This paper is concerned with the representation of spectra synthesized steady-state vowels in temporal aspects discharges auditory-nerve fibers. The results are based on a study responses large numbers single fibers anesthetized cats. By presenting same set stimuli to all encountered each cat, we can directly estimate population response those stimuli. Period histograms unit were constructed. fiber harmonic component stimulus taken be amplitude corresponding Fourier transform unit’s period...

Responses of large populations auditory-nerve fibers to synthesized steady-state vowels were recorded in anesthetized cats. Driven discharge rate vowels, normalized by dividing saturation (estimated from the driven CF tones 50 dB above threshold), was plotted versus fiber for a number vowel levels. For /I/ and /ε/, such profiles showed peak region first formant another second third formants, sound levels below about 70 SPL. /a/ at 40 SPL there are peaks formants. At higher these disappear...

1. Single-unit responses in the dorsal cochlear nucleus of unanesthetized, decerebrate cats have been divided into two categoreis. These differentiated on basis to best-frequency tones. Type IV units responded tones with excitation from threshold about 20 or 30 dB above threshold; at higher levels, their response was inhibitory. In a few cases, excitatory area near not seen and others, became again high levels. could be groups based length time that inhibition maintained long are...

A study was made of the response peripheral vestibular neurons in squirrel monkey to head vibration and air-borne sound frequency range from 50-4000 Hz. Responses were measured terms phase locking discharge changes firing rate. The lowest phase-locking thresholds for −70 −80 dB re 1 g, median values most sensitive (200–400 Hz) −20 −40 g; minimum 76 120–130 SPL, respectively. Rate-change 10–30 above thresholds. sacculus has no special sensitivity comparison with other end-organs; threshold...

1. The responses of neurons in the ventral cochlear nucleus (VCN) decerebrate cats are described with regard to their regularity discharge and latency. Regularity is measured by estimating mean standard deviation interspike intervals as a function time during short tone bursts (25 ms). This method extends usual interspike-interval analysis based on interval histograms allowing study temporal changes transient responses. coefficient variation (CV), equal ratio interval, used measure...

This study describes the effects of broadband background noise on average discharge rate to best-frequency (BF) tones auditory nerve fibers in cat. The exposure long-term continuous are compared gated and off simultaneously with test tones. Addition causes a shift dynamic portion tone-evoked versus level functions higher tone intensities. occurs at mean 0.61 dB for each 1-dB increment level. is independent best frequency spontaneous rate. which begins dependent consistent frequency-dependent...

1. Single units and evoked potentials were recorded in dorsal cochlear nucleus (DCN) response to electrical stimulation of the somatosensory column spinal trigeminal nuclei (together called MSN for medullary nuclei) tactile stimuli. Recordings from paralyzed decerebrate cats. 2. DCN principal cells (type IV units) strongly inhibited by (single 50-microA bipolar pulse) or stimulation. Units fusiform cell deep layers inhibited, suggesting that inhibition affects both types (i.e., giant cells)....

The dorsal cochlear nucleus (DCN) is a second-order auditory structure that also receives nonauditory information, including somatosensory inputs from the column and spinal trigeminal nuclei. Here we investigate peripheral sources of to DCN. Electrical stimulation was applied cervical nerves C1-C8, branches C2, nerve, hindlimb nerves. largest evoked potentials in DCN were produced by C2 its innervate pinna. pattern inhibition excitation principal cells comparable with seen previous studies...

The rate responses of auditory nerve fibers were measured for best frequency (BF) tone bursts in the presence continuous background noise. Rate functions BF tones constructed over a 32-dB range levels, centered on behavioral masked thresholds cats. level at which noticeable changes are evoked by corresponds closely to threshold all noise levels used (-10- 30-dB spectrum level). As increases, response approaches saturation, and incremental decreases. At high low medium spontaneous larger than...

It is well known that many stimulus parameters, such as sound location in the auditory system or contrast visual system, can modulate timing of first spike sensory neurons. Could first-spike latency be a candidate neural code? Most studies measuring information assume brain has an independent reference for onset from which to extract latency. This assumption creates obvious confound casts doubt on feasibility codes. If measured relative internal calculated responses population, conveyed by...

The representation of steady-state vowels in terms both average rate and temporal aspects the discharge patterns populations auditory-nerve fibers is discussed. effects nonlinearities on this emphasized. Aspects two rate-related nonlinearities, saturation two-tone suppression, are reviewed. At low sound levels, profiles versus characteristic frequency show well-defined peaks at frequencies corresponding to formants a vowel stimulus. levels above about 60 dB SPL, these not seen because...

We have studied the response properties of single units in cochlear nucleus unanesthetized decerebrate cats. The purpose study was to compare as described two commonly used classification schemes. Units were first classified according their receptive-field based on relative prominence excitatory and inhibitory responses tones noise. then basis discharge patterns short tone bursts at best frequencies (BFs). Our results show that systematic relationships exist between units. Type I give only...

A population study of cat auditory-nerve fibers was used to characterize the permanent deficits induced by exposure 110–115 dB SPL, narrow-band noise. Fibers in region acoustic trauma (roughly 1–6 kHz) showed a loss sensitivity at best frequency (BF) about 50–60 and an increased tuning bandwidth. correlation between weakened two-tone suppression found for with BFs above 1 kHz. Single-fiber responses vowel /ɛ/ were recorded intensities ranging from near threshold maximum 110 SPL. In normal...

1. The principal cells of the dorsal cochlear nucleus (DCN) are mostly inhibited by best frequency (BF) tones but excited broadband noise (BBN), producing so-called type IV response characteristic. narrowband inhibitory responses can be explained influence interneurons with II characteristics. However, it is not clear that all details accounted for this neural circuit. In particular, many units band-reject (notch noise); tend to only weakly these stimuli, if at all. paper we study...

1. Convergence of auditory nerve (AN) fibers onto bushy cells the ventral cochlear nucleus (VCN) was investigated with a model that describes electrical membrane properties these cells. The consists single compartment, representing soma, and includes three voltage-sensitive ion channels (fast sodium, delayed-rectifier-like potassium, low-threshold potassium). These have characteristics derived from voltage clamp data VCN also contains leakage channel, capacitance, synaptic inputs. accurately...

1. Response maps of 49 type IV neurons in cat dorsal cochlear nucleus (DCN) were studied by moving a tone small steps along the frequency dimension and intensity dimension. Type responses are recorded from DCN principal cells. Data collected 38 units with best frequencies (BFs) 2.16 to 50.3 kHz use electrode penetrations long (strial) axis DCN; an additional 11 previous study analyzed. A stereotypical response map is defined as consisting two excitatory inhibitory regions. both pyramidal...

Acoustic trauma degrades the auditory nerve’s tonotopic representation of acoustic stimuli. Recent physiological studies have quantified degradation in responses to vowel /ɛ/ and investigated amplification schemes designed restore a more correct than is achieved with conventional hearing aids. However, it difficult from data quantify how much different aspects cochlear pathology contribute impaired responses. Furthermore, extensive experimental testing potential aids infeasible. Here, both...