Psychobiology

Miller, Susan;Potegal, Michael;Abraham, Larry

doi: 10.3758/bf03326763pmid: N/A

Abstract Rats were trained to return to a water spout after being passively transported away from it along paths containing a 90-deg turn. Path lengths were successively increased to as much as 132 cm by a modified titration procedure. The task was successfully relearned after enucleation. Subsequent vestibular nucleus damage produced a severe, lasting deficit in this task when compared with the effects of cerebellar cortex lesions. In contrast, the vestibular lesions produced only a mild, transient impairment in an olfactory localization task. The most anterior vestibular lesions also affected air righting.

Abraham, L.;Potegal, M.;Miller, S.

doi: 10.3758/bf03326764pmid: N/A

Abstract Potegal (1972) proposed that the caudate nucleus was involved in processing sensory (especially vestibular) cues for egocentric spatial orientation. The purpose of these experiments was to determine the effect of caudate nucleus lesions on a return from passive transport (RPT) task, which has been shown to depend on vestibular input (Miller, Barnett, & Potegal, Note 1). In the first experiment, 18 male rats were trained on RPT. Six then received bilateral posterior caudate lesions, 6 received bilateral control lesions in the dorsal hippocampus, and 6 served as sham-operated controls. Postsurgical retraining revealed deficits in RPT for the caudate group, relative to hippocampal and sham groups. To test the specificity of the caudate lesion effect, a second experiment examined the effect of caudate and hippocampal lesions on an exteroceptive-cue-based spatial task, olfactory trail finding (OTF). Neither posterior caudate lesions nor dorsal hippocampal lesions produced deficits in OTF. These results suggest that the role of the posterior caudate in spatially oriented behavior is restricted to egocentric orientation based on vestibular cues. Since the caudate lesions had no effect on air-righting behavior, any vestibulostriatal contribution to RPT must be separate from the regulation of righting reflexes. This contribution may be mediated via the posterior portion of the caudate. Failure to find an effect of hippocampal lesions on RPT supports the suggestion that hippocampal involvement in spatial behavior may be restricted to memory and mapping of exteroceptive cues (O’Keefe & Nadel, 1978).

Eason, Robert G.;Oakley, Marta;Flowers, Lynn

doi: 10.3758/bf03326765pmid: N/A

Abstract Two controversial issues were investigated. One concerned the question of whether centrifugal fibers project to the human retina, and the other, the question of whether precortical filters which differentially transmit relevant and irrelevant information during selective attention exist. The issues were addressed jointly by studying the effects of selective attention on evoked responses obtained from the retina and over the occipital cortex. Selective attention was manipulated by requiring subjects to respond to stimuli presented at various locations in the visual field while attempting to ignore stimuli presented at other locations. Retinal responses to stimuli presented at attended to locations were found to be larger than those at unattended to locations. A similar result was obtained for responses recorded over the occipital cortex. The results are interpreted as follows: (1) They support the hypothesis that sustained voluntary attention to specific locations in space is mediated, at least partly, by centrally controlled centrifugal pathways which differentially modify synaptic transmission at a precortical level; (2) such differential alteration can occur as far peripherally as the retina; and (3) such alteration at the retinal level necessarily requires the existence of centrifugal optic nerve fibers. The results are discussed within the context of existing evidence bearing on the issues.

Simons, Daniel J.;Finger, Stanley

doi: 10.3758/bf03326766pmid: N/A

Abstract In an earlier study, it was found that rats with little or no sparing of sensorimotor cortex areas SmI and SmII performed extremely poorly on a battery of five tactile discriminations, whether the lesions were made on the 2nd day of life or at maturity. In contrast, infant-operated rats with 13%–28% of the anterolateral part of SmI spared performed better than adult- or infant-operated animals with larger, more complete lesions, although their learning scores were still worse than those of sham-operated animals. In order to determine whether adult-operated rats could use spared fragments of target tissue as well as the infant-operated animals could, lesions sparing 15%–31% of the same regions of sensorimotor cortex were made in mature rats that were subsequently tested for their ability to learn the discrimination problems. The results provide some support for the hypothesis that infant-operated animals can make more efficient use of spared fragments of target tissue than can their adult-operated counterparts even though, in both age groups, animals with subtotal lesions perform better than do animals with almost all or all of the sensorimotor cortex destroyed.

Thompson, Robert

doi: 10.3758/bf03326767pmid: N/A

Abstract Except for amygdaloid lesions and cortical cerebellar ablations, selective destruction of virtually any part of the tel-, di-, mes-, or metencephalon was found to impede spatial reversal learning in the rat. (These data contrast sharply with those reported in recent studies on visual reversal learning in the rat.) Test trials given after learning each reversal problem disclosed significant (or marginally significant) deficits in retention only in those groups sustaining damage to the cingulate cortex, ventral hippocampus, rostral caudoputamen, lateral supraoptic hypothalamus, posterolateral hypothalamus, lateral thalamic complex, mediodorsal thalamus, ventromedial thalamus, parafascicular nucleus, substantia nigra, interpeduncular-central tegmental area, pontomesencephalic reticular formation, or pontine reticular formation. It is proposed that there may be at least three classes of learning (amnesic) disorders observed on any given task: (1) a learning impairment only, (2) a retention impairment only, and (3) both a learning and retention impairment.

Glassman, Robert B.

doi: 10.3758/bf03326768pmid: N/A

Abstract Blindfolded cats in which SII and adjacent areas had been ablated were tested for their ability to locate cutaneous stimuli as demonstrated by their bringing the mouth into contact with the stimulated point. During recovery, seven cats went through a phase in which they displayed dissociations of the vertical and horizontal components of the orientation-localization movement: either they moved the head downward before initiating any lateral movement or they turned towards the side of stimulation well before achieving accurate proximodistal localization. Hypotheses are offered about which aspects of anatomy and physiology are involved in proximodistal and lateral localization, and a simple mathematical model is given to suggest that one reason why such central associative functions in movement may have evolved is because they require fewer neurons than an alternative conceivable design.

Ryan, Jeanne P.;Isaacson, Robert L.

doi: 10.3758/bf03326769pmid: N/A

Abstract Rats with cannulas implanted into either the nucleus accumbens or the interventricular foramen were handled or handled and injected with 0, 20, 50, 80, or 1,000 ng of ACTH1–24 and then were observed for 1 h afterwards in small testing chambers. Excessive grooming was displayed in animals that had received 80 and 1,000 ng into the nucleus accumbens, but only the 1,000-ng dose was effective in eliciting excessive grooming in animals with intraventricular injections. The excessive grooming found after the 80-ng dose of ACTH in the nucleus accumbens was similar in amount and time course to that observed when 1,000 ng was injected into the ventricular system. The results indicate that the nucleus accumbens is an effective site for ACTH1–24 as it relates to excessive grooming.

Schmajuk, Nestor A.;Spear, Norman E.;Isaacson, Robert L.

doi: 10.3758/bf03326770pmid: N/A

Abstract Rats with hippocampal, cortical, and sham lesions were trained in two simultaneous discriminations: one between two odors, and the other between two visual stimuli. One odor signaled shock and another odor “no shock,” both with probability of 1. A visual stimulus signaled shock with probability of 1, but the other visual stimulus signaled “no shock” only two-thirds of the time. In this situation, the odor dimension overshadowed the visual dimension in sham animals but not in the hippocampal-lesioned animals. No assessment can be made of the behavior of animals with only neocortical damage, since they did not learn the visual stimulus-shock association even when the visual stimulus was given alone. These results support a description of some of the sequelae of the hippocampal lesions in terms of attentional deficits.

Martin, Russell L.;Hammond, Geoffrey R.

doi: 10.3758/bf03326771pmid: N/A

Abstract Bilateral implantation of bipolar stimulating electrodes in the lateral hypothalamic area was found to be sufficient itself to disrupt a generalized aversion to NaCl in LiCl-poisoned rats. The primary aversion to LiCl remained undisturbed. This finding was confirmed in a second experiment, which also showed that electrical stimulation did not have any additional disruptive effect upon the generalized aversion. The only additional effect of stimulation was a reduction in intensity of the primary aversion. The impairment of the generalized aversion therefore appears to be an artifact of tissue damage resulting from electrode implantation. In a third experiment, it was shown that electrode implantation in the lateral hypothalamic area increases sodium preference measured in a two-bottle preference test. It is suggested that enhanced sodium appetite in implanted animals is the mechanism by which the generalized aversion to NaCl is disrupted after LiCl poisoning; such animals consume NaCl freely, but their intake of LiCl is limited due to the rapid onset of toxic reactions following consumption. The differential effect on consumption of the two substances is a result of their differential toxicity.

Thorne, B. Michael;Lin, Ker-Neng;Weaver, Maxie L.

doi: 10.3758/bf03326772pmid: N/A

Abstract Water intake, muricidal behavior, irritability to handling, and open-field activity were assessed in Long-Evans male hooded rats subjected to either septal damage or control operations. Because of a failure to observe increased water intake after septal damage, it was concluded that increased water intake was not necessary for the display of either the transient irritability or the open-field inactivity usually seen in rats with septal damage. Muricidal behavior was not seen in the present study.