Reading focus
Syllabus: How Do Neural Circuits Turn Sensation into Action?
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?
Why this reading
A neuron may respond during a perceptual task without contributing to the judgment. Salzman and colleagues go further by introducing current near direction-selective neurons and measuring whether the animal's choices shift in the predicted direction. The experiment makes a causal proposal precise enough to confront behavioral evidence.
Before you read
Area MT contains neurons responsive to visual motion. Microstimulation delivers small electrical currents through an electrode, affecting a local population and potentially connected circuitry. The monkeys judged the direction of moving dots; coherence describes the proportion providing a consistent motion signal. A psychometric curve relates stimulus strength to the probability of a response. A shift in that curve differs from a general loss of task performance.
Read for
- Connect the direction preference measured near the electrode to the predicted change in the animal's choices.
- Examine comparisons between trials with and without stimulation, the distribution of effects across sites, and the controls involving eye movements.
- Distinguish a change in a trained report from a complete explanation of motion perception. Consider which cells and pathways the current may have recruited.
Consider afterwards
- What result would be more consistent with nonspecific disruption than with adding evidence for a particular direction?
- How would you distinguish stimulation that changes sensory evidence from stimulation that directly biases the reporting action?
Editorial context
The publisher's erratum corrects transposed Figures 2 and 3; the linked university reprint presents the two-part graph as Figure 2 and the histogram as Figure 3. The task and stimulation were tailored to the recorded direction preference. Their causal result therefore concerns a specified circuit contribution under these conditions, not the creation of a whole percept by a single neuron. The broader interpretive problems of perturbing connected circuits are developed by Wolff and Ölveczky.