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J Mallick

Publications and source records attributed to J Mallick.

6 recordsLinked to original sources
PubMed1995

Towards a sociobiological model of depression. A marsupial model (Petaurus breviceps).

BACKGROUND: This is a sociobiological approach to depression using hierarchy and its hypothesised relevance to self-esteem in the marsupial sugar glider (Petaurus breviceps). METHOD: Differential access to resources between the dominant and submissive animal is measured by observation in four stable colonies. The dominant animals from two of these colonies are then introduced into the other two, resulting in the transferred former dominants becoming subordinate. Behavioural and biochemical measures relevant to depression and involving access to resources are then repeated. These measures include eating, drinking, social and sexual access, motility, grooming and biochemical estimates of cortisol and testosterone. RESULTS: Subordinate animals have significantly less access to resources, both in the stable colony and when the formerly dominant animals become subordinate. CONCLUSIONS: A sociobiological approach using a hierarchy model equating resource-holding potential with self-esteem, exemplified by this study, may provide new concepts and insights into the phenomenology and pathophysiology of depression. It allows comparisons to be made between animal behaviour and cognition: the lack of such has been a major difficulty in animal studies hitherto. The findings are possibly more relevant to dysthymia than to affective disorder and imply a relationship between low resource-holding potential in sub-human animals as a phylogenetic antecedent of some of the cognitive and affective aspects of depression in man.

Animals↗
PubMed1994

Somatosensory evoked response source localization using actual cortical surface as the spatial constraint.

We localized right median nerve somatosensory evoked responses in a normal human subject using an equivalent dipole method applied to magnetic field recordings. High resolution, 3-dimensional MRI data were used to confine source locations to the cortical surface. Results localized in Brodmann area 3b corresponding to location of hand somatosensory cortex derived from direct brain stimulation studies. The solution was unique and total computational time for an exhaustive, brute-force search was small and the results realistic due to applied anatomical constraints. This study demonstrates feasibility of accurate, non-invasive, realistic localization of dynamic human cortical function using spatial constraints provided by MRI images.

Adult↗
PubMed1994

Behavioral and endocrinological correlates of social status in the male sugar glider (Petaurus breviceps Marsupialia: Petauridae).

Socially dominant male sugar gliders are heavier than socially subordinate males, have higher plasma testosterone and lower cortisol concentrations, win more social encounters, scan the arena more, scent-mark more, and are more active and move more quickly, even though they spend more time in the colony nesting box. When they are transferred into a foreign stable colony there is an impressive reversal of behavioral measures and a concomitant decrease in concentration of plasma testosterone and rise in cortisol that is apparent over the first 3 weeks of observation.

Animals↗