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J S Buchwald

Publications and source records attributed to J S Buchwald.

At least 37 records · Page 2Linked to original sources
PubMed1984

Binaural interaction effects on the auditory brainstem response of the cat and kitten.

The auditory brainstem response (ABR) is a series of volume conducted potentials that can be recorded from the scalp within 10 ms following auditory stimulation. Differences between ABRs evoked with binaural stimulation and those constructed by summing equivalent numbers of monaural stimulation to each ear indicate the presence of binaural interaction for some ABR potentials but not for others. In the present study, ABR binaural interactions were studied in both cats and kittens. Binaural interactions were not seen for waves 1-3 but were present at the latencies of waves 4, 5 and, in most cases, 6. The sound intensities used were selected to insure that acoustic cross-over, i.e. sound presented monaurally to one ear stimulating the other, did not influence binaural interaction effects. Experiments with cats that had been monaurally deafened confirmed that the effects observed were not due to acoustic cross-over. Systematic manipulation of stimulus rate and intensity produced marked changes in the level of binaural interaction. Increases in stimulation rate from 10 to 100 clicks/s reduced binaural interaction for wave 4 and reversed the direction of binaural interaction for wave 5. Wave 6 was not generally present at rates above 10 clicks/s. Reduction of stimulus intensity reduced binaural interaction for wave 4. Binaural interaction effects were at adult levels in kittens of 20 days for waves 4 and 5. Wave 6 was not present until 30 days of age. These data suggest a possible model of the physiological processes producing binaural interaction which is based on occlusion as seen in other areas of the nervous system. In such a model, convergent input becomes more important in driving the generators of some ABR potentials when the system is stressed (as, for example, by increased stimulus rate), than it is when the system is not stressed.

Age Factors↗
PubMed1983

Depth evoked potential and single unit correlates of vertex midlatency auditory evoked responses.

The rostral brainstem and thalamus of awake cats were studied for depth correlates of a surface-recorded midlatency auditory evoked potential, wave "A', with a latency range of 17-25 ms. In response to clicks or pure tones, midlatency potentials were recorded from the level of the cuneiform nucleus (14-15 ms latencies) forward through the medial tegmentum to the level of the intralaminar thalamic nuclei centralis lateralis (CL) and center median (CM) (17-19 ms latencies). While this medial projection system to the thalamus involved primarily CL and CM, slightly longer latency responses were also found in nucleus ventralis anterior (VA) and ventralis lateralis (VL). A ventral diencephalic response was characterized by latencies averaging 0.5-1.2 ms less than those from the dorsal thalamic regions. Both surface and depth midlatency potentials showed comparable sensitivity to rate of stimulation. At click rates above 1/s, peak amplitudes diminished, and for rates greater than 10/s, both surface and depth midlatency responses were abolished. This rate sensitivity differs from that of the auditory brainstem responses (ABRs), which are essentially unchanged at rates of 20/s. Whereas ABRs are unaffected by surgical levels of sodium pentobarbital, the surface and depth midlatency potentials are replaced by a deep negativity within minutes following administration of anesthesia. Extracellular recordings of acoustically responsive single units in CL and CM demonstrated latencies comparable to the CL and CM field potential latencies. Both the units and field potentials were similarly rate sensitive. Each auditory unit showed a best frequency response, but none demonstrated somatosensory convergence. Bilateral aspiration of the inferior colliculus did not abolish the midlatency depth or surface responses. Rather, recordings in CL and CM suggested response enhancement over a two week postoperative period. Taken together these data suggest that the midlatency vertex potential, wave "A', reflects a generator system which projects from cuneiform nucleus, through the medial tegmentum to the medial thalamus, particularly to CL and CM. The functional significance of this medial auditory projection system remains to be determined. It could mediate physiological correlates of "state', modulate sensory input or motor output, or it could provide an integrative mechanism for the focusing of auditory attention.

Acoustic Stimulation↗
PubMed1983

Auditory evoked responses in clinical populations and in the cat.

An overview is presented of auditory brainstem responses (ABRs) and middle- and long-latency auditory evoked responses recorded from clinical populations and from an experimental model, the cat. The research strategy of this program is to use auditory evoked responses as surface probes of central auditory processing functions and of substrate systems. Comparisons of ABRs between normal and mentally handicapped populations indicate specific types of abnormalities in particular subpopulations. Generator substrates of these responses have been suggested from analytical animal experiments. Middle- and long-latency responses are now beginning to be compared in normal and mentally handicapped subjects. Experimental data from the cat suggest that these responses reflect the relatively independent activation of several parallel forebrain systems which receive input from brainstem levels.

Animals↗
PubMed1983

Central transmission time differences in the auditory brainstem response as a function of sex, age, and ear of stimulation.

Averaged auditory brainstem responses (ABRs) to monaural clicks were recorded from twenty-nine men and women and twenty children. Differences in the wave I to wave V transmission time, and wave I to wave III transmission time as a function of ear of stimulation and reference, sex, size and age were investigated. The wave I-V transmission time was shorter for the women compared to the men. Individual wave latencies were compared and the transmission time difference was found to be due to small, incremental differences between successive waves rather than to one particular wave component. Size differences, as measured by nasion-inion length and subject height, did not correlate to the transmission time difference and did not appear to contribute to the sex difference. An ear of stimulation difference was found in the women's group. The sex difference in transmission time was seen in the children's data, but the difference was not significant. Thus, sex differences, age differences, and ear of reference differences are seen in ABR transmission times.

Acoustic Stimulation↗
PubMed1982

Sources of variability in auditory brain stem evoked potential measures over time.

Auditory brain stem EPs elicited in 10 normal adults by monaural clicks delivered at 72 dB HL, 20/sec showed no significant change in wave latencies or in the ratio of wave I to wave Y amplitude across 250 trial subsets, across 250 trial subsets, across 1500 trial blocks within a test session, or across two test sessions separated by several months. Sources of maximum variability were determined by using mean squared differences with all but one condition constant. 'Subjects' was shown to contribute the most variability followed by 'ears', 'sessions' and 'runs'; collapsing across conditions, wave III latencies were found to be the least variable, while wave II showed the most variability. Some EP morphologies showed extra peaks between waves II and IV, missing wave IV or wave IV fused with wave V. Such variations in wave form morphology were independent of EMG amplitude and were characteristic of certain individuals.

Adult↗
PubMed1980

Brain stem auditory evoked response development in the kitten.

The development of brain stem auditory evoked responses (BAERs), recorded from a surface electrode as short-latency, volume-conducted potentials, was studied in a series of kittens over a postnatal period ranging from birth to 60 days. Repeated, longitudinal observations on particular kittens were supplemented with observations on additional kittens during the first and second postnatal week to determine age of onset of the BAERs. The position of the animal and sound source within the recording chamber were held constant across recording sessions, as was click intensity except during recordings in which intensity effects were specifically studied. Click rates of 1, 10, 50 and 100/sec were routinely presented. Reference electrodes at the tongue, pinna and neck showed volume-conducted responses to the click stimuli and resulted in considerable distortion of the activity recorded by the vertex electrode; the forepaw, in contrast, showed no activity and a vertex-forepaw electrode configuration provided good resolution of the BAERs across development. A number of new observations were made. BAERs were first observed at 4 days of age, approximately the same age at which depth evoked potentials are first recorded in brain stem auditory nuclei. Initially the BAERs were diffuse, high threshold and fatigued rapidly, characteristics shared with depth evoked potentials in the early postnatal period. Over the first two weeks, the potentials showed marked decrease in threshold, increased resistance to fast click rates, and better definition of wave forms. All BAER components showed exponential decreases in latency. Because all of the brain stem evoked potentials could be recorded concurrently and longitudinally in the same subject a number of developmental comparisons were possible among the BAER components. Wave 1, related to the acoustic nerve in the adult cat, showed a developmental time course and adult latency similar to that reported for N1. Wave 2, related to the cochlear nucleus in the adult, showed a marked bimodality over the first month; wave 2a was a large amplitude clearly separated wave which gradually fused as an inconspicuous leading shoulder on wave 2b. Wave 2b developed with a time course and adult latency similar to that reported for the ventral cochlear nucleus. Wave 3, related to the region of the superior olivary complex in the adult, showed a clear but transient bimodality during the third week of development. Wave 5, related to the inferior colliculus in the adult, appeared later than waves 1-4 and showed a significantly slower rate of development than waves 1-4. These data indicate that differential developmental changes occur within the brain stem auditory pathway and that the BAERs provide a dynamic probe of concurrent maturational interactions.

Acoustic Stimulation↗
PubMed1980

Changes of acoustic nerve and cochlear nucleus evoked potentials due to repetitive stimulation.

Evoked potential recordings were studied in the acoustic nerve and cochlear nucleus of adult decerebrate cats as a function of the tone duration (1-1500 msec) and the tone repetition rate (0.5/sec-200/sec). Response decrements due to repetitive tonal stimulation were primarily a function of the inter-tone interval. At inter-tone intervals longer than 100 msec, no response decrements were observed in the acoustic nerve or the cochlear nucleus. With shorter inter-tone intervals, reversible response decrements of identical magnitudes ocurred in both the acoustic nerve and the cochlear nucleus evoked potentials. The mechanism of response decrement may be due to depression at the hair cell-acoustic nerve junction.

Acoustic Stimulation↗
PubMed1978

Vocalization in the cat and kitten.

Vocal responses of kittens and mature cats were recorded in a variety of standard behavioral situations. Sonographic analysis of these responses showed similarities of responses obtained repeatedly from different cats within each recording situation. Marked differences in response patterns were noted in different recording situations. The kitten and cat vocal repertoires thus include a variety of specific responses to particular motivational or behavioral circumstances.

Age Factors↗
PubMed1978

Factors that affect the amplitudes and latencies of the vertex short latency acoustic responses in the cat.

The latencies and amplitude of the short latency (less than 10 msec) acoustic evoked responses recorded from the vertex of the cat have been studied as a function of acoustic stimulus parameters. A change in the stimulus intensity, duration, or rate of repetition resulted in parallel changes in the first 5 evoked responses, i.e., the latencies shifted the same amount and the amplitudes were modified in the same proportion. Comparison of responses to monaural versus binaural stimuli indicated an occlusive effect of binaural stimulation only in potential 4.

Acoustic Stimulation↗
PubMed1977

Classical conditioning with auditory discrimination of the eye blink in decerebrate cats.

Cats were subjected to complete lower brainstem transection, and were then tested for learning ability according to a classical conditioning paradigm. An auditory stimulus was systematically paired with a brief shock to the eyelid. Within a few weeks after the operation, the decerebrate cats could learn the conditioned response with a tone frequency discrimination and then a discrimination reversal. Our results support the notion that the brainstem reticular formation can support a conditioned response which isbehaviorally similar to that obtained in the intact animal.

Acoustic Stimulation↗
PubMed1975

Far-field acoustic response: origins in the cat.

Short-latency evoked potentials recorded from the vertex of adult cats in response to click stimulation (the far-field acoustic response) were analyzed in a series of lesion experiments to determine the origins of each component. The resultant data indicate that the primary generator of potential is the acoustic nerve; of potential 2, the cochlear nucleus; of potential 3, neurons of the superior olivary complex activated by projections crossing the midline; of potential 4, neurons of the ventral nucleus of the lateral lemniscus and preolivary region activated equally by crossed and uncrossed projections; and of potential 5, neurons of the inferior colliculus activated primarily by crossed projections.

Acoustic Stimulation↗