How Do Neural Circuits Turn Sensation into Action?

From electrical signals and synapses to sensory selection, movement, and the evidence for circuit mechanisms.

Level: Intermediate
Reading load: 10 core readings in 5 units
Prerequisites: The Biological Psychology foundation, or comparable familiarity with neurons, neural recording, and the difference between an association and a causal explanation. Willingness to work through technical reviews and diagrams. Terms are introduced in the guides; reproducing mathematical models is not a prerequisite.
Last reviewed: September 2026

Introduction

To catch a moving object is to bring a small society of processes into accord. Light reaches the eye, neural signals pass among cells, and the body adjusts as the object approaches. The action looks simple because we see its result. Explaining it requires us to connect electrical currents, patterns of activity, and the consequences of changing the circuit.

This path begins inside and between cells, then follows how circuits select and transform sensory signals. It turns to movement as a problem of both generating coordinated activity and correcting action with uncertain feedback. A final pair asks how an intervention can establish a circuit's contribution without turning every behavioral effect into a complete mechanistic explanation.

The cellular reviews are demanding, and the whole path may benefit from several sittings. Keep a running diagram of one example, such as reaching toward a moving cup: what is measured, what operation is proposed, and what comparison could distinguish it from another account? By the end, you should be able to separate a cell's response from a circuit computation, explain why state and feedback matter, and evaluate the assumptions behind a causal claim.

Unit 1 of 5

How do cells communicate?

Begin by separating electrical signaling within a neuron from influence between neurons. Bean explains why a spike depends on interacting cellular properties; Pereda shows that even the distinction between electrical and chemical connections does not make those mechanisms independent. This supplies the vocabulary needed to interpret circuit diagrams as more than wires.

Reading
1 of 10
The Action Potential in Mammalian Central Neurons
Bean, B. P. (2007). The action potential in mammalian central neurons. Nature Reviews Neuroscience, 8(6), 451–465. https://doi.org/10.1038/nrn2148
Major synthesis · Challenging · Full work: 15 pages
Follow how channel interactions shape spikes and repeated firing, keeping the recording conditions in view.
Why you’re reading it. This establishes what the signal entering a circuit consists of before we ask what the circuit computes.
A question to consider. If two cells produce similar spikes, what would you need to measure before assuming that the same mechanism produced them?
Reading
2 of 10
Electrical Synapses and Their Functional Interactions with Chemical Synapses
Pereda, A. E. (2014). Electrical synapses and their functional interactions with chemical synapses. Nature Reviews Neuroscience, 15(4), 250–263. https://doi.org/10.1038/nrn3708
Major synthesis · Challenging · Full work: 14 pages
Track how a signal in one cell can affect another through chemical transmission, electrical coupling, or their interaction.
Why you’re reading it. This adds communication between cells to Bean's account of electrical events within them.
A question to consider. Draw a two-cell connection in which changing chemical input also changes electrical coupling. Which measurements would separate the two effects?

Unit 2 of 5

How does a circuit transform an input?

A response to a feature is something to explain, not the explanation itself. Hubel and Wiesel make visual selectivity observable through controlled stimulation. Yuste then broadens the level of analysis to connected populations, including recurrent activity. Compare what a response map establishes with the network mechanisms that could produce it.

Reading
3 of 10
Receptive Fields of Single Neurones in the Cat's Striate Cortex
Hubel, D. H., & Wiesel, T. N. (1959). Receptive fields of single neurones in the cat's striate cortex. The Journal of Physiology, 148(3), 574–591. https://doi.org/10.1113/jphysiol.1959.sp006308
Landmark empirical study · Methodological contribution · Moderate · Full work: 18 pages
Follow the transition from a light stimulus to a mapped response, distinguishing recorded effects from proposed connections.
Why you’re reading it. This turns the cellular vocabulary into an empirical question about sensory transformation.
A question to consider. What experiment would help determine whether an orientation-selective response depends only on incoming signals or also on interactions within cortex?
Reading
4 of 10
From the Neuron Doctrine to Neural Networks
Yuste, R. (2015). From the neuron doctrine to neural networks. Nature Reviews Neuroscience, 16(8), 487–497. https://doi.org/10.1038/nrn3962
Foundational argument · Major synthesis · Challenging · Full work: 11 pages
Compare feedforward and recurrent explanations of an organized response, using Hubel and Wiesel's findings as a concrete case.
Why you’re reading it. A cell's selectivity must fit an account of how connected populations operate; it does not choose that account by itself.
A question to consider. Propose a population recording or perturbation that could distinguish two networks producing the same single-cell response.

Unit 3 of 5

How are signals selected and combined?

The same anatomical pathway can operate differently when goals or bodily conditions change. Moran and Desimone change which part of a display is relevant while measuring responses. Bargmann explains how modulators can change circuit participation and interaction. These are complementary routes into state-dependent function, not evidence that one transmitter or one location implements attention.

Reading
5 of 10
Selective Attention Gates Visual Processing in the Extrastriate Cortex
Moran, J., & Desimone, R. (1985). Selective attention gates visual processing in the extrastriate cortex. Science, 229(4715), 782–784. https://doi.org/10.1126/science.4023713
Landmark empirical study · Moderate · Full work: 3 pages
Keep the physical display, fixation requirements, and task-relevant location separate as you interpret the recorded activity.
Why you’re reading it. This tests whether a receptive field is a fixed filter whose output depends only on the incoming stimulus.
A question to consider. How would your account of Hubel and Wiesel's response maps change if the same display produced different responses under two attentional instructions?
Reading
6 of 10
Beyond the Connectome: How Neuromodulators Shape Neural Circuits
Bargmann, C. I. (2012). Beyond the connectome: How neuromodulators shape neural circuits. BioEssays, 34(6), 458–465. https://doi.org/10.1002/bies.201100185
Foundational argument · Major synthesis · Moderate · Full work: 8 pages
Trace an example in which a changing state alters which cells participate or how their connections influence behavior.
Why you’re reading it. This provides possible mechanisms for flexible circuit operation without assuming that anatomy has been rewired.
A question to consider. Choose one state-dependent example and name what a connectome, a neural recording, and a receptor manipulation would each contribute to explaining it.

Unit 4 of 5

How is movement organized and corrected?

An action needs coordinated output as well as sensitivity to its consequences. Kiehn separates rhythm generation from coordination and shows how sensory feedback shapes locomotion. Wolpert and Ghahramani ask what estimates and predictions a controller needs when information is uncertain or delayed. Keep the computational problem and its physiological implementation connected but distinguishable.

Reading
7 of 10
Decoding the Organization of Spinal Circuits That Control Locomotion
Kiehn, O. (2016). Decoding the organization of spinal circuits that control locomotion. Nature Reviews Neuroscience, 17(4), 224–238. https://doi.org/10.1038/nrn.2016.9
Major synthesis · Challenging · Full work: 15 pages
Separate the production of a rhythm from left–right coordination, muscle timing, and sensory adjustment.
Why you’re reading it. This gives a physiological example in which several circuit functions combine to produce an action.
A question to consider. If a walking animal keeps stepping at the same rate but stumbles when the surface changes, which components of the explanation would you investigate first?
Reading
8 of 10
Computational Principles of Movement Neuroscience
Wolpert, D. M., & Ghahramani, Z. (2000). Computational principles of movement neuroscience. Nature Neuroscience, 3(Suppl.), 1212–1217. https://doi.org/10.1038/81497
Foundational argument · Major synthesis · Challenging · Full work: 6 pages
Follow how prediction, state estimation, and feedback address uncertainty during movement.
Why you’re reading it. This asks what a motor circuit must compute, extending the physiological account without equating a model diagram with anatomy.
A question to consider. For the stumbling example, what observation would distinguish inaccurate state estimation from faulty coordination of otherwise appropriate commands?

Unit 5 of 5

What establishes a circuit mechanism?

Recording and modeling constrain explanations; intervention adds another kind of evidence. Salzman and colleagues predict how stimulation near direction-selective neurons should bias a motion judgment. Wolff and Ölveczky then examine the assumptions needed to interpret such manipulations. End by designing a stronger explanation, with measurements that connect the targeted change to the behavior.

Reading
9 of 10
Cortical Microstimulation Influences Perceptual Judgements of Motion Direction
Salzman, C. D., Britten, K. H., & Newsome, W. T. (1990). Cortical microstimulation influences perceptual judgements of motion direction. Nature, 346(6280), 174–177. https://doi.org/10.1038/346174a0
Landmark empirical study · Methodological contribution · Moderate · Full work: 4 pages
Compare the predicted direction of the choice shift with the stimulation results and their controls.
Why you’re reading it. This moves from observing sensory selectivity to experimentally changing a circuit contribution to a judgment.
A question to consider. How could you adapt the logic to test whether a candidate population contributes to estimating the cup's motion rather than merely preparing the reaching response?
Reading
10 of 10
The Promise and Perils of Causal Circuit Manipulations
Wolff, S. B. E., & Ölveczky, B. P. (2018). The promise and perils of causal circuit manipulations. Current Opinion in Neurobiology, 49, 84–94. https://doi.org/10.1016/j.conb.2018.01.004
Methodological contribution · Critical reappraisal · Moderate · Full work: 11 pages
Use the review's distinctions to reassess both the microstimulation experiment and the locomotor interventions.
Why you’re reading it. The final step is to connect a causal effect with a defensible account of normal circuit operation.
A question to consider. Choose one intervention from the syllabus and design a follow-up that separates a loss of task-relevant information from disruption of another region's ability to function.

Scope and omissions

This specialist introduction develops a route from cellular signals through selected sensory and motor examples. It is not a comprehensive survey of neuroanatomy or every sensory modality. Visual studies provide tractable comparisons, while invertebrate circuits, vertebrate locomotion, and computational movement accounts broaden the kinds of explanation. Glial biology, detailed molecular signaling, motor disorders, and engineering of stimulation devices are outside its scope. Learning and plasticity, bodily regulation, motivation, sleep, and conscious experience require additional paths. Findings from anesthetized cats, trained monkeys, small invertebrate circuits, and isolated spinal preparations do not automatically describe everyday human behavior.

Synthesis

Sensation and action belong to a continuing exchange. Excitable cells and their connections respond to incoming information in ways shaped by the circuit's current state; movement then changes what information arrives. The body participates in the process it is controlled by. An adequate account must explain this return of action into sensation, as well as the passage from sensation into action.

Different evidence answers different parts of that explanation. A receptive-field map characterizes a response; a connection map constrains possible influence; a computational model specifies an operation; and an intervention tests a contribution under particular conditions. A convincing mechanism must connect these accounts and explain the consequences of a change, including its effects elsewhere in the network. Neither anatomical detail nor a behavioral deficit supplies that connection alone.

To examine how circuits acquire and change their organization, continue with How Does the Nervous System Develop and Change?. It connects developmental assembly and sensitive periods with learning, adult plasticity, and the limits of recovery.

Return to the moving cup. Draw the proposed sensory transformation, relevant state change, estimate of body position, and motor output. Identify one actual measurement and one discriminating intervention for each part, and mark where the explanation remains hypothetical. For a complementary account of how experience changes performance, continue with How Does Practice Build Skill?.