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1924 UNIT ACTIVITIES IN THE FIFTH LAYER AND LOCAL FIKLD POTENTIAL OF THE SOMAT@

SENSORY CORTEX DlJRlNG ‘VIBRISSAL SNIFFING MO\%MENTS” OF RATS.

*YA UKAZU HAMADA IYASHITA. ““SHIGEMI MOHI. **‘HIROSHI TANAKA S , ““EIZO M

* Deot. of PathobilolopV. Medical Research Inslitute. Tokvo Medical and Dental Univ.. Tokvo. 113. Jauau **Lab. Neurobiol. Nd.

c * ** Deat of Information Medicine. Medi b Institute. Tokyo Medical and

Ik!ntal Univ., Tokyo. 113. Jaoan

“%?brissaI sniffing movements” of rats are &served during their exploring bebasior. We recorded both multi-unit activities in the

ffth layer and local field poteutial of the sup4cial area of the somatwawq cortex of awake rats during tbe sniffmg movements

Ilnd passive mwemmts of the vibrissae. Formvar coated Nicbrome wire electrodes were cbroaically implanted into the

smratoseusory cortex under k&mine hydr@&Ioride anesthesia. Retarded multi-unit activities were changed into single units

activities using a duster cutting method. Applying corrhtion analysis or Hazard function audysis to these single unit activities a!

fmc series data, oscillatory activities(20-50 Hz) in single units during &f&g movements were suggested.

1925 IMMUNOiilSTOCHEMiCAL STUDY ON LEU-ENKEPHALIN IMMUNOREACTIVE NEURONS

AND NERVE FIBERS IN LAMINAE 1 AND n OF THE CHICKEN SPINAL CORD. TOYOKO KAWATE,

S_AQ&QmmfiTSUMI, Dept. of &at., Yamanashi Med,-Qniv., Tamaha. Yamanashi.. 409-35, Japan.

Leu-enkephalin immunoreactive (L-Enk-IR) neurons and nerve fibers in laminae I and nof the chicken dorsal horn were studied using anti-leu-enkephalin antiserum (UC6 Bioproducts) immunohistochemically (PAP technique) by light and electron microscopy. We observed three types of L-Enk-IR neurons and many fibers in laminae I and II. In the lamina 1, large GelIs extended dendrites in rostra-caudal direction. In the lamlna 1 , two kinds of neurons were observed. The one was large and was localized adjacent to the iamina N. The other was small and had dendrites extending rostrocaudally. The latter was scattered throughout the lamina II. L-Enk-IR nerve fibers were different in distribution and size between laminae 1 and II. L-Enk-IR

fibers with varicosities in the lamina 1 were larger than those in the lamina n and bui It a network structure in dormlateral direction. In some cases these fibers extended along large unlabeled dendrites, and their vari- cosities were presynaptic to L-Enk-IR perikarya and dendrites. In the lamina a, smaller L-Enk-IR fibers with varicositiss extended rostrocaudally.

1926 RECEPTIVE FIELD PROPERTIES OF THE NEURONS IN THE SECOND SOMATOSENSORY CORTEX OF THE AWAKE MONKEY. MIKI TAOKAI, V&ASH1 TODA', ATSUSHI IRIK11j2,

MTCHIO TANAKA', Y5SHIAI-Z IWAMWRAI. lDept. of Physiol., *PRESTO, Res. Dev. Corp. Jpn., Tokyo 143, Japan.

Toho Univ. Sch. of Med.,

We recorded responses of single units in ;he second somatosensory cortex ISIII _ A total of 574 units were isolated from three hemispheres of two animals, receptive fields (RFs) were identified in 325 neurons-

and the

bilateral RFs. Sixty percent of them had

Twenty percent of the neurons had RFs on two or more body parts, mostly on both upper and lower limbs. Sixteen neurons responded to the stimuli applied to ahy region of the body surface. Forty percent of the SII bilateral hand neurons had RFs covering more than 5 parts of the hand, postcentral bilateral hand neurons covering

while 20% of the 5 parts of the hand. These findings

indicate that the RI? properties of SII neurons were more complex than those found in the postcentral gyrus. This conclusion hierarchically

supports the idea that SII is higher than the postcentral

somatosensory information processing. somatosensory cortex in the