Congenital auditory deprivation (deafness) leads to a dysfunctional intrinsic cortical microcircuitry. This chapter reviews these deficits with a particular emphasis on layer-specific activity within the primary auditory cortex. Evidence for a delay in activation of supragranular layers and reduction in activity in infragranular layers is discussed. Such deficits indicate the incompetence of th...

Recent studies using functional imaging and electrophysiology demonstrate that processes related to sensory integration are not restricted to higher association cortices but already occur in early sensory cortices, such as primary auditory cortex. While anatomical studies suggest the superior temporal sulcus (STS) as likely source of visual input to auditory cortex, little evidence exists to su...

This study shows the neural representation of cat vocalizations, natural and altered with respect to carrier and envelope, as well as time-reversed, in four different areas of the auditory cortex. Multiunit activity recorded in primary auditory cortex (AI) of anesthetized cats mainly occurred at onsets (<200-ms latency) and at subsequent major peaks of the vocalization envelope and was signific...

This study addressed the issue of multiple parallel auditory processing systems and their relationship to the skull-recorded auditory evoked potentials (AEPs) in the unanesthetized, unrestrained rat. In the preceding paper (Brain Res., 602 (1993) 240-250) it has been shown that auditory cortex activity does not contribute significantly to the vertex maximal AEPs recorded from the dorsal skull o...

Environmental acoustic exposure to a complex tone sequence within the critical period in infant rats resulted in the emergence of large-scale, selective changes that radically altered primary auditory cortex (A1) organization. In the sound exposure-revised A1, responses were segregated into two explicit zones representing spectrally and temporally separated lower and higher frequency tone seque...

Experiments in animals have provided an important complement to human studies of pitch perception by revealing how the activity of individual neurons represents harmonic complex and periodic sounds. Such studies have shown that the acoustical parameters associated with pitch are represented by the spiking responses of neurons in A1 (primary auditory cortex) and various higher auditory cortical ...

Pitch, one of the primary auditory percepts, is related to the temporal regularity or periodicity of a sound. Previous functional brain imaging work in humans has shown that the level of population neural activity in centers throughout the auditory system is related to the temporal regularity of a sound, suggesting a possible relationship to pitch. In the current study, functional magnetic reso...

Neuronal responses in auditory cortex show a fascinating mixture of characteristics that span the range from almost perfect copies of physical aspects of the stimuli to extremely complex context-dependent responses. Fast, highly stimulus-specific adaptation and slower plastic mechanisms work together to constantly adjust neuronal response properties to the statistics of the auditory scene. Evid...

Primary and nonprimary cerebral cortex mature along different timescales; however, the differences between the rates of maturation of primary and nonprimary cortex are unclear. Cortical maturation can be measured through changes in tissue microstructure detectable by diffusion magnetic resonance imaging (MRI). In this study, diffusion tensor imaging (DTI) was used to characterize the maturation...

Cortical development is an active field of study. The gerbil provides an excellent model for research because at the moment of birth its brain is rather immature, anatomically and functionally. Furthermore, the gerbil auditory cortex is particularly amenable to investigation in that the gerbil’s onset of hearing occurs approximately after 14 days of postnatal life. Despite these advantages of t...