Perturbing human V1 degrades the fidelity of visual working memory

The main function of working memory is to extend the duration with which information remains available for use by a host of high-level cognitive systems ¹ . Decades of electrophysiological studies provide compelling evidence that persistent neural activity in prefrontal cortex is a key mechanism for working memory ² . Surprisingly, sophisticated human neuroimaging studies have convincingly demonstrated that the contents of working memory can be decoded from primary visual cortex (V1) ^3,4 . The necessity of this mnemonic information remains unknown and contentious. Here, we provide causal evidence that transcranial magnetic stimulation to human V1 disrupted the fidelity of visual working memory. Magnetic stimulation during the retention interval of a visuospatial working memory task caused a systematic increase in memory errors. Errors increased only for targets that were remembered in the portion of the visual field disrupted by stimulation, and were invariant to when in the delay stimulation was applied. Moreover, concurrently measured electroencephalography confirmed that stimulation disrupted not only memory behavior, but a standard neurophysiological signature of working memory. These results change the question from whether V1 is necessary for working memory into what mechanisms does V1 use to support memory. Moreover, they point to models in which the mechanisms supporting working memory are distributed across brain regions, including sensory areas that here we show are critical for memory storage.