Ebook An introduction to the physiology of hearing (4th edition): Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook An introduction to the physiology of hearing (4th edition): Part 2
Ebook An introduction to the physiology of hearing (4th edition): Part 2
CHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2st in the core areas and then in the belt and the parabelt areas, rhe core areas and some of the surrounding areas arc tonotopically organized, with further patterns of organization (e.g. ear dominance, latency and degree of sensitivity to frequency-modulated stimuli) superimposed on the tonotopic o Ebook An introduction to the physiology of hearing (4th edition): Part 2rganization. Cells in the auditory cortex can show a wide variety of tuning curves, with cither broad or narrow tuning, and single or multiple peaks oEbook An introduction to the physiology of hearing (4th edition): Part 2
f frequency sensitivity. They can show specific responses to amplitude and frequency-modulated stimuli and to the location of sound sources. Neurones CHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2 necessary for the response to relatively basic features of the auditor)' stimulus, such as detecting the direction of frequency change, and for sound localization, while the belt and parabell areas detect more complex features. Il is suggested that the auditory cortex is necessary for the represent Ebook An introduction to the physiology of hearing (4th edition): Part 2ation of ‘auditory objects’, that is the assembly of information about all auditory features of a stimulus, including its location. It has been speculEbook An introduction to the physiology of hearing (4th edition): Part 2
ated that in primates the information IS then divided into two general streams, with ‘what' information being passed anteriorly in the cerebral cortexCHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2the cerebral cortex arc divided into core areas, with further surrounding areas. The initial detailed analysis of the auditory cortex was performed in the cat. This was undertaken in accordance with the concepts prevailing at the lime, which included a single primary receiving area (Al), plus an adj Ebook An introduction to the physiology of hearing (4th edition): Part 2acent secondary area (All) and further surrounding ‘association’ areas. However, later analysis in the cat and in particular the extension of the analEbook An introduction to the physiology of hearing (4th edition): Part 2
ysis to a wider range of species including primates has led to a reassessment of this approach. The specific receiving area, which receives its input CHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2there are multiple adjacent areas, called the211212An Introduction to the Physiology of Hearingbelt, and further areas surrounding those, called the parabelt. In many mammalian species, there are believed to be three separate areas with the characteristics of core auditory cortex, and up to eight se Ebook An introduction to the physiology of hearing (4th edition): Part 2parate auditory areas in the adjacent belt, with further areas in the parabelt. These multiple cortical representations are thought to contribute to pEbook An introduction to the physiology of hearing (4th edition): Part 2
arallel processing of the auditory stimulus, with the different areas preferentially processing selected aspects of the auditory input.7.1.1.1Core areCHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2onic appearance of the cortex, determined with Nissl staining which marks the cell bodies and proximal dendrites, shows that the core auditors' cortex has the same appearance as the primary sensory cortex for other modalities. Cortex with this appearance is known as ‘koniocortex’ (‘dustcortex’), def Ebook An introduction to the physiology of hearing (4th edition): Part 2ined as having a large number of small cells with relatively even packing. Layer IV, which receives the afferent axons, is well developed, while thereEbook An introduction to the physiology of hearing (4th edition): Part 2
arc no large pyramidal cells, normally rhe large output cells, in the deepest, output layers. Core sensory cortices also arc marked by certain commonCHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2the neurotransmitter acetylcholine (acetylcholinesterase) and a dense reaction for the calcium-binding protein parvalbumin (sec Kaas and Hackett, 2000).Secondly, the core areas have substantial direct inputs from the specific auditory division of the medial geniculate body, that is from the ventral Ebook An introduction to the physiology of hearing (4th edition): Part 2or ‘lemniscal’ division. In contrast, the bell or adjacent areas have few or no connections with the specific ventral division, but receive their majoEbook An introduction to the physiology of hearing (4th edition): Part 2
r inputs from the core auditory areas, They also receive inputs from the non-specific medial and dorsal divisions of the medial geniculate (Winer, 199CHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2haracteristic frequencies across the cortical area, from high frequencies to low, or vice versa. Therefore, a progression of characteristic frequencies across an area of cortex that goes from low to high and to low again, in other words, that includes a frequency reversal, can be taken as a good ind Ebook An introduction to the physiology of hearing (4th edition): Part 2ication that the area in fact contains two cortical areas, one for each frequency progression.rhe core areas arc heavily interconnected by reciprocalEbook An introduction to the physiology of hearing (4th edition): Part 2
connections, and this forms a further criterion by which they are grouped together.In terms of its cytoarchitecture, core auditory cortex shares some CHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2arse staining in layer V (Rose, 1949; see also review by Winer. 1992). In layers II—IV, the cortical cells arc organized in vertical columns, separated by zones of dendrites and axons and situated around the periphery' of small vertical cylinders 50 60 pm in diameter w hich are oriented orthogonal t Ebook An introduction to the physiology of hearing (4th edition): Part 2o the cortical surface. The columnar arrangement is also visible in human beings, where the cell bodies appear in what have beenThe auditory cortex213Ebook An introduction to the physiology of hearing (4th edition): Part 2
called a ‘rain-shower' formation (von Economo and Koskinas, 1925; Moore and Guan, 2001). rhe main cells receiving the dialamo-cortical inputs are pyraCHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2cells. Overall, 25% of the neurones in primary' cortex arc GABAcrgic and therefore inhibitory; this proportion rises to 94% for neurones within layer 1 (Prieto et at., 1994). Axons and dendrites within AỈ have substantial patchy lateral ramifications that run across as well as along the frequency-ba Ebook An introduction to the physiology of hearing (4th edition): Part 2nd strips (Matsubara and Phillips. 1988). There is also a particularly rich ramification vertically within each column of cells. Callosal afferent*, fEbook An introduction to the physiology of hearing (4th edition): Part 2
rom the contralateral cortex, similarly ramify vertically within ‘callosal columns’, that is within columns of cells having a particularly rich callosCHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2ctivation enhances activity in the region that projects to that area of the cortex and suppresses activity in adjacent areas of the cortex (Zhang and Suga, 1997). The conicofugal fibres also form a way that activity can be transmitted from core cortical areas to other areas (for review, see Smith an Ebook An introduction to the physiology of hearing (4th edition): Part 2d spirou, 2002).Figures 7.1 and 7.2 show the auditory cortical areas in the cat and macaque. In the cat, areas currently classed as core by the aboveEbook An introduction to the physiology of hearing (4th edition): Part 2
criteria arc the traditional primary auditory cortex Al, the anterior auditory field AAF and the posterior auditory field PAF (Reale and Imig, 1980). CHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2 as projecting heavily to each other, the core areas project to the adjacent bell areas, but without connections to the more distant auditory fields. The bell areas therefore form an obligatory stage in the output from the core.7.1.1.2The belt and parabeltThe belt areas arc adjacent to the core. Bel Ebook An introduction to the physiology of hearing (4th edition): Part 2t areas arc defined by the following criteria: (i) major connections with rhe dorsal or medial divisions of the medial geniculate, (ii) no or only minEbook An introduction to the physiology of hearing (4th edition): Part 2
or connections with the ventral division of die medial geniculate and (iii) having recordable auditory' responses. Each bell area receives inputs fromCHAPTER SEVENThe auditory cortexThe auditor)' cortex consists of core areas, surrounded by belt and parabelt areas. Auditory stimuli are analysed firs Ebook An introduction to the physiology of hearing (4th edition): Part 2ion of the cochlea. This is borne out functionally in the macaque, where four of die belt areas have their own frequency progressions (Fig. 7.2E).The macaque parabelt consists of two areas, the rostral and caudal parabelt areas, lateral to the belt. While the core and belt arc buried in rhe lateral Ebook An introduction to the physiology of hearing (4th edition): Part 2sulcus, the parabelt is visible on the lateral surface of the superior temporal gyrus (Fig. 7.2B). The parabelt is defined as an area where injectionsEbook An introduction to the physiology of hearing (4th edition): Part 2
of tracers give heavy labelling of neurones in the belt, but little in the core itself (1 lackett el al., 1998). It is divided into rostral and caudaGọi ngay
Chat zalo
Facebook