Emergence of temporal-pattern sensitive neurons in the midbrain of weakly electric fish Gymnarchus niloticus

Multiple Cases of Striking Genetic Similarity Between Alternate Electric Fish Signal Morphs in Sympatry

“…These neurons do not interact with each other in the ELL, but project to common areas in the midbrain (Kawasaki and Guo, 1998). There, 'sign selective' neurons selectively respond to the sense of rotation of these two stimulus parameters (Carlson and Kawasaki, 2004;Kawasaki and Guo, 2002).…”

From stimulus estimation to combination sensitivity: encoding and processing of amplitude and timing information in parallel, convergent sensory pathways

“…3 and 4). This finding was expected, given the anatomical convergence of the amplitude-and time-coding pathways in the midbrain (Kawasaki and Guo 1998), and the sensitivity of midbrain neurons to different temporal combinations of sinusoidal AM and PM (Kawasaki and Guo 2002;Kawasaki 2004,2006b). …”

“…Unlike gymnotiforms, in which PM information is extracted in the midbrain (Carr et al 1986a;Carr et al 1986b), S-afferents in Gymnarchus give rise to PM-sensitive pyramidal neurons in the ELL through a combination of direct and indirect synaptic inputs (Kawasaki andGuo 1996Kawasaki andGuo 1998;Matsushita and Kawasaki 2004). Both AM-and PM-sensitive pyramidal neurons project to the midbrain torus semicircularis, where the amplitude-and time-coding pathways converge (Kawasaki and Guo 1998), and many neurons are sensitive to particular combinations of AM and PM (Kawasaki and Guo 2002;Kawasaki 2004, 2006b), similar to the convergence of amplitudeand time-coding pathways in the midbrain of the barn owl auditory system (Knudsen and Konishi 1978;Peña and Konishi 2001). …”

Neuronal Sensitivity to Microsecond Time Disparities in the Electrosensory System ofGymnarchus niloticus

“…Therefore, the measured sensitivities of the ELL neurons are conservative. Behavioral and neuronal recording studies (Kawasaki, 1993;Kawasaki and Guo, 2002) demonstrate that the JAR occurs with phase differences between any body surfaces (head-trunk, leftright, etc. ), and different ELL neurons are tuned to detect phase differences with different spatial orientations.…”

“…In the current study, however, we examined time-disparity sensitivity of all encountered pyramidal cells exclusively with the head-trunk configuration alone. We assume that most pyramidal cells would respond to 5 s of time disparity if the best orientation of the neurons for phase difference were used (Kawasaki and Guo, 2002). Rose and Heiligenberg (1986) found a comparable level of time-disparity sensitivity in midbrain neurons of the gymnotiform electric fish Eigenmannia, which has evolved its electrosensory system and JAR independently of the mormyriform Gymnarchus (Lauder and Liem, 1983).…”