Limits...
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.

Show MeSH

Related in: MedlinePlus

Representation of the intended extent of the ablation of frontal cortex (in the left hemisphere, top row, dark grey) and the inferotemporal cortex (in the right hemisphere, bottom row, light grey) shown from ventral, lateral and, in the frontal case, medial views. The shaded areas indicate the areas of intended removal. AMTS, anterior middle temporal sulcus; AS, arcuate sulcus; CIN, cingulate sulcus; IOS, intraoccipital sulcus; LOS, lateral orbital sulcus; LS, lateral sulcus; MOS, medial orbital sulcus; OTS, occipitotemporal sulcus; PS, principal sulcus; ROS, rostral sulcus; RS, rhinal sulcus; STS, superior temporal sulcus.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2327205&req=5

fig01: Representation of the intended extent of the ablation of frontal cortex (in the left hemisphere, top row, dark grey) and the inferotemporal cortex (in the right hemisphere, bottom row, light grey) shown from ventral, lateral and, in the frontal case, medial views. The shaded areas indicate the areas of intended removal. AMTS, anterior middle temporal sulcus; AS, arcuate sulcus; CIN, cingulate sulcus; IOS, intraoccipital sulcus; LOS, lateral orbital sulcus; LS, lateral sulcus; MOS, medial orbital sulcus; OTS, occipitotemporal sulcus; PS, principal sulcus; ROS, rostral sulcus; RS, rhinal sulcus; STS, superior temporal sulcus.

Mentions: Neurosurgical procedures were performed in a dedicated operating theatre under aseptic conditions. Each monkey's first neurosurgical procedure consisted of a left unilateral frontal lobe ablation, their second procedure was a right unilateral inferotemporal cortex ablation, and their third procedure was a bilateral transection of the fornix. Previous studies have demonstrated that there is no effect of the side on which the unilateral ablations are performed, in this task and others (e.g. Gaffan et al., 2002; Browning et al., 2005, 2007). The intended extents of the frontal and inferotemporal ablations are shown in Fig. 1. Surgical procedures for frontal-temporal disconnection in cases M1 and M2 are described in the earlier report (Browning et al., 2005). Case M3 has not been previously reported. All surgical procedures (frontal-temporal disconnection and Fx in case M3, and Fx in cases M1–M3) took place under general anaesthesia (sodium thiopentone, i.v., to effect in cases M1 and M2, and isoflurane, 1–2.75%, to effect, in 100% oxygen in case M3).


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)

Representation of the intended extent of the ablation of frontal cortex (in the left hemisphere, top row, dark grey) and the inferotemporal cortex (in the right hemisphere, bottom row, light grey) shown from ventral, lateral and, in the frontal case, medial views. The shaded areas indicate the areas of intended removal. AMTS, anterior middle temporal sulcus; AS, arcuate sulcus; CIN, cingulate sulcus; IOS, intraoccipital sulcus; LOS, lateral orbital sulcus; LS, lateral sulcus; MOS, medial orbital sulcus; OTS, occipitotemporal sulcus; PS, principal sulcus; ROS, rostral sulcus; RS, rhinal sulcus; STS, superior temporal sulcus.
© Copyright Policy
Related In: Results  -  Collection

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

fig01: Representation of the intended extent of the ablation of frontal cortex (in the left hemisphere, top row, dark grey) and the inferotemporal cortex (in the right hemisphere, bottom row, light grey) shown from ventral, lateral and, in the frontal case, medial views. The shaded areas indicate the areas of intended removal. AMTS, anterior middle temporal sulcus; AS, arcuate sulcus; CIN, cingulate sulcus; IOS, intraoccipital sulcus; LOS, lateral orbital sulcus; LS, lateral sulcus; MOS, medial orbital sulcus; OTS, occipitotemporal sulcus; PS, principal sulcus; ROS, rostral sulcus; RS, rhinal sulcus; STS, superior temporal sulcus.
Mentions: Neurosurgical procedures were performed in a dedicated operating theatre under aseptic conditions. Each monkey's first neurosurgical procedure consisted of a left unilateral frontal lobe ablation, their second procedure was a right unilateral inferotemporal cortex ablation, and their third procedure was a bilateral transection of the fornix. Previous studies have demonstrated that there is no effect of the side on which the unilateral ablations are performed, in this task and others (e.g. Gaffan et al., 2002; Browning et al., 2005, 2007). The intended extents of the frontal and inferotemporal ablations are shown in Fig. 1. Surgical procedures for frontal-temporal disconnection in cases M1 and M2 are described in the earlier report (Browning et al., 2005). Case M3 has not been previously reported. All surgical procedures (frontal-temporal disconnection and Fx in case M3, and Fx in cases M1–M3) took place under general anaesthesia (sodium thiopentone, i.v., to effect in cases M1 and M2, and isoflurane, 1–2.75%, to effect, in 100% oxygen in case M3).

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