Adaptation-induced plasticity and spike waveforms in cat visual cortex

Abstract

Orientation-selective neurons shift their preferred orientation after being adapted to a nonpreferred orientation. These shifts of the peaks of tuning curves may be in the attractive or repulsive direction in relation to the adapter orientation. In anaesthetized cats we recorded evoked electrical responses from the visual cortex in a conventional fashion. The recorded spikes in cortex may present two typical waveforms: regular spikes or fast spikes. However, there is no evidence whether the shapes of spikes are related to the attractive or repulsive shifts of orientation tuning curves of cells. Our results show that after adaptation the recorded cells with both attractive and repulsive shifts display one or the other shape of spike. However, the magnitude of shifts is systematically higher for regular spikes, which is attributed to putative pyramidal cells, while tuning curves for fast spikes have smaller magnitudes and are evoked by putative interneurons.

Adaptation and Neuronal Network in Visual Cortex

“…Pyramidal cells are found in layers II-III, V and VI and are the only type of neurons that send axons outside the cortex. These neurons exhibit two levels of their dendritic extension: basal level close to the cell body and relatively long apical dendritic branches extending sometimes over the entire thickness of the cortex.Classically, spike waveforms allow cells' distinction into two functional cell-groups, that is, excitatory pyramidal cells and inhibitory interneurons [11,46,47]. …”

“…Recent investigations revealed the ability of visual neurons to respond to different stimuli conditions (deprivation or imposition) by changing their optimal properties acquired after birth. This adaptation of neurons for visual perception suggests the existence of neuronal plasticity in adults, hence a mature brain.Adaptation-induced-plasticity of orientation in primary visual cortex is characterized by authors as the ability of cortical neurons to change their preferred orientation following a long [11,61,63] or short [62,65] exposure to a non-preferred orientation for the primary Adaptation and Neuronal Network in Visual Cortex 329 visual cortex neurons in cats, e.g. Long adaptation leads to the shift of orientation tuning towards attractive direction [61].…”

“…Red arrows depict adapting orientation (non-preferred orientation in control). Attractive shifts are more frequent than repulsive shifts in longer adaptation durations (≥ 6 min) [11,61]. Repeated or prolonged exposure to an adapter diminished neuronal responses evoked by the original optimal properties, furthermore in parallel, if it is the neuron's preferred stimulus [61].…”

“…Recent investigations have revealed the ability of visual neurons to respond to different stimuli conditions by changing their optimal properties acquired after birth. Most of these studies have been done by visual deprivation [9,[83][84][85][86], whereas only a few have centered on induced adaptation [11,62,64,87]. This adaptation of neurons to non-optimal stimuli suggests the adaptability of neuronal code to visual stimuli.…”

High noise correlation between the functionally connected neurons in emergent V1 microcircuits

“…On the other hand, a 'CCG' is a histogram of the firing rate of the target neuron with reference to the spiking of another neuron, and it provides the direction and type of functional link between neurons (Alonso and Martinez 1998;Barthó et al 2004;Fujisawa et al 2008;Bharmauria et al 2014;Bharmauria et al 2015). A peak offset from zero (quasi-3 synchrony) in a 'CCG' indicates a putative excitatory or inhibitory connection, whereas a peak straddling zero (synchrony) signifies a common input to neurons (Perkel et al 1967;Shadlen and Newsome 1998;Dong et al 2008;Bachatene et al 2012). …”