The early crying paradox

In contemporary Western societies, infants in the first 3 months cry more than at any other time during their life. Although this crying is believed to function to assure nutrition, protection, and mother-infant interaction thought to be essential for later attachment, it also predisposes to complaints of excessive crying (“colic”), discontinuing breast-feeding, and, in the extreme case, child abuse. A resolution of this apparent paradox is proposed based on evidence that elements of caregiving are important determinants of some aspects of early crying. It is argued that early human crying under caretaking conditions typical in Western societies is characterized by prolonged crying bouts, that it is specifically the length of crying bouts (rather than frequency or pattern) that is affected by caregiving practice, and that prolonged crying bouts are probably not characteristic with caretaking practices typical in non-Western societies and possibly in our evolutionary past. It is suggested that caregiving behaviors may recruit normal physiological functions that potentiate cry bout duration in Western caregiving contexts, but reduce it in others. Frequent, short bouts are sufficient, and probably better suited than long bouts, to promote all the positive and presumably adaptive functions claimed for infant crying. Furthermore, they may have provided a mechanism by which infants could enhance their own fitness.     

Unit responses in the "locomotor strip" of the cat hindbrain to microstimulation

Synaptic responses of single units in the "locomotor strip" of the hindbrain were recorded extracellularly. Short-latency responses appeared in neurons of the rostral part of the strip to stimulation of the "locomotor region" of the mesencephalon. Neurons of the caudal part of the strip responded to microstimulation of its other regions, including rostral. If the distance between the neuron and point of stimulation was under 2–3 mm, short-latency (1.2–1.6 msec) responses could be observed. The thresholds and latent periods of the responses increased when the distance apart increased. Polysynaptic responses with a latent period of 3–4 msec could be potentiated by an increase in the frequency of stimulation up to 30–40 Hz. It is suggested that axons of the "locomotor strip" are oriented in the rostrocaudal direction for a distance of 2–3 mm and give off collaterals which run toward neighboring neurons. The strip may be an integrative center, "intercalated" between the rostral portions of the brain stem and spinal cord.Deceased.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 10, No. 5, pp. 510–518, September–October, 1978.     

"Timer" and "scanner" neurons in the cat visual cortex with low stimulus-background contrast

The response pattern and orientation detection of "timer" and "scanner" neurons were investigated in awake, immobilized cats with reduced contrast (2.3 and 10.0) between the light stimulus and the background. These two divisions had already been made [3, 5] at a high contrast level of 100. During this action, all scanners were found to retain their properties: they did not change into timers. The number of timers, however, dropped to 40% of their original total. The relationship between the properties of neurons belonging to these groups remained as it was during maximum contrast: with timers, response began and peaked earlier; it was also of higher frequency and briefer, while its capacity for orientation detection was far inferior to that of scanners. The neurons leaving the timer group following a reduction in contrast manifested a pattern somewhere between timer and scanner cells, resembling the latter in a number of parameters. Findings confirmed the deduction that both timer and scanner neurons are present and operate consistently under a wide range of conductions in the cat visual cortex; the former fulfill the functions of synchronizers and the latter of directional filters which are rearranged in time [5].Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 805–812, November–December, 1986.     

"Timers" and "scanners" among orientation detectors in cat visual cortex

Experiments were carried out on immobilized cats to determine whether, among visual cortical neurons, besides the "scanners" described by the writers previously, which are responsible for a dynamic shift of preferred orientation, there exist also "timer" cells, which do not change the temporal parameters of their responses during rotation of a flashing stimulus. The existence of such cells is postulated on the basis of the previous hypothesis on the spatiotemporal principle of orientational coding. Of 76 neurons tested 27, i.e., 36%, were classed as "timers." They differed significantly from the "scanners" (64%) by the following properties: shorter latent periods, shorter time to the peak and duration of responses, more rapid rise of discharge frequently in the volley. The "timers" had less sharp orientational tuning and a low ratio between values of responses to presentation of preferred and worst stimuli (on account of a considerable increase in responses to unpreferred orientations). The set of preferred orientations of the "timers" was found to be highly selective and additional relative to the corresponding distribution for "scanners."The difference in frequency-temporal properties of responses and orientational tuning of the "timers" and "scanners" and their possible mutually complementary role in orientational coding at the visual cortical level are discussed.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 17, No. 1, pp. 35–43, January–February, 1985.     

The occurrence of "mixed" nuclear bag intrafusal fibers in the cat muscle spindle

A total of 147 muscle spindles was studied histochemically in serial transverse sections of 42 cat tenuissimus muscle specimens. Nuclear bag1, nuclear bag2 and nuclear chain intrafusal muscle fibers were distinguished by the differential staining resulting from the reactions for myosin adenosine 5'-triphosphatase and nicotinamide adenine dinucleotide tetrazolium reductase. The majority of intrafusal fibers were of the same histochemical type at both fiber poles. However, seven muscle spindles contained one nuclear bag fiber each that presented as a bag1 in one pole and as a bag2 in the other pole. These "mixed" nuclear bag fibers were found in spindles that also contained at least one bag1 and one bag2 fiber of equivalent histochemical presentation in both fiber poles. The "mixed" bag fibers displayed differences of apparent fiber diameter and relative polar length between the two fiber poles. The motor innervation pattern, as revealed by staining for cholinesterase, was also dissimilar between the two poles of "mixed" bag fibers. The study indicates that the spindle equatorial region may in some instances serve as a boundary between two morphologically and histochemically different poles of the same intrafusal fiber.     

Electrographic manifestations of "falling asleep" in isolated cat cortex]

Experiments were conducted on unrestricted cats; a study was made of the electrical activity of the neuronally isolated cortex during the wakeful hours and sleep. Transition from wakefulness to sleep was accompanied in the isolated cortex by the manifestations of drowsiness accompanied by the corresponding changes in the electrocorticogram of the isolated hemisphere. Electrographic manifestation of drowsiness in the isolated cortex depended on the time lapse after the operation and was mostly pronounced during the late period after the isolation of the cortex.