Are bipolar cells excitatory or inhibitory?
The primary task of the photoreceptor-ON bipolar cell synapse is to invert the “sign” of the synapse. Glutamate is a canonical excitatory transmitter, but at this synapse, its acts essentially as an inhibitory transmitter by hyperpolarizing ON bipolar cells.
Are bipolar cells excitatory?
Both non-NMDA receptors and NMDA receptors are activated by depolarization of single bipolar cells. The neurotransmitter released from retinal bipolar cells is proposed to be the excitatory amino acid glutamate (Slaughter and Miller, 1983; Ehinger et al., 1988; Tachibana and Okada, 1991).
Where are bipolar cells found?
Often found in the retina, bipolar cells are crucial as they serve as both direct and indirect cell pathways. The specific location of the bipolar cells allow them to facilitate the passage of signals from where they start in the receptors to where they arrive at the amacrine and ganglion cells.
When are bipolar cells depolarized?
ON-center bipolar cells are depolarized by small spot stimuli positioned in the receptive field center. OFF-center bipolar cells are hyperpolarized by the same stimuli. Both types are repolarized by light stimulation of the peripheral receptive field outside the center (Fig. 1).
What is special about bipolar cells?
A bipolar neuron, or bipolar cell, is a type of neuron that has two extensions (one axon and one dendrite). Many bipolar cells are specialized sensory neurons for the transmission of sense. As such, they are part of the sensory pathways for smell, sight, taste, hearing, touch, balance and proprioception.
Are bipolar cells depolarized in the dark?
On-center and off-center bipolar cells and ganglion cells. In the dark, photoreceptors are depolarized (dark gray color) and increase their release of glutamate neurotransmitter. Light causes these photodetectors to hyperpolarize and decrease their glutamate release (light blue color).