GABAB receptor-dependent bidirectional regulation of critical period ocular dominance plasticity in cats

Abstract

Gama amino butyric acid (GABA) inhibition plays an important role in the onset and offset of the critical period for ocular dominance (OD) plasticity in the primary visual cortex. Previous studies have focused on the involvement of GABAA receptors, while the potential contribution of GABAB receptors to OD plasticity has been neglected. In this study, the GABAB receptor antagonist SCH50911 or agonist baclofen was infused into the primary visual cortex of cats concurrently with a period of monocular deprivation (MD). Using single-unit recordings we found that the OD shift induced by four days of MD during the critical period was impaired by infusion of the antagonist SCH50911, but enhanced by infusion of the agonist baclofen. In contrast, seven days of MD in adult cats did not induce any significant OD shift, even when combined with the infusion of SCH50911 or baclofen. Together, these findings indicate that an endogenous GABAB receptor-mediated inhibition contributes to juvenile, but not adult, OD plasticity.

Management of Abnormal Visual Developments

“…It has been concluded that the reduction of inhibition in the visual cortex is the core to restore the plasticity of adult amblyopia after the critical period. Studies on animal models have shown that reducing GABAergic inhibition with pharmacological treatment such as blockers of GABA synthesis or GABA receptor antagonists or environmental paradigms which contain environment enrichment and dark exposure can increase plasticity in the adult brain, enabling ocular dominance plasticity and favoring recovery from amblyopia [112][113][114]. New research has found that transplanted embryonic inhibitory neurons from the medial ganglionic eminence reinstate ocular dominance plasticity in adult amblyopic mice, with the recovery of both visual cortical responses and performance on a behavioral test of visual acuity [115].…”

Closing the Critical Period Is Required for the Maturation of Binocular Integration in Mouse Primary Visual Cortex

“…, where Nx was the numbers of cells with ocular dominance category equal to x and N was the total number of examined cells. All units were also scored for noise and response strengths on a 1 (weak noise/response firing) to 3 (strong noise/response firing) (Cai et al, 2017). On this basis, ∼30% of recorded units were discarded of the analysis.…”

Synaptic and circuit development of the primary sensory cortex

“…It is also known that the expression of LYNX1, which inhibits nicotinic signaling, controls the critical period by controlling cholinergic innervation and the excitatory–inhibitory balance 66 . Recently, the GABA-B receptor has also been shown to modulate ocular dominance plasticity 67 . Also, the synthesis of adenosine by ectonucleotidases and the disruption of the adenosine A1 receptor have been reported to be important for juvenile plasticity in the auditory cortex 68 .…”