Elsevier

Archives of Gerontology and Geriatrics

Volume 53, Issue 2, September–October 2011, Pages 206-209
Archives of Gerontology and Geriatrics

Is there an advanced aging effect on the ability to mentally represent action?

https://doi.org/10.1016/j.archger.2010.10.006Get rights and content

Abstract

Motor programming theory suggests that an integral component in an effective outcome is an adequate action (mental) representation of the movements; a representation reflected in the ability to use motor imagery. Recent reports show a decline with advanced age (>64 years) using a variety of motor simulation tasks. Here, we examined the possible effects of advanced age on motor imagery ability in the context of estimation of reachability – that is, estimating whether an object is within reach or out of grasp. Thirty young adults (mean age: 20) and 23 older adults (mean age: 77) were instructed to estimate, using motor imagery, whether randomly presented targets in peripersonal (within actual reach) and extrapersonal (beyond reach) space were within or out of reach of their dominant limb while seated. Results indicated that the younger group was significantly more accurate than the older adults, p < 0.001. Whereas both groups made more errors in extrapersonal space, the values were significantly higher for the older group; that is, they overestimated to a greater extent. In summary, these findings add to the general notion that there is a decline in the ability to mentally represent action with advanced age.

Introduction

Motor programming theory suggests that an integral component in an effective outcome is an adequate action representation of the movements. That is, the ability to create an appropriate and effective action representation used to plan and execute movements. Theory suggests that action representation is a component of an internal forward model, which is a neural system that simulates the dynamic behavior of the body in relation to the environment (Wolpert, 1997, Wolpert and Kawato, 1998). This theory proposes that internal models make predictions (estimates) about the mapping of the self to parameters of the external world; processes that enhance planning and execution of action. These representations are hypothesized to be an integral part of action planning (Wolpert, 1997, Skoura et al., 2005, Choudhury et al., 2007a, Choudhury et al., 2007b, Molina et al., 2008).

Central to our interests is the suggestion that motor imagery provides a window into the process of action representation (Jeannerod, 2001, Munzert et al., 2009). Complementing the internal model idea, motor imagery is involved in the prediction of the consequences of one's actions (Bourgeois and Coello, 2009, Kunz et al., 2009, Lorey et al., 2010). From another perspective, motor imagery is an off-line recruitment of the same neural networks involved in perception and action (Jeannerod, 2007).

In addition to research interests in the early developmental nature of internal models and the ability to mentally represent action via motor imagery (Choudhury et al., 2007a, Choudhury et al., 2007b, Molina et al., 2008, Caeyenberghs et al., 2009, Gabbard, 2009), recent attention has also focused on research with older persons. From this body of work, there are indications of decline with advanced age (>64 years) (Mulder et al., 2008, Skoura et al., 2008, Saimpont et al., 2009, Personnier et al., 2010a). For example, Personnier et al. (2010b), using a mental chronometry paradigm with imagined and executed arm pointing actions in young and older adults, found that whereas older adults displayed the ability to mentally represent action, the quality (i.e., isochrony between executed and imagined movements) declined with advancing age. From another perspective, those findings indicated that in the elderly, there is likelihood of weakness in internal models of action. In that study and a subsequent investigation (Personnier et al., 2010b), the researchers concluded that the decline in motor imagery may reflect functional changes in the aging brain; for example, the parietal cortex. Complementing those reports, Saimpont et al. (2009) reported a significant age effect regarding the ability to mentally simulate a complex sequential action involving the whole body (rising from the floor). That is, compared to younger adults, older persons displayed a significant level of difficulty.

One of the key behavioral observations from those papers is that elderly persons appear to have more difficulty making accurate predictions of their intended actions. Arguably, one of the important aspects of an action plan is the ability to predict the outcome and consequences of intended actions. Imagining an action can serve several useful goals to that endeavor. For example, during imagery important timing information is provided by the forward model, which aids in predicting the sensory consequences of the movement. According to Bourgeois and Coello (2009), motor representation can be viewed as a component of a predictive system, which includes a neural process that simulates through motor imagery the dynamic behavior of the body in relation to the environment.

With the present study, we examined the possible effects of advanced age on motor imagery ability (action representation) in the context of estimation of reachability. That is, the ability to use motor imagery to estimate whether an object is within reach or out of grasp. Estimating reach requires efficient use of allocentric cues (target and surrounding information) and a mapping to the body via body-scaling to establish egocentric coordinates. This tactic is reported to be useful for examining action representation and planning of body-scaling movements (Coello and Delevoye-Turrell, 2007, Lamm et al., 2007, Coello et al., 2008, Gabbard, 2009).

Section snippets

Subjects

We tested 30 young adults (mean age 20.07 ± 1.46) and 23 older adults (mean age 77.13 ± 8.59); all participants were right-handed as determined via the lateral preference inventory (Coren, 1993). In addition, all participants were in good health, with normal or corrected vision and did not indicate or present any neurological, muscular or cognitive impairment as determined via questionnaire. Although not a research question, participants were also asked to self-report ‘regular’ weekly physical

Results

Analysis of variance results for total accuracy indicated that the younger group was significantly more accurate than the older adults; F(1, 51) = 13.16, p < 0.01, r2 = 0.205. For the younger group, mean score was 26.61 ± 3.96, and for the older participants, 29.93 ± 2.70.

In regard to the distribution and general direction of error, whereas both groups made more errors in extrapersonal space (targets 5–7), values were significantly higher for the older group; that is, they overestimated to a greater

Discussion

In this paper we addressed the affect that advanced age might have on the ability to mentally represent action in the form of using motor imagery to estimate reach. Previous studies, using different motor imagery tasks and questionnaires, found that there was a decline in ability to mentally represent action. Our results support the general notion of decline with advanced age as evidenced by significant estimation differences favoring the young adult group. The second observation of note was

Conclusions

In summary, these findings add to the general notion that there is a decline in the ability to mentally represent action with advanced age. More specific, we found this to be evident with the individual's ability to plan (estimate) reach actions. In addition to providing insight to the action processing abilities associated with advancing age during adulthood, abilities which may affect motor planning and execution, this work may have implications associated with considerations of movement

Conflict of interest statement

None.

References (40)

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    This area of enhanced processing (‘peripersonal space’) can be defined as the space immediately accessible around our hands and body, whereas ‘extrapersonal space’ would refer to the area that is not within the reach of the arm (Rizzolatti et al., 1997; Holmes and Spence, 2004). Prior studies have noted an expanded representation of peripersonal space in older adults (cf., F2; see Fig. 1) (Gabbard et al., 2011, but see Gabbard and Cordova, 2013). In particular, Poliakoff et al. (2006a) showed that the visuo-tactile congruency effect, which is normally restricted to the space near the hand, was found in older adults also when visual distractors were presented near the unstimulated hand, in the contralateral hemispace (Poliakoff et al., 2006a; see also Mahoney et al., 2014b).

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