Recording Sessions Research Articles

ABBA Gold, and: Electric Ladyland, and: Sign 'O' the Times, and: The Velvet Underground and Nico, and: Unknown Pleasures (review)

ABBA Gold. By Elisabeth Vincentelli. New York: Continuum, 2004. (33 1/3.) [131 p. ISBN 0826415466. $9.95.] Electric Ladyland. By John Perry. New York: Continuum, 2004. (33 1/3.) [132 p. ISBN 0826415717. $9.95.] Sign 'O' the Times. By Michaelangelo Matos. New York: Continuum, 2004. (33 1/3.) [121 p. ISBN 0826415474. $9.95.] The Velvet Underground and Nico. By Joe Harvard. New York: Continuum, 2004. (33 1/3.) [152 p. ISBN 0826415504. $9.95.] Unknown Pleasures. By Chris Ott. New York: Continuum, 2004. (33 1/3.) [xvi, 117 p. ISBN 0826415490. $9.95.] Continuum's 33 1/3 series is a collection of short books dedicated to rock's essential albums. The canon of rock music is a slowly evolving list perpetuated by magazines like Rolling Stone and MOJO, books like Dave Marsh and Kevin Stein's The Book of Rock Lists (NewYork: Dell, 1981), classic rock radio station playlists and countdown programs on music channel VHl. Author Nick Hornby humorously captured the personal implications of this musically obsessive pastime in his novel and the movie High Fidelty. Books in the 33 1/3 series focus on one album each and are 100 to 150 pages in length. Each author has chosen a record they love from the past forty years to write about. The books are highly personalized, but all follow the same basic structure: part 1 is dedicated to the author's personal connection to the record and why the record is significant in the artist's catalog and in the broader context of rock music history; part 2 documents the making of the record; part 3 is a song-by-song analysis of the album. Authors for the series are musicians and/or writers for notable popular music publications. Wisely, the series avoids records that have multiple or significant books dedicated to their study, like the Beatles's Sgt. Pepper's Lonely Hearts Club Band or Miles Davis's Kind of Blue. Instead Continuum has chosen mostly under-investigated records rang-ing from mainstream pop to underground classics. Outside of magazine articles, liner notes, fanzines, and artist biographies, these records are rarely discussed at length. Several books in the series cover records from the last two decades of rock. A sampling of five books from the series were available for review: Abba Gold by Elisabeth Vincentelli, Electric Ladyland by John Perry, Sign O' the Times by Michaelangelo Matos, The Velvet Underground and Nico by Joe Harvard, and Unknown Pleasures by Chris Ott. Elisabeth Vincentelli's meditation on Abba Gold is illuminating. The book is a unique volume in the series since it explores a greatest hits compilation rather than an album proper. Her introductory essay addresses the value of best-of records, the importance of singles vs. albums in propelling musicians' careers and how a posthumous record can reintroduce a group fallen out of favor to a new generation of listeners. Vincentelli takes us into Abba's recording sessions as Benny and Bjorn's songs take shape. In the absence of great lyrics, the author shifts our focus to the music and performances. She describes their music videos vividly and speculates on the personal angst of the two women in the group. Although Vincentelli appreciates Abba without irony, she can't help a goodnatured dig at their seventies fashion excess. …

Soul on Soul: The Life and Music of Mary Lou Williams (review)

Soul on Soul: The Life and Music of Mary Lou Williams. By Tammy L. Kernodle. Boston: Northeastern University Press, 2004. [328 p. ISBN 155553-609-9. $30.] Illustrations, bibliography, discography, index. This is second biographical monograph to appear on Mary Lou Williams (1910-1981), jazz pianist, arranger, and composer. Lately there seems to be a Williams revival, and a reaffirmation in print of her music and writings. Along with two biographies and several unpublished dissertations, we also have Williams' remarkable 11-article series on her early career that originally appeared in Melody Maker (10 April-12 June 1954, later collected by Max Jones as My Life With Kings of Jazz, most recently reprinted in Reading Jazz, ed. Robert Gottlieb [New York: Pantheon, 1996]). Her voluminous papers, which include various attempts at autobiographical writing, are now maintained at Institute of Jazz Studies, Rutgers University, Newark NJ; an online description of those materials may be accessed at http://newarkwww.rutgers .edu/ijs/mlw/collectionIJS.html (accessed 23 February 2005). Williams was born out of wedlock as Mary Lou Scruggs in Atlanta, Georgia in 1910, and from 1915 she was raised in Pittsburgh, Pennsylvania. She began playing keyboard at age 3 or 4, in imitation of harmonium lessons her mother was taking. Developing her own piano technique and learning to play songs by ear became ways for growing girl to withdraw from her alcoholic mother. By age 8 she was playing piano around various local spotsincluding a brothel-and before long she became known as the little piano girl of East Liberty, her Pittsburgh neighborhood. In 1925, she dropped out of high school and joined a black vaudeville troupe in which she met her first husband, saxophonist John Williams, whose last name she would adopt. Three years later John Williams joined The Dark Clouds of Joy, which later renamed itself as Andy Kirk's Clouds of Joy. Today listeners of jazz and black popular music prize 1929-41 Clouds of Joy records for Mary Lou Williams's contributions as pianist and arranger. Yet, it should be noted that Kirk was reluctant, even hesitant, to make use of her talents, and that he did so only at urging of Brunswick Records producer Jack Kapp at Clouds' first recording session. Through 1930s Williams was a regular member of Clouds, especially when they were based in Kansas City, and she proved to be most valuable and versa tile musician of group, pounding out boogie-woogie blues and negotiating most chromatic 32-measure ballads. In 1943 Williams established herself in New York City. Within three years she had written several notable arrangements for Duke Ellington, composed Zodiac Suite (1945-46), played a regular gig at Cafe Society Downtown, hosted a radio series on WNEW in New York, and had a small but significant recording contract with Moe Asch. She also responded favorably to new bebop style, becoming a mentor to Thelonious Monk and Bud Powell, and a lifelong friend with Dizzy Gillespie. Personal problems-including a failed second marriage to trumpet player Harold Shorty Baker, and her ongoing drama with her mother in Pittsburgh-as well as mounting debts gnawed at her success, and a 1952-54 European stay provided neither escape nor solutions. Instead, while in France in 1954, she experienced an ecstatic vision of Virgin Mary, whereupon she resolved to leave music, return to New York City, and devote herself to sick and poor, including jazz musicians addicted to narcotic drugs. On returning to United States in 1955, she concentrated on finding spiritual peace in Roman Catholicism, assisted many musicians in her Harlem neighborhood, but also passed up many opportunities to perform. …

Automatic evaluation of the exteroceptive suppression of the temporalis muscle activity

Aim. – To set up a reliable automated method of allowing to identify the ES1 and ES2 periods of exteroceptive suppression of the temporal muscle (EST), thereby reducing their intra- and inter-individual variability. Materials and methods. – Analyses were performed in 79 healthy subjects with strict inclusion and exclusion criteria. Each individual underwent two separate examinations 1 week apart. Activity of the left and right temporal muscles was recorded in response to unilateral stimulation of the left and right labial commissures. Wave forms were successively rectified, averaged, and filtered; the intersections of the resulting curve with values corresponding to 50%, 60%, 70%, 75%, and 80% of the control period (20 ms preanalysis time) were automatically determined. Results. – All subjects reached a 80% level of attenuation for ES2. The values of ES2 durations were normally distributed. The mean ES1 and ES2 durations didn’t vary between the two recording session, and there was a good individual reproducibility from one session to the other. Though relatively high, the inter-individual variability was slightly lower in the second than in the first session. Conclusions. – Computed analysis of EST may contribute to decrease inter- and intra-individual test variability. Letting patient habituate through a first recording session could increase test sensitivity, too. The obtained values for ES2 duration are normally distributed and well-reproducible at both the population and individual level. We suggest taking into account both ES2 duration and level of attenuation.

Functional interaction between the associative parietal cortex and hippocampal place cell firing in the rat

The hippocampus and associative parietal cortex (APC) both contribute to spatial memory but the nature of their functional interaction remains unknown. To address this issue, we investigated the effects of APC lesions on hippocampal place cell firing in freely moving rats. Place cells were recorded from APC-lesioned and control rats as they performed a pellet-chasing task in a circular arena containing three object cues. During successive recording sessions, cue manipulations including object rotation in the absence of the rat and object removal in the presence of the rat were made to examine the control exerted by the objects or by non-visual intramaze cues on place field location, respectively. Object rotations resulted in equivalent field rotation for all cells in control rats. In contrast, a fraction of place fields in APC-lesioned rats did not rotate but remained stable relative to the room. Object removal produced different effects in APC-lesioned and control rats. In control rats, most place fields remained stable relative to the previous object rotation session, indicating that they were anchored to olfactory and/or idiothetic cues. In APC-lesioned rats, a majority of place fields shifted back to their initial, standard location, thus suggesting that they relied on uncontrolled background cues to maintain place field stability. These results provide strong evidence that the hippocampus and the APC cooperate in the formation of spatial memory and suggest that the APC is involved in elaboration of a hippocampal map based on proximal landmarks.

Fetal magnetoencephalography—a multimodal approach

Past studies have shown the feasibility of recording fetal evoked responses to external stimuli using a non-invasive technique called magnetoencephalography (MEG). These studies were all performed using either auditory or visual stimuli and showed a fairly low detection rate for each modality, thus making this technology currently unreliable for fetal clinical applications. This study is based on the hypothesis that a multimodal approach of applying both auditory and visual stimulation paradigms in successive recording sessions could improve the probability of obtaining a fetal evoked response. A total of 34 studies were performed on 11 normal healthy fetuses at different stages of gestation starting as early as 28 weeks with a 151-channel fetal MEG system. The success rate of obtaining a response to either (or both) stimuli from a study at a given gestation age was 91%. All the 11 fetuses showed a response at least once over the gestation period the recordings were performed. A multimodal testing approach can improve the ability of the MEG technique to reliably monitor the functional development of the fetal brain.

Spike detection, characterization, and discrimination using feature analysis software written in LabVIEW

Rapid and accurate discrimination of single units from extracellular recordings is a fundamental process for the analysis and interpretation of electrophysiological recordings. We present an algorithm that performs detection, characterization, discrimination, and analysis of action potentials from extracellular recording sessions. The program was entirely written in LabVIEW (National Instruments), and requires no external hardware devices or a priori information about action potential shapes. Waveform events are detected by scanning the digital record for voltages that exceed a user-adjustable trigger. Detected events are characterized to determine nine different time and voltage levels for each event. Various algebraic combinations of these waveform features are used as axis choices for 2-D Cartesian plots of events. The user selects axis choices that generate distinct clusters. Multiple clusters may be defined as action potentials by manually generating boundaries of arbitrary shape. Events defined as action potentials are validated by visual inspection of overlain waveforms. Stimulus-response relationships may be identified by selecting any recorded channel for comparison to continuous and average cycle histograms of binned unit data. The algorithm includes novel aspects of feature analysis and acquisition, including higher acquisition rates for electrophysiological data compared to other channels. The program confirms that electrophysiological data may be discriminated with high-speed and efficiency using algebraic combinations of waveform features derived from high-speed digital records.

The methodology of corpus cavernosum electromyography revisited.

The methodology of corpus cavernosum electromyography (CC-EMG) was revisited, in order to overcome current methodological difficulties that hinder its clinical application. Using an 8-channel device, CC-EMG was performed in 12 healthy volunteers. Surface electrodes were placed bilaterally on the penile shaft and the kneecap (reference electrode), the pubis region and the anterior superior iliac spine (ASIS). A band pass filter with cut-off frequencies of 0.1 and 20 Hz was used. At least 2 sessions of recordings were performed in each subject. Thirty-five of 46 recordings were interpretable. Significant time delays between potentials recorded from different sites of the CC were detected. Clear spatial voltage gradients related to CC-potentials were observed on the pubis region. No voltage changes related to CC-potentials, but electrical activity from other sources were recorded from the ASIS. In contrast to frequency, a clear correlation could be demonstrated between amplitude, duration and polyphasity of CC-potentials recorded in 2 different sessions in the same individual. Multichannel monopolar recording of CC-EMG with surface electrodes is practical and has several advantages compared with bipolar recording. The results provide evidence that the recorded signals indeed reflect electrical activity of the CC and therefore offer a basis to pursue further clinical validation studies.

Sleep and Sleepiness among Brazilian Shift-Working Bus Drivers

The aim of this study was to evaluate daytime and nighttime sleep, as well as daytime and nighttime sleepiness of professional shift-working bus drivers. Thirty-two licensed bus drivers were assessed by nocturnal and diurnal polysomnography (PSG) recording and multiple sleep latency testing (MSLT) sessions. Sleep length was shorter and sleep efficiency reduced during daytime sleep compared with nighttime sleep. Thirty-eight percent of the drivers had indices of obstructive apnea and hypopnea syndrome (>5/h sleep) during nighttime and daytime sleep; more drivers snored during daytime than nighttime sleep (50% vs. 35%, p < 0.05), and 38% of the drivers evidenced periodic leg movements. The MSLT revealed that 42 and 38% of the bus drivers met the criteria for sleepiness when the test was conducted during the day and night, respectively. The daytime as compared to nighttime sleep of shift-working bus drivers was shorter and more fragmented and was associated in many with evidence of excessive sleepiness. Respiratory disorder was a common finding among the professional shift-working bus drivers. All these sleep deficiencies may adversely affect on the job driving performance.

Visual and electrical evoked response recorded from subdural electrodes implanted above the visual cortex in normal dogs under two methods of anesthesia

Sensitive methods are required to record electrical evoked potentials over the visual cortex to evaluate the efficacy and safety of a retinal prosthesis before it can be implanted on the retinal surface of patients afflicted by outer retinal diseases. This study was designed to examine subdural electrodes as a mean to evaluate cortical evoked potentials in response to light and electrical stimulation of the retina in three dogs under two methods of anesthesia–halothane and propofol. Results showed that subdural electrodes could be stabilized over the visual cortex for several (3–5) months, and that they were 6.95 times more sensitive than subdermal electrodes in recording cortical visual evoked potentials (VEPs) and 4.31 times more sensitive in recording cortical electrical evoked potentials under both methods of anesthesia. The waveforms’ shape changed for each electrode in the subdural array during 6/6 (100%) and 20/38 (52%) multi-channel recording sessions under halothane and propofol, respectively. This change could point to a cortical retinotopic organization versus hierarchical organization of different cortical areas for a given retinal stimulus. In summary, subdural electrodes show promising results for recording visual and electrical evoked responses (EERs) and thus for evaluation of the retinal prosthesis.

TeCo3D—Sharing Interactive and Dynamic 3D Models

In this paper we present a method for sharing interactive and dynamic 3D models that are collaboration-unaware, i.e., models that have not been designed to be used by multiple users at the same time. This functionality is an essential requirement for the inclusion of arbitrary 3D models, as generated by standard CAD or animation software, into teleconferencing sessions. A key aim of this work is to show that a large part of the required functionality can be developed in a way so that it is reusable for other applications such as shared whiteboards or networked computer games. Our method therefore consists of both an application dependent part that handles the specific tasks required for sharing 3D models, and of a number of generic services such as synchronization, scalable support for latecomers, and the ability to record and replay sessions. The generic services are based on an abstract media model and the RTP/I application level protocol for distributed interactive media. Any other application for a medium that shares this model and that uses RTP/I may reuse these generic services. We have implemented a prototype called TeCo3D demonstrating the feasibility of our approach.

Drum pillow and method for using same

A drum pillow for use in a bass drum is disclosed herein. The drum pillow can be permanently or removably inserted into the interior of the bass drum shell. The preferred embodiment of the drum pillow is used to “deaden” or modify the sound, esp. overtones, of the bass drum during live performances, particularly when the drum is being struck by a typical foot-operated bass beater. An alternate embodiment is designed for use in studio recording sessions, where the situation calls for an even “deader” sound. Also disclosed herein is a method for using the drum pillow for the purposes described.

Narrowband Phocoena-like clicks produced by a delphinid species

A distinction is traditionally made between the echolocation clicks of the whistling members of the family Delphinidae and those of nonwhistling smaller odontocetes, which include the family Phocoenidae and members of genus Cephalorhynchus and Kogia. The larger, whistling delphinids typically emit clicks that are short (40–70 μs) and broadband (30–60 kHz) with peak frequencies ranging from 40 to 130 kHz. Clicks of the smaller nonwhistling odontocetes are generally longer (&amp;gt;100 μs), more narrowband (15–25 kHz) with peak frequencies between 90 and 160 kHz. Here we report findings of long (∼135 μs), narrowband (10–25 kHz) clicks produced by a whistling species of delphinid, the Hawaiian spinner dolphin (Stenella longirostris). These clicks typically have peak frequencies between 90 and 100 kHz and predominantly occur in a doublet pattern with clicks consistently spaced 13 ms apart within a doublet and 23 ms between doublets. The vast majority of free-ranging spinner dolphin clicks conform to the more traditional delphinid form. Narrowband clicks appear to be produced rarely, having been observed on only 4 out of 25 recording sessions. It is presently not clear whether these clicks represent echo location or communication signals.

Modulation of mismatch negativity by stimulus deviance and modality of attention.

We studied the effect of attention on the processing of auditory sensory inputs by means of the mismatch negativity (MMN) potential, which can be derived from event-related EEG. A series of frequent standard and rare deviant auditory stimuli were presented to 20 healthy subjects in two recording sessions about five weeks apart. Deviant stimuli were either low or highly deviant as compared to the standard stimulus. While MMN was recorded, subjects were performing a visual and, subsequently, an auditory discrimination task. Directing attention towards the auditory task was associated with increased MMN amplitude only in response to low deviant stimuli and only in the first recording session. No change of MMN amplitude was found when directing attention towards the visual task or when MMN was recorded in response to highly deviant auditory stimuli. The latter may trigger an involuntary switch of attention, thereby overwriting the effect of task-directed attention. Conversely, the effects of attention on the processing of low deviant stimuli appear to be fragile and diminish with increasing automaticity of task execution.

Sympathetic nerve activity to amputated lower leg in humans: Evidence of altered skin vasoconstrictor discharge

Transection of a peripheral nerve in the cat is known to cause a regional change in sympathetic impulse pattern. Our aim was to determine whether microneurography can be used to study sympathetic activity in the transected nerve of human amputees, and whether any such activity shows an abnormal pattern similar to that observed in the cat. Seven successful sympathetic recording sessions were performed in the peroneal nerve of four subjects with posttraumatic transtibial leg amputation; one of them was studied on four occasions. Muscle nerve sympathetic activity (MSA) was detected in all four subjects. Skin nerve sympathetic activity (SSA) was found in one patient only, but on three occasions. It was more difficult to obtain high quality sympathetic recordings than for intact nerves, particularly in patients amputated many years before our studies. MSA showed a qualitatively normal pattern at rest and during various manoeuvres. In three recordings from skin nerve fascicles without innervation zone, SSA displayed normal characteristics at room temperature and qualitatively normal responses to arousal stimuli and various manoeuvres. During body cooling there was an abnormal shift in SSA pattern with a reduction in burst duration instead of the increase occurring normally. Cardiac rhythmicity of SSA was more pronounced during body cooling than during body heating. This is also a reversal of the normal pattern. The abnormal SSA pattern during body cooling suggests increased baroreflex regulation of cutaneous vasoconstrictor neurones, similar to the change after nerve transection in the cat. This is the first time that human nerve recordings support the hypothesis of a regional alteration in sympathetic impulse pattern following a nerve lesion. The implications of this phenomenon for pain conditions remains to be explored; our patients did not suffer from phantom or stump pain.

Heart rate variability, a target for the effects of angiotensin II in the brain of the trout Oncorhynchus mykiss

This study was conducted on unanesthetized rainbow trout equipped with two ECG electrodes and with an intracerebroventricular (i.c.v.) micro-guide. The ECG signal was recorded during three experimental sessions of 30 min and the heart rate variability (HRV) spectral analysis was performed during stabilized periods of recording. The first recording session was conducted during the control period and the mean heart rate (HR) of the trout was 44±2 bpm. The total power spectral density (PSD) of the R–R interval signal of the ECG was 21233±4400 ms 2/Hz. A major high frequency (HF) spectral band centered at 0.16 Hz and a minor low frequency (LF) spectral band centered at 0.04 Hz were the two main components of the PSD. An i.c.v. injection of 0.5 μl of vehicle during the second session had no significant statistical effect, either on the mean HR (43±2 bpm), the total PSD (24693±6394 ms 2/Hz) or on the center frequency and power of the two main spectral bands. Conversely, an i.c.v. injection of ANGII (1.5, 6.25 and 50 pmol) during the third recording session induced a significant increase in the mean HR (+3%, +15%, +30%, respectively) but the effect of the peptide was more obvious on the total PSD which was profoundly decreased (−27%, −65%, −76%, respectively). The two main spectral bands of the PSD were totally blunted after the injection of 50 pmol of ANGII. In another group of control trout, intraperitoneal (i.p.) injection of atropine abolished the PSD of the R–R interval signal of the ECG demonstrating that the parasympathetic system is the main contributor of HRV in trout. Our results have thus demonstrated for the first time, at least in a non-mammalian species, that i.c.v. injection of native ANGII profoundly reduces HRV. We hypothesize that ANGII in the brain of the trout alters the pattern of the electrical activity along preganglionic cardiac vagal motoneurons.

Alpha3 integrin receptors contribute to the consolidation of long-term potentiation

Several lines of evidence suggest that integrin receptors play a pivotal role in consolidation of long-term potentiation (LTP), but which of the many integrin dimers are involved remains to be discovered. The present study used an LTP reversal paradigm to test if α3 integrins make an important contribution. Function blocking α3 monoclonal antibodies or vehicle were locally infused into recording sites in field CA1 of rat hippocampal slices and LTP induced with theta burst stimulation. Low frequency trains of pulses were applied 30 min after the theta bursts. Previous work indicates that low frequency stimulation reverses LTP when applied immediately after induction but is largely ineffective after 30–45-min delays. If the antibodies were to block consolidation, then they should extend the period over which potentiation is vulnerable to disruption. There was no detectable difference between the two groups in the initial degree of LTP or within slice decay of potentiation 1–10 min after induction; a small but reliable decay occurred from 10 to 30 min with antibody treatment ( P<0.01) but not in control slices. Percent potentiation was not statistically different for vehicle (55±19%, mean±S.D.) and anti-α3 (43±21%) slices at 30 min post-theta bursts. Five-Hz stimulation (‘theta pulse’ stimulation) 30 min after induction caused a reduction of LTP. The percent loss of potentiation after the 1-min trains was greater in the antibody-treated slices than in controls (98±4% vs. 62±28%, P<0.01, U-test) and correlated ( r=0.84, α3 slices) with the percent LTP present prior to low frequency stimulation, as expected if the stimulation reversed potentiation. Recovery occurred in both groups but percent LTP was significantly smaller in experimental slices at 10 min post-theta pulses (5±11% vs. 36±15%, P<0.01). Recovery continued for 20 min after theta pulses and, in accordance with earlier work, was nearly complete for the control slices (50±19% vs 55±15%, 40 min post- vs. immediately pre-theta pulses). LTP remained depressed after 40 min of recovery in the anti-α3 slices (23±19% vs. 43±21%) at which point it was substantially less than that found in controls ( P<0.01). Western blots with anti-α3 antibodies identified a polypeptide with the molecular mass (155 kDa) expected for the α3 subunit and further showed that it is broadly distributed in brain. Subcellular fractionation experiments demonstrated that α3 is concentrated in synaptic membranes over homogenates to about the same degree as the GluR1 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate-type glutamate receptor. From these results we suggest that α3-containing integrins are localized to synapses and are needed to stabilize a slowly decaying form of LTP. The findings also show that vulnerability to reversal can be used in place of extended recording sessions in studying consolidation.

Measuring P50 suppression and prepulse inhibition in a single recording session.

Two distinct measures have been used to assess inhibitory gating deficits in schizophrenia patients: P50 suppression and prepulse inhibition of the startle response. It remains unclear whether both measures can be assessed in a single testing session. Twelve normal subjects underwent testing in a carefully designed combined P50/prepulse inhibition session using stimulus characteristics similar to those described in the existing literature. The levels of both P50 suppression and prepulse inhibition obtained in the combined session were highly similar to those obtained in independent testing of previous cohorts of normal subjects. As in previous experiments, P50 suppression and prepulse inhibition were not significantly correlated. Measuring P50 suppression and prepulse inhibition in a single session is feasible and offers a unique opportunity to assess these two distinct gating measures contemporaneously in cohorts of normal comparison subjects and schizophrenia patients, so that temporal shifts in one or both measures are minimized.

Gaze shifts evoked by electrical stimulation of the superior colliculus in the head-unrestrained cat. II. Effect of muscimol inactivation of the caudal fastigial nucleus.

The medioposterior cerebellum [vermian lobules VI and VII and caudal fastigial nucleus (cFN)] is known to play a major role in the control of saccadic gaze shifts toward a visual target. To determine the relative contribution of the cFN efferent pathways to the brainstem reticular formation and to the superior colliculus (SC), we recorded in the head-unrestrained cat the effects of cFN unilateral inactivation on gaze shifts evoked by electrical microstimulation of the deeper SC layers. Gaze shifts evoked after muscimol injection still exhibited the typical qualitative features of normal saccadic gaze shifts. Nevertheless, consistent modifications in amplitude and latency were observed. For ipsiversive movements (evoked by the SC contralateral to the inactivated cFN), these changes depended on the locus of stimulation on the motor map: for the anterior 2/3 of the SC, amplitude increased and latency tended to decrease; for the posterior 1/3 of the SC, amplitude decreased and latency increased. For the contraversive direction, amplitude moderately decreased and latency tended to increase for all but the caudal-most stimulated SC site. These modifications of SC-evoked gaze shifts during cFN inactivation differed from the ipsiversive hypermetria/contraversive hypometria pattern observed for visually triggered gaze shifts recorded during the same recording sessions. We conclude that (i) the topographical organization of gaze shift amplitude in the deeper SC layers is influenced by the cerebellum and is either severely distorted or demonstrates an amplitude reduction during inactivation of the contralateral or ipsilateral cFN, respectively; (ii) gaze shifts evoked by SC microstimulation and visually triggered gaze shifts either rely on distinct cerebellar-dependent control processes or differ by the location of the caudal-most active SC population. We present a functional scheme providing several predictions regarding the modulatory influence of the cerebellum on SC neuronal activities and on the topographical organization of fastigial-SC projections.

Effects of ethanol on flash-evoked potentials of rats: lack of antagonism by naltrexone

The present study examined the effects of ethanol and naltrexone hydrochloride (a nonselective opiate receptor antagonist) on flash-evoked potentials recorded from both the visual cortex (VC) and the superior colliculus (SC) of chronically implanted hooded rats. There were four treatment conditions administered on separate days: Either saline or naltrexone (10 mg/kg; volume of 1.0 ml/kg) was given 10 min before either saline or ethanol (2.0 g/kg; 20% ethanol solution in a volume of 1.26 ml/100 g). Evoked potentials were recorded 15 min after the intraperitoneal injections were completed. Animals were tested at 23.1°C room temperature. In the VC, ethanol significantly decreased the amplitude of components N1, P3, and N3, whereas it increased the amplitude of P2. Components P1 and N2 were unaffected by ethanol treatment. The SC components P3 and N4 were reduced in amplitude by ethanol, but component P1 was not altered. Latencies of all components in both structures were increased by ethanol. Naltrexone alone did not significantly affect the potentials, nor did naltrexone pretreatment significantly alter the effects of ethanol on the potentials. Naltrexone produced a modest hypothermia of about 0.25°C, whereas ethanol resulted in hypothermia of about 1.0°C. Ethanol, either alone or in combination with naltrexone, significantly reduced body movement during the evoked-potential recording sessions. The results indicate that endogenous opioid systems do not play a major role in the acute effects of ethanol on flash-evoked potentials recorded from primary areas of the visual system.

Event-related potentials, CNV, readiness potential, and movement accompanying potential recorded from posterior thalamus in human subjects. A SEEG study

Intracranial recordings were obtained from three patients with intractable chronic pain who underwent analgesic electrical stimulation of the contralateral thalamus. Multilead electrode made it possible to record from several thalamic nuclei. The electrode was targeted into the ventroposterolateral (VPL) nucleus of the thalamus. During separate recording sessions, the following tests were performed: somatosensory evoked potentials (SEP) of the median or posterior tibial nerve, event-related cognitive potentials (auditory oddball P3 wave), readiness potential (RP) and contingent negative variation (CNV) using auditory warning (S1) and visual imperative (S2) stimuli. The movement accompanying potential (MAP), which was present in the VPL in all but one of the recordings, behaved as a far-field potential. Recordings obtained from the VPL confirmed its established role as a relay nucleus, processing somatosensory information to the primary somatosensory cortex. The VPL generated the ‘thalamic’ SEP, which was the only potential regularly recorded in this nucleus. In the recordings from one patient (No. 3), auditory and visual evoked potentials of the CNV protocol, peaking at approximately 300 ms, were obtained from the VPL and appeared to be generated in situ. Neither RP, CNV nor ˈoddballˈ ERPs appeared in the VPL. From the pulvinar, only a visually evoked potential was recorded. Oddball P3, RP, CNV, and middle and long latency auditory and visual potentials (evoked in the CNV paradigm) appeared to be generated ‘dorsally’ to the VPL, probably in the nucleus posterolateralis (PL). This structure may therefore be involved in both the processing of afferent information and in cognitive operations.