Confabulation With a Selective Descriptor Process Impairment

Abstract

Confabulation is usually assumed to result from a deficit in either the memory verification processes alone or in both the search and the verification processes. The present study concerns a patient who, in contrast to other patients, displayed confabulations but had preserved memory verification abilities. She exhibited only a selective impairment of the search processes. Recognition abilities were preserved, and cued recall was better than free recall. On the latter task, she recalled fewer correct items and produced more intrusions than control subjects. The patient had normal performance in several tests usually assumed to tap "executive functions." It is thus concluded that an impairment in verification, regardless of whether it is specific or not to memory, is not a necessary component of confabulations. The case is discussed in relation to two memory control processes models

Confabulation: Damage to a specific inferior medial prefrontal system

“…This is consistent with group studies carried out in patients selected on the basis of their amnesia (Moscovitch and Melo, 1997;Schnider and Ptak, 1999), and fits with previous 24 case reports (Baddeley and Wilson, 1988;Box et al, 1999;Dab et al, 1999;Damasio et al, 1985;Delbecq-Derouesne et al, 1990;Demery et al, 2001;Fotopoulou et al, 2004;Kapur and Coughlan, 1980;Kopelman et al, 1997;Mattioli et al, 1999;Mercer et al, 1977;Shapiro et al, 1981;Stuss et al, 1978;Vilkki, 1985, see Gilboa andMoscovitch, 2002, for a review). It is also consistent with clinical observations of confabulation following rupture and repair of anterior communicating artery aneurysms, which tend to result in ventromedial and basal forebrain lesions (Alexander and Freedman, 1984;De Luca and Diamond, 1995;Fischer et al, 1995).…”

“…Confabulation is frequently reported in association with aetiologies involving frontal lobe damage, including rupture and repair of anterior communicating artery aneurysms (Alexander and Freedman, 1984;Baddeley and Wilson, 1988;Burgess and McNeil, 1999;Dab et al, 1999;Damasio et al, 1985;DeLuca and Diamond, 1995;DelbecqDerouesne et al, 1990;Fischer et al, 1995;Kapur and Coughlan, 1980;Kopelman et al, 1995;Moscovitch 1989;Stuss et al, 1978;Vilkki, 1985), posterior communicating artery aneurysms (Dalla Barba et al, 1997;Mercer et al, 1977), frontal tumours (Fotopoulou et al, 2004), head injury (Baddeley and Wilson, 1988;Berlyne, 1972;Box et al, 1999;Damasio et al, 1985;Demery et al, 2001;Moscovitch and Melo, 1997), frontotemporal dementia (Nedjam et al, 2000; Moscovitch and Melo , 1 9 9 7 ) , K o r s a k o f f ' s s y n d r o m e (Berlyne, 1972;Benson et al, 1996;Dalla Barba et al, 1990;Kopelman, 1987;Kopelman et al, 1997;Korsakoff, 1955;Mercer et al, 1977;Talland, 1965), A l z h e i m e r ' s d i s e a s e ( D a l l a B a r b a et al, Kern et al, 1992;Kopelman, 1987;Nedjam et al, 2000;Tallberg and Almkvist, 2001), and herpes simplex encephalitis (Del Grosso Destreri et al, 2002;Moscovitch and Melo, 1997). Nearly all the evidence regarding the critical lesion site has come fro...…”

An evaluation of statistical procedures for comparing an individual's performance with that of a group of controls

“…Often the criterion used is whether the score for the patient lies within the control range (e.g., Dab et al, 1999), within the 95% confidence interval for the control subjects (e.g., Barrett, Schwartz, Raymer, Crucian, & Rothi, 1998), or within 2 SDs of the mean for controls (e.g., Parkin et al, 1999). As an approach to assessing patient/control differences, descriptive methods of this kind leave a lot to be desired.…”

“…There is wide use in cognitive neuropsychology of single case methodology in which it is necessary to compare the performance of an individual patient with that of a control group (e.g., Dab, Claes, Morais, & Shallice, 1999;Laeng, Kosslyn, Caviness, & Bates, 1999;Parkin, Ward, Bindschaedler, Squires, & Powell, 1999;Watson & Humphreys, 1999, to give a few recent examples). In such studies, the deeper theoretical issues often pivot on whether it is possible to establish that the patient's data can be thought of as coming from the same population as that of the controls.…”

Black legs

“…8 It has also been reported in patients with brain lesions of the dorsomedial thalamic nucleus 9 and the posterior orbitofrontal cortex, 10 although the underlying anatomical localisation and mechanisms are controversial. 11 It is also unclear whether confabulation results from patients deliberately trying to hide their memory deficits or whether it is involuntary. 12 Although confabulation is often difficult to distinguish from delusions, brain magnetic resonance imaging can be used to investigate specific organic lesions in people with amnesia and confabulation.…”