms with a distinct biological significance.     

The cortical representation of centrally presented words: A magnetic stimulation study

The right and left visual fields each project to the contralateral cerebral hemispheres. The current study aimed to investigate the extent of the functional overlap of the two hemifields along the vertical meridian. We applied repetitive transcranial magnetic stimulation (rTMS) over the left and right occipital cortex to investigate whether the foveal representation of words is bilaterally represented or is split between the two hemispheres. Employing a lateralized lexical decision task, we first showed a double dissociation between the stimulated cortical site and performance; right visual field (RVF) but not left visual field (LVF) performance was impaired when the left visual cortex was stimulated, and LVF but not RVF performance was impairred when the right visual cortex was stimulated. Unilateral stimulation also significantly impaired lexical decision latencies to centrally presented words. These findings support the suggestion that foveal representation of words is split. We discuss future strategies for the use of TMS in further tests of the split representation account.     

How consumers “see” a visually warm store: Differences between affective and cognitive processors

Store atmosphere can influence shoppers' perceptions and behaviors. This research contributes to the literature by showing that a visually warm store atmosphere can induce psychological warmth perception among in‐store consumers. An empirical study was conducted to investigate the effect of warmth through a visually warm or cold store atmosphere on consumers' perceptions/behaviors and the moderating role of consumers' processing styles. Results (N = 181) showed that a visually warm (vs. cold) atmosphere induces the perception of intimacy toward the store among affective processors and the perception of assortment similarity among cognitive processors. Such perceptions were found to mediate the effect of the visually warm atmosphere on consumers' approach behaviors toward the store. Based on the grounded cognition theory, this study extends the current knowledge of the warmth experience on psychological perceptions to a retail context. Findings not only contribute to the extant literature of store atmospherics and retailing but they also offer practical guidelines for retailers and designers of store environments.     

Defensive reactions of “wild-type” and “Domesticated” wild rats to approach and contact by a threat stimulus

Selective breeding of wild rats over many generations on the basis of low or high defensive threat and attack to human approach and contact has produced highly polarized “domesticated” and “wild-type” animals. Because the selection procedure selectively involves these two defense patterns, and these clearly differ in the two groups, it is of interest to determine if other, nonselected, defensive behaviors to threat stimuli also change. “Domesticated” and “wild-type” rats of the thirty-fifth generation were run in a fear defense test battery (F/DTB) to systematically evaluate defensive behaviors to a variety of present threat stimuli. “Domesticated” rats showed reduced avoidance and slower flight speed to an approaching experimenter, reduced jump/startle response to handelap and dorsal contact, less vocalization and boxing to vibrissae stimulation or to an anesthetized conspecific, and reduced defensiveness to an attempted pickup by the experimenter. These results indicate that selective bi-directional breeding for defensive threat and attack to human approach and contact produces group differences in a variety of defensive behaviors, and in defensiveness to stimuli other than those on which the selection was based. © 1994 Wiley-Liss, Inc.     

Correlation of overt escape behavior, multiunit thalamic activity, and midbrain lemniscal stimulation in rats.

An acute and a chronic experiment were conducted in order to assess the extent to which ventral thalamic multiunit activity could account for the specific form of bar-pressing escape behavior in rats stimulated by trains of midbrain medial lemniscal pulse pairs. A paradigm used by Kestenbaum, Deutsch, and Coons was utilized in which the intra-pair interval of the train was varied. Results in anesthetized and freely moving animals indicated that midbrain lemniscal stimulation produces both an excitatory short-latency thalamic response showing the property of temporal facilitation and a long-lasting inhibitory process consistent with results of studies using anesthetized cats. The overall electrophysiological response, however, correlated significantly with the behavioral response function.     

Evolution of hemispheric specialization: advantages and disadvantages

Lateralization of the brain appeared early in evolution and many of its features appear to have been retained, possibly even in humans. We now have a considerable amount of information on the different forms of lateralization in a number of species, and the commonalities of these are discussed, but there has been relatively little investigation of the advantages of being lateralized. This article reports new findings on the differences between lateralized and nonlateralized chicks. The lateralized chicks were exposed to light for 24 h on day 19 of incubation, a treatment known to lead to lateralization of a number of visually guided responses, and the nonlateralized chicks were incubated in the dark. When they were feeding, the lateralized chicks were found to detect a stimulus resembling a raptor with shorter latency than nonlateralized chicks. This difference was not a nonspecific effect caused by the light-exposed chicks being more distressed by the stimulus. Instead, it appears to be a genuine advantage conferred by having a lateralized brain. It is suggested that having a lateralized brain allows dual attention to the tasks of feeding (right eye and left hemisphere) and vigilance for predators (left eye and right hemisphere). Nonlateralized chicks appear to perform these dual tasks less efficiently than lateralized ones. Reference is made to other species in discussing these results.     

Masked priming is abstract in the left and right visual fields

Two experiments assessed masked priming for words presented to the left and right visual fields in a lexical decision task. In both Experiments, the same magnitude and pattern of priming was obtained for visually similar (kiss-KISS) and dissimilar (read-READ) prime–target pairs. These findings provide no support for the hypothesis that word identification is mediated by separate and lateralized abstract and specific visual form systems. Strikingly, equivalent priming was observed when primes and targets were presented to the same or opposite visual fields, suggesting that priming occurs after visual information from the two hemispheres is integrated.     

Normal and abnormal visual development in kittens: insights into the mechanisms that underlie visual perceptual development in humans

For many years the mechanisms that underlie normal and abnormal development of visual perception in human infants have been explored in anatomical and physiological studies on two species of frontal-eyed mammals, namely, cats and, to a lesser extent, monkeys. The unstated assumption underlying the investigations on cats is that despite substantial differences in the organization of the visual pathways of cats and humans, as well as quantitative differences in their perceptual abilities, principles of development established in the former also apply to humans. This review examines the extent to which this assumption may be valid. Following a review of certain anatomical peculiarities of the cat visual system, several of the differences as well as the parallels between the perceptual abilities of cats and humans are summarized. The latter similarities, as well as the larger number of parallels between the two species that can be drawn during development, attest to the validity of the choice of the cat for study of the mechanisms that underlie human visual development.     

Deficits in visual learning produced by posterior temporal lesions in cats

Eight cats with lesions in the posterior temporal (PT) cortex, seven cats with lesions in the basolateral amygdala (BLA), and eight intact controls were observed on eight tests of visual discrimination learning and of spontaneous responses to salient visual stimuli. The effects of the two lesions were somewhat dissociable. The PT lesions were accompanied by a severe deficit in pattern discrimination learning but no loss in visual tracking or orientation to the silhouette of a threatening cat. The BLA lesions produced a milder and less consistent loss in pattern discrimination but serious defects in tracking and reponse to the cat silhouette. Both operated groups performed well on the visual cliff. The deficit from PT lesions appeared independent of damage to the geniculocortical system. The parallel of symptoms from PT lesions in cats and inferotemporal lesions in monkeys is discussed.     

Masked priming is abstract in the left and right visual fields

Two experiments assessed masked priming for words presented to the left and right visual fields in a lexical decision task. In both Experiments, the same magnitude and pattern of priming was obtained for visually similar (kiss-KISS) and dissimilar (read-READ) prime-target pairs. These findings provide no support for the hypothesis that word identification is mediated by separate and lateralized abstract and specific visual form systems. Strikingly, equivalent priming was observed when primes and targets were presented to the same or opposite visual fields, suggesting that priming occurs after visual information from the two hemispheres is integrated.     

Partial kindling and emotional bias in the cat: lasting aftereffects of partial kindling of the ventral hippocampus. I. Behavioral changes

Repeated electrical evocation of afterdischarges in the perforant-path ventral hippocampal system of the cat produces lasting changes in species characteristic behavioral responses to environmental threat. After 7 to 12 afterdischarges, cats showed greatly enhanced defensive (withdrawal) responses to rats, and mildly enhanced defensive responses toward mice. Measures of predatory attack which negatively correlate with withdrawal from rats were also changed in a direction consistent with the increase in withdrawal tendency. There was little effect of afterdischarges on the same parameters of attack on mice. Thus the stimulation seemed to attenuate predatory aggression by increasing defensive sensitivity to the threat posed by prey self-defense, and not by reducing predatory motivation per se. The change in defensiveness was not restricted to the predatory test situation, however. Tests of defensive response to conspecific threat vocalizations revealed an increased defensive responding to this stimulus as well. On the other hand, there was no change in social responsiveness shown toward a highly familiar human. Given the sudden onset (1 hr to 24 hr after the last afterdischarge), the long-lasting nature of the change (30-60 days) which persisted in the absence of seizures, and the generality of expression of the behavioral change, it was concluded that the afterdischarges produced an interictally maintained alteration in a defensive personality characteristic of the cats.     

Perception and imagery of faces generate similar gender aftereffects

Visual adaptation is known to bias perception away from the properties of the adapting stimuli, toward opposite properties, resulting in perceptual aftereffects. For example, prolonged exposure to a face has been shown to produce an identity aftereffect, biasing perception of a subsequent face toward the opposite identity. Such repulsive aftereffects have been observed for both visually perceived and visually imagined faces, suggesting that both perception and imagery yield typical aftereffects. However, recent studies have reported opposite patterns of aftereffects for perception and imagery of face gender. In these studies, visually perceived faces produced typical effects in which perception of androgynous faces was biased away from the gender of the adaptor, whereas imagery of the same stimuli produced atypical aftereffects, biasing the perceived gender of androgynous faces toward the gender of the adaptor. These findings are highly unusual and warrant further research. The present study aimed to gather new evidence on the direction of gender aftereffects following perception and imagery of faces. Experiment 1 had participants view and imagine female and male faces of famous and non-famous individuals. To determine the effect of concomitant visual stimulation on imagery and adaptation, participants visualized faces both in the presence and in the absence of a visual input. In Experiment 2, participants were adapted to perceived and imagined faces of famous and non-famous actors matched on gender typicality. This manipulation allowed us to determine the effect of face familiarity on the magnitude of gender aftereffects. Contrary to evidence from previous studies, our results demonstrated that both perception and imagery produced typical aftereffects, biasing the perceived gender of androgynous faces in the opposite direction to the gender of the adaptor. Famous faces yielded largest adaptation effects across tasks. Experiment 2 confirmed that these effects depended on familiarity rather than on sexual dimorphism. In both experiments, this effect was greater for perception than imagery. Additionally, imagery of famous faces produced strongest aftereffects when it was performed in the absence of visual stimulation. The implications of these findings are discussed.     

Reward versus performance in self-stimulation: electrode-specific effects of alpha-methyl-p-tyrosine on reward in the rat.

The hypothesis that alpha-methyl-p-tyrosine (AMPT), an inhibitor of catecholamine synthesis, reduces brain stimulation reward was tested, using a measure of reward previously shown to be relatively unaffected by variables that alter performance but not reward. The rewarding effectiveness of stimulation was determined by the location of the sharp rise in the function relating running speed in an alley to the number of pulses received as a reward. For some electrodes, AMPT depressed self-stimulation performance (speed of running) without producing any sizable effect on the measure of reward (location of rise). For other electrodes, the rewarding effectiveness of the stimulation was greatly reduced by AMPT and restored by L-dopa. These opposing results could be repeatedly demonstrated on different electrodes in the same rat. The electrode-specific differential sensitivity to AMPT suggests neurochemically disparate substrates for reward.