David M. Bear

Hemispheric Specialization in Nonverbal Communication

Subjects sustaining right hemisphere damage were impaired in the ability to evaluate emotional situations presented through nonverbal means, particularly through facial expressions. Left brain damage, even of considerable extent, led to significantly milder deficits. In agreement with these findings, a study in split-brain patients showed the isolated right hemisphere to be competent in evaluating facial expressions but less sensitive to body movements, while the left hemisphere showed the opposite pattern.

Sequential change in receptive fields of striate neurons in dark adapted cats.

Summary1.A general purpose, digital computer was employed to map quantitatively the receptive fields of units in cats striate cortex.2.Receptive fields were studied as a function of barbiturate anesthetic level under dark adapted conditions.3.Receptive fields obtained from lateral geniculate axons were topographically simple and usually represented a single peak with concentric zones of decreasing excitability. Such fields were stable under all anesthetic and electroencephalographic conditions.4.Responses were recorded from striate cells, both simple and complex in the sense of Hubel and Wiesel. These demonstrated varied field configurations such as an excitatory cylinder in an inhibitory field, excitatory vertical axis flanked by asymmetric inhibitory areas, and more complex patterns including potentially direction and velocity sensitive ones.5.Many cortical maps were unstable over time, especially in the presence of low voltage, fast electroencephalographic activity. Changes were not random nor did they represent simple linear displacements of peaks, but included axis shifts, gradient change, and expansion or contraction of excitatory and inhibitory zones with centers at fixed relative positions.6.Heavy barbiturate anesthesia and spontaneous spindling in the EEG markedly reduced the variability in these maps; the encephale isole preparation was more stable than spinally intact animals. This association suggests a role of the midbrain reticular formation in cortical variability.7.Random rather than iterative presentation of matrix points resulted in higher mean firing rates and more stable receptive fields, probably the result of photochemical recovery in dispersed receptors and time averaging of cellular excitability.8.When stability was analyzed as a function of time interval of response (early on, late on, early off, late off), initial on responses were often more stable than longer latency late on- or off-responses. This factor, among others discussed, makes eye movement an unlikely explanation for map variability. It suggests additionally that late on- and off- responses represent input to the cortical cell from units other than those producing the early on-response.9.The effects of pentobarbital, in addition to stabilization of the receptive field, included striking phase reversals in which inhibitory regions became excitatory and visa versa. Firing rate often changed substantially, but both increases and decreases were observed.10.It is argued that visual response under pentobarbital is a special and not the general case of visual perception and that sequential receptive field changes during aroused brain states reflect integrative, purposive processes at the cortical level.

The Temporal Lobes: An Approach to the Study of Organic Behavioral Changes

From a clinical perspective, alterations in the emotions or behavior of an individual primarily present a problem in differential diagnosis. For this reason, a simple rule or generalization has long been sought to distinguish behavioral syndromes of organic causation from functional—idiopathic or learned—psychiatric disorders.

Quantitative characterization of unit response in the visual system

SummaryA quantitative approach to characterization of unit response in the visual system was proposed. Temporal parameters of response were analyzed by post stimulus time-histograms obtained from point visual stimulation. Explicit temporal intervals were chosen to coincide with discrete response components. By calculating net firing rate within these intervals as a function of stimulus position, quantitative receptive field maps were constructed. To estimate response between stimulated matrix mesh points, a general contouring program was described. Latency, and synchronicity — a logarithmic probability function sensitive to temporal consistency of response — were also mapped as functions of stimulus position.Representative firing rate maps morphologically resembled previously described receptive fields; latency and synchronicity maps, it is argued, allow for additional mechanistic and functional analysis of striate units. By explicitly separating temporal and spatial variables and quantifying unit response, the present methods will hopefully enlarge the scope and sensitivity of receptive field analysis.

New clock comparison searches for Lorentz and CPT violation

We present two new measurements constraining Lorentz and CPT violation using the 129Xe/3He Zeeman maser and atomic hydrogen masers. Experimental investigations of Lorentz and CPT symmetry provide important tests of the framework of the standard model of particle physics and theories of gravity. The two-species 129Xe/3He Zeeman maser bounds violations of CPT and Lorentz symmetry of the neutron at the 10−31 GeV level. Measurements with atomic hydrogen masers provide a clean limit of CPT and Lorentz symmetry violation of the proton at the 10−27 GeV level.

Characterization and stabilization of fiber-coupled laser diode arrays

We have characterized the spectra and performance of an ensemble of 11 fiber-coupled laser diode arrays (LDAs) manufactured by Opto Power Inc. These high-power LDAs operate near 795 nm and are of a type commonly used for spin-exchange optical pumping of noble gases. We find the Opto Power LDAs to vary significantly in output power, spectral width, and other important characteristics, in a manner not correlated with age, operating lifetime, or information supplied by the manufacturer. In addition we have developed a two-loop feedback technique for use with LDAs that stabilizes the Rb magnetization in an optical pumping cell to better than one part in a thousand.

Contributions of the Right Cerebral Hemisphere in Perceiving Paralinguistic Cues of Emotion

Discoveries in neurology and linguistics indicate that many aspects of human language are determined by specific structural features of the brain, a notion which differs radically from the more prevalent idea of language being an arbitrary, culturally evolved set of symbols and combinatorial rules which during development somehow become represented upon an infinitely malleable nervous system. The present study has attempted to examine whether such neurological specification might extend to other aspects of our social interactions as well, particularly the communication of affect through paralinguistic cues. But before describing the rationale for our own studies, it might be best to mention a little more about spoken language.

Synchronized retinal afterdischarge and neural dark adaptation in the monkey (Cebus albifrons)

Abstract The relationship between the duration of synchronized after-discharge (30/sec), recorded from the optic chiasm of monkeys following cessation of illumination, and the intensity and duration of an immediately preceding test light; intensity and duration of prior conditioning illumination; duration of dark adaptation between conditioning and test lights; wavelength of test light; and intensity of background illumination following test light were studied. Observations were made under similar conditions of barbiturate anesthesia on animals with chronically implanted electrodes. Unanesthetized animals, however, demonstrated the synchronized afterdischarge, but at a higher characteristic frequency (50–60/sec). Antidromic stimulation of fibers in the optic tract failed to initiate or block the ganglion cell “oscillation”. The monotonic logarithmic relationships holding between the intensity or duration of the test light, and the duration of the after-discharge suggest the existence of a physiological “capacitance” in the retina. The association of this response with the photopic system, its hypothetical role in the mechanism of neural dark adaptation, and its relation to the genesis of light-sensitive seizures are discussed.

Intelligence: Why it Matters. Biological Significance of Emotional Intelligence and Its Relation to Hemispheric Specialization in Man

Students of artificial intelligence often focus on processes involved in solving highly abstract problems: synthesizing a chemical structure from given precursors, optimizing the design of an electrical circuit, or constructing a winning chess strategy. These problems are of obvious interest to the human mind-and brain-and yet we cannot say that our lives depend directly on their solution!

Functional interpretation of the flash-evoked response in the chiasma of the monkey (Cebus albifrons)

Abstract Cebus albifrons monkeys were used to study the relationship of the chiasmatic response evoked by light stimulation to various parameters of stimulation. The usual pattern of the gross response consisted of an early positive and a later positive-negative component which, to some extent, could be modified independently. Characteristics of these responses sugegst that they reflect respectively faster cone and slower rod modulation of retinal ganglion cell output. The appearance of a second positive wave under certain conditions is hypothesized to represent activity in a ‘slow’ cone-horizontal ganglion cell network. The technique of isolating rod and cone contributions by temporal evaluation of the flash-evoked, optic tract response is emphasized as a potential experimental tool. Responses to monochromatic stimuli of varying wave-length, utilizing this method of analysis as well as the electroretinogram, suggest that the species Cebus albifrons is deuteranopic rather than protanopic as previously reported.