A comparison of the effects of medial frontal, dorsomedial thalamic, and combination lesions on discrimination and spontaneous alternation in the rat

Weis, Bonita J.; Means, Larry W.

doi:10.3758/bf03337466

Cited by 27 publications

(11 citation statements)

References 35 publications

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“…While investigators generally offer several interpretations for the observed lesion-related behavioral changes (e.g., Means, Hunt, Whiteside, & Bates, 1973;Means, Huntley, Anderson, & Harrell, 1973), the statements that the mediodorsal nucleus has some kind of choice function (Weis & Means, 1980) and that lesions in it result in a reduced ability to initiate responses leading to the reward (Thompson, 1979;Vanderwolf, 1971) fit most of the outcomes of the above mentioned studies and agree with the results of our first experiment as well. The results of our Experiment 2 suggest, however, the existence of a consolidation or retrieval deficit, that is, a memory-related role of the mediodorsal nucleus (cf.…”

Section: Discussionsupporting

confidence: 88%

“…Deficits in acquisition or retention following lesions of the mediodorsal nucleus in rats, cats, and monkeys have been reported for a variety of tasks. Most frequently, delayed-response (Chow, 1954;Peters, Rosvold, & Mirsky, 1956;Schulman, 1964), delayed-alternation (Kessler & Markowitsch, 1981;Markowitsch, 1982;Peters et al, 1956), spontaneous alternation (Means, Harrell, Mayo, & Alexander, 1974;Weis & Means, 1980), and sensory discrimination tasks (Chow, 1954;Means, Huntley, Anderson, & Harrell, 1973;Peters et al, 1956;Schulman, 1964;Thompson, 1979;Waring & Means, 1976;Warren & Akert, 1960;Weis & Means, 1980) were used. While deficits were observed in all kinds of species and tasks, the degree of destruction of the mediodorsal nucleus appears to have the highest predictive value for a task-related impairment.…”

Section: Discussionmentioning

confidence: 99%

“…Although memory impairments caused by lesions of the mediodorsal nucleus are less severe in rats than in humans, the mediodorsal nucleus of the rat does seem to be somewhat involved in the processing of memory-related information (Gross, Chorover, & Cohen, 1965;Kessler & Markowitsch, 1981;Kolb, 1977;Means, Hershey, Waterhouse, & Lane, 1975;Means, Hunt, Whiteside, & Bates, 1973;Means, Huntley, Anderson, & Harrell, 1973;Tigner, 1974;Weis & Means, 1980;Wuensch, Broome, Means, & Harris, 1978;Wuensch & Means, 1976).…”

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confidence: 92%

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Subtle but distinct impairments of rats with chemical lesions in the thalamic mediodorsal nucleus, tested in a radial arm maze.

Kessler¹,

Markowitsch²,

Otto³

1982

Journal of Comparative and Physiological Psychology

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The performance of rats trained in a radial arm maze was tested before and after chemical lesions of the thalamic mediodorsal nucleus or the ventral tegmental area. Their behavior was compared with that of a sham-operated con trol group. Lesions were produced with ibotenic acid, a compound that selec tively destroys neurons while apparently leaving fibers of passage intact. Results revealed no intergroup difference in the number of errors performed when all six trials were given in one session without interruption. The group with mediodorsal lesions made, however, significantly more errors than either of the other two groups when a delay of 1 hr was interposed between the first four and the last two trials. Furthermore, these rats differed from rats of the other groups in the number of sessions necessary to reach criterion, in the time needed to finish a session, and in the directness with which a goal was approached. Rats with lesions of the ventral tegmental area did not differ from rats of the sham-operated control group in any of the measures taken. It is suggested that the deficits of rats with mediodorsal lesions resemble qualitatively those found in human patients with lesions of the mediodorsal nucleus.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 92%

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Subtle but distinct impairments of rats with chemical lesions in the thalamic mediodorsal nucleus, tested in a radial arm maze.

Kessler¹,

Markowitsch²,

Otto³

1982

Journal of Comparative and Physiological Psychology

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“…Such studies have focused almost exclusively on the MD thalamus, and have yielded equivocal results. For example, whereas some authors have reported impairments following MD thalamic lesions in tests of spontaneous and reinforced alternation (Weiss & Means, 1980; Vicedomini et al ., 1982), others have found no impairments on such tasks (Brito et al ., 1982; Green & Naranjo, 1986; Hunt & Aggleton, 1991, 1998; Neave et al ., 1993). Furthermore, in cases where positive results were obtained, it is difficult to determine the critical task factor.…”

Section: Introductionmentioning

confidence: 99%

Effects of selective thalamic and prelimbic cortex lesions on two types of visual discrimination and reversal learning

Chudasama

Bussey

Muir

2001

Eur J of Neuroscience

113

105

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The effects of excitotoxic lesions of the mediodorsal nucleus of the thalamus, the anterior thalamic nuclei and of the prelimbic cortex were examined on two tests of discrimination and reversal learning. In experiment 1A (visual discrimination and reversal), rats were required to discriminate two stimuli, and respond to the stimulus associated with reward (the S+ stimulus). There was no effect of lesion on acquisition of this task. However, when stimulus-reward contingencies were reversed, animals with lesions of the mediodorsal nucleus of the thalamus made significantly more errors than control animals or animals of other lesion groups. In experiment 1B (conditional discrimination), animals were required to learn a rule of the type 'If stimulus A then go left, if stimulus B then go right'. No main effect of lesion on acquisition was observed in this experiment. To test the generality of the reversal effect obtained in experiment 1A, a second cohort of animals with the same lesions was tested on acquisition of the visuospatial conditional task immediately postsurgery, followed by the reversal of the conditional rule (experiment 2). As in experiment 1B, no main effect of lesion group was observed during acquisition of the task. However, lesions of the mediodorsal nucleus of the thalamus resulted in a mild impairment according to number of sessions required to attain criterion performance of the task when the response rule was reversed. The results of the present study provide evidence for a role for the mediodorsal nucleus of the thalamus in new learning, particularly when stimulus-reward contingencies are reversed. Furthermore, they show that the functions of this thalamic nucleus can be dissociated from those of the anterior thalamus and the prelimbic cortex.

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“…For example, MDN lesions cause a mild, but significant, impairment in discriminative responding in a running wheel avoidance task, and also decrease training-related multiple-unit activity in MDN projection cortex (Gabriel et al 1989). Other discriminative/reversal deficits following MDN damage have also been reported (Weis and Means 1980;Staubli et al 1987;Lu and Slotnick 1990). Additionally, some investigators report that tests of spatial memory are sensitive to MDN damage (Means et al 1975;Kessler et al 1982;Stokes andBest 1988, 1990), although others report no effect on such tasks (Hunt and Aggleton 1991).…”

Section: Powell and Churchwellmentioning

confidence: 96%

Mediodorsal Thalamic Lesions Impair Trace Eyeblink Conditioning in the Rabbit

Powell¹,

Churchwell²

2002

Learn. Mem.

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Rabbits received lesions of the mediodorsal nucleus of the thalamus (MDN) or sham lesions and were subjected to classical eyeblink (EB) and heart rate (HR) conditioning. All animals received trace conditioning, with a .5-sec tone conditioned stimulus, a .5-sec trace period, and a 50-msec periorbital shock unconditioned stimulus. Animals with MDN lesions acquired the EB conditioned response (CR) more slowly than sham-lesioned animals. However, previous studies have shown that MDN damage does not affect delay conditioning using either .5-sec or 1-sec interstimulus intervals. The lesions had no significant effect on the HR CR. These results suggest that information processed by MDN and relayed to the prefrontal cortex is required for somatomotor response selection under nonoptimal learning conditions.The mediodorsal nucleus of the thalamus (MDN) is a primary thalamic nucleus providing projections to the prefrontal cortex, and, like the prefrontal cortex, has been implicated in various aspects of learning and memory. We have shown previously that lesions of MDN slightly retard the acquisition of a classically conditioned eyeblink (EB) response (Buchanan and Thompson 1990), but do not affect asymptotic performance. Similar small, although significant, MDN-lesion effects are seen on acquisition of an EB instrumental avoidance response (Buchanan 1994). Much more severe MDN-lesion effects are seen in a discrimination/reversal paradigm, particularly during the reversal phase. Thus, these lesions have little effect on the original acquisition of a discrimination between a reinforced conditioned stimulus (CS+) and a nonreinforced conditioned stimulus (CS−). However, if, after this discrimination has been acquired, the stimuli are reversed such that the previously reinforced CS+ is no longer reinforced and the previously nonreinforced CS− is now the CS+, MDN lesions dramatically impair acquisition of this reversal task (Buchanan 1991). Other investigators have reported similar findings (Gabriel et al. 1989). We have also shown that MDN damage significantly impairs EB conditioning when the interstimulus interval (ISI) is not optimal (i.e., a 2-sec ISI), or during partial reinforcement, when the schedule involves 25%, but not 100% or 50% reinforcement (Buchanan et al. 1997b). Further, multiple unit activity recorded from MDN during classical EB conditioning is correlated with acquisition of the conditioned response (CR) (Buchanan et al. 1997a), but such changes are relatively small and do not show a clear acquisition function.These findings suggest that MDN, or its inputs to PFC, may be important for acquisition of the classically conditioned EB response, although not essential. It appears that MDN function may be most critical under conditions of greater task complexity or difficulty, such as discrimination/ reversal or nonoptimal ISI or partial reinforcement conditions, but is less important for relatively simple tasks acquired under optimal conditions. Similar findings have been reported after damage to the hippocampus. Th...

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A comparison of the effects of medial frontal, dorsomedial thalamic, and combination lesions on discrimination and spontaneous alternation in the rat

Cited by 27 publications

References 35 publications

Subtle but distinct impairments of rats with chemical lesions in the thalamic mediodorsal nucleus, tested in a radial arm maze.

Subtle but distinct impairments of rats with chemical lesions in the thalamic mediodorsal nucleus, tested in a radial arm maze.

Effects of selective thalamic and prelimbic cortex lesions on two types of visual discrimination and reversal learning

Mediodorsal Thalamic Lesions Impair Trace Eyeblink Conditioning in the Rabbit

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