Introduction to synaptic circuits, Gordon M.Shepherd and Christof Koch membrane properties and neurotransmitter actions, David A.McCormick peripheral ganglia, Paul R.Adams and Christof Koch spinal cord - ventral horn, Robert E.Burke olfactory bulb, Gordon M.Shepherd, and Charles A.Greer retina, Peter Sterling cerebellum, Rodolfo R.Llinas and Kerry D.Walton thalamus, S.Murray Sherman and Christof Koch basal ganglia, Charles J.Wilson olfactory cortex, Lewis B.Haberly hippocampus, Thomas H.Brown and Anthony M.Zador neocortex, Rodney J.Douglas and Kevan A.C.Martin Gordon M.Shepherd. Appendix: Dendretic electrotonus and synaptic integration.

The synaptic organization of the brain

中枢神経系疾患の治療は正常細胞（ニューロン）の機能維持を目的とするが，脳血管障害のように機能障害の原因が細胞の死滅に基づくことは多い．一方，脳腫瘍の治療においては薬物療法や放射線療法といった腫瘍細胞の死滅を目標とするものが大きな位置を占める．いずれの場合にも，細胞死の機序を理解することは各種病態や治療法の理解のうえで重要である．現在のところ最も研究の進んでいる細胞死の型はアポトーシスである．そのなかで重要な位置を占めるミトコンドリアにおける反応および抗アポトーシス因子について概要を紹介する．

Neuroscience 細胞死：最近の知見

In mammals, environmental sounds stimulate the auditory receptor, the cochlea, via vibrations of the stapes, the innermost of the middle ear ossicles. These vibrations produce displacement waves that travel on the elongated and spirally wound basilar membrane (BM). As they travel, waves grow in amplitude, reaching a maximum and then dying out. The location of maximum BM motion is a function of stimulus frequency, with high-frequency waves being localized to the “base” of the cochlea (near the stapes) and low-frequency waves approaching the “apex” of the cochlea. Thus each cochlear site has a characteristic frequency (CF), to which it responds maximally. BM vibrations produce motion of hair cell stereocilia, which gates stereociliar transduction channels leading to the generation of hair cell receptor potentials and the excitation of afferent auditory nerve fibers. At the base of the cochlea, BM motion exhibits a CF-specific and level-dependent compressive nonlinearity such that responses to low-level, near-CF stimuli are sensitive and sharply frequency-tuned and responses to intense stimuli are insensitive and poorly tuned. The high sensitivity and sharp-frequency tuning, as well as compression and other nonlinearities (two-tone suppression and intermodulation distortion), are highly labile, indicating the presence in normal cochleae of a positive feedback from the organ of Corti, the “cochlear amplifier.” This mechanism involves forces generated by the outer hair cells and controlled, directly or indirectly, by their transduction currents. At the apex of the cochlea, nonlinearities appear to be less prominent than at the base, perhaps implying that the cochlear amplifier plays a lesser role in determining apical mechanical responses to sound. Whether at the base or the apex, the properties of BM vibration adequately account for most frequency-specific properties of the responses to sound of auditory nerve fibers.

/pdf/mechanics-of-the-mammalian-cochlea-368l279klj.pdf

Mechanics of the Mammalian Cochlea

Phantom auditory perception (tinnitus): mechanisms of generation and perception

The temporal properties of speech appear to play a more important role in linguistic contrasts than has hitherto been appreciated. Therefore, a new framework for describing the acoustic structure of speech based purely on temporal aspects has been developed. From this point of view, speech can be said to be comprised of three main temporal features, based on dominant fluctuation rates: envelope, periodicity, and fine-structure. Each feature has distinct acoustic manifestations, auditory and perceptual correlates, and roles in linguistic contrasts. The applicability of this three-featured temporal system is discussed in relation to hearing-impaired and normal listeners.

Temporal Information in Speech: Acoustic, Auditory and Linguistic Aspects

A two‐interval, forced‐choice paradigm was used to measure the critical ratio of human subjects detecting a tone burst in continuous noise and noise gated simultaneously with the tone bursts. Noise spectrum levels of 35, 15, and − 5 dB SPL/Hz were used; tone frequencies were 500, 1000, 2000, 4000, and 8000 Hz. At 4000 and 8000 Hz, critical ratios were significantly larger for the simultaneously gated noise than for continuous noise. There were no significant differences between the critical ratios for continuous and gated noise at frequencies of 500, 1000, and 2000 Hz. These results are consistent with those of Wier et al. [J. Acoust. Soc. Am. 61, 1298–1300 (1977)] and extend those results to higher frequencies where differences between the continuous and simultaneously gated masking cases are greater.

Human tone detection in continous‐ and pulsed‐noise maskers

Processing of the Auditory-Nerve Code for Speech by Populations of Cells in the Anteroventral Cochlear Nucleus

The auditory sensitivity of red‐winged blackbirds (Agelaius phoeniceus) has been measured with two behavioral techniques. The first was a two‐alternative forced‐choice procedure in which a bird initiated a trial by pecking a center key; a tone was presented with 50% probability on each trial. The bird was rewarded with food for pecking a right or left key, depending on whether a tone was present or not. In the second technique, a bird pecked the center key continuously until a 2‐sec tone sounded; reinforcement then occurred for pecking the right key during the tone. The method of constant stimuli was employed to determine thresholds in the frequency range of 125 Hz to 10 kHz. The two procedures produced similar audiograms. The lowest threshold were 5–15 dB SPL in the 2–4‐kHz range. At lower frequencies, thresholds rise gradually to 65 SPL at 125 Hz. At higher frequencies thresholds rise sharply above 6 kHz; at 10‐kHz thresholds were 70–75 dB SPL. Both procedures are also being used to obtain frequency‐ an...

Murray B. Sachs

Papers

Human tone detection in continous‐ and pulsed‐noise maskers

Processing of the Auditory-Nerve Code for Speech by Populations of Cells in the Anteroventral Cochlear Nucleus

Auditory sensitivity of red‐winged blackbirds

Of vowel spectra in the auditory nerve