The groundbreaking, viewpoint theory of Merker et al. explains several properties of the conscious field, including why the observer cannot directly apprehend itself. We propose that viewpoint theory might also provide a progressive, constitutive marker of consciousness and shed light on why most of the contents of consciousness are encapsulated.

Passive frame theory attempts to illuminate what consciousness is, in mechanistic and functional terms; it does not address the “implementation” level of analysis (how neurons instantiate conscious states), an enigma for various disciplines. However, in response to the commentaries, we discuss how our framework provides clues regarding this enigma. In the framework, consciousness is passive albeit essential. Without consciousness, there would not be adaptive skeletomotor action.

What is the primary function of consciousness in the nervous system? The answer to this question remains enigmatic, not so much because of a lack of relevant data, but because of the lack of a conceptual framework with which to interpret the data. To this end, we have developed Passive Frame Theory, an internally coherent framework that, from an action-based perspective, synthesizes empirically supported hypotheses from diverse fields of investigation. The theory proposes that the primary function of consciousness is well-circumscribed, serving the somatic nervous system. For this system, consciousness serves as a frame that constrains and directs skeletal muscle output, thereby yielding adaptive behavior. The mechanism by which consciousness achieves this is more counterintuitive, passive, and “low level” than the kinds of functions that theorists have previously attributed to consciousness. Passive frame theory begins to illuminate (a) what consciousness contributes to nervous function, (b) how consciousness achieves this function, and (c) the neuroanatomical substrates of conscious processes. Our untraditional, action-based perspective focuses on olfaction instead of on vision and is descriptive (describing the products of nature as they evolved to be) rather than normative (construing processes in terms of how they should function). Passive frame theory begins to isolate the neuroanatomical, cognitive-mechanistic, and representational (e.g., conscious contents) processes associated with consciousness.

Although the prefrontal cortex (PFC) is consistently found to be associated with various working memory processes, the necessity of the PFC for such processes remains unclear. To elucidate PFC contributions to storage and rehearsal/maintenance processes engaged during verbal working memory function, we assessed behavior of patients with lesions to the left or right lateral PFC, and neural activity of healthy young subjects during fMRI scanning, during performance of working memory tasks. We found that PFC lesions did not affect storage processes—which is consistent with the notion that posterior cortical networks can support simple retention of information. We also found that PFC lesions did not affect rehearsal/maintenance processes, which was in contrast to our finding that healthy subjects performing a verbal delayed recognition task showed bilateral PFC activation. These combined imaging and behavioral data suggest that working memory rehearsal/maintenance processes may depend on both hemispheres, which may have implications for recovery of function and development of rehabilitation therapies after frontal injury. (JINS, 2006, 12, 248–260.)

Response bias reflects the decision rule an individual uses when faced with uncertainty on recognition memory tasks. Recent studies indicate frontal regions may mediate response bias performance. One theory of aging also implicates frontal lobe contributions in age-related cognitive changes. This suggests that frontal lobe changes may mediate response bias in older adults. Consistent with this frontal aging hypothesis, we predicted that response bias would become more liberal with age. Methods: Participants were 181 younger (30–49) and 112 older normal adults (75+) that were part of the California Verbal Learning Test-second edition (CVLT-2) normative sample (total n = 1078). We used parametric measures of discriminability and response bias provided by the CVLT-2 scoring program. Groups were similar in IQ and education. Multi-level regression models were created to examine the effects of moderating variables. The interaction between age and age group significantly predicted response bias. Post hoc analysis indicated that increasing age was associated with more liberal bias in the older but not in the younger group. In the light of reported relationships between frontal regions and both aging and response bias, we hypothesize that frontal changes may be the underlying mechanism explaining the increase in liberal response bias with age. (JINS, 2006, 12, 1–7.)