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Addition of fornix transection to frontal-temporal disconnection increases the impairment in object-in-place memory in macaque monkeys.

Wilson CR, Baxter MG, Easton A, Gaffan D - Eur. J. Neurosci. (2008)

Bottom Line: If the contribution of the fornix to scene learning is via interaction with or modulation of frontal-temporal interaction--that is, if they form a unitary system--then Fx should have no further effect when added to frontal-temporal disconnection.However, if the contribution of the fornix is to some extent distinct, then fornix lesions may produce an additional deficit in scene learning beyond that caused by frontal-temporal disconnection.The increased impairment following the addition of Fx provides evidence that the fornix and frontal-inferotemporal interaction make distinct contributions to episodic memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University of Oxford, Oxford, UK. charles.wilson@psy.ox.ac.uk

ABSTRACT
Both frontal-inferotemporal disconnection and fornix transection (Fx) in the monkey impair object-in-place scene learning, a model of human episodic memory. If the contribution of the fornix to scene learning is via interaction with or modulation of frontal-temporal interaction--that is, if they form a unitary system--then Fx should have no further effect when added to frontal-temporal disconnection. However, if the contribution of the fornix is to some extent distinct, then fornix lesions may produce an additional deficit in scene learning beyond that caused by frontal-temporal disconnection. To distinguish between these possibilities, we trained three male rhesus monkeys on the object-in-place scene-learning task. We tested their learning on the task following frontal-temporal disconnection, achieved by crossed unilateral aspiration of the frontal cortex in one hemisphere and the inferotemporal cortex in the other, and again following the addition of Fx. The monkeys were significantly impaired in scene learning following frontal-temporal disconnection, and furthermore showed a significant increase in this impairment following the addition of Fx, from 32.8% error to 40.5% error (chance = 50%). The increased impairment following the addition of Fx provides evidence that the fornix and frontal-inferotemporal interaction make distinct contributions to episodic memory.

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Learning curves for within-session learning of object-in-place problems for the four stages. The mean scores for the three monkeys are represented at stages Pre-Op (filled circles), Unilateral FL (open triangles), FLxIT (filled squares) and FLxIT + Fx (open diamonds). The graph shows the rapid speed with which monkeys acquired these problems preoperatively, and the impaired learning after the disconnection, and further after the addition of Fx.
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fig03: Learning curves for within-session learning of object-in-place problems for the four stages. The mean scores for the three monkeys are represented at stages Pre-Op (filled circles), Unilateral FL (open triangles), FLxIT (filled squares) and FLxIT + Fx (open diamonds). The graph shows the rapid speed with which monkeys acquired these problems preoperatively, and the impaired learning after the disconnection, and further after the addition of Fx.

Mentions: The learning rate in object-in-place learning was measured at each stage as the mean number of errors made in Trials 2–8 in the final 10 sessions of each performance test. Table 1 shows the learning rates for these sessions expressed as percent error for all three monkeys at each of the four stages in the present experiment. The learning curves for the monkeys at the four stages are displayed graphically in Fig. 3, whilst the mean percent error at each stage is shown in Fig. 4. In both cases they demonstrate the small change between stages Pre-Op and Unilateral FL, but a large increase in percent error at stage FLxIT, and a further increase in percent error in each monkey at stage FLxIT + Fx.


Addition of fornix transection to frontal-temporal disconnection increases the impairment in object-in-place memory in macaque monkeys.

Wilson CR, Baxter MG, Easton A, Gaffan D - Eur. J. Neurosci. (2008)

Learning curves for within-session learning of object-in-place problems for the four stages. The mean scores for the three monkeys are represented at stages Pre-Op (filled circles), Unilateral FL (open triangles), FLxIT (filled squares) and FLxIT + Fx (open diamonds). The graph shows the rapid speed with which monkeys acquired these problems preoperatively, and the impaired learning after the disconnection, and further after the addition of Fx.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2327205&req=5

fig03: Learning curves for within-session learning of object-in-place problems for the four stages. The mean scores for the three monkeys are represented at stages Pre-Op (filled circles), Unilateral FL (open triangles), FLxIT (filled squares) and FLxIT + Fx (open diamonds). The graph shows the rapid speed with which monkeys acquired these problems preoperatively, and the impaired learning after the disconnection, and further after the addition of Fx.
Mentions: The learning rate in object-in-place learning was measured at each stage as the mean number of errors made in Trials 2–8 in the final 10 sessions of each performance test. Table 1 shows the learning rates for these sessions expressed as percent error for all three monkeys at each of the four stages in the present experiment. The learning curves for the monkeys at the four stages are displayed graphically in Fig. 3, whilst the mean percent error at each stage is shown in Fig. 4. In both cases they demonstrate the small change between stages Pre-Op and Unilateral FL, but a large increase in percent error at stage FLxIT, and a further increase in percent error in each monkey at stage FLxIT + Fx.

Bottom Line: If the contribution of the fornix to scene learning is via interaction with or modulation of frontal-temporal interaction--that is, if they form a unitary system--then Fx should have no further effect when added to frontal-temporal disconnection.However, if the contribution of the fornix is to some extent distinct, then fornix lesions may produce an additional deficit in scene learning beyond that caused by frontal-temporal disconnection.The increased impairment following the addition of Fx provides evidence that the fornix and frontal-inferotemporal interaction make distinct contributions to episodic memory.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University of Oxford, Oxford, UK. charles.wilson@psy.ox.ac.uk

ABSTRACT
Both frontal-inferotemporal disconnection and fornix transection (Fx) in the monkey impair object-in-place scene learning, a model of human episodic memory. If the contribution of the fornix to scene learning is via interaction with or modulation of frontal-temporal interaction--that is, if they form a unitary system--then Fx should have no further effect when added to frontal-temporal disconnection. However, if the contribution of the fornix is to some extent distinct, then fornix lesions may produce an additional deficit in scene learning beyond that caused by frontal-temporal disconnection. To distinguish between these possibilities, we trained three male rhesus monkeys on the object-in-place scene-learning task. We tested their learning on the task following frontal-temporal disconnection, achieved by crossed unilateral aspiration of the frontal cortex in one hemisphere and the inferotemporal cortex in the other, and again following the addition of Fx. The monkeys were significantly impaired in scene learning following frontal-temporal disconnection, and furthermore showed a significant increase in this impairment following the addition of Fx, from 32.8% error to 40.5% error (chance = 50%). The increased impairment following the addition of Fx provides evidence that the fornix and frontal-inferotemporal interaction make distinct contributions to episodic memory.

Show MeSH
Related in: MedlinePlus