Biomedical subjects

Bjorn Merker

Publications and source records attributed to Bjorn Merker.

4 recordsLinked to original sources

PubMed2005

The liabilities of mobility: a selection pressure for the transition to consciousness in animal evolution.

The issue of the biological origin of consciousness is linked to that of its function. One source of evidence in this regard is the contrast between the types of information that are and are not included within its compass. Consciousness presents us with a stable arena for our actions-the world-but excludes awareness of the multiple sensory and sensorimotor transformations through which the image of that world is extracted from the confounding influence of self-produced motion of multiple receptor arrays mounted on multijointed and swivelling body parts. Likewise excluded are the complex orchestrations of thousands of muscle movements routinely involved in the pursuit of our goals. This suggests that consciousness arose as a solution to problems in the logistics of decision making in mobile animals with centralized brains, and has correspondingly ancient roots.

Animals↗

PubMed2005

The conformal motive in birdsong, music, and language: an introduction.

Human song and music are part of what may be called a ritual stratum of human culture. As such, they involve special behaviors and neural mechanisms with an uneven but interesting distribution in nature. This may be turned to account not only for shedding light on the biological background of human song and music, but also for elucidating the nature of the cultural traditions within which these arts are practiced and elaborated. The purpose of this chapter is accordingly threefold: (1) to highlight the uniqueness of human culture compared to that of other primates by defining and contrasting two very different types of traditions that coexist within it: those of instrumental culture and those of ritual culture; (2) to outline the crucial role of the mechanism of vocal learning as an enabling device for ritual culture, specifically, by way of the well-studied behavioral biology of birdsong; and (3) to introduce the conformal motive as a so-far neglected, but essential, aspect of the neural mechanisms required for vocal learning. Taken together, these considerations will then be used to sketch some of the roles this postulated conformal motive appears to play in human culture, stratified into instrumental, ritual, and language traditions. Some of the implications of this perspective for our understanding of a number of issues related to the human facility for imitation, expressive mimesis, and deliberate teaching are also briefly touched upon.

Animals↗

PubMed2004

Cortex, countercurrent context, and dimensional integration of lifetime memory.

The correlation between relative neocortex size and longevity in mammals encourages a search for a cortical function specifically related to the life-span. A candidate in the domain of permanent and cumulative memory storage is proposed and explored in relation to basic aspects of cortical organization. The pattern of cortico-cortical connectivity between functionally specialized areas and the laminar organization of that connectivity converges on a globally coherent representational space in which contextual embedding of information emerges as an obligatory feature of cortical function. This brings a powerful mode of inductive knowledge within reach of mammalian adaptations. It combines item specificity with classificatory generality, as embodied in "latent semantic analysis" algorithms. Its neural implementation is proposed to depend on an obligatory interaction between the oppositely directed feedforward and feedback currents of cortical activity, in countercurrent fashion. Direct interaction of the two streams along their cortex-wide local interface supports a scheme of "contextual capture" for information storage responsible for the lifelong cumulative growth of a uniquely cortical form of memory termed "personal history." This approach to cortical function helps elucidate key features of cortical organization as well as cognitive aspects of mammalian life history strategies.

Evoked Potentials↗

PubMed2004

Siamang gibbons exceed the saccular threshold: intensity of the song of Hylobates syndactylus.

Measurements are reported of the intensity of the siamang gibbon loud call obtained from the vocal bouts of three family groups at Twycross Zoo, UK. Across 25 samples the maximum intensity ranged from 95 to 113 dB SPL (linear frequency-weighting and fast time-weighting) and exhibited three frequency modes of 250-315 Hz, 630-800 Hz and 1.2-1.6 kHz. The lowest frequency mode, which may correspond to the "boom" sound produced by resonance of the siamang inflated vocal sac, had a mean maximum intensity of 99 dB SPL. These values, which are in excess of the saccular acoustic threshold of about 90 dB at 300 Hz for air conducted sound, suggest that primate loud calls recruit a primitive mode of acoustic sensitivity furnished by the sacculus. Thus reproductive vocal behavior of primates may be influenced by a primitive acoustical reward pathway inherited from a common ancestor with anamniotes. In humans such a pathway could explain the compulsion for exposure to loud music.

Animals↗