Crossed unilateral lesions of the medial forebrain bundle and either inferior temporal or frontal cortex impair object–reward association learning in Rhesus monkeys

Easton, Alexander; Gaffan, David

doi:10.1016/s0028-3932(00)00098-1

Cited by 37 publications

(16 citation statements)

References 33 publications

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“…First and surprisingly, our results demonstrated that unilateral neurotoxic MDmc lesions following the first neurosurgery are sufficient to produce deficits during learning as seen in the object-in-place scene discrimination task when compared with preoperative performance. Contrastingly, selective unilateral cortical lesions to PFv+o, like unilateral lesions to several other brain regions in primates ( Easton and Gaffan 2001 ; Wilson et al 2007 ), leave new learning intact on this task. Another study has also confirmed a lack of deficits after unilateral lesions to PFv+o when monkeys are required to rapidly learn conditional visuomotor associations ( Bussey et al 2002 ).…”

Section: Discussionmentioning

confidence: 90%

Evidence for Mediodorsal Thalamus and Prefrontal Cortex Interactions during Cognition in Macaques

2015

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It is proposed that mediodorsal thalamus contributes to cognition via interactions with prefrontal cortex. However, there is relatively little evidence detailing the interactions between mediodorsal thalamus and prefrontal cortex linked to cognition in primates. This study investigated these interactions during learning, memory, and decision-making tasks in rhesus monkeys using a disconnection lesion approach. Preoperatively, monkeys learned object-in-place scene discriminations embedded within colorful visual backgrounds. Unilateral neurotoxic lesions to magnocellular mediodorsal thalamus (MDmc) impaired the ability to learn new object-in-place scene discriminations. In contrast, unilateral ablations to ventrolateral and orbital prefrontal cortex (PFv+o) left learning intact. A second unilateral MDmc or PFv+o lesion in the contralateral hemisphere to the first operation, causing functional MDmc–PFv+o disconnection across hemispheres, further impaired learning object-in-place scene discriminations, although object discrimination learning remained intact. Adaptive decision-making after reward satiety devaluation was also reduced. These data highlight the functional importance of interactions between MDmc and PFv+o during learning object-in-place scene discriminations and adaptive decision-making but not object discrimination learning. Moreover, learning deficits observed after unilateral removal of MDmc but not PFv+o provide direct behavioral evidence of the MDmc role influencing more widespread regions of the frontal lobes in cognition.

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Section: Discussionmentioning

confidence: 90%

Evidence for Mediodorsal Thalamus and Prefrontal Cortex Interactions during Cognition in Macaques

2015

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“…In experiment 1, with crossed unilateral lesions, it is possible that the effects seen were effects of unilateral lesions alone rather than effects specifically of crossed unilateral lesions. Previous experiments that have used the technique of prefrontal-temporal disconnection by crossed unilateral lesions have sometimes included a test of unilateral temporal or unilateral prefrontal lesions alone, and have always found that the unilateral lesions alone do not produce the impairments seen after disconnection (Gaffan and Murray, 1990;Gaffan and Hornak, 1997;Parker and Gaffan, 1998a,b;Easton and Gaffan, 2001;Bussey et al, 2002b;Gaffan et al, 2002;Browning et al, 2005Browning et al, , 2007. However, because these experiments used visual learning and memory tasks that were not identical to the present task, we cannot rule out the possibility that unilateral lesions alone may impair serial visual compound learning.…”

Section: Discussionmentioning

confidence: 99%

Prefrontal Cortex Function in the Representation of Temporally Complex Events

Browning¹,

Gaffan²

2008

J. Neurosci.

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The frontal cortex and inferior temporal cortex are strongly functionally interconnected. Previous experiments on prefrontal function in monkeys have shown that a disconnection of prefrontal cortex from inferior temporal cortex impairs a variety of complex visual learning tasks but leaves simple concurrent object-reward association learning intact. We investigated the possibility that temporal components of visual learning tasks determine the sensitivity of those tasks to prefrontal-temporal disconnection by adding specific temporal components to the concurrent object-reward association learning task. Monkeys with crossed unilateral lesions of prefrontal cortex and inferior temporal cortex were impaired compared with unoperated controls at associating two-item sequences of visual objects with reward. The impairment was specific to the learning of visual sequences, because disconnection was without effect on object-reward association learning for an equivalent delayed reward. This result was replicated in monkeys with transection of the uncinate fascicle, thus determining the anatomical specificity of the dissociation. Previous behavioral results suggest that monkeys represent the two-item serial compound stimuli in a configural manner, similar to the way monkeys represent simultaneously presented compound stimuli. The representation of simultaneously presented configural stimuli depends on the perirhinal cortex. The present experiments show that the representation of serially presented compound stimuli depends on the interaction of prefrontal cortex and inferior temporal cortex. We suggest that prefrontal-temporal disconnection impairs a wide variety of learning tasks because in those tasks monkeys lay down similar temporally complex representations.

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“…Several differences – including lesion method and extent, reward schedule, and test apparatus – limit any comparison among the studies. These differences notwithstanding, the present results serve as an instance additional to that cited in the Introduction of selective, excitotoxic amygdala lesions yielding effects that qualitatively differ from those that follow aspirative lesions, probably because the latter type of lesion interrupts fibre pathways coursing near the amygdala (Goulet et al ., 1998; Easton & Gaffan, 2001).…”

Section: Discussionmentioning

confidence: 99%

Opposing effects of amygdala and orbital prefrontal cortex lesions on the extinction of instrumental responding in macaque monkeys

Izquierdo

Murray

2005

Eur J of Neuroscience

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Extinction is a well-known behavioural phenomenon that allows organisms to respond flexibly to a changing environment. Although recent work implicates the amygdala and orbital prefrontal cortex (PFo) in extinction of Pavlovian conditioned fear and aversion, much less is known about the neural bases of instrumental extinction. To explore the contribution of the macaque amygdala to flexible responding in the face of changing reward contingency, we tested the effects of selective, excitotoxic lesions of the amygdala on extinction of an instrumental response. For comparison, we evaluated the effects of ablation of PFo on the same task. Amygdala lesions facilitated the extinction of instrumental responses, whereas lesions of PFo had the opposite effect.

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Crossed unilateral lesions of the medial forebrain bundle and either inferior temporal or frontal cortex impair object–reward association learning in Rhesus monkeys

Cited by 37 publications

References 33 publications

Evidence for Mediodorsal Thalamus and Prefrontal Cortex Interactions during Cognition in Macaques

Evidence for Mediodorsal Thalamus and Prefrontal Cortex Interactions during Cognition in Macaques

Prefrontal Cortex Function in the Representation of Temporally Complex Events

Opposing effects of amygdala and orbital prefrontal cortex lesions on the extinction of instrumental responding in macaque monkeys

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