Neural circuit

A neural circuit is a population of neurons interconnected by synapses to carry out a specific function when activated.

Thus, Hebbian pairing of pre-synaptic and post-synaptic activity can substantially alter the dynamic characteristics of the synaptic connection and therefore either facilitate or inhibit signal transmission.

In 1959, the neuroscientists, Warren Sturgis McCulloch and Walter Pitts published the first works on the processing of neural networks.

[4] They showed theoretically that networks of artificial neurons could implement logical, arithmetic, and symbolic functions.

The establishment of synapses enables the connection of neurons into millions of overlapping, and interlinking neural circuits.

[5] One principle by which neurons work is neural summation – potentials at the postsynaptic membrane will sum up in the cell body.

Temporal characteristics refers to the continuously modified activity-dependent efficacy of synaptic transmission, called spike-timing-dependent plasticity.

It has been observed in several studies that the synaptic efficacy of this transmission can undergo short-term increase (called facilitation) or decrease (depression) according to the activity of the presynaptic neuron.

In some cells, however, neural backpropagation does occur through the dendritic branching and may have important effects on synaptic plasticity and computation.

A neuron in the brain requires a single signal to a neuromuscular junction to stimulate contraction of the postsynaptic muscle cell.

[6] Neural circuits in the spinal cord called central pattern generators are responsible for controlling motor instructions involved in rhythmic behaviours.

This type of circuit is exemplified in the respiratory center of the brainstem, which responds to a number of inputs from different sources by giving out an appropriate breathing pattern.

Connectionist models serve as a test platform for different hypotheses of representation, information processing, and signal transmission.

[10] The single cell experiments used intracranial electrodes in the medial temporal lobe (the hippocampus and surrounding cortex).

[11] Sometimes neural circuitries can become pathological and cause problems such as in Parkinson's disease when the basal ganglia are involved.

[12] Problems in the Papez circuit can also give rise to a number of neurodegenerative disorders including Parkinson's.

Anatomy of a multipolar neuron
From "Texture of the Nervous System of Man and the Vertebrates" by Santiago Ramón y Cajal . The figure illustrates the diversity of neuronal morphologies in the auditory cortex .
Proposed organization of motor-semantic neural circuits for action language comprehension. Gray dots represent areas of language comprehension, creating a network for comprehending all language. The semantic circuit of the motor system, particularly the motor representation of the legs (yellow dots), is incorporated when leg-related words are comprehended. Adapted from Shebani et al. (2013)
Model of a neural circuit in the cerebellum