Spatial working memory alters the efficacy of input to visual cortex

Abstract

Prefrontal cortex modulates sensory signals in extrastriate visual cortex, in part via its direct projections from the frontal eye field (FEF), an area involved in selective attention. We find that working memory-related activity is a dominant signal within FEF input to visual cortex. Although this signal alone does not evoke spiking responses in areas V4 and MT during memory, the gain of visual responses in these areas increases, and neuronal receptive fields expand and shift towards the remembered location, improving the stimulus representation by neuronal populations. These results provide a basis for enhancing the representation of working memory targets and implicate persistent FEF activity as a basis for the interdependence of working memory and selective attention.

Simultaneous representation of sensory and mnemonic information in human visual cortex

“…On the other hand, a mismatch test stimulus would drive a new set of neurons, which may lead to a lower overall response due to inhibitory competition with the already active neurons tuned to the sample feature (Serences, 2016;Gayet, et al, 2017). The same logic also applies if the top-down modulations supporting VWM do not lead to sustained patterns of spiking in sensory cortices, and instead only influence sub-threshold potentials (Mendoza-Halliday, Torres, & Martinez-Trujillo, 2014;Merrikhi et al, 2017). Differences in the local comparison circuit output would still be expected due to interactions between the top-down feature-selective bias and the sensory response evoked by the test stimulus.…”

Frontotemporal Coordination Predicts Working Memory Performance and its Local Neural Signatures

“…This leading role of the FEF dovetails with previous results showing Granger-based causality of the FEF on IT during memory maintenance, but not the reverse 17 . The known influence of FEF neurons on the visual responses in visual cortex [18][19][20] , and the evidence that FEF neurons send memory-related spiking activity directly to visual areas 21 , further support the idea that FEF spiking activity has a direct impact on IT during WM. It is important to note that this is not the first time a spatial signal has been shown to enhance feature selectivity.…”

“…We calculated a time-frequency map of the LFP power spectra for each of the FEF sites (51 M1, 35 M2) and IT sites (36 M1, 22 M2) using a wavelet transform (see Methods). During the delay period, FEF power in the beta (β, [20][21][22][23][24][25][26][27][28] and gamma (γ, 50-130 Hz) bands reflected the sample location (see Table S1 and Supplementary Information). Despite this spatial selectivity, there was no significant difference in LFP power between correct and wrong trials during the delay period for either the beta or the gamma band (Δpower β = -0.030 ± 0.029, p = 0.078; Δ power γ = -0.011 ± 0.033, p = 0.416, n = 85 sites; Fig.…”

A Sensory Memory to Preserve Visual Representations Across Eye Movements

“…due to abrupt change in flow of visual information) might be enough but these areas also receive a copy of motor command (e.g. via the tectopulvinar pathway to MT(Lyon et al, 2010)) as well as attentional signal (via direct projections from the Frontal Eye Field (Merrikhi et al, 2017; Noudoost and Moore, 2011). Considering that V4 is expected to receive the motor command through MT and the dynamics of response changes in MT did not lead those in V4 (STAR Methods; Figure S8C), the role of top-down and intrinsic signals and their interactions need to be a focus of future studies.…”