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D J Micco

Publications and source records attributed to D J Micco.

9 recordsLinked to original sources
PubMed1980

Glucocorticoids, the hippocampus, and behavior: interactive relation between task activation and steroid hormone binding specificity.

A previous investigation established a modulatory effect of adrenal glucocorticoids on a behavior generally believed to require participation of the hippocampus for normal expression. For further delineation of whether the observed effects on appetitive extinction are consistent with a glucocorticoid action on hippocampus, adrenalectomized rats were administered either corticosterone or dexamethasone, a synthetic glucocorticoid that is accumulated much less intensively by the hippocampus than is corticosterone. While corticosterone normalized extinction, dexamethasone did not. In two other hippocampal-dependent behaviors, alternation and exploration, there was no glucocorticoid modulation of behavior, which may indicate that factors such as the level of activation of the type of learning determine whether a glucocorticoid effect will occur. These findings of a glucocorticoid action on one of three tasks that involve hippocampal function reinforce the notion that in addition to their well-studied actions in protein and carbohydrate metabolism, the adrenal glucocorticoids may also be subtle modulators of behavior.

Adrenocorticotropic Hormone↗
PubMed1979

Modulation of behavioral inhibition in appetitive extinction following manipulation of adrenal steroids in rats: implications for involvement of the hippocampus.

Corticosterone, the principal glucocorticoid in the rat, binds selectively to the CA1 pyramidal neurons of the hippocampus where the hormone has been demonstrated to exert a moderate chronic suppression of spontaneous activity. In the first experiment of the current study, the functional behavioral significance of this hormone--brain interaction was investigated in the extinction of an appetitive runway response in normal rats and those with lesions of the hippocampus. During extinction, half of the animals in each group were given daily subcutaneous injections of corticosterone. Whie the classical retardation effect of hippocampal lesions on appetitive extinction was replicated, hormone treatment was without effect in normal or hippocampally damaged subjects. The absence of a hormone effect in normals was primarily attributed to a saturated limited-binding system operating in the normal animal. Experiment 2 tested this notion, repeating the first experiment, with adrenal-ectomized (ADX), ADX + corticosterone replacement, and normal groups of animals. Adrenalectomy produced a striking facilitation of extinction which was speculated to be the result of a hyperactive inhibitory neural organ free from an inhibitory endocrine feedback. Corticosterone treatment normalized the progress of extinction in ADX animals, providing support for the afore-mentioned speculation. In the normal animal, it appears that a stress-induced surge in hormone level interacts with a limited-capacity neural binding to produce a transient dynamic range of behavioral disinhibition, perhaps promoting persistence during initial stages of frustrative nonreward in moderate stress tasks.

Animals↗
PubMedDate not supplied

Organization of brainstem behavioral systems.

A review of recent literature suggests that the brainstem may play a more fundamental role in the elaboration of adaptive behaviors than has often been assumed. This view is indicated by current reports documenting the substantial behavioral repertoire of decerebrate animals and by the recent findings that electrical stimulation of localized areas in all major levels of the brainstem can induce complex and coordinated behaviors, including eating, grooming and attack. Indeed, behaviors elicited from sites in the caudal brainstem evidence unexpected goal specificity and stimulus control over response topography. Additional neuroanatomical and behavioral data are reviewed which further implicate caudal brainstem networks in process of reward and aversion. From these and other findings it is argued that integrating mechanisms for the expression of many aspects of species-characteristic behaviors are intrinsic to the brainstem. In line with this view, rostral hypothalamic-limbic mechanisms, while perhaps contributing refinement to the integration of behaviors, may best be viewed as phylogenetically newer control mechanisms making the expression of species-characteristic behaviors subordinate to additional class of exteroceptive and interoceptive stimuli.

Aggression↗
PubMedDate not supplied

Lightweight, multi-contact, slip-ring commutator for recording and stimulation with small animals.

A slip-ring commutator which can be used to electrically stimulate and/or record from the brains of small, unrestrained animals is described. In addition to providing 4 to 10 independent electrical contacts, featues of this model include its small size, low torque characteristics, low rate of contact oxidation, and minimal noise generated at the brush-ring surface. The compactness and light weight of this unit permit it to be suspended from a counterweighted boom assembly, thus providing additional freedom for vertical movement.

Animals↗