Visual homeostatic processing in V1: when probability meets dynamics

Perception of the difference between past and present stimulus: A rare orientation illusion may indicate incidental access to prediction error-like signals

“…Our experiments in cats showed consistent generation of the difference signal in primary visual cortex with increasing switch time intervals [15]. This is in accordance with the present results and is most likely based on increasing impact of inhibitory suppressive mechanisms over time [15,16,53]. Thus, the fact that in the present human study the illusory percept occurred very rarely may straightforwardly depend on currently unknown impact of factors producing difference signals (such as stimulus durations, contrast, spatial frequencies) that vary in individual subjects or on psychometric factors (e.g., internal noise, attention) that influence individual perceptual decision processes during which signals of current stimuli compete with simultaneously present difference signals, Fig 5).…”

“…This allows interpretation of the "deviant" error signal as a result of computing the arithmetic difference of subsequent stimuli (i.e., as the difference between past and present orientations) rather than resulting from a complete stimulus exchange. Our previous experiments in cat primary visual cortex [15,16] showed that after the switch from superimposed to single gratings, populations of neurons encode the present (sustained, and thus, adapted) orientation with suppressed amplitudes, whereas populations tuned to the removed orientation produce a strong and persistent [54,55] "off" response [15], as depicted in Fig 5 (cf. changes of peak activity at bottom [past vs. present], blue and red, respectively). Signals following stimulus removal are commonly referred to as visual off-responses, which tend to increase with stimulus duration [56].…”

“…Hence, the observation that repeated visual stimuli lead to reduced cortical activation during context-dependent cognitive tasks involving expectations and attention (for review see [5]) has been interpreted as an outcome of "predictive coding" at various stages of processing [4,[6][7][8][9][10][11][12][13]. While it remains an open question whether reduction of visual responses to repeated or prolonged input may strictly emerge from computation of repetition probabilities [7] rather than arising from specific local adaptation dynamics [14][15][16], it has frequently been shown that abrupt alterations in temporal sequences of sensory input produce change-related signals that are generated "automatically" at early steps of cortical processing and that are typically labeled as prediction errors (for review see [17]). Basic forms of predictive coding have been proposed to exist already at earliest steps of visual processing in the retina [18] and LGN [19,20] where, in the framework of information theory [21], center-surround antagonism within receptive fields allow reduction in redundancies by removing predictable components of visual input.…”

Noninvasive Ultrasonic Drug Uncaging Maps Whole-Brain Functional Networks

“…1C). Interestingly, at 1.8 MPa, at the end of sonication, we observed an increase in VEP amplitude relative to baseline in some animals, potentially due to post-inhibitory rebound spiking (Nortmann et al, 2015; Sanchez-Vives et al, 2000). Notably, this phenomenon has been observed previously with optogenetic halorhodopsin inhibition (Yang et al, 2018) and also has been hypothesized in silico to underlie the paradoxical excitatory action of subanesthetic doses of propofol (McCarthy and Kopell, 2012).…”