Rats with damage to the hippocampal-formation are impaired on the transverse-patterning problem but not on elemental discriminations.

We assessed the effects of hippocampal-formation (HF) damage on the rat's ability to learn two sets of concurrent visual discriminations. Each set included three problems. One set, called the transverse-patterning problem, was constructed so that each choice stimulus was ambiguous; sometimes it was the correct (+) and sometimes it was the incorrect (–) choice as follows: A+ vs B–, B+ vs C–, and C+ vs A–. It could not be solved unless rats used configural associations. The stimuli were not ambiguous in the second, elemental problem set, A+ vs B–, C+ vs D–, and E+ vs F–. Rats could solve this set without the use of configural associations. Rats with HF damage solved the set of elemental problems, but their performance on the transverse-patterning problem was impaired. These results support Sutherland and Rudy's (see record 1989-38933-001) theory that the hippocampal formation is critical for the acquisition of configural associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fornix lesions can facilitate acquisition of the transverse patterning task: a challenge for "configural" theories of hippocampal function

Configural theories of hippocampal function predict that hippocampal dysfunction should impair acquisition of the transverse patterning task, which involves the concurrent solution of three discrimination problems: A+ versus B-; B+ versus C-; and C+ versus A-. The present study tested this prediction in rats using computer-graphic stimuli presented on a touchscreen. Experiment 1 assessed the effects of fornix lesions when the three problems were introduced sequentially (phase 1: A+ vs B-; phase 2: A+ vs B-, B+ vs C-; phase 3: A+ vs B-, B+ vs C-, C+ vs A-). Fornix lesions significantly facilitated acquisition of the complete transverse patterning task (phase 3) but had no effect on the number of sessions or errors required to attain criterion during phase 1 or phase 2. In experiment 2, in which all three problems were presented concurrently from the outset of training, fornix-lesioned animals outperformed control animals during the seventh block of acquisition trials and were not impaired during any stage of acquisition. Importantly, these same animals were significantly impaired on two allocentric spatial tasks: T-maze alternation (experiments 1 and 2) and the Morris Swim Task (experiment 1). These results contradict the predictions of configural theories of hippocampal function and cast doubt on the popular notion that spatial learning is a special case of configural learning.     

Configural learning in two species of marsupial (Setonix brachyurus and Sminthopsis crassicaudata).

Four experiments examined the ability of quokkas (Setonix brachyurus) and fat-tailed dunnarts (Sminthopsis crassicaudata) to solve 2 configural tasks: transverse and negative patterning. Transverse patterning requires the simultaneous solution of 3 overlapping discrimination problems (A+B-, B+C-, C+A-). Both species could solve the nonoverlapping (elemental) version of this task (U+V-, W+X-, Y+Z-), but only dunnarts solved the transverse patterning task. Negative patterning requires conditioned responses to 2 stimuli when presented separately but not together (A+, B+, AB-). Both species formed a selective conditioned response to A+ and B+ stimuli and inhibited responding to a simple nonreinforced stimulus (C-), but only dunnarts successfully inhibited responding to the AB- compound to solve the negative patterning task. These experiments are the first to demonstrate configural learning in a marsupial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discriminating the stimulus elements during human odor–taste learning: A successful analytic stance does not eliminate learning.

Odor “sweetness” may arise from experiencing odors and tastes together, resulting in a flavor memory that is later reaccessed by the odor. Forming a flavor memory may be impaired if the taste and odor elements are apparent during exposure, suggesting that configural processing may underpin learning. Using a new procedure, participants made actual flavor discriminations for one odor–taste pair (e.g., Taste A vs. Odor X–Taste A) and mock discriminations for another (e.g., Odor Y–Taste B vs. Odor Y–Taste B). Participants, who were successful at detecting the actual flavor discriminations, demonstrated equal amounts of learning for both odor–taste pairings. These results suggest that although a capacity to discriminate flavor into its elements may be necessary to support learning, whether participants experience a configural or elemental flavor representation may not. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Hippocampal lesions do not impair negative patterning: A challenge to configural association theory.

According to configural association (CAS) theory (R. J. Sutherland and J. W. Rudy; see record 1989-38933-001), an intact hippocampus is required for rats to solve learning problems that are based on "configural" processes. This theory identifies the negative patterning discrimination as a critical example of this type of problem. Rudy and Sutherland (see record 1990-03930-001) reported disruption of negative patterning following hippocampal formation damage produced by intracranial infusion of a mixture of kainic acid?+?colchicine (KA?+?COL). Acquisition of negative patterning was assessed in rats with hippocampal damage produced by KA?+?COL compared with rats with more selective ibotenate lesions of hippocampus. Neither group showed impaired negative patterning relative to controls. A transfer test provided evidence that all groups used configural processes to solve the problem. Thus contrary to CAS theory, the hippocampus is not an important substrate for the operation of configural processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of similarity in human associative learning.

In 2 experiments, humans received sequences of patterns that were similar (AX→BX, AY→BY, AZ→BZ) or dissimilar (CX→DY, CY→DZ, CZ→DX). The patterns were portrayed as bugs that could be eliminated with 2 insecticide sprays (red or blue). Either spray eliminated bugs with Features A and C, and participants learned by trial and error to use one spray (e.g., red) to eliminate bugs with Feature B and the other spray (e.g., blue) to eliminate those with Feature D. In Experiment 1, participants' spray choice for bugs with Feature A came to match that used to eliminate bugs with Feature B, but there was no such associative transfer between Features C and D. That is, similarity promoted associative transfer of responding between paired patterns when the features used to manipulate similarity (i.e., X, Y, and Z) were irrelevant. In Experiment 2, in which X, Y, and Z were relevant to the solution of configural discrimination, similarity hindered such associative transfer. These results complement those found in pigeons (R. A. Rescorla & D. J. Gillan, 1980) and indicate that similarity should not be accorded independent status as a principle of associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Value transfer in a simultaneous discrimination appears to result from within-event Pavlovian conditioning.

When pigeons acquire a simple simultaneous discrimination, some of the value acquired by the S+ transfers to the S–. The mechanism underlying this transfer of value was examined in three experiments. In Experiment 1, pigeons trained on two simultaneous discriminations (A?+?B– and C?+?D–) showed a preference for B over D. This preference was reduced, however, following the devaluation of A. In Experiment 2, when after the same original training, value was given to D, the pigeons' preference for C did not significantly increase. In Experiment 3, when both discriminations involved partial reinforcement (S±), A?+?C– training resulted in a preference for B over D, whereas B?+?D– training resulted in a preference for A over C. Thus, simultaneous discrimination training appears to result in bidirectional within-event conditioning involving the S+ and S–. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer of value from S+ to S- in a simultaneous discrimination.

Value transfer theory has been proposed by L. von Fersen et al (see record 1991-29523-001) to account for transitive inference effects, in which following training on 4 simultaneous discriminations (A?+?B–, B?+?C–, C?+?D–, D?+?E–) pigeons showed a preference for B over D. According to this theory, some of the value of reinforcement acquired by each stimulus always associated with reinforcement (S+) transfers to the stimulus associated with nonreinforcement (S–). In the transitive inference experiment, C (associated with both reward and nonreward) could transfer less value to D than A (associated only with reward) could transfer to B. Support for value transfer theory was demonstrated in 2 experiments, involving a total of 20 pigeons, in which an S– presented in the context of an S+ was preferred over an S– presented in the context of a stimulus to which responses were sometimes reinforced (S±). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Carolina rinse and adenosine rinse on microvascular perfusion and intrahepatic leukocyte-endothelium interaction after liver transplantation in the rat

Flushing hepatic grafts immediately before revascularization with a specially designed rinse solution such as "Carolina rinse" has been reported to improve survival after liver transplantation in the rat. This study investigated the influence of Carolina rinse and adenosine rinse on early graft function, microcirculation, and leukocyte (WBC)-endothelial cell interaction of arterialized syngeneic orthotopic liver transplants in Lewis rats. Livers were preserved for 24 hr in University of Wisconsin solution and flushed immediately before reperfusion with either Ringer's lactate (group A: n = 7), Ringer's lactate + 0.2 mmol/liter adenosine (group B: n = 6), or Carolina rinse (group C: n = 7). Microvascular perfusion and WBC accumulation were assessed by intravital fluorescence microscopy. In group C, acinar perfusion was significantly improved, accompanied by a lower percentage of nonperfused sinusoids 1 hr after reperfusion (mean +/- SEM: 26 +/- 2% [group A], 21 +/- 2% [B], 11 +/- 1% [C], P < 0.01 for C vs. A or B). In addition, Carolina rinse and, to a lesser extent, adenosine rinse reduced the number of WBC sticking in sinusoids and postsinusoidal venules. Better graft function in group C was indicated by increased bile flow during the observation period of 90 min after reperfusion (0.5 +/- 0.3 ml/100 g liver [group A], 1.5 +/- 0.7 [B], 3.7 +/- 0.6 [C], P < 0.01 for C vs. A or B). We conclude that Carolina rinse is able to improve early excretory hepatocellular function, microvascular perfusion, and intrahepatic WBC accumulation after prolonged cold ischemia and reperfusion, but adenosine is unlikely to be the key component of this rinse solution.     

Perirhinal cortex and place–object conditional learning in the rat.

The present study examined whether excitotoxic lesions of the perirhinal cortex can affect acquisition of a place–object conditional task in which object and spatial information must be integrated. Testing was carried-out in a double Y-maze apparatus, in which rats learned a conditional rule of the type, "In Place X, choose Object A, not Object B (A+ vs B–); in Place Y, choose Object B, not Object A (A– vs B+)." Perirhinal cortex lesions significantly impaired acquisition of this task while sparing performance of an allocentric spatial memory task performed in a radial arm maze. Perirhinal cortex lesions also had no apparent effect on a 1-pair object discrimination task performed in the double Y-maze or on retention and acquisition of 4-pair concurrent discrimination problems performed in a computer-automated touch screen testing apparatus. The results suggest that, although the perirhinal cortex and hippocampus can be functionally dissociated, their normal mode of operation includes the integration of object and spatial information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual modulation of stimulus generalization in rats.

One connectionist analysis of the acquired equivalence/distinctiveness of cues assumes that when similar compounds (e.g., AX and BX) are paired with the same outcome (e.g., food, +; or no food, ?), their components come to activate the same configural unit (ABX). When these compounds are paired with different outcomes, their components will come to address different units. Here, rats received appetitive training with eight compounds (e.g., AX+, BX+, CX?, DX?, AY+, BY?, CY?, DY+) that should generate the following configural units: ABX, CDX, ADY, and BCY. In Experiment 1, rats then received aversive conditioning to A, which should activate and revalue representations ABX and ADY. Subsequently, compounds that provided dual activation (i.e., BX and DY) of one of the revalued configural units (ABX and ADY) were shown to elicit greater fear than those compounds that provided a single source of activation to each unit (i.e., DX and BY). Experiment 2 confirmed and extended these findings. These results provide support for the connectionist analysis outlined above and are consistent with the application of this approach to the acquired equivalence/distinctiveness of cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Solving XOR": Correction to Grand and Honey (2008).

Reports an error in "Solving XOR" by C. Grand and R. C. Honey (Journal of Experimental Psychology: Animal Behavior Processes, 2008[Oct], Vol 34[4], 486-493). Figure 2 in the article was printed incorrectly due to an editing error. The correct version of Figure 2 is provided in the erratum. (The following abstract of the original article appeared in record 2008-14849-005.) Three experiments examined the way in which exclusive-or (XOR) problems are solved by rats. All rats first received food-rewarded positive and negative patterning problems with two stimulus sets: either A+, B+, AB- and C-, D-, CD+, or A-, B-, AB + and C+, D +, and CD-. Subsequently, rats received revaluation trials in which A was paired with shock and C was not, prior to generalization test trials with B, D, AB, and CD (Experiments 1 & 2); or received A→shock trials prior to tests with B and CD (Experiment 3). There was greater generalized fear to B than to either D (Experiments 1 & 2) or AB (Experiment 2) and CD (Experiments 2 & 3). These results are inconsistent with configural, connectionist models, but are consistent with an alternative connectionist model that can represent the logical structure of XOR problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A non-randomized comparison of two radiotherapy protocols in inoperable squamous cell carcinoma of the oesophagus

Furosemide (F)-induced nephrocalcinosis (NC) has been traditionally described in low birth weight premature infants. To investigate the role of age on F-induced nephrocalcinosis we studied 24 Sprague-Dawley male rats grouped by age and F therapy vs. control as follows: A (4-week-old control), B (4-week-old + F), C (6-week-old control), D (6-week-old + F), E (10-week-old control), F (10-week-old + F). The rats were placed in metabolic cages for measurement of urine output, food and water intake. At day 14 they were anesthetized, exsanguinated and their kidneys harvested. Renal calcium deposition was assessed using NC score (scale 0-4) and quantitative calcium analysis in the contralateral kidney. Treated animals gained less weight and had higher urine output and fluid intake than the age-matched controls demonstrating the diuretic effect of furosemide. Control groups A, C, and E scored 0 histologically compared with B 2.75 +/- 0.50, D 2.00 +/- 0.58, and F 3.00 +/- 0.82 (p < 0.05 in all three paired groups). Kidney calcium content (micrograms/g dry weight) in B was 2,815.68 +/- 1,553.77 vs. A 202.58 +/- 32.02 (p = 0.04); D 1,574.05 +/- 540.21 vs. C 212.22 +/- 30.91 (p = 0.02); F 2,591.40 +/- 1,269.80 vs. E 210.38 +/- 26.79 (p = 0.02). There was no difference in the magnitude of NC among the three treated groups themselves. To determine the possible effect of age on timing of onset of NC additional 30 4-week-old and 30 10-week-old rats were studied. All 60 rats received furosemide. Six rats from each group were sacrificed on days 1, 3, 5, 7 and 11. In both groups, significant calcifications were seen already on day 3 and maximum calcification noted between days 3 and 5. We conclude that in this model the development of NC occurs within a few days of furosemide administration and that this phenomenon is not age dependent but rather reflects a property of the loop diuretic itself.     

Borderline personality disorder features in nonclinical young adults: I. Identification and validation.

Two studies were conducted that sought to (a) establish and validate a self-report method of identifying nonclinical young adults who present with significant borderline personality disorder (BPD) features and (b) evaluate the clinical correlates of this classification across a number of relevant areas of functioning. Specifically, the Personality Assessment Inventory Borderline Features Scale (PAI-BOR; L. C. Morey, 1991) was used to screen and select nonclinical participants whose scores indicated the presence of significant BPD features (B+ group) and participants whose scores indicated the relative absence of BPD features (B– group). B+ and B– participants were compared across a range of domains that are believed to be related to BPD in clinical samples (e.g., depression, personality traits, coping, Axis I disorders, interpersonal problems). Results supported the validity of this method of classification based on PAI-BOR scores and documented the level of dysfunction exhibited by the B+ participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition and facilitation by B over C after A+, AB–, and ABC+ training with multimodality stimulus combinations.

Previous research with keylight conditioned stimuli has revealed that pigeons failed to show inhibition by Stimulus B over Stimulus C in BC versus C testing after A+, AB–, ABC+ training where Stimulus A and Stimulus Compound ABC had signaled food, and Stimulus Compound AB had signaled no food. Indeed, B slightly facilitated responding to C on the BC trials. The present research addressed the same issue with multimodality stimulus arrangements in autoshaping with pigeons, conditioned suppression with rats, and instrumental discrimination learning with rats. Stimulus B facilitated responding to C if A and B were of the same modality and C was of a different modality. However, B inhibited responding to C if A and C were of the same modality and B was of a different modality, or if B and C were of the same modality and A was of a different modality. These results are correctly predictable by Pearce's configural model with a minor modification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of kainic acid plus colchicine and ibotenic acid-induced hippocampal formation damage on four configural tasks in rats.

J. W. Rudy and R. J. Sutherland (1989) suggested that the hippocampal formation (HF) is necessary for performance of configural tasks and that rats with kainic acid?+?colchicine (K–C) damage to the HF were impaired on the negative patterning problem (A+, B+, AB–). However, M. Gallagher and P. C. Holland (1992) found spared performance on a similar task (AC+, B+, AB–, C–) when ibotenic acid (IBO) was used. This study compared the effects of K–C and IBO-induced HF damage on 4 configural tasks: (a) negative patterning, (b) the Gallagher-Holland task, (c) transverse patterning, and (d) place learning. Rats with IBO lesions performed like controls on the Gallagher-Holland task (replicating M. Gallagher & P. C. Holland) but were impaired on negative patterning, transverse patterning, and place learning. In contrast, rats with K–C lesions were impaired on all 4 tasks. The implications of these results for theories of HF function are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solving XOR.

[Correction Notice: An erratum for this article was reported in Vol 35(1) of Journal of Experimental Psychology: Animal Behavior Processes (see record 2009-00257-012). Figure 2 in the article was printed incorrectly due to an editing error. Below is the correct version of Figure 2.] Three experiments examined the way in which exclusive-or (XOR) problems are solved by rats. All rats first received food-rewarded positive and negative patterning problems with two stimulus sets: either A+, B+, AB- and C-, D-, CD+, or A-, B-, AB + and C+, D +, and CD-. Subsequently, rats received revaluation trials in which A was paired with shock and C was not, prior to generalization test trials with B, D, AB, and CD (Experiments 1 & 2); or received A→shock trials prior to tests with B and CD (Experiment 3). There was greater generalized fear to B than to either D (Experiments 1 & 2) or AB (Experiment 2) and CD (Experiments 2 & 3). These results are inconsistent with configural, connectionist models, but are consistent with an alternative connectionist model that can represent the logical structure of XOR problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning about associations: Evidence for a hierarchical account of occasion setting.

In 2 experiments rats were trained on a switching discrimination, with 4 occasion setters, A, B, C, and D and 2 target stimuli, x and y. When signaled either by A or by B, x was reinforced with food and y was not, whereas when signaled either by C or by D these reinforcement relations were reversed (i.e., A: → x+, A: y → ?, B: x → +, B: y → ?, C: x → ?, C: y → +, D: x → ?, D: y → +). In a subsequent Stage A was paired with shock, and then the degree to which food–reinforced (Experiment 1a) and nonreinforced (Experiment 1b) presentations of x and y were capable of eliciting fear was assessed. Those conditioned stimulus (CS)/unconditioned stimulus (US) relations that had been operative in the presence of the fear-eliciting occasion setter A (i.e., x → +, y → ?) elicited more fear than the alternative CS/US combinations (i.e., x → ?, y → +). The implications of these findings are discussed with reference to theories of occasion setting and of configural learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Within-compound associations modulate the relative effectiveness of differential and Pavlovian conditioned inhibition procedures.

Four conditioned suppression experiments with 98 male albino rats compared the inhibitory strength of a Pavlovian conditioned inhibitory stimulus (CS–) and a differential CS– and identified some postconditioning manipulations that modulate the measured effectiveness of the CS–. In Exp I, more inhibition was detected to a differential inhibitor than to a Pavlovian inhibitor in summation and retardation tests. Exps II–IV provided evidence that some inhibition conditioned to the Pavlovian CS–, but not to the differential CS–, was masked by a within-compound association. In Exp II, postconditioning extinction presentations of the Pavlovian conditioned excitatory stimulus (CS+) increased the inhibition observed to its CS–. In Exp III, postconditioning pairings of the Pavlovian CS+ with a more powerful UCS than that used for conditioning reduced the inhibition observed to its CS–. In Exp IV, nonreinforced postconditioning presentations of the Pavlovian CS– increased the inhibition observed to that CS–. The unmasking and masking of inhibition conditioned to the Pavlovian CS– by operations that modulate the strength of the within-compound association also changed the relative effectiveness of the Pavlovian and differential procedures. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object-based representations: Transfer between cases of continuous and discrete models of change.

The authors examined why similarities and differences between the objects of analogous problems affect transfer. They present results showing that object attributes affect transfer by affecting the way in which people represent problem structures (e.g., speed changes continuously and monetary investments discretely). Participants learned to solve problems involving either constant change in speed or in investment. They were then tested for transfer to problems that were matched on a variety of object attributes but involved entities known to be changing either continuously or discretely (e.g., melting ice vs. ice delivered to a restaurant). Although the manner of change was never specified as a constraint for solving the training problems, transfer in the continuous-to-discrete direction was rare and involved laborious mappings, whereas transfer in the discrete-to-continuous direction was frequent and straightforward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)