Neil Greenberg

Adaptive Functions of the Corpus Striatum: The Past and Future of the R-Complex

Neil Greenberg — Thu, 13 Dec 2012 12:14:22 PST

The basal ganglia is emerging from the shadow cast by the most conspicuous clinical expression of its dysfunction: motor disorders.What is revealed is the nexus of a widely distributed system which functions in integrating action with cognition, motivation, and affect. Prominent among non-motor functions are striatal involvement in building up of sequences of behavior into meaningful, goal-directed patterns and repertoires and the selection of appropriate learned or innate sequences in concert with their possible predictive control. Further, striatum seems involved in declarative and strategic memory (involving intentional recollection and the management of retrieved memories, respectively). Findings from reptile experiments indicate striatal control over specific assemblies of innate units of behavior that involve autonomic modulation. Its involvement in the appropriate expression of species-typical action patterns in reptiles and primates provides an interesting vantage point from which to interpret its involvement in the assembly of units of behavior into specific adaptive behavioral patterns.

For the current version with updated commentary, see https://notes.utk.edu/bio/greenberg.nsf/9e9a470d5230cdda852563ef0059fa56/89b6c6545b8412c185256a2c0060b638?OpenDocument

Ethological Aspects of Stress in a Model Lizard, Anolis carolinensis

Neil Greenberg — Thu, 13 Dec 2012 12:10:31 PST

Research on the stress response in reptiles can provide a useful comparative perspective for understanding how the constituent elements of the response can be put into service of diverse behavioral adaptations. A summary of the neural and endocrine causes and consequences of specific behavioral patterns seen in the small diurnal lizard, Anolis carolinensis, has provided a model for the exploration of the dynamics of autonomic and neurohormonal contributions to adaptive behavior.

In this species, changes in body color provide indices of the flux of circulating stress relevant hormones, and are seen in situations from spontaneous exploration through agonistic behavior. Furthermore, adult males spontaneously and consistently manifest social dominance relationships in captivity that provide all the elements of a stress mediated adaptive behavioral patterns. These patterns include suppressed reproduction and long-term coping apparently based more on stress-mediated changes in motivation than acquired changes in behavior.

For the current version with updated commentary, see https://notes.utk.edu/bio/greenberg.nsf/93c3cdb85c9d4c7d85256876001faff2/16b5f418b10b413f85256a2c0059baf7?OpenDocument

The Saurian Psyche Revisted: Lizards in Research

Neil Greenberg — Thu, 13 Dec 2012 12:08:03 PST

This essay is intended to guide researchers interested in lizards as prospective experimental models to identify an appropriate species for their research needs and to care for lizards in a manner that will not compromise their utility. Coupled with these is a concern for critical thinking about the ethical dimension of lizard research, one guide for which is to consider the intersection of human needs and lizard needs.

Before proceeding further, several arbitrary premises must be made clear:

1. While wholly deserving of study because of their intrinsic interest, I will assume that the lizard research to be undertaken is to obtain information that has generality and utility that transcends the species involved. That is, the information possess external validity__ potential applicability beyond the particulars of the individuals under study and the study environment; such data would contribute to the solving of more general problems.

2. We are concerned with animal welfare rather than animal rights. The failure to distinguish these two issues, concerned respectively with the reduction of pain and suffering on one hand and the possession by animals of rights comparable to those of humans, is a significant source of confusion (Schmidt 1990).

3. We are concerned with research rather than testing: the popular view of the scientist often confuses white_coated testers of toxicity with researchers in basic science. We are trying to attain original insights and advance basic knowledge, not set the agenda for commercial development or the limits for safe implementation.

Because of the great diversity of lizards and their life_styles, much of this review necessarily deals in generalities anchored in the specifics of my experience with a few iguanid species.

For the current version with updated commentary, see: https://notes.utk.edu/bio/greenberg.nsf/9e9a470d5230cdda852563ef0059fa56/c95b2abf95ee46ed85256a1d005affb4?OpenDocument

Art, Science, Areté

Neil Greenberg — Mon, 10 Dec 2012 10:23:21 PST

Ethological Considerations in the Experimental Study of Lizard Behavior

Neil Greenberg — Mon, 10 Dec 2012 10:17:43 PST

The importance of an ethological approach to the experimental study of an unfamiliar species is described and several of its problems discussed. The selection of units of behavior is a crucial first step in the development of a behavior inventory. The correlation of a behavioral unit with a particular context is necessary to ascribe function to that to that unit and to develop an ethogram. Methods of studying lizards under controlled conditions are described and discussed. Constraints on behavior that must be considered in an experimental study include the microclimate and its thermal qualities, food and water, shelter utilization, and social behavior. Ritualized display patterns are proposed as sources of hypotheses about the neurophysiological control of social communications.

Ethological Causes and Consequences of the Stress Response

Neil Greenberg et al. — Thu, 25 Mar 2010 12:45:18 PDT

Stress involves real or perceived changes within an organism or in the environment that activate an organism’s attempts to cope by means of evolutionarily ancient neural and endocrine mechanisms. Responses to acute stressors involve catecholamines released in varying proportion at different sites in the sympathetic and central nervous systems. These responses may interact with and be complemented by intrinsic rhythms and responses to chronic or intermittent stressors involving the hypothalamic-pituitary-adrenal axis. Varying patterns of responses to stressors are also affected by an animal=s assessment of their prospects for successful coping. Subsequent central and systemic consequences of the stress response include apparent changes in affect, motivation, and cognition that can result in an altered relationship to environmental and social stimuli. This review will summarize recent developments in our understanding of the causes and consequences of stress. Special problems that need to be explored involve the manner in which ensembles of adaptive responses are assembled, how autonomic and neurohormonal reflexes of the stress response come under the influence of environmental stimuli, and how some specific aspects of the stress response may be integrated into the life history of a species.

For a current copy with updated commentary, see: https://notes.utk.edu/bio/greenberg.nsf/9e9a470d5230cdda852563ef0059fa56/390fa88f83ffa27c85256e270055a7b5?OpenDocument

The Biology of Reality Testing - Implications for Cognitive Education

Neil Greenberg — Wed, 24 Mar 2010 07:49:59 PDT

• This report explores the proposition that teaching effectiveness can be enhanced by accommodating the key differences between two complementary and deeply engrained modes of reality testing, each predominantly centered in different hemispheres of the brain. • (1) Correspondence involves “reality-testing” of a percept, the cerebral representation of an experience in the world. • (2) Coherence involves “textualizing”, that is, reality-testing of a percept by how easily it relates to previous and ongoing parallel and collateral experiences. • Confidence in the validity of any percept throughout development is related to the interplay of these key processes. • As organisms develop, the “reference base” of previous experiences is enlarged and refined. • Motivation to enlarge the “reference base” is more or less intentionally energized by two variables: developmentally: an initial intrinsic desire to explore followed by the real or apparent need for additional experience and, ecologically, the costs and benefits of obtaining that experience.

"THE NATURAL HISTORY OF TRUTH: The Neurobiology of Belief"

Neil Greenberg — Wed, 24 Mar 2010 07:11:42 PDT

The pursuit of truth is woven into the fabric of every organism*. Any estimate of how best to survive and thrive in the reality in which we are immersed requires a sense of self, of the world, and of their relationship to each other. I wish to explore the idea that this pursuit has at its heart two complementary modes of reality testing utilizing separate cerebral systems which deal, respectively with the correspondence of experience with the world and the coherence of the experience with previous experiences: “is it real” and “does it fit?” At multiple levels of the nervous system, confidence in the validity of a belief depends on these two processes working independently and in concert.

I wish to explore the biological significance of “belief” and “truth” from the integrative perspective of ethology. That is, the lenses of developmental biology, ecology, evolutionary biology, and physiology will be focused on the process of extracting meaning from experiences.

Two complementary cerebral processes ordinarily work in lockstep to provide us with varying degrees of confidence in the strength of ensuing beliefs: These processes involve an estimation of the validity of correspondence and coherence. Such estimations of validity guides the continuing reconciling of intentions, expectations, and actions at every level of the nervous system, invoking energetically more expensive higher levels only when lower levels are inadequate. A third cerebral area reveals itself only in extraordinary circumstances and appears to evoke “hypergnosia,” an overwhelming and sometimes ecstatic sense of truth.

Correspondence” involves “reality-testing” of a percept, the cerebral representation of a fragment of experience [in the world]. “Coherence” involves “theorizing,” that is, reality-testing of a percept by how well it relates to previous and ongoing parallel and collateral experiences. As organisms develop, the “reference base” of previous experiences is enlarged and refined. A valid correspondence is consonant with a theory; a valid theory is corroborated by correspondences. In large measure, these mutually supportive cerebral processes are lateralized in different hemispheres of the brain. Their function is more-or-less balanced, but asymmetrical influence on confidence can be evoked by developmental circumstances that range from the willing suspension of disbelief to expectations and other cognitive biases that can undermine our effectiveness in the real world. .

The Beasts in Our Brain

Neil Greenberg — Wed, 24 Mar 2010 06:23:11 PDT

In the neuropsychology of art, we must remember that the Brain of Man has not abandoned its ancient animal foundations, it has built upon them . . . . But it has also reconstructed them as the shifting earth beneath dictates . . . . We have done the best possible in the landscape in which we have found ourselves with the raw materials we have inherited." --(Greenberg, Prolegomena to a Study of Mind, 1973, ch. 42)