Neural Gate Keeping: The Role of Interhemispheric Interactions in Resource Allocation and Selective Filtering.

Abstract

The corpus callosum has been proposed to contribute to attention by modulating resource allocation between the hemispheres and filtering interhemispheric signal transmission (M. T. Banich, 1998). The resource allocation hypothesis predicts that interhemispheric interactions become more advantageous with increasing resource demands. The selective filtering hypothesis predicts that interhemispheric interactions become less advantageous as filtering requirements increase. The authors tested both predictions by comparing within- and across-hemisphere letter matching under dual-task (Experiment 1) and selective attention conditions (Experiment 2). Task-specific resource demands (i.e., letter processing load) alter the bihemispheric advantage, but the general demand imposed by an unrelated secondary task does not. Filtering requirements influenced the advantage from interhemispheric interactions, providing new evidence for the role of the corpus callosum in selective attention.

Competition in Visual Cortex Impedes Attention to Multiple Items

“…We found no evidence, then, that the attentional systems of the two hemispheres were functioning independently during performance of this difficult triple conjunction detection task. Although this may seem surprising given the recent excitement over the ability of the hemispheres’ attentional systems to operate in parallel (Scalf et al, 2007; Alvarez & Cavanagh, 2005; Delvenne, 2005), we note that conditions of high attentional demand usually prevent the hemispheres from acting in parallel (Banich, 1998; Mikels & Reuter-Lorenz, 2004; Scalf et al, 2007). Indeed, nearly two decades of data suggest that high attentional demands usually cause the connected hemispheres to increase their interactions and function as a coordinated unit that is responsive to information in both visual fields (Luck et al, 1989; Banich & Belger, 1990; Belger & Banich, 1992; Banich, 1998, Weissman & Banich, 2000; Mikels & Reuter-Lorenz, 2004, Scalf et al, 2007).…”

Behavioral evidence of prolonged interhemispheric transfer time among psychopathic offenders.

“…Numerous studies have demonstrated that information processing is dynamically coupled or decoupled across the cerebral hemispheres in response to task demands (Weissman & Banich, 2000; Weissman & Compton, 2003). Efficient integration of information across the hemispheres improves performance on complex, multidimensional tasks, presumably because of the advantage of parallel processing, whereas strategic decoupling can reduce interference in situations demanding selective attention (Banich, 1998; Belger & Banich, 1992; Compton, Heller, Banich, Palmieri, & Miller, 2000; Mikels & Reuter-Lorenz, 2004). This dynamic, adaptive coordination of processing across the hemispheres is believed to rely heavily on the integrity of the corpus callosum, the major tract of fibers connecting the cerebral cortices of the left and right hemispheres.…”

Trouble crossing the bridge: Altered interhemispheric communication of emotional images in anxiety.

“…Behavioral studies of interhemispheric interaction have long emphasized its dynamic nature. For example, researchers have conceived of the callosum as a selective filter that can adaptively control information flow between the hemispheres (e.g., Liederman, 1986;Mikels & Reuter- Lorenz, 2004;Weissman & Banich, 1999). Studies using behavioral methods have shown that interhemispheric communication is modulated by changing task demands (Weissman & Banich, 2000) and situational factors such as evaluation stress (Compton & Mintzer, 2001;Compton et al, 2004).…”

“…Prior research indicates that the dynamics of interhemispheric communication can yield insights about information processing that may not be evident by studying levels of activity in either hemisphere alone (e.g., Banich, 2003). For example, interhemispheric communication contributes to selective attention, presumably by facilitating the transfer of task-relevant information and inhibiting the transfer of task-irrelevant information (e.g., Mikels & Reuter-Lorenz, 2004; Weissman & Banich, 1999). Studying interhemispheric dynamics could therefore shed light on information processing in anxiety, particularly because anxiety is characterized by biases in selective attention (e.g., MacLeod & Rutherford, 2004; Mineka, Rafaeli, & Yovel, 2003).…”