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Papers by Meena Dharmaretnam
SIGLEAvailable from British Library Document Supply Centre- DSC:DX180165 / BLDSC - British Librar... more SIGLEAvailable from British Library Document Supply Centre- DSC:DX180165 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Journal of the National Science Foundation of Sri Lanka, 2010
HAYATI Journal of Biosciences, 2021
Axis axis ceylonensis (Ceylon spotted deer) is a sub species endemic to Sri Lanka. Ecological obs... more Axis axis ceylonensis (Ceylon spotted deer) is a sub species endemic to Sri Lanka. Ecological observations in wild populations of this subspecies have been reported but there is no published research on its behaviour. We report here a behavioural study on a free ranging population of A. a. ceylonensis inhabiting a temple surroundings in Trincomalee, Sri Lanka. Behaviour was quantified by focal sampling on sex age groups in three time zones: 6:30 to 7:30, 12:30-13:30, and 17:00 to 18:00 hours. The deer were more active in the hour after dawn and an hour before dusk. The main activities were feeding and play, the latter common in juveniles. There was a preference to graze on grasses and browse on Ficus sp. leaves. Resting was highest in the afternoon across all groups. This bimodal activity pattern is similar to that of both wild Ceylon and Indian A. axis subspecies despite the absence of predators in the study area. The bimodal activity may be related to thermoregulatory functions wh...
Journal of the National Science Foundation of Sri Lanka, 2010
Laterality: Asymmetries of Body, Brain and Cognition, 2002
Lateralisation of a variety of visual functions: food discrimination, fear response, copulation, ... more Lateralisation of a variety of visual functions: food discrimination, fear response, copulation, and performance of topographical and other tasks, such as olfactory and auditory functions, have been described in the domestic chick, Gallus gallus domesticus. A bias to left hemisphere control on day 8 and to the right on day 11 has also been demonstrated in the domestic chick. In this study we show that motor control as to foot preference in initiating a scratching bout and a tape-removing task is lateralised in both adults and chicks. There was a preference for the right leg to initiate a bout of ground scratching in both male and female adult birds. Second, foot preference is also affected by the changes in shifts of bias on day 8 and day 11. The right leg preference in initiating a ground scratching bout observed on day 5 is reversed to a left leg preference on day 8. This then reverts to the right leg preference after day 11. Hence it is postulated that the hemisphere that is not activated due to the bias of age controls the first leg to be used in initiating routine movements such as ground scratching. For the tape-removing task the right leg was used to remove a tape adhered to the beak of the chick for the trained group on day 8; but there was no preference in the naive group. Similarly, on day 11 a left foot bias was observed for the trained group and right foot bias for the naive group. To remove a tape the activated hemisphere on days of bias is used; whereas in a novel situation the foot use is reversed. Thus, footedness is affected by age, type of task, and changing hemispheric dominance.
Laterality: Asymmetries of Body, Brain and Cognition, 1996
Chicks were imprinted to the sound of a cluck, by differing durations of exposure in the dark on ... more Chicks were imprinted to the sound of a cluck, by differing durations of exposure in the dark on the first day of life. At test, when the chicks were placed centrally in an arena lit only by infra-red, those receiving two or three hours of exposure turned their right ear towards a source of clucks, just before approach to the source, but used their left ear instead after five or six hours exposure; after four hours there was no clear bias. This shift was not due to differences in age nor in time of day, but was a direct consequence of lengthening prior exposure. As learning about (and/or attaching to) the cluck progresses, there thus appears to be a shift from predominant use of the left hemisphere in listening and responding to the cluck. There is other evidence that the left hemisphere may be particularly involved in the chick in initial selection of important cues, while the right hemisphere elaborates relatively unselected records.
Behavioural Brain Research, 2005
Behavioural Brain Research, 2005
Cerebral lateralisation once thought to be confined to humans has been reported for a range of ve... more Cerebral lateralisation once thought to be confined to humans has been reported for a range of vertebrate species now. We report here biases in visual perceptual processing in a teleost fish. Female guppy fish used the right eye preferentially to view a familiar stimulus. This bias reversed on being presented with a strange female guppy, the left eye being used more to view it. This pattern of viewing is probably associated with the right eye system, which is used to view a stimulus with an intention to approach it. The increase in the left eye use, to view a stranger may be associated with the role of the left eye in comparing the features of a strange conspecific. In the second experiment, lateralisation of viewing visual stimuli that could evoke different levels of motivation to biologically relevant stimuli was tested. It is known that female guppies prefer to approach orange coloured males. Lateralisation of detour response as well as eye use after detour to view a dull or an orange male stimulus was recorded in deprived female fish. There was a bias to detour to the left side; which was more significant for the orange than the dull male. Once the female guppies detoured the cage they preferentially used the left eye to view the male conspecific; this being significant for the deeply orange male. Thus, colouration of males evoking different levels motivation can be used to measure lateralisation in guppies.
Behavioural Brain Research, 2009
SIGLEAvailable from British Library Document Supply Centre- DSC:DX180165 / BLDSC - British Librar... more SIGLEAvailable from British Library Document Supply Centre- DSC:DX180165 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Journal of the National Science Foundation of Sri Lanka, 2010
HAYATI Journal of Biosciences, 2021
Axis axis ceylonensis (Ceylon spotted deer) is a sub species endemic to Sri Lanka. Ecological obs... more Axis axis ceylonensis (Ceylon spotted deer) is a sub species endemic to Sri Lanka. Ecological observations in wild populations of this subspecies have been reported but there is no published research on its behaviour. We report here a behavioural study on a free ranging population of A. a. ceylonensis inhabiting a temple surroundings in Trincomalee, Sri Lanka. Behaviour was quantified by focal sampling on sex age groups in three time zones: 6:30 to 7:30, 12:30-13:30, and 17:00 to 18:00 hours. The deer were more active in the hour after dawn and an hour before dusk. The main activities were feeding and play, the latter common in juveniles. There was a preference to graze on grasses and browse on Ficus sp. leaves. Resting was highest in the afternoon across all groups. This bimodal activity pattern is similar to that of both wild Ceylon and Indian A. axis subspecies despite the absence of predators in the study area. The bimodal activity may be related to thermoregulatory functions wh...
Journal of the National Science Foundation of Sri Lanka, 2010
Laterality: Asymmetries of Body, Brain and Cognition, 2002
Lateralisation of a variety of visual functions: food discrimination, fear response, copulation, ... more Lateralisation of a variety of visual functions: food discrimination, fear response, copulation, and performance of topographical and other tasks, such as olfactory and auditory functions, have been described in the domestic chick, Gallus gallus domesticus. A bias to left hemisphere control on day 8 and to the right on day 11 has also been demonstrated in the domestic chick. In this study we show that motor control as to foot preference in initiating a scratching bout and a tape-removing task is lateralised in both adults and chicks. There was a preference for the right leg to initiate a bout of ground scratching in both male and female adult birds. Second, foot preference is also affected by the changes in shifts of bias on day 8 and day 11. The right leg preference in initiating a ground scratching bout observed on day 5 is reversed to a left leg preference on day 8. This then reverts to the right leg preference after day 11. Hence it is postulated that the hemisphere that is not activated due to the bias of age controls the first leg to be used in initiating routine movements such as ground scratching. For the tape-removing task the right leg was used to remove a tape adhered to the beak of the chick for the trained group on day 8; but there was no preference in the naive group. Similarly, on day 11 a left foot bias was observed for the trained group and right foot bias for the naive group. To remove a tape the activated hemisphere on days of bias is used; whereas in a novel situation the foot use is reversed. Thus, footedness is affected by age, type of task, and changing hemispheric dominance.
Laterality: Asymmetries of Body, Brain and Cognition, 1996
Chicks were imprinted to the sound of a cluck, by differing durations of exposure in the dark on ... more Chicks were imprinted to the sound of a cluck, by differing durations of exposure in the dark on the first day of life. At test, when the chicks were placed centrally in an arena lit only by infra-red, those receiving two or three hours of exposure turned their right ear towards a source of clucks, just before approach to the source, but used their left ear instead after five or six hours exposure; after four hours there was no clear bias. This shift was not due to differences in age nor in time of day, but was a direct consequence of lengthening prior exposure. As learning about (and/or attaching to) the cluck progresses, there thus appears to be a shift from predominant use of the left hemisphere in listening and responding to the cluck. There is other evidence that the left hemisphere may be particularly involved in the chick in initial selection of important cues, while the right hemisphere elaborates relatively unselected records.
Behavioural Brain Research, 2005
Behavioural Brain Research, 2005
Cerebral lateralisation once thought to be confined to humans has been reported for a range of ve... more Cerebral lateralisation once thought to be confined to humans has been reported for a range of vertebrate species now. We report here biases in visual perceptual processing in a teleost fish. Female guppy fish used the right eye preferentially to view a familiar stimulus. This bias reversed on being presented with a strange female guppy, the left eye being used more to view it. This pattern of viewing is probably associated with the right eye system, which is used to view a stimulus with an intention to approach it. The increase in the left eye use, to view a stranger may be associated with the role of the left eye in comparing the features of a strange conspecific. In the second experiment, lateralisation of viewing visual stimuli that could evoke different levels of motivation to biologically relevant stimuli was tested. It is known that female guppies prefer to approach orange coloured males. Lateralisation of detour response as well as eye use after detour to view a dull or an orange male stimulus was recorded in deprived female fish. There was a bias to detour to the left side; which was more significant for the orange than the dull male. Once the female guppies detoured the cage they preferentially used the left eye to view the male conspecific; this being significant for the deeply orange male. Thus, colouration of males evoking different levels motivation can be used to measure lateralisation in guppies.
Behavioural Brain Research, 2009