Ken-Ichiro Muramoto

Paraventricular nucleus connections to spinal cord and pituitary

In rats anesthetized with pentobarbital or a mixture of urethane and chloralose, horseradish peroxidase (HRP) was injected into the intermediolateral column of the spinal cord (Th7 and Th9) or the posterior pituitary lobe. HRP positive cells were found mainly in the dorsomedial part of the paraventricular nuclease (PVN) of the spinal injected animals. These cells are large in size and are bipolar or multipolar. On the other hand, those in the pituitary injected animals were predominantly localized in the dorsolateral cap of the PVN. These latter cells are more rounded, have fewer projections, and are the same size as those in the dorsomedial part of the PVN.

Monkey lateral hypothalamic neuron response to sight of food, and during bar press and ingestion

Unit activity of 144 lateral hypothalamus (LHA) neurons was analyzed in monkey during bar pressing feeding behavior. Eighteen neurons responded only when the animal saw food, and 23 responded only during ingestion of food. Ten responded at both the sight of food and throughout the bar pressing and ingestion periods, even in high fixed ratio schedules. Three neurons responded, not at the sight of food, but at the sight of non-food. Nineteen out of a total of 54 of the above responding neurons were studied for response to differences between food and non-food. Eight responded similarly at the sight of both food and non-food, while 11 responded differently. Responses during the ingestion period were strong and lasted longer than 5--10 sec. The data indicate that some LHA neurons are involved in the discrimination of food, the drive to obtain it and the perception of reward.

Role of the lateral hypothalamus and the amygdala in feeding behavior

Abstract Unit activities of the lateral hypothalamic area (LHA) and amygdala (AM) were recorded during bar pressing feeding behavior in monkeys. Out of 103 LHA neurons tested, 9 decreased its firing selectively at the sight of food and not to non-food, and most of this initial response continued all through the subsequent bar pressing period. The firing decreased again after the animal put food into mouth. The discrimination ratio of food was calculated to be 54% in the LHA. Even in the AM, some neurons responded uniquely to food, and not to non-food. This differential response became more clear in the repeated subsequent trials. The discrimination ratio of food was calculated to be 25% to 44%. Although almost all of the initial responses were not maintained during the bar pressing period, 22 neurons (18% of tested) increased firing at the reward period in the AM. These data suggest that the LHA is deeply involved in the bar pressing feeding behavior all through the perception of food, the driving mechanism to obtain food, and the final reward response, while the AM seems to be concerned in some perception and reward response.

Long-term lateral hypothalamic single unit analysis and feeding behavior in freely moving rats

Lateral hypothalamus activity was observed in 23 single units for more than 24 h each in freely moving rats. The activity of 3 neurons was circadian related: low in the day and high at night. Ten neurons responded with inhibition related to individual feeding acts. These two neuron types might be important for long-term feeding rhythm and short-term feeding behavior.

Single unit activity in monkey caudate nucleus during operant bar pressing feeding behavior

Unit activity and changes during bar press feeding behavior after presentation of food or non-food were analyzed in 198 neurons in the head of the caudate nucleus of monkey. Eight neurons responded uniquely at the sight of food. The degree of the food-specific responses differed depending on the nature of the food and the hunger-satiation state. On the other hand, 17 neurons responded more or less to the sight of food and during bar pressing for food. These two types of neuron seem to be important to bar pressing feeding behavior, which consists of recognition of food and a bar press task to obtain food.

Retrograde transport of horseradish peroxidase in sciatic nerve of rats and dystrophy mice.

The relationship between nerve or muscle activity and retrograde HRP transport was studied in rat Sciatic nerve and in dystrophy mice. sciatic nerve stimulation facilitated transport to 250% of control level, while colchicine decrease transport depending on dosage. Tendonectomy as well as colchicine treatment ultimately decreased HRP transport, but before the decrease, there was a transient facilitatory phase in both colchicine treated and tendonectomized rats. In dystrophy mice, almost twice as much nerve trunk injected HRP was transported as in control mice. This suggests that retrograde transport level increases in some stage of dystrophy.

A microcomputer-based system for detailed analysis of rat behavior

A microcomputer-based system that can measure rotational behavior and moving velocity is described. Infrared photobeams detect the animal behavior. One advantage of this system is that data can be stored on floppy disks and analyzed in arbitrary time intervals. This system may be useful for detailed analysis of rat behavior in physiological or psychopharmacological experiments.

Measurement of Z-R relations using a small Doppler radar and image data of snow particles

Presents a new system to measure physical snowfall parameters using image processing techniques. It is possible to calculate the snowfall rate from the mass and volume of each snow particle. Using image data, it is also possible to calculate the radar reflectivity Z, assuming Rayleigh scattering and discrete data. The relationship between X-band wave attenuation, Z and snowfall rate was investigated and compared to the characteristics of snow particles. It was suggested that the power spectrum is related with the content of ice crystals.

A microcomputer aided control system for visual tracking task of monkey

A microcomputer aided control system for visual tracking tasks is described. A video monitor displays positions of target and pointer. In a handle task, the horizontal position of a pointer is coupled to the angular position of a manipulandum. The task involves alignment and maintenance of a pointer on the target. In a bar press task, the pointer moves incrementally after each preset number of bar presses. A microcomputer and video monitor afford system flexibility, while a panel of manual switches permits the setting up of a variety of experimental conditions without extensive keyboard inputs and has the added advantage of constant display of task details. The program is written in assembly language to meet requirements for program control speed and allow timing measurement in msec. This system may be useful in the behavioral study of physiological and neurophysiological functions.