Extrapyramidial mechanisms in handedness in the rat.

Abstract

From previous work on handedness in the rat (Peterson, 1934, Peterson and Fracarol, 1938) we know that there is a highlylocalized area in the contralateral frontal region of the cerebral cortex which controls this trait. Widespread occipital and temporal destructions are without influence in producing transfers when this area is intact. It is known that after bilateral pyramidal destructions, handedness is disturbed and a temporary loss of function may occur, but with practice, the use of one hand may again become predominant. Several theories as to how this "extrapyramidal" handedness functions present themselves: 1. It may be due to vicarious functioning. 2. It may be "learning to get along without the lost functions" (Lashley, 1933). 3. It may be due to the use of a system that previously functioned with the pyramidal system.The present study seeks for other mechanisms of handedness in the brain. Two general methods of investigation were used: 1. Cerebellar destructions were produced in some cases with both pyramidal systems intact and in others with these systems destroyed. 2. Assorted cortical and subcortical destructions were produced after the pyramidal systems were destroyed.It is unfortunate that destructions in the corpus striatum could not be produced while leaving the cortex intact, but this was not possible without interfering with the fibers of the pyramidal system that run out through the basal ganglia. Brown, et al., (1936) andBeach (1941), describe methods of destroying subcortical tissue with minimal destruction of the cerebral cortex, but they do not tell us how to avoid destruction of fiber paths from the cerebral cortex that run out through the corpus striatum. Since in the rat a relatively small number of fibers are involved in handedness (under 5% destructions have been shown to pro-

The Vermicelli Handling Test: A simple quantitative measure of dexterous forepaw function in rats

“…The failure to find clear evidence for population bias (left versus right) in forepaw preferences for handling pasta in intact rats is consistent with studies of rat forelimb reaching behavior (Peterson, 1934;Whishaw, 1992). However, individual rats often had limb preferences for vermicelli handling behaviors.…”

“…The most well developed formal tests of forelimb function in rodents are the skilled reaching tests (a.k.a. reach-to-grasp tests), in which rats are placed in an enclosure and reach with the forepaw past some obstacle to grasp and retrieve food pieces (Peterson, 1934). This includes single pellet retrieval tasks (Castro, 1972;Whishaw et al, 1986), tray reaching tasks (Brácha et al, 1990;Whishaw and Pellis, 1990), the pasta matrix reaching task (Ballermann et al, 2001) and the Montoya staircase task (Montoya et al, 1991;reviewed in Nichols et al, 2005).…”

A gene-culture model of human handedness

“…Collins (1975) found that mice, initially equally divided among those favoring their left or right paw, became predominantly right-pawed if exposed to a biased environment in which it is easier to get food with the right paw. Selective breeding for pawedness in mice, rats, and cats generated no genetic response (Peterson, 1934;Collins, 1969), a result which suggests that no genetic variation underlies this lateralization. Morgan and Corballis (1978) suggest that variation in handedness is of nongenetic origin and that left-handedness is due to environmental influences.…”

The Vermicelli and Capellini Handling Tests: Simple quantitative measures of dexterous forepaw function in rats and mice

“…In our experience, the reaching tests are more complicated and laborious to perform and, for some experimental questions, the present tests may provide a more efficient alternative. However, unlike the tests described here, skilled reaching tests have been in use for decades (Peterson, 1934) and they now include a versatile set of highly sensitive measures and test parameters (Ballermann et al, 2001;Farr & Whishaw, 2002;Montoya et al, 1991;Whishaw et al, 1992). In contrast, the Vermicelli and Capellini Handling Tests extend from relatively recent characterizations of the adroit food handling behavior of rats (Whishaw and Coles, 1996).…”