Correction to Thomas.

Reports an error in the article "Delayed Alternation in Rats After Pre- or Postcommissural Fornicotomy" by Garth J. Thomas (Journal of Comparative and Physiological Psychology, 1978, Vol. 92, No. 6, pp. 1128-1136), on p. 1128, line 3 in the abstract, "text" should read "test." On p. 1130, the right-hand column should begin as follows: "on a deprivation regimen of about 7 g of wet mash once a day." (This abstract originally appeared in the following article see record 1980-09224-001) Investigated the contribution of the pre- and postcommissural fornices to short-term spatial memory in 15 male Long-Evans rats by evaluating the effect of small electrolytic lesions, located stereotaxically, with texts of reinforced alternation in a T-maze. Lesions in the postcommissural fornix were without behavioral effect. Ss with lesions that damaged the precommissural fornix were temporarily impaired in alternation with massed trials. They largely recovered their efficiency by the end of 5 postoperative sessions. Both the interpolation of irrelevant vestibular input (rotation) and lengthened intertrial intervals (1-4 min) reinstated an alternation deficit that had recovered in the massed-trial condition of testing. It is suggested that the recovery did not represent relearning to alternate but represented experience-dependent switching to parallel neural circuits that also mediate short-term spatial memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Damage to hippocampus and hippocampal connections: Effects on DRL and spontaneous alternation.

A total of 162 male Sprague-Dawley albino rats were tested both pre- and postoperatively either on a DRL 20-sec schedule (Exp I) or for spontaneous alternation (Exp II). Selective lesions were produced in the hippocampus and its fiber connections. Performance of both behaviors was consistently disrupted by total fornix, medial fornix, and septum lesions, while neither behavior was significantly disrupted by postcommissural fornix or entorhinal cortex lesions. Anterior hippocampus lesions consistently disrupted only DRL performance, while neither posterior hippocampus nor lateral fornix lesions resulted in consistently impaired performance of either behavior. Data suggest a possible functional differentiation between anterior and posterior portions of the hippocampal system. (44 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial mapping, working memory, and the fimbria–fornix system.

13 Long-Evans male hooded rats with lesions severing either the subcallosal fornix (Fo) or the medial half of the fimbria (Fi) were compared with 9 control (Co) and sham-operated Ss in a working memory task (serial alternation) and a reference memory task (cue-guided alternation). Neither task required spatial mapping strategy. Findings indicate that damaging the Fi, but not the Fo, caused a severe deficit in the serial alternation task. Analysis of individual performance revealed that Fi Ss either adopted a "side strategy," resulting in chance performance, or actively repeated previous successful choices, resulting in worse than chance performance. This active perseveration required an intact working-memory mechanism. In the cue-guided alternation task, Fo Ss proved superior to Co and Fi Ss. Findings are inconsistent with notions that the exclusive role of the hippocampus is spatial mapping or storing of recent memories, and indicate differential involvement of the fimbria and fornix fibers in behavior. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Running-wheel avoidance behavior following septal area lesions in rats.

Studied acquisition of a running-wheel avoidance response in 52 male Wistar rats with (a) septal lesions, (b) septal and postcommissural fornix lesions, or (c) septal, postcommissural fornix, and anterior thalamic damage. Ss with lesions confined to the septum were deficient in acquiring the avoidance response compared with both normal Ss and Ss with the more posterior lesions. Ss sustaining combined septal-fornical and septal-fornical-thalamic lesions did not differ from normal Ss or from each other in their acquisition scores. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preoperative chemotherapy followed by concurrent chemoradiation therapy based on hyperfractionated accelerated radiotherapy and definitive surgery in locally advanced non-small-cell lung cancer: mature results of a phase II trial

The ability of rats to learn the location of a hidden platform in a swim maze was compared in animals with excitotoxic lesions of the anterior or posterior (retrosplenial) cingulate cortex or radiofrequency lesions of the cingulum bundle or fimbria-fornix. Performance of this allocentric spatial task was unaffected by the posterior cingulate cortex lesions, while anterior cingulate cortex damage produced only a mild acquisition deficit. Transection of the fornix and lesions of the cingulum bundle produced similar patterns of impairment on initial acquisition, but the cingulum bundle lesions had less effect on reversal of the task. The results from the water maze, and from a subsequent T-maze alternation task, indicate that cingulum bundle lesions can produce a spatial deficit that is similar, but milder, to that observed after fornix transection. The results of the excitotoxic lesions suggest that previous studies examining conventional cingulate lesions may have been influenced by damage to adjacent fibre tracts, such as the cingulum bundle.     

Fimbria-Fornix lesions impair spatial working memory but not cognitive mapping.

Evaluated the relative merits of 2 theories of hippocampal function, the cognitive mapping theory, and the working memory theory. 49 albino male rats were tested in a series of maze tasks that varied in memory requirements. In Exps I and III, which required cognitive mapping but not working memory, Ss with fimbria–fornix lesions reached stable levels of performance that were as accurate as those of controls, and they also performed accurately during transfer tests, demonstrating that they used a cognitive mapping strategy to solve the discrimination. In Exp II, which required working memory, Ss with fimbria–fornix lesions performed at chance levels during all of postoperative testing, and they distributed their choices randomly between the correct and the incorrect goals. Results are consistent with the predictions of the working memory but not the cognitive mapping theory. Additional analyses examined the nature of a transitory impairment exhibited by Ss with fimbria–fornix lesions in 2 tasks that did not require working memory. Postoperatively, the performance of the Ss with lesions was initially impaired but recovered to normal levels with a time course similar to that seen during preoperative acquisition. Results require an extension of the working memory theory of hippocampal function, and discussion is focused on the possibility of a temporary retrograde amnesia following fimbria–fornix lesions and the distinctions between different types of memory abilities. (51 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CD28-costimulation activates cyclic AMP-responsive element-binding protein in T lymphocytes

The retrosplenial cortex (RSC) receives cholinergic afferent fibers from the medial septal nucleus and diagonal band of Broca (DBB) by way of the cingulate bundle and the fornix. Bilateral lesions of both the cingulate and fornix pathways result in a complete depletion of cholinergic input to the RSC. In the present study we have examined the effects of transplanting cholinergic neurons from fetal rat pups to the RSC of adult rats following lesions of the cingulate bundle and fornix. The animals with lesions exhibited severe spatial memory impairments with a complete loss of extrinsic cholinergic afferents to the RSC. Animals with intraretrosplenial cortical transplants exhibited significant improvements in learning and memory performance as revealed by decreased escape latencies in spatial reference memory tests, increased numbers of platform crossings in spatial navigation tests, and a higher percentage of correct choices in a spatial working memory task. These improvements appeared to be cholinergically mediated because atropine administration significantly disrupted spatial navigation performance. The survival of the transplanted cholinergic neurons and their innervation of the RSC were characterized using a monoclonal antibody to choline acetyltransferase (ChAT). The staining of graft-derived ChAT-positive fibers also revealed a pattern of innervation that mimicked that of the cholinergic input in normal animals. These results indicate that intraretrosplenial cortical transplants of cholinergic neurons can rectify spatial memory deficits produced by the loss of intrinsic cholinergic afferents from the medial septal nucleus.     

Transection of direct anterior thalamic afferents from the hippocampus: Effects on activity and active avoidance in rats.

Demonstrated the importance of the direct hippocampo-anterior thalamic component of the postcommissural fornix in the control of general locomotion and active avoidance; 40 adult male Sprague-Dawley rats were Ss in 3 experiments. Transection of anterior thalamic afferents from the hippocampal formation (subicular cortex), at the point where they exit from the fornix posterior to the septum, enhanced bidirectional active avoidance acquisition and increased general activity. This transection may also interrupt fibers to or from other thalamic nuclei and the anterior septum. However, destruction of connections of the anterior septum with the hippocampus, habenula, and thalamus by transection in the coronal plane anterior to the descending fornix columns, without damage to the subiculothalamic fibers, increased general activity levels without affecting active avoidance behavior. The activity increase in this case resembled that seen after septal lesions rather than that seen after hippocampal lesions. Thus, destruction of a single fornix component contributing afferents to the anterior thalamic nuclei reproduces at least part of the hippocampal syndrome. This suggests that these fibers contribute significantly to the control of these behaviors and may mediate active avoidance changes resulting from hippocampal and fornix damage. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lesions of the fornix and anterior thalamic nuclei dissociate different aspects of hippocampal-dependent spatial learning: Implications for the neural basis of scene learning.

The present study used 2 different discrimination tasks designed to isolate distinct components of visuospatial learning: structural learning and geometric learning. Structural learning refers to the ability to learn the precise combination of stimulus identity with stimulus location. Rats with anterior thalamic lesions and fornix lesions were unimpaired on a configural learning task in which the rats learned 3 concurrent mirror-image discriminations (structural learning). Indeed, both lesions led to facilitated learning. In contrast, anterior thalamic lesions impaired the geometric discrimination (e.g., swim to the corner with the short wall to the right of the long wall). Finally, both the fornix and anterior thalamic lesions severely impaired T-maze alternation, a task that taxes an array of spatial strategies including allocentric learning. This pattern of dissociations and double dissociations highlights how distinct classes of spatial learning rely on different systems, even though they may converge on the hippocampus. Consequently, the findings suggest that structural learning is heavily dependent on cortico-hippocampal interactions. In contrast, subcortical inputs (such as those from the anterior thalamus) contribute to geometric learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preserved negative patterning and impaired spatial learning in pigeons (Columba livia) with lesions of the hippocampus.

Pigeons (Columba livia) with bilateral electrolytic lesions of the hippocampus and area parahippocampalis were compared with control pigeons on 2 tasks: negative patterning and delayed spatial alternation. Negative patterning demands configural stimulus representations for its successful solution. The only effect of hippocampal lesions on this task was an increased response rift to the rewarded stimuli. On the delayed spatial alternation task, hippocampal birds showed deficits relative to controls. Differences in the results of prior studies on negative patterning appear to be due to different response requirements to the nonreinforced stimuli. These results are consistent with prior work with rats and suggest that the avian hippocampus is essential for spatial memory and response inhibition but is not involved in configural learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampal and amygdaloid involvement in nonspatial and spatial working memory in rats: Effects of delay and interference.

Parametric manipulations of the task demand were used to examine the role of the hippocampus and amygdala in nonspatial and spatial working memory in male rats. Hippocampal lesions produced an immediate and long-lasting impairment of nonspatial working memory in an operant task. The memory deficits increased as the delay interval and the amount of proactive interference increased. Hippocampal lesions severely impaired spatial working memory in spatial alternation. Extensive postoperative testing reduced the magnitude of impairment of nonspatial but not spatial working memory. Amygdaloid lesions did not impair any aspect of performance in 2 tasks. The results suggest that the hippocampus, but not the amygdala, is involved in working memory and the task demand is a critical determinant for observing impairments of nonspatial working memory following hippocampal lesions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pilocarpine and physostigmine attenuate spatial memory impairments produced by lesions of the nucleus basalis magnocellularis.

Three experiments, with 63 male Long-Evans rats, investigated the effects of bilateral ibotenic acid-induced lesions of the nucleus basalis magnocellularis (NBM) on the acquisition and retention of several spatial memory tasks. Maintenance of spatial memory in a food-search task was impaired following NBM lesions. Acquisition of spontaneous alternation and reinforced alternation in a T-maze, but not the acquisition of a position habit, was also significantly impaired in Ss with these lesions. In several of the tasks, there was evidence of some learning in the lesioned Ss after substantial training, although they were significantly deficient when compared with controls. Intraperitoneal administration of the cholinergic agonists physostigmine sulfate (0.5 mg/kg) or pilocarpine nitrate (3 mg/kg) prior to behavioral testing resulted in a rapid and significant improvement in the performance of the lesioned Ss. Lesions significantly reduced the activity of choline acetyltransferase in the anterior and the posterior neocortex but not the hippocampus. Results indicate that the cholinergic projections originating in the NBM are involved in the learning and memory of spatial tasks. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of the rat hippocampal system in several effects of context in extinction.

The effect of fornix lesions on some effects of manipulating the context on performance in extinction were studied. In renewal, subjects' responding to an extinguished CS recovered when the CS was presented in the context in which it had been conditioned after extinction in a different context. In reinstatement, it recovered when the CS was tested after independent presentation of the unconditioned stimulus (UCS; an effect mediated by contextual conditioning.) In spontaneous recovery, it recovered after the passage of time, that is, when the CS was tested in a new temporal context. In the conditioned suppression method, fornix lesions had no effect on conditioning, extinction, renewal, or spontaneous recovery; however, they abolished the reinstatement effect. The results suggest that the hippocampal system may be important in the formation of context–UCS associations, but not in other types of learning about the context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Double dissociation of function within the hippocampus: Spatial memory and hyponeophagia.

Complete and dorsal hippocampal lesions impaired spatial performance on 2 working memory tasks: rewarded alternation on the T maze and matching to position in the water maze. In contrast, ventral hippocampal lesions had no effect on these tasks, even when task difficulty was increased by the introduction of delays. Ventral lesions did resemble complete lesions in reducing anxiety in 3 commonly used tests of anxiety (social interaction, plus-maze, and hyponeophagia). Dorsal lesions also appeared to be anxiolytic in the social interaction and plus-maze tests, but they did not affect hyponeophagia. Complete- and dorsal-lesioned rats displayed hyperactivity, whereas ventral-lesioned rats did not. These results show a double dissociation between dorsal and ventral hippocampal lesions (hyponeophagia vs. spatial memory), suggesting differentiation of function along the septotemporal axis of this structure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of the mesocortical dopaminergic system on activity, food hoarding, social-agonistic behavior, and spatial delayed alternation in male rats.

In order to assess the behavioral role of the dopaminergic mesocortical input to the prefrontal cortex, bilateral lesions were made in the ventral tegmental area (VTA). The possibility of a functional recovery by the administration of a dopamine agonist was examined. General activity, food hoarding, social–agonistic behavior, and spatial delayed alternation performance were recorded in rats with VTA lesions and in sham-operated animals. In the open field animals with VTA lesions were more active but showed less anxiety. Food hoarding was impaired. In dyadic interactions with sham-operated opponents, VTA rats were socially more active, whereas sham operates performed more keeping down and aggressive grooming. This behavioral deficit was partially recovered when apomorphine was administered prior to testing. VTA animals were impaired in the performance of a spatial delayed alternation task with an intertrial interval of 15 sec, whereas no impairment was found with a 0-sec intertrial interval. The theoretical implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning and Retrieval of Concurrently Presented Spatial Discrimination Tasks: Role of the Fornix.

In macaque monkeys (Macaco mulatta), memory for scenes presented on touch screens is fornix dependent. However, scene learning is not a purely spatial task, and existing direct evidence for a fornix role in spatial memory comes exclusively from tasks involving learning about food-reward locations. Here the authors demonstrate that fornix transection impairs learning about spatial stimuli presented on touch screens. Using a new concurrent spatial discrimination learning task, they found that fornix transection did not impair recall of preoperatively learned problems. Relearning, on the other hand, was mildly impaired, and new learning was strongly impaired. New learning of smaller sets of harder problems was also markedly impaired, as was spatial configured learning. This pattern supports a functional specialization according to stimulus domain in the medial temporal lobe. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Double dissociation of fornix and caudate nucleus lesions on acquisition of two water maze tasks: Further evidence for multiple memory systems.

Examined the effect of lesions of the caudate nucleus or fimbria-fornix on the acquisition of 2 water maze tasks. In both tasks, 2 rubber balls with different visual patterns were used as cues. The correct cue was attached to a submerged rectangular platform and could be mounted by an animal to escape the water. The incorrect cue was attached to a thin round pedestal and could not be mounted. In a spatial version of the task, the correct cue was located in the same quadrant of the maze on all trials, whereas the visual pattern on the cue was varied from trial to trial. Lesions of the fornix, but not the caudate nucleus, impaired acquisition of this spatial task in relation to control animals. In a simultaneous visual discrimination version of the task, the correct cue on all trials was one with a specific visual pattern, and the spatial location of the correct cue was varied from trial to trial. Lesions of the caudate nucleus, but not the fornix, impaired acquisition of this visual discrimination task in relation to control animals. The double dissociation observed supports the hypothesis that the hippocampus and caudate nucleus are parts of systems that differ in the type of memory they mediate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition impaired and association intact in the memory of monkeys after transection of the fornix.

Three rhesus monkeys with transection of the fornix were compared with 3 operated control monkeys in 4 memory tasks. They were tested repeatedly at each task until a stable level of performance was achieved. Ss with transection of the fornix were severely impaired in the 3 tasks that tested recognition memory and unimpaired in a test of pure associative memory which was very similar in all but the essential respects to one of the recognition tasks. It is suggested that damage to the hippocampal system in monkeys causes an anterograde amnesia comparable to that observed in human patients with similar lesions and consisting in a specific deficit of recognition memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery of delayed alternation in rats after lesions in medial frontal cortex and septum.

Two experiments using contingently reinforced T-maze alternation with 48 male Long-Evans and hooded rats found that (a) normal Ss, after achieving high accuracy in alternation with brief (0 sec) intertrial intervals (ITIs), dropped to chance levels with longer ITIs (90 sec) but reacquired effective alternation with additional practice; (b) small lesions in mediodorsal pregenual cortex had no effect on postoperative retention of alternation at either short or long ITIs; (c) however, small lesions in posterodorsal septum temporarily disrupted alternation at brief ITIs, whereas at long ITIs Ss chose randomly and never recovered; and (d) large lesions in medial frontal cortex disrupted retention of alternation at brief ITIs of 10 sec but significant recovery did occur with additional experience. Implications regarding task difficulty and locus of lesion for recovery of function are discussed. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampal system dysfunction and odor discrimination learning in rats: Impairment of facilitation depending on representational demands.

The performance of normal rats and that of rats with hippocampal system damage were compared on acquisition of different versions of the same two-odor discrimination task that placed different encoding and representational demands on memory. Rats with fornix lesions were impaired when explicit comparisons among multiple odor cues and differential response choices were encouraged. However, when odor-cue comparisons was hindered and explicit cues for response choice were eliminated, rats with fornix lesions out performed normal animals. The results support a hypothesis that the hippocampal system is critical to a memory representation based on encoding relations among multiple percepts, and other brain systems support performance adaptations based on encodings of stimuli individually. (PsycINFO Database Record (c) 2010 APA, all rights reserved)