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T Ganes

Publications and source records attributed to T Ganes.

45 records · Page 3Linked to original sources
PubMed1976

Spindle wave synchrony in the somatosensory cortex of the cat.

(1) Spontaneous barbiturate spindles were recorded from the primary and secondary somatosensory cortex. The recordings were concentrated to areas surrounding several reference loci. The recording sites producing the maximal response evoked by stimulation of an exposed nerve in a contralateral limb were used as reference loci. (2) Spindles recorded at various distances from the respective reference loci were cross-correlated to spindles developing simultaneously in the latter. High correlation coefficients, indicating a considerable degree of wave synchrony, were obtained between spindles in the reference locus and spindles recorded a few millimeters from this site. The correlation coefficients decreased with increasing interelectrode distance. A relatively sharp fall in the correlation coefficients was generally found 2-3 mm from the reference locus. Small amounts of sodium pentobarbital, given intravenously at intervals of 5 min, had no effect upon this pattern. (3) The change in the correlation coefficients was followed by a parallel change in the amplitude of the evoked potentials. The iso-correlation lines of spindle wave synchrony and the iso-amplitude lines of the evoked potentials had a similar distribution and extension for each particular reference locus. (4) Lateral spread of spindle waves in the cortex seems to be of minor importance, since a vertical lesion cutting the cortico-cortical fibres did not reduce the wave synchrony of the spindles recorded from either side of the lesion. (5) The majority of the spindles recorded in the close vicinity of a reference locus started simultaneously within +/- 0.1 sec. This pattern changed with increasing distance from the reference locus and 5.6 mm away only a fraction of the spindles started simultaneously. However, within the entire primary somatosensory cortex a small but significant coupling existed between onset of the spindles.

Animals↗
PubMed1976

Brbiturate spindle activity in the association cortex of the cat and its relation to spindle activity in the somatosensory system.

(1) Spontaneous barbiturate spindle activity was recorded simultaneously from nucleus ventralis poster-lateralis (VPL) of the thalamus, from the corresponding projection site in the primary somatosensory cortex (SI) and from the lateral (LAT) and middle suprasylvian (SSM) gyri. (2) Barbiturate spindles occurred more frequently in LAT and SSM than in the somatosensory cortex. Spindles in LAT and SSM were of longer duration than SI spindles while the intraspindle frequency was higher in spindles from the latter areas. The amplitude of the spindle waves was significantly higher in LAT and SSM than in SI. The largest spindle waves were recorded from the anterior part of LAT and SSM. (3) Barbiturate spindles recorded at various interelectrode distances were cross-correlated. In LAT and SSM the cross-correlation coefficients remained high up to an interelectrode distance of 4-5 mm while spindles recorded at this distance in SI gave low coefficients when cross-correlated. (4) Extensive removal of the somatosensory cortex had no effect on spindle formation in LAT or SSM. Furthermore, cutting of the cortico-cortical connections between two recording sites in either of these gyri produced no reduction in spindle wave synchrony between the recording sites. (5) Spindles in the VPL-SI only rarely started simultaneously with spindles in LAT and SSM. Those few coincident spindles which occurred were cross-correlated. The cross-correlation coefficients were invariably low suggesting that no wave synchrony existed between spindles in the VPL-SI system and those in the LAT and SSM.

Animals↗
PubMed1975

Barbiturate spindle activity in functionally corresponding thalamic and cortical somato-sensory areas in the cat.

(1) Spontaneous barbiturate spindles were recorded from a locus in the thalamic nucleus ventralis postero-lateralis (VPL) and the corresponding projection area in the somato-sensory cortex (SI) in the cat. (2) Type I spindles32 recorded from such sites in the thalamus and cortex, regarded as being functionally on line, were cross-correlated. The analysis gave high negative cross-correlation coefficients, indicating that a considerable degree of wave synchrony existed between the spindles. Maximal wave synchrony was present in the first and middle part of the spindle. (3) The thalamo-cortical spindle wave synchrony was reduced by a small displacement of the cortical electrode within the somato-sensory cortex. Starting with a very lightly anaesthetized animal, small amounts of barbiturate did not influence the size of the cortical area which had spindles in synchrony with the thalamic spindles. (4) Spindles recorded from a VPL locus and from its cortical projection site started simultaneously. When the thalamic and cortical electrodes were positioned functionally off line this spindle coincidence decreased. The intervals between the spindle onsets increased with increasing off line positions of the electrodes. Those few thalamic and cortical spindles which occurred simultaneously showed no, or only weak, spindle wave synchrony. (5) These data suggest a point-to-point topographical relation between thalamic and cortical loci engaged in barbiturate spindle activity. (6) Type I and type II spindles32 differed with respect to spindle characteristics (amplitude, duration, incidence) and also with respect to corresponding thalamic rhythmic activity. These spindle types are, therefore, probably produced by different mechanisms. We suggest that type II spindles represent a purely cortical process initiated by type I spindles.

Animals↗
PubMed1975

Barbiturate spindle activity in the thalamic lateral ventro-posterior nucleus and the second somato-sensory area of the cortex.

(1) Barbiturate spindles recorded from the second somato-sensory cortical area (SII) were similar to spindles in the primary somato-sensory area (SI) both with respect to incidence, duration of each spindle and per cent spindle time. The spindle wave amplitude was smaller in SII. The highest spindle wave amplitude was observed in the anterior part of SII which receives input from nucleus ventralis postero-lateralis (VPL). No spindle activity was observed in the posterior part of SII which receives input from the posterior nuclear group (PO) of the thalamus. (2) Barbiturate spindles recorded from a locus in VPL and its projection area in SII were cross-correlated. The analysis resulted in high cross-correlation factors, indicating that a considerable degree of spindle wave synchrony existed between the spindles. This wave synchrony was reduced by moving the cortical electrode a short distance. (3) Cortical spindles recorded from corresponding sites in SI and SII were cross-correlated, and gave a high cross-correlation coefficient. This synchrony was markedly reduced if one of the electrodes was moved a few millimetres away from the optimal point. (4) Spindles started simultaneously in corresponding sites of SI and SII. A high degree of coincidence was found also between spindles in a VPL locus and the corresponding projection site in SII. Local anaesthesia applied to or total removal of SI failed to influence the spindle activity in SII and vice versa. Similarly, the SI-SII synchrony survived a deep incision cutting all connections between the two areas. (6) It is suggested that spindles in corresponding sites of SII and SI have a common thalamic pacemaker which probably projects to both areas by axonal branching.

Anesthesia, General↗
PubMed1975

Two generators of hippocampal theta activity in rabbits.

Spontaneous and hypothalamically induced theta activity was studied in rabbits lightly anaesthetized with urethane or urethane-chloralose. Well-developed theta activity was found over a large area of the dorsal part of the hippocampal formation, roughly corresponding to the CA1 field. Cross-correlation analysis between a stationary and a moving electrode showed that a large sheet of tissue oscillated in remarkable synchrony. This region was at least 8 mm along the longitudinal axis of the hippocampus and 6 mm in a plane transverse to this axis, thus comprising the whole of the rostro-caudal extension of the CA1 region. For technical reasons the temporal half was not explored. Depth recordings showed two foci of theta activity, one in the basal part of CA1 (stratum oriens) and a second, separate region with considerably larger amplitudes in the dentate region, having its maximum in the molecular layer. Due to the folded nature of the dentate fascia, an electrode often recorded two maxima corresponding to its upper and lower blades. Wave form analysis showed that the dentrate and CA1 rhythmic activity was roughly 180 degrees out of phase. The dentate theta activity remained in conditions where the CA1 theta activity was absent, either spontaneously or due to experimental interference. Systematic micro-electrode tracking showed absence of theta activity in the CA3 region. Nor was convincing theta activity found in the subiculum, parasubiculum, presubiculum or entohinal areas.

Animals↗
PubMedDate not supplied

Complete ulnar innervation of the thenar muscles combined with normal sensory fibres in a subject with no peripheral nerve lesion.

A complete ulnar innervation of all thenar muscles, including the opponens, have to our knowledge been described only in patients with severe traumatic lesions of the median nerve. The present study reports a subject with exclusive ulnar innervation of the thenar muscles in the right hand. The patient had no anamnestic or objective signs of peripheral nerve lesions. While his sensory and motor ulnar nerve fibres were normal, electrophysiological examination of the right median nerve showed normal course of the sensory fibres but apparently no motor fibres to the thenar muscles.

Adult↗
PubMedDate not supplied

Fibre density in idiopathic ano-rectal incontinence.

Fibre density (FD) was measured in the external anal sphincter (EAS) in 54 patients with idiopathic anal incontinence and compared to normative data from a control group of 18 patients. The aim of the study was primarily to establish a diagnostic tool which could give an objective analysis of the anal sphincter muscles. Secondly, to examine whether or not FD was correlated to clinical symptoms of incontinence and manometric measurements from the anal canal. Our data show that the FD was increased in patients with anal incontinence and further that FD was correlated to clinical symptoms of incontinence as well as to manometric parameters of the function of the anal canal. In conclusion, we suggest that FD measurement should be used as a routine in patients with idiopathic anal incontinence. FD values will give an objective estimate of the state of denervation/reinnervation present in the EAS. This is particularly valuable in patients being considered for operative treatment since severe denervation of the EAS generally is correlated to a poor result of surgery.

Adult↗