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PubMed1990

[Non-invasive diagnosis of phlebothrombosis of the limbs. Prospective evaluation of mercury gauge plethysmography associated with ultrasonic Doppler].

Associated ultrasonic Doppler study (D) and plethysmography (P) were evaluated as compared to phlebography in diagnosis of venous thrombosis of the lower limbs (TVP). Probes (5 and 7.5 MHz respectively) were used in D for examination of proximal and calf veins. Plethysmography using a mercury ring gauge (Perivein, ETNA) was considered pathologic if filling volume was less than 1.5 vol% and/or emptying volume less than 40 ml/min/100 ml. One hundred and four patients hospitalized in an internal medicine department for suspected deep venous thrombosis were studied, including 97 for whom phlebography interpretation was unmistakable: 11 calf vein, 28 collector trunk and 42 total limb involvement TVP. In these localizations, D sensitivity was respectively 55, 72 and 100% (mean 85.5%) and that of P 63.5, 68 and 88% (mean 77.7%); association of D or P improved sensitivity: 82, 82 and 100% (mean 91.5%). Specificity was 86.6% for D, a poor 62.5% for P and 93.5% for associated D and P. The results are comparable to those in the literature but disappointing for diagnosis of isolated calf vein TVP. False-negatives in both D and P were due to strong collateral circulation or limited thrombus extension.

Adolescent↗
PubMed1989

Multiple electrosensory maps in the medulla of weakly electric gymnotiform fish. I. Physiological differences.

The electrosensory lateral line lobe in the weakly electric gymnotiform fish Eigenmannia contains 3 topographic maps of high-frequency (tuberous) electroreceptive information from the body surface. The maps receive identical primary afferent input since axonal collaterals of both amplitude- and phase-coding afferents project to all 3 maps (Heiligenberg and Dye, 1982). Response properties of the amplitude-coding pyramidal neurons in the multiple maps were investigated in order to determine whether the maps differ physiologically. Units in the lateral map have larger receptive fields and are more sensitive than units in the centromedial map. The former units respond more phasically and with shorter latencies to step changes in stimulus amplitude (measured from the stimulus onset to the maximum response). Although 75% of pyramidal cells in all maps show a center-surround receptive-field organization, the strength of the inhibitory surround varies among maps, tending to be weakest for units in the lateral map and strongest for units in the centromedial map. Pyramidal neurons also differ in their responses with respect to the temporal frequency of amplitude modulations; the majority of units in the lateral map prefer high temporal frequencies, while those in the centromedial map prefer low frequencies. These results suggest that the multiple electrosensory maps could provide the initial separation of spatial and temporal processing of sensory information, much as has been suggested for X and Y ganglion cells in the cat retina (Shapley and Perry, 1986). The centromedial map could provide high spatial contrast with correspondingly poor temporal resolution, while the more sensitive units in the lateral map could best provide information about temporal changes in stimulus amplitude.

Adaptation, Physiological↗
PubMed1995

Immediate 201Tl reinjection: an alternative approach in myocardial perfusion scintigraphy? A comparison with contrast angiographic findings.

Thallium-201 (201Tl) stress-redistribution/reinjection imaging provides a reliable diagnostic approach in patients evaluated for myocardial ischaemia. Immediate reinjection of 201Tl after completing the stress images followed by imaging 1 h later shortens the investigation time to 2.5 h and may provide a novel approach. In this study, we validated the immediate reinjection approach in the assessment of myocardial perfusion and viability using contrast angiographic findings as the reference standard. We studied 114 patients with documented cardiac catheterization data using quantitative planar 201Tl stress/immediate reinjection imaging. The 201Tl findings were compared with contrast angiographic data, coronary arteriographic findings and electrocardiographic data. Myocardial regions were considered to be viable if they (1) showed normal or hypokinetic wall motion, (2) were supplied by patent coronary arteries or by occluded arteries with adequate collateral circulation, or (3) were not related to electrocardiographic infarct site. Myocardial regions were considered to be non-viable if they (1) showed akinetic or dyskinetic wall motion, (2) were supplied by occluded vessels with inadequate collateral circulation, or (3) were related to electrocardiographic infarct site. Of 280 regions with normal or hypokinetic wall motion, 47 (17%) regions showed persistent 201Tl defects compared with 21 of 26 (81%) regions with akinetic/dyskinetic wall motion (P < 0.0001). Of 318 regions supplied by patent vessels, 65 (20%) regions showed persistent 201Tl defects compared with 14 of 22 (64%) regions subtended by occluded vessels (P < 0.0001). When the 201Tl findings were compared with electrocardiographic infarct site, 37 of 259 (14%) remote regions showed persistent defects compared with 42 of 83 (51%) infarct-related regions (P < 0.0001). We conclude that persistent defects on 201Tl immediate reinjection images are significantly more often associated with severe left ventricular wall motion abnormalities, coronary artery occlusion and infarct-related regions. In particular, agreement between the wall motion approach and scintigraphic findings was excellent, with 21 of 26 akinetic or dyskinetic segments showing persistent defects and 233 of 280 normal or hypokinetic segments measured as viable by the reinjection technique, resulting in a sensitivity of 81%, a specificity of 83% and an overall accuracy of 83%. These findings show the potential of immediate 201Tl reinjection imaging for assessing myocardial perfusion and viability.

Adult↗
PubMed2006

Massive and specific dysregulation of direct cortical input to the hippocampus in temporal lobe epilepsy.

Epilepsy affects 1-2% of the population, with temporal lobe epilepsy (TLE) the most common variant in adults. Clinical and experimental studies have demonstrated hippocampal involvement in the seizures underlying TLE. However, identification of specific functional deficits in hippocampal circuits associated with possible roles in seizure generation remains controversial. Significant attention has focused on anatomic and cellular alterations in the dentate gyrus. The dentate gyrus is a primary gateway regulating cortical input to the hippocampus and, thus, a possible contributor to the aberrant cortical-hippocampal interactions underlying the seizures of TLE. Alternate cortical pathways innervating the hippocampus might also contribute to seizure initiation. Despite this potential importance in TLE, these pathways have received little study. Using simultaneous voltage-sensitive dye imaging and patch-clamp recordings in slices from animals with epilepsy, we assessed the relative degree of synaptic excitation activated by multiple cortical inputs to the hippocampus. Surprisingly, dentate gyrus-mediated regulation of the relay of cortical input to the hippocampus is unchanged in epileptic animals, and input via the Schaffer collaterals is actually decreased despite reduction in Schaffer-evoked inhibition. In contrast, a normally weak direct cortical input to area CA1 of hippocampus, the temporoammonic pathway, exhibits a TLE-associated transformation from a spatially restricted, highly regulated pathway to an excitatory projection with >10-fold increased effectiveness. This dysregulated temporoammonic pathway is critically positioned to mediate generation and/or propagation of seizure activity in the hippocampus.

Action Potentials↗
PubMed2004

Saturation and quantization reduction in microarray experiments using two scans at different sensitivities.

We present a mathematical model to extend the dynamic range of gene expression data measured by laser scanners. The strategy is based on the rather simple but novel idea of producing two images with different scanner sensitivities, obtaining two different sets of expression values: the first is a low-sensitivity measure to obtain high expression values which would be saturated in a high-sensitivity measure; the second, by the converse strategy, obtains additional information about the low-expression levels. Two mathematical models based on linear and gamma curves are presented for relating the two measurements to each other and producing a coherent and extended range of values. The procedure minimizes the quantization relative error and avoids the collateral effects of saturation. Since most of the current scanner devices are able to adjust the saturation level, the strategy can be considered as a universal solution, and not dependent on the image processing software used for reading the DNA chip. Various tests have been performed, on both proprietary and public domain data sets, showing a reduction of the saturation and quantization effects, not achievable by other methods, with a more complete description of gene-expression data and with a reasonable computational complexity.

Journal Article↗
PubMedDate not supplied

Leukoaraiosis: correlation of MR and CT findings with blood flow, atrophy, and cognition.

Hypodense periventricular white-matter lesions detected by CT (leukoaraiosis) and high-intensity T2 signals detected by MR imaging were correlated with measurements of local cerebral blood flow (LCBF), cerebral atrophy, and cognitive performance. Subjects studied included elderly volunteers who were neurologically normal (n = 6), patients with chronic cerebral infarctions and intact cognition (n = 2), patients with multiinfarct dementia (n = 14), and patients with Alzheimer dementia (n = 9). Leukoaraiosis correlated with periventricular high-intensity lesions detected by MR, LCBF reductions, cognitive impairments, and cerebral atrophy. Moderate to severe leukoaraiosis was associated with LCBF reductions in the cortex, basal ganglia, and frontal white matter. Periventricular MR lesions correlated with cerebral atrophy but not with cognitive impairments or reductions in LCBF. The exquisite sensitivity of MR revealed small lesions that did not correlate with LCBF reductions and cognitive impairments. Remote subcortical white-matter lesions detected by MR did not correlate with periventricular MR lesions, leukoaraiosis, LCBF, cerebral atrophy, or cognitive performance, indicating little clinical relevance. We concluded that diffuse cerebral hypoperfusion, particularly in combination with the poor collateral circulation of white matter surrounding the lateral ventricles, is responsible for leukoaraiosis.

Aged↗
PubMed1982

The value of electroencephalography and ocular pneumoplethysmography in carotid shunting.

To investigate whether it is possible to detect in a non-invasive way those patients who undergo carotid surgery under general anesthesia and do not tolerate carotid clamping without EEG changes, preoperative EEG and OPG carotid compression tests were compared with the results of intraoperative carotid clamping and EEG control. Eleven of 126 patients (8.7%) who were studied had EEG changes after carotid clamping. They also had preoperatively either EEG changes or a Collateral Ophthalmic Artery Pressure, as measured with OPG compression tests, lower than 30 mm Hg, or both criteria. However, preoperative positive criteria for EEG and OPG were also seen in patients who had no EEG changes during intraoperative carotid clamping. Therefore these non-invasive tests can select those patients who will need a shunt (sensitivity 100%), but according to those methods too many patients will be shunted (specificity 76%).

Carotid Arteries↗
PubMed1996

Differential actions of serotonin, mediated by 5-HT1B and 5-HT2C receptors, on GABA-mediated synaptic input to rat substantia nigra pars reticulata neurons in vitro.

The ability of serotonin to modulate GABA-mediated synaptic input to substantia nigra pars reticulata (SNr) neurons was investigated with the use of whole-cell patch-clamp recording from slices of rat midbrain. Fast evoked GABA(A) receptor-mediated synaptic currents (IPSCs) were attenuated reversibly approximately 60% by serotonin, which also caused an inward current with reversal potential of -25 mV. This inward current was blocked by the 5-HT2 receptor antagonist ritanserin, whereas the IPSC depression was blocked by the 5-HT1B receptor antagonist pindolol. The amplitude ratio of IPSC pairs (50 msec interpulse interval) was enhanced by serotonin (in ritanserin) and also by the GABA(B) receptor agonist baclofen (which also depressed the IPSC), consistent with a presynaptic site of action in both cases. In contrast, spontaneous tetrodotoxin-sensitive GABA(A) synaptic currents (sIPSCs) were increased in frequency by serotonin (an action that was sensitive to ritanserin, but not pindolol) but reduced in frequency by baclofen. SNr neurons therefore receive inhibitory synaptic input mediated by GABA(A) receptors from at least two distinct sources. One, probably originating from the striatum, may be depressed via presynaptic 5-HT1B and GABA(B) receptors. The second is likely to arise from axon collaterals of SNr neurons themselves and is facilitated by an increase in firing via postsynaptic, somatodendritic 5-HT2C receptor activation, but it is depressed by GABA(B) receptor activation. Thus, serotonin can both depolarize and disinhibit SNr neurons via 5-HT2C and 5-HT1B receptors, respectively, but excitation may be limited by GABA released from axon collaterals.

Animals↗
PubMed1999

Evaluation of magnetic resonance angiography in detection of gastric varices.

We evaluated the detection of gastric varices, inflowing blood vessels to gastric varices, and outflowing blood vessels from gastric varices via magnetic resonance (MR) angiography in 31 patients with gastric varices. Twenty-four patients had F2 type varices and 7 had F3 type, classified according to the Japanese Research Society for Portal Hypertension. Seventeen patients had cardiofornical varices, and 14 had fundal varices. All patients were examined with an MR system operating at 1.5T. MR angiography was performed using the two-dimensional time-of-flight method. With MR angiography, the imaging of gastric varices was clearly delineated in 28 of the 31 patients (90.3%). From the images of MR angiography, flow direction itself cannot be determined. The outflowing blood vessels of gastric varices were reported to be the gastro-renal shunt and the subphrenic vein, and angiographic findings have shown the inflowing blood vessels to be the left gastric vein (LGV), the short gastric vein (SGV), and the posterior gastric vein (PGV). In 25 of the 31 patients (80.7%), the outflowing blood vessels from gastric varices were detected (gastro-renal shunt in 24; subphrenic vein in 1). MR angiography provided clear images of the inflowing blood vessels to gastric varices in 18 of the 31 patients (58.1%). These inflowing vessels were categorized as SGV in 7 patients, LGV in 5, LGV and SGV in 4, and LGV and PGV in 2. We suggest that MR angiography be used as a routine method for detecting and diagnosing collateral veins in patients with gastric varices.

Adult↗
PubMed1998

Cell type and pathway dependence of synaptic AMPA receptor number and variability in the hippocampus.

It has been suggested that some glutamatergic synapses lack functional AMPA receptors. We used quantitative immunogold localization to determine the number and variability of synaptic AMPA receptors in the rat hippocampus. Three classes of synapses show distinct patterns of AMPA receptor content. Mossy fiber synapses on CA3 pyramidal spines and synapses on GABAergic interneurons are all immunopositive, have less variability, and contain 4 times as many AMPA receptors as synapses made by Schaffer collaterals on CA1 pyramidal spines and by commissural/ associational (C/A) terminals on CA3 pyramidal spines. Up to 17% of synapses in the latter two connections are immunonegative. After calibrating the immunosignal (1 gold = 2.3 functional receptors) at mossy synapses of a 17-day-old rat, we estimate that the AMPA receptor content of C/A synapses on CA3 pyramidal spines ranges from <3 to 140. A similar range is found in adult Schaffer collateral and C/A synapses.

Aging↗
PubMed2004

The Beck effect is back, now in color: a demonstration.

It has been repeatedly found (e.g., Beck, 1982; Beck & Ambler, 1973) that a tilted T is detected better than an L when presented on the background of a number of upright Ts, although in isolation both are discriminated from an upright T about equally well. We demonstrate that an analogous interaction between context presence and stimulus type can be obtained with color stimuli: A light green was discriminated from a dark green better than an olive brown was, yet that occurred only in the context of a background of three dark green disks. This indicates that the effects, both original and novel, probably are not due to anything peculiar to form perception, such as line arrangement or supraelement configurations. It is suggested that the presence of collateral background stimuli probably enables the perceptual system to capitalize on relative judgment involving contrasts or deviations from a presented anchor value.

Attention↗
PubMed2004

The influence of pH strategy on cerebral and collateral circulation during hypothermic cardiopulmonary bypass in cyanotic patients with heart disease: results of a randomized trial and real-time monitoring.

OBJECTIVE: The optimal pH strategy during hypothermic cardiopulmonary bypass remains controversial. Systemic pulmonary collateral circulation may develop in patients with cyanotic anomalies. The purpose of this study was to evaluate the effect of pH strategies on cerebral oxygenation and systemic pulmonary collateral circulation during hypothermic cardiopulmonary bypass in cyanotic patients with heart disease. METHODS: Forty cyanotic patients (age > 1 year) with heart disease were prospectively randomized into 2 groups. Group 1 (n = 19, 14.3 +/- 1.5 kg) underwent hypothermic cardiopulmonary bypass with alpha-stat strategy and group 2 (n = 21, 12.5 +/- 0.9 kg) with pH-stat. Cardiopulmonary bypass was established with pump-assisted drainage. Cerebral oxygenation was assessed by near-infrared spectroscopy and the systemic pulmonary collateral circulation was calculated by pump flows [% systemic pulmonary collateral circulation = perfusion flow - drainage flow)/perfusion flow x 100]. Lactate was measured as an index of systemic anaerobic metabolism. RESULTS: There were no significant differences in preoperative hematocrit, oxygen saturation, Qp/Qs, cardiopulmonary bypass duration, minimum temperatures, perfusion flow and pressure, urine output, and depth of anesthesia between the groups. Oxyhemoglobin signal and tissue oxygenation index of near-infrared spectroscopy monitoring were significantly lower in group 1 compared with group 2 (P =.008 and P <.0001, respectively), suggesting inadequate cerebral oxygenation with alpha-stat. Deoxygenated hemoglobin signal was significantly higher in group 1 relative to group 2 (P <.0001). The % systemic pulmonary collateral circulation was significantly lower in group 2 compared with group 1, suggesting a reduced pulmonary collateral circulation with pH-stat (P <.0001, average; group 1, 20.1% +/- 1.2%; group 2; 7.7% +/- 0.7%). Serum lactate was significantly lower in group 2 (P <.0001). CONCLUSIONS: The pH-stat strategy results in an improved environment, including sufficient cerebral oxygenation, decreased systemic pulmonary collateral circulation, and lower lactate level during hypothermic cardiopulmonary bypass in cyanotic patients with heart disease. Future studies should investigate the long-term neurological outcome.

Analysis of Variance↗
PubMed1977

Myocardial stress perfusion scintigraphy with rubidium-81 versus stress electrocardiography.

Fifty-six patients who subsequently underwent selective coronary angiography were studied noninvasively with relative myocardial perfusion scintigraphy with rubidium-81 and graded stress electrocardiography in an attempt to evaluate the ability of these tests to identify the presence of significant ischemia and, indirectly, coronary stenosis. Both the sensitivity (0.91) and specificity (0.91) of perfusion scintigraphy were impressive and better than the sensitivity (0.79) and specificity (0.64) of stress electrocardiography, the specificity of scintigraphy significantly so (P less than 0.05). Additionally, perfusion scintigraphy yielded excellent localizing information and was reliable even in the presence of drug effect, conduction abnormalities and nonspecific electrocardiographic abnormalities. Rare cases of triple vessel disease, prior myocardial infarction or single vessel disease with widespread collateral vessels were causes of scintigraphic misdiagnosis. Although ribidium-81 perfusion scintigraphy with the scintillation camera requires special collimation and significant quality control, it provides well resolved images and may prove particularly useful in facilitating quick successive multiple scintigraphic cardiac studies.

Angina Pectoris↗
PubMed1997

MR first pass imaging: quantitative assessment of transmural perfusion and collateral flow.

Recent advances with fast switching gradient coils, and the optimization of magnetic resonance techniques for multislice imaging have made it possible to apply models of contrast agent transit for the quantification of myocardial perfusion, and determination of the transmural distribution of blood flow. This article summarizes some of these recent developments and presents examples of quantitative, multi-slice myocardial perfusion imaging studies in patients and animal models. Multi-slice, true first pass imaging, with high temporal resolution, and T1-weighted, arrhythmia insensitive contrast enhancement is used for the quantification of perfusion changes accompanying mild to severe ischemia. The first pass imaging technique and the modeling approach are sufficiently robust for fitting of tissue residue curves corresponding to a wide, physiologically realistic range of myocardial blood flows. In animals this was validated by comparison to blood flow measurements with radiolabeled microspheres as gold standard. It is demonstrated that with the proposed modeling approach one can determine the myocardial perfusion reserve from two consecutive MR first pass measurements under resting and hyperemic conditions. In patients with microvascular dysfunction the MR studies show for the first time that the myocardial perfusion reserve correlates with Doppler flow measurements (linear regression with slope of 1.02 +/- 0.09; r = 0.80). Since perfusion limitations usually begin in the subendocardium as coronary flow is gradually reduced, first pass imaging with the prerequisitie spatial and temporal resolution allows early detection of a mild coronary stenosis.

Animals↗
PubMed2002

MR imaging of the metacarpophalangeal joints of the fingers: part II. Detection of simulated injuries in cadavers.

PURPOSE: To evaluate and compare conventional magnetic resonance (MR) imaging and MR arthrography in the diagnosis of the most common traumatic metacarpophalangeal (MCP) joint injuries, which were created surgically in cadavers. MATERIALS AND METHODS: Injuries to various MCP joint structures were surgically created randomly in 28 fingers of seven human cadaveric hands. Injuries to the main collateral ligaments (CLs) (n = 12), accessory CL (n = 15), sagittal band (n = 14), transverse fibers of the extensor hood (n = 5), first annular pulley (n = 16), deep transverse metacarpal ligament (DTML) (n = 5), and palmar plate (n = 10) were analyzed. Conventional MR images and MR arthrograms were evaluated, with differences in interpretation resolved in consensus. The sensitivities, specificities, and accuracies of both MR imaging methods were determined, and the differences were tested for significance by using the McNemar test. RESULTS: Sensitivity was 28.6%-93.8% with conventional MR imaging versus 50.0%-93.3% with MR arthrography. Specificity was 66.7%-100% with conventional MR imaging versus 83.3%-100% with MR arthrography. Although the MR arthrographic results usually were higher, the differences were not significant. The kappa values for interobserver agreement were 0.314-0.638 for conventional MR imaging versus 0.364-1.00 for MR arthrography. Sensitivity for the detection of lesions of the main and accessory CLs and the first annular pulley was slightly higher than that for the detection of lesions of the extensor hood, DTML, and palmar plate structures. CONCLUSION: MR imaging and MR arthrography enable the diagnosis of simulated MCP joint injuries. MR arthrography does not have a significant advantage over conventional MR imaging.

Aged↗
PubMed1985

Esophageal varices: correlation of left gastric venography and endoscopy in patients with portal hypertension.

Selective left gastric venography was performed via percutaneous transheptic catheterization in 100 patients with portal hypertension to study hemodynamics and left gastric collaterals. Flow was hepatofugal in 81 patients, while 63 had varices supplied by the left gastric vein; azygos/hemiazygos collaterals were seen in 27 patients, gastrorenal shunts in 18, and other collaterals in 58. In 79 cases, enlarged, tortuous veins arising from thin parallel vessels at the esophagogastric junction on venography corresponded with varices on endoscopy in both size and course. Venography failed to show small varices which were seen endoscopically, whereas endoscopy often interpreted non-tortuous veins as varices. Using endoscopy as a reference, the sensitivity of venography for varices was 76%, specificity 100%, and accuracy 78%. There was a significant correlation between venographic demonstration of varices and previous hematemesis. Left gastric venography is necessary prior to embolization of varices and is also useful in their diagnosis as well as study of hemodynamics and assessment of bleeding risk.

Esophageal and Gastric Varices↗
PubMed2001

Postnatal development of the retinal projection to the nucleus of the optic tract and accessory optic nuclei in the hooded rat.

Retinal projections to the nucleus of the optic tract (NOT) and accessory optic nuclei (AON) were studied in the postnatal hooded rat after monocular injection of cholera toxin B subunit (CTB) into the vitreous chamber of the eye. At all postnatal ages, retinal axons were labeled sensitively; they revealed dense projections to the contralateral, and sparse but distinct projections to the ipsilateral, NOT and AON. The CTB labeling enabled the first delineation of the complete morphology of developing retinal axons in the ipsilateral NOT and AON. From postnatal day (P) 1 to P3, axons with complex growth cones were seen, and unbranched collaterals with simple growth cones increased and extended gradually. At P6, complex growth cones disappeared while branched collaterals with simple growth cones as well as small-sized varicosities increased. By P12 (two days before eye-opening) the adult-like pattern of terminal arbors appeared. The branched collaterals with tiny, small-sized varicosities present probably represented developing synaptic boutons. At P16 (after eye opening), the pattern of terminal arbors was well developed, almost to the same extent as in the adult. By contrast, a broadly distributed, transient retinal projection around NOT and AON was gradually eliminated; it started to disappear during the first few postnatal days, and was fully retracted by the time of eye-opening time to a pattern normal for the adult.

Animals↗
PubMed2003

Feedback inhibition defines transverse processing modules in the lateral amygdala.

The lateral amygdaloid (LA) nucleus is the main input station of the amygdala for sensory afferents. However, it is unclear how the lateral nucleus transforms these inputs, because its intrinsic connectivity is poorly understood. Here, we took advantage of the fact that glutamatergic neurons of the lateral nucleus send a primarily unidirectional projection to the basomedial nucleus. Consequently, it was possible to infer the targets of their intranuclear axons (projection cells vs inhibitory interneurons) by backfiring some projection neurons from the basomedial nucleus and analyzing evoked responses in other LA projection cells. Basomedial stimuli evoked markedly different synaptic responses depending on the orientation of the slices. In coronal slices (intact and decorticated), the prevalent response of LA neurons was an inhibition, regardless of the stimulation intensity. This inhibition was sensitive to GABA(A) and non-NMDA receptor antagonists, suggesting that it was mediated by the activation of GABAergic cells of the LA. In contrast, basomedial stimuli primarily evoked EPSPs in horizontal slices, regardless of the position of recorded neurons. In light of these findings, we conclude that the prevalent target of the intrinsic axon collaterals of projection cells depend on the rostrocaudal position of target neurons with respect to the parent cell body: inhibitory interneurons at rostrocaudal proximity versus other projection cells at a distance. Thus, feedback interneurons effectively divide the lateral nucleus in transverse processing modules that prevent runaway excitation within each module but allow intermixing of sensory information in the rostrocaudal plane.

Action Potentials↗