Sadka R S, Wollberg Z
Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2004 May;190(5):403-13. doi: 10.1007/s00359-004-0506-7. Epub 2004 Mar 17.
Previous studies have demonstrated that despite its blindness, the subterranean blind mole rat (Spalax ehrenbergi) possesses a noticeable lateral geniculate nucleus and a typical cyto-architectural occipital cortex that are reciprocally connected. These two areas, as revealed by the metabolic tracer 2-deoxyglucose, are activated by auditory stimuli. Using single unit recordings, we show that about 57% of 325 cells located within the occipital cortex of anesthetized mole rats responded to at least one of the following auditory stimuli--white noise, pure tones, clicks, and amplitude modulated tones--with the latter two being the most effective. About 85% of cells driven by either contralateral or ipsilateral stimulation also responded to binaural stimulation; about 13% responded only to binaural stimulation; and 2% were driven exclusively by contralateral stimulation. Comparing responsiveness and response strength to these three modes of stimulation revealed a contralateral predominance. Mean latency (+/-SD) of ipsilateral and contralateral responses were 48.5+/-32.6 ms and 33.5+/-9.4 ms, respectively. Characteristic frequencies could be divided into two distinct subgroups ranging between 80 and 125 Hz and between 2,500 and 4,400 Hz, corresponding to the most intensive spectral components of the vibratory intraspecific communication signals and airborne vocalizations.
先前的研究表明，尽管地下盲鼹鼠（Spalax ehrenbergi）双目失明，但它拥有一个明显的外侧膝状体核和一个典型的细胞构筑枕叶皮质，二者相互连接。代谢示踪剂2-脱氧葡萄糖显示，这两个区域会被听觉刺激激活。通过单单元记录，我们发现，在麻醉的鼹鼠枕叶皮质内的325个细胞中，约57%对以下至少一种听觉刺激有反应——白噪声、纯音、滴答声和调幅音，其中后两种刺激最为有效。由对侧或同侧刺激驱动的细胞中，约85%也对双耳刺激有反应；约13%仅对双耳刺激有反应；2%仅由对侧刺激驱动。比较对这三种刺激模式的反应性和反应强度，发现存在对侧优势。同侧和对侧反应的平均潜伏期（±标准差）分别为48.5±32.6毫秒和33.5±9.4毫秒。特征频率可分为两个不同的亚组，范围在80至125赫兹之间以及2500至4400赫兹之间，分别对应于种内振动通讯信号和空中发声中最强的频谱成分。
