Strength as a factor influencing mirror movements

Armatas, Christine; Summers, Jeffery J.; Bradshaw, John L.

doi:10.1016/0167-9457(96)00019-x

Cited by 22 publications

(31 citation statements)

References 20 publications

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“…The load limit for these LVDT units was 5 kilograms (kg). Previous testing of forces of up to 9 kg with known weights revealed that these units accurately measured force beyond the 5 kg value set by the manufacturer (Armatas et al, 1996a). This meant that maximum finger strength could be determined accurately for all participants using this apparatus.…”

Section: Methodsmentioning

confidence: 99%

“…Persistence of mirror movements into adulthood is considered to be abnormal and may be familial (Bauman, 1932;Heck, 1964;Regli et al, 1967;Somers et al, 1976;van den Berg et al, 2000). However, neurologically intact individuals do exhibit mirror movements when performing tasks involving muscle fatigue and extremes of effort (Armatas et al, 1994(Armatas et al, , 1996a(Armatas et al, , 1996bCernacek, 1961;Liederman & Foley, 1987;Stern et al, 1976;Todor & Lazarus, 1986;Yensen, 1965).…”

Section: Introductionmentioning

confidence: 97%

“…This study therefore investigated the effects of attentional processes and age on motor overflow, measured by the mirror movements exerted during a finger force task (i.e., involuntary movement observed in one hand while the opposite hand is exerting force), adopting our previously developed experimental technique (Armatas et al 1996a(Armatas et al , 1996bGeorgiou-Karistianis et al, 2004;Hoy et al, 2004a). The intensity of overflow occurring under conditions where attention was directed to the active, passive or neither hand was compared across three age groups.…”

Section: Introductionmentioning

confidence: 99%

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The influence of attention and age on the occurrence of mirror movements

Baliz

Armatas

Farrow

et al. 2005

J. Inter. Neuropsych. Soc.

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This study utilised a finger force task to investigate the influence of attention and age on the occurrence of motor overflow in the form of mirror movements in neurologically intact adults. Forty right-handed participants were recruited from three age groups: 20-30 years, 40-50 years, and 60-70 years. Participants were required to maintain a target force using both their index and middle fingers, representing 50% of their maximum strength capacity for that hand. Attention was directed to a hand by activating a bone conduction vibrator attached to the small finger of that hand. Based on Cabeza's (2002) model of hemispheric asymmetry reduction in older adults, it was hypothesised that mirror movements would increase with age. Furthermore, it was expected that when the attentional demands of the task were increased, motor overflow occurrence would be exacerbated for the older adult group. The results obtained provide support for the model, and qualified support for the hypothesis that increasing the attentional demands of a task results in greater motor overflow. It is proposed that the association between mirror movements and age observed in this study may result from an age-related increase in bihemispheric activation that occurs in older adults, who, unlike younger adults, benefit from bihemispheric processing for task performance. (JINS, 2005, 11, 855-862.)

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The influence of attention and age on the occurrence of mirror movements

Baliz

Armatas

Farrow

et al. 2005

J. Inter. Neuropsych. Soc.

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“…In contrast, when distal muscles were activated to perform the tasks of spreading the small ®nger and squeezing the index ®nger and thumb together, mirror activity occurred signi®cantly more often with movements of the left side in both right-and left-handed individuals. A problem with comparing these results with that of other studies (e.g., Armatas et al, 1996a), however, is that differences between the hands with respect to the level of force exerted by participants on the ®nger squeezing task were not controlled and no ®nger strength data were provided. However, Durwen and Herzog's results suggest that the active body part as well as the task characteristics in¯uence motor over¯ow occurrence.…”

mentioning

confidence: 88%

“…Although, more usually associated with congenital or acquired neurological damage, motor over¯ow has been documented in neurologically normal adults (Armatas, Summers, & Bradshaw, 1996a;Liederman & Foley, 1987;Stern, Gold, Hoine, & Barocas, 1976). In non-clinical adults the occurrence of motor over¯ow is indicated by EMG activity in a passive limb (Cernacek, 1961) or inferred from unintended force exertion in the absence of observable movement (Armatas et al, 1996a;Stern et al, 1976).…”

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confidence: 94%

The Influence of Task Characteristics on the Intermanual Asymmetry of Motor Overflow

Armatas¹,

Summers²

2001

Journal of Clinical and Experimental Neuropsychology

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The two studies reported here were designed to test the proposition that greater motor overflow occurs when movements are performed by the non-dominant hand. Unlike previous studies using normal adults, the task in these studies did not require force production. In the first study, a group of 19 right-handed participants performed unweighted finger lifting. That the frequency of motor overflow occurrence was the same regardless of which hand performed the task, did not support findings from other studies where tasks involving force production resulted in more overflow when performed by the non-dominant hand. To investigate further the influence of task characteristics on motor overflow occurrence, in the second study participants were required to remember and reproduce a prescribed sequence of four finger lifts. Left- and right-handed participants (N = 30) performed both single and sequenced finger lifting. The relative frequency of motor overflow (unintended lifts of fingers of the passive hand) was compared between hand preference groups, active hand and task type (single/sequenced). Contrary to the expectation that motor overflow would be greater for the sequenced finger lifting task, overflow was exhibited with a significantly greater frequency on single finger lifting. This finding indicates that task characteristics influence the pattern of overflow occurrence in normal adults. The task used in this study did not involve force production and did not result in an intermanual asymmetry of motor overflow. This contrasts with findings from other studies requiring adults to exert forces where greater overflow occurred when the non-dominant hand was active. However, this study confirms previous findings which show that left-handers produce greater overflow compared to right-handers regardless of the task being performed and the hand performing the task.

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Hand digit control in children: motor overflow in multi-finger pressing force vector space during maximum voluntary force production

et al. 2008

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The aim of this study was to investigate the contralateral motor overflow in children during single-finger and multi-finger maximum force production tasks. Forty-five right handed children, 5-11 years of age produced maximum isometric pressing force in flexion or extension with single fingers or all four fingers of their right hand. The forces produced by individual fingers of the right and left hands were recorded and analyzed in four-dimensional finger force vector space. The results showed that increases in task (right) hand finger forces were linearly associated with non-task (left) hand finger forces. The ratio of the non-task hand finger force magnitude to the corresponding task hand finger force magnitude, termed motor overflow magnitude (MOM), was greater in extension than flexion. The index finger flexion task showed the smallest MOM values. The similarity between the directions of task hand and non-task hand finger force vectors in four-dimensional finger force vector space, termed motor overflow direction (MOD), was the greatest for index and smallest for little finger tasks. MOM of a four-finger task was greater than the sum of MOMs of single-finger tasks, and this phenomenon was termed motor overflow surplus. Contrary to previous studies, no single-finger or four-finger tasks showed significant changes of MOM or MOD with the age of children. We conclude that the contralateral motor overflow in children during finger maximum force production tasks is dependent upon the task fingers and the magnitude and direction of task finger forces.

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Strength as a factor influencing mirror movements

Cited by 22 publications

References 20 publications

The influence of attention and age on the occurrence of mirror movements

The influence of attention and age on the occurrence of mirror movements

The Influence of Task Characteristics on the Intermanual Asymmetry of Motor Overflow

Hand digit control in children: motor overflow in multi-finger pressing force vector space during maximum voluntary force production

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