Dynamic gamma frequency feedback coupling between higher and lower order visual cortices underlies perceptual completion in humans

To perceive a coherent environment, incomplete or overlapping visual forms must be integrated into meaningful coherent percepts, a process referred to as ?Gestalt? formation or perceptual completion. Increasing evidence suggests that this process engages oscillatory neuronal activity in a distributed neuronal assembly. A separate line of evidence suggests that Gestalt formation requires top-down feedback from higher order brain regions to early visual cortex. Here we combine magnetoencephalography (MEG) and effective connectivity analysis in the frequency domain to specifically address the effective coupling between sources of oscillatory brain activity during Gestalt formation. We demonstrate that perceptual completion of two-tone ?Mooney? faces induces increased gamma frequency band power (55?71 Hz) in human early visual, fusiform and parietal cortices. Within this distributed neuronal assembly fusiform and parietal gamma oscillators are coupled by forward and backward connectivity during Mooney face perception, indicating reciprocal influences of gamma activity between these higher order visual brain regions. Critically, gamma band oscillations in early visual cortex are modulated by top-down feedback connectivity from both fusiform and parietal cortices. Thus, we provide a mechanistic account of Gestalt perception in which gamma oscillations in feature sensitive and spatial attention-relevant brain regions reciprocally drive one another and convey global stimulus aspects to local processing units at low levels of the sensory hierarchy by top-down feedback. Our data therefore support the notion of inverse hierarchical processing within the visual system underlying awareness of coherent percepts.

Game theory and reciprocity in some extensive form experimental games

We examine decision making in two-person extensive form game trees using nine treatments that vary matching protocol, payoffs, and payoff information. Our objective is to establish replicable principles of cooperative versus noncooperative behavior that involve the use of signaling, reciprocity, and backward induction strategies, depending on the availability of dominated direct punishing strategies and the probability of repeated interaction with the same partner. Contrary to the predictions of game theory, we find substantial support for cooperation under complete information even in various single-play treatments.

Fostering Change: Toward Understanding, Valuing, and Informing the Therapeutic Role of Foster Parents

Foster parents have the potential to effect lasting therapeutic change through their role with the children they temporarily foster. Therapists working with foster parents can understand, support, and inform foster parents in their role based on a commonality that exists between the roles of therapists and foster parents. Similarities at different stages of both the therapeutic and foster parenting relationships are addressed, as well as the use of these relationships in a therapeutic manner. Advantages (for foster parents, foster children, therapists, and the foster care system) of articulating the foster parenting relationship through the lens of the therapeutic relationship are also discussed. Future research into the experience of foster parents in their role will be essential in creating an effective and sustainable system of care for vulnerable children.

In support of children [microform] : many successes but much to be done : hearing before the Select Committee on Hunger, House of Representatives, One Hundredth Congress, second session, hearing held in Washington, DC, March 23, 1988.

"Serial no. 100-23."

Development and evaluation of a pedestrian safety training program for elementary school bus riders. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Harry and Lucy concluded : being the last part of early lessons /

Harry and Lucy was started by Richard Lovell Edgeworth, the author's father.

The educator's role in the prevention and treatment of child abuse and neglect /

Aug. 1979.

Leader's manual : a curriculum on child abuse and neglect /

September 1979.

Child abuse and neglect audiovisual materials.

Previously issued as DHEW publication.

Television and social behavior; reports and papers.

Includes bibliographies

Television and juvenile delinquency; interim report pursuant to S. Res. 274, 88th Cong., 2d sess.,

Mode of access: Internet.

Child and family services plan.

"June 1997."

The laws respecting women : as they regard their natural rights or their connections and conduct in which their interests and duties as daughters, wards, heiresses, spinsters, sisters, wives, widows, mothers, legatees, executrixes, &c. are obligations of parent and child and the condition of minors. The whole laid down according to the principles of the common and statute law...and the substance of the trial of Elizabeth, duchess dowager of Kingston on an indictment for bigamy before the House of peers, April 1776. In four books.

Includes bibliographical references and index.

Mother and child.

Title from caption.

Parents and their problems; child welfare in home, school, church and state,

Contains bibliographies.