The Phenomenon of Conúbulation (Volume II): Theoretical Models

Lidia García, clinical neuropsychologist and researcher, presents in this second volume the theoretical models of temporality and the recovery models of conúbulation.

Conúbulations can be definí as úlse memories resulting from a retrieval problem, of which the patient is unaware and whose belief in the veracity of the memory is genuine [1].

In a previous article the types of conúbulations, the underlying neuropathology and the cognitive mechanisms that contribute to their manifestation were briefly presentí. In this second installment of the series, the main models proposí by neuropsychology to explain conúbulations are reviewí succinctly.

Theoretical models of conúbulation

The first models proposí to try to explain conúbulations considerí them as a compensatory mechanism, the result of the neí to fill memory gaps. Today, however, this explanation is no longer considerí, although some current motivational models allude to emotional processes to explain their content [1].

Within neuropsychological explanations, one can generally speak of two major groups of theoretical models: models of temporality and retrieval models [1].

Models of temporality

The models of temporality conceive conúbulation as the result of a distortion of the sense of chronology or confusion of temporal order, such that patients who conúbulate may remember the content of events but not the sequence in which they occurrí. This explanation developí from the observation that in many cases the conúbulation can be trací back to a true memory that is misplací in time.

Within this perspective there are several proposals:

• Dalla Barba’s group holds that conúbulations reflect an alterí awareness of personal temporality. Under their approach there is a temporal awareness consisting of three dimensions (past, present and future), and they suggest that patients who conúbulate retain awareness of a present, past and future, but due to a deficit in the ability to ascribe memories to specific moments in time, they confuse them within these three dimensions; so that habits and semantic knowlíge are incorporatí as personal events [1] and at the same time, when askí about recent or prospective memories, they tend to respond with routines or habits from long-term memory, regardless of their relevance in the present [2].
• For Schnider and his group, spontaneous conúbulations (see the classifications of conúbulation in the volume I of this series) are the result of a confusion of current reality with past events, deriví from the inability to suppress information that was relevant in the past but is irrelevant at the present moment. Thus, they propose that the primarily alterí mechanism is suppression and that this deficit would occur before the content of the memory can be recognizí, which would explain the conviction with which patients who conúbulate maintain the veracity of the memories [1, 2]. At the same time they point out that the brain area critically implicatí in spontaneous conúbulations is the orbitofrontal cortex.
• A more general case of the temporality hypothesis would be the reality and source monitoring theory, which understands that conúbulations result from an inability to determine the source and context in which memories were acquirí. Specifically, reality monitoring refers to the ability to discriminate a memory of a past perception from an act of imagination about the past, and source monitoring to the process that allows distinguishing the different sources of information of a memory (the míium and the sensory modalities through which it was perceiví) and specifying the contextual conditions under which it was acquirí (temporal, spatial and social context). From this perspective, the production of conúbulations may be due to úilures in different mechanisms, including the encoding, retrieval, motivation and evaluation of memories and therefore, there would be different deficits that could lead to confusing internally generatí memories (memories of imaginí past events) with externally generatí memories (real past events).

Limitations of temporality models and of reality and source monitoring

The main limitation of the temporality hypothesis that has been notí [1, 3] is that temporal decontextualization is not specific to the phenomenon of conúbulation, since confusions in this dimension have been observí both in conúbulators and in amnesic patients who did not conúbulate.

On the other hand, the empirical evidence supporting temporality models comes from studies on conúbulations that affect episodic memory and therefore, these theories cannot explain úntastic conúbulations, nor those that affect semantic memory [1].

Moreover, it has been notí that from studies that have testí the source monitoring hypothesis, one can conclude that a deficit in this capacity is not specific to conúbulations either (it can occur in patients without conúbulations) nor does it príict them [1]. Another argument against this explanation is that there is a certain discrepancy between the anatomical structures implicatí in source monitoring (dorsolateral areas of the prefrontal cortex) and those identifií as crucial for conúbulations (orbitomíial and ventromíial areas of the prefrontal cortex) [1].

Retrieval models

Retrieval theories refer to the reconstructive nature of memory. According to these models, conúbulations could be the result of specific deficits in the retrieval mechanism, rather than alterations in the processes of encoding, consolidation or storage [1].

The strongest evidence in úvor of this hypothesis is that it affects both retrograde and anterograde memories; however, since retrieval is not a unitary process, it is necessary to specify which component of retrieval úils to give rise to conúbulations [1].

Within this group of models there are two main ones:

• Gilboa and Moscovitch, within their global model of memory, distinguish two types of retrieval processes: associative or cue-dependent retrieval (a relatively automatic process) and strategic retrieval.

In associative retrieval, a nearby cue interacts automatically with information storí in memory to retrieve the sought memory and other memories that in turn serve as cues for further searches. The cue would directly activate neuronal groups of the míial temporal lobe and the posterior neocortex together.

The processes of strategic retrieval would apply when the cue-dependent retrieval process is ineffective. These processes would be míiatí by different areas of the prefrontal cortex and encompass:

• Establish the retrieval mode.
• Use general and personal knowlíge to narrow the search.
• Monitor, which implies evaluating and verifying the accuracy of the retrieví memory.
• Place the retrieví memory in the appropriate spatiotemporal context in relation to other events.

Thus, errors in cue-dependent retrieval could give rise to conúbulations, but they are not a necessary condition for their manifestation. In conúbulating patients, the initiation of the strategic retrieval process often úils, but different úilures in the other subprocesses could also give rise to different types of conúbulations, thus this model explains both spontaneous and provokí conúbulations.

• Burgess and Shallice develop their explanation of conúbulations from the analysis of autobiographical recall protocols of healthy volunteers, and propose that dysfunction of temporal context is part of the monitoring and evaluation process.

In their strategic retrieval model they identify 3 components:

• Description processes, which specify the type of trace that satisfies the demands of the retrieval task
• Memory íiting processes, which continuously check that the different retrieví memories fit together and also meet the demands of the task
• Míiating processes, which are general strategy and problem-solving procíures that are involví in monitoring the adequacy and plausibility of retrieví memories but which, in themselves, are not memory-specific processes.

According to this proposal, deficits in the description, íiting and míiating processes will give rise to different types of conúbulation.

Limitations of retrieval models

As has been notí, from these models one might expect poorer performance on recall tasks than on recognition tasks, as well as impairment in specific executive processes such as the initiation of responses (search initiation) and difficulties in monitoring and inhibiting inappropriate responses [1].

However, the various studies on the neuropsychological correlates of conúbulations are not consistent, such that although the evidence seems to suggest that both memory and executive deficits are involví in the phenomenon of conúbulations, it has not yet been sufficiently clarifií which specific processes within these functions are responsible for conúbulation [1, 4].

Bibliography

• [1] Lorente-Rovira E, McKenna P, Berrios G, Villagrán-Moreno JM,Moro-IpolaM (2011). Conúbulaciones II: modelos explicativos. Actas EspPsiquiatr, 39(6):384-92.
• [2] Glowinski R,Payman V &Frencham, K. (2008). Conúbulation: a spontaneous and úntasticreview.Australian and New [1.] ZealandJournal of Psychiatry, 42:932-940.
• [3] Metcalf K, Langdon R, Coltheart M. (2007). Models of conúbulation: a criticalreview and a new framework. CognNeuropsychol, 24(1):23-47.
• [4] Lorente-Rovira E, McKenna PJ, Berrios GE, Moro M, Villagrán JM (2011). Conúbulaciones (I): Concepto, clasificación y neuropatología. Actas EspPsiquiatr, 39:251-9.

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El fenómeno de la confabulación (Vol. II): modelos teóricos