Ultrasound modulation of macaque prefrontal cortex selectively alters credit assignment–related activity and behavior
Davide Folloni, Elsa Fouragnan, Marco K. Wittmann, Lea Roumazeilles, Lev Tankelevitch, Lennart Verhagen, David Attali, Jean-François Aubry, Jerome Sallet, Matthew F. S. Rushworth
Science Advances 2021, 7 · 10.1126/sciadv.abg7700
Abstract
Credit assignment is the association of specific instances of reward to the specific events, such as a particular choice, that caused them. Without credit assignment, choice values reflect an approximate estimate of how good the environment was when the choice was made—the global reward state—rather than exactly which outcome the choice caused. Combined transcranial ultrasound stimulation (TUS) and functional magnetic resonance imaging in macaques demonstrate credit assignment–related activity in prefrontal area 47/12o, and when this signal was disrupted with TUS, choice value representations across the brain were impaired. As a consequence, behavior was no longer guided by choice value, and decision-making was poorer. By contrast, global reward state–related activity in the adjacent anterior insula remained intact and determined decision-making after prefrontal disruption.
Abstract via europepmc.
Exposures
Exposure 1: TUS to area 47/12o (bilateral)
Target: orbitofrontal cortex — “area 47/12o (lateral orbitofrontal cortex, at border of orbital/ventral prefrontal cortex)”
Device: Sonic Concepts · Sonic Concept · H115-MR ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 250 | ✓✓✓ |
| Pulse duration (ms) | 30 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 10 | ✓✓✓ |
| Duty cycle (%) | 30pulse duration × PRF gives 30% | ✓✓✓ |
| Sonication duration (s) | 40 | ✓✓✓ |
| Free-field pressure (kPa) | 1,170, 1,290swept | ✓✓✓ |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | simulationmean or range across subjects | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 42.6, 34.6swept | ✓✓✓⚑ |
| In-situ Ispta (W/cm²) | not reported |
Offline TUS protocol: bilateral stimulation of area 47/12o applied several minutes before the behavioral/fMRI testing session, using a single-element transducer with a coupling cone, applied once for 40 s per session; five 47/12o TUS sessions and five interleaved sham sessions per animal in experiment 1 (counterbalanced order).
Flags from extraction
exposures[0].in_situ.isppa_w_cm2— Reported as an approximate range (35-40 W/cm2) across the two bilateral target hemispheres (left 42.6, right 34.6 W/cm2 from simulation), not a range across subjects; reported_as vocabulary has no exact match for this case.sham_type— Study used both a no-stimulation sham condition (transducer procedures mirrored but sonication not triggered) and a genuine active-stimulation control at a different site (aPFC); both are recorded.randomised— Sham/TUS days were counterbalanced and interleaved but the paper does not use the word 'randomised' for session order.