Prospective Coding for Objects in Primate Prefrontal Cortex

Abstract

We examined neural activity in prefrontal (PF) cortex of monkeys performing a delayed paired associate task. Monkeys were cued with a sample object. Then, after a delay, a test object was presented. If the test object was the object associated with the sample during training (i.e., its target), they had to release a lever. Monkeys could bridge the delay by remembering the sample (a sensory-related code) and/or thinking ahead to the expected target (a prospective code). Examination of the monkeys' behavior suggested that they were relying on a prospective code. During and shortly after sample presentation, neural activity in the lateral PF cortex primarily reflected the sample. Toward the end of the delay, however, PF activity began to reflect the anticipated target, which indicated a prospective code. These results provide further confirmation that PF cortex does not simply buffer incoming visual inputs, but instead selectively processes information relevant to current behavioral demands, even when this information must be recalled from long-term memory.

Dynamics of the semantic priming shift: behavioral experiments and cortical network model

“…A recent family of cortical network (CN) models has been proposed to account for the spike rate of neurons recorded in priming experiments on behaving monkeys. Two fundamental types of activities are reported during priming protocols involving a single prime picture preceding a related or unrelated target picture (e.g., Erickson and Desimone 1999;Sakai and Miyashita 1991;Rainer et al 1999;Miller et al 1996): retrospective activity-that is, increased firing rate of neurons coding for the prime during the ISI following its presentation-is believed to underlie activation of the prime in working memory; and prospective activity-that is, increasing firing rate, during the ISI, of neurons coding for the target yet to be presented (Naya et al 2001Yoshida et al 2003;Fuster 2001;Rainer et al 1999;Sakai and Miyashita 1991;Miyashita 1988;Miyashita and Chang 1988), sub-tending priming effects (Erickson and Desimone 1999). (102) 659 (108) 661 (96) Network architecture and neurons dynamics…”

Working Memory: Maintenance, Updating, and the Realization of Intentions

“…Badre and D'Esposito 2009) could contribute to maintaining the current goal. When the realization of an intention is much delayed and/or interfered with by various distracting events, long-term memory processes will be critical for reactivating the relevant frontal goal representations based on sensorimotor cues (Rainer et al 1999;cf. Miller and Cohen 2001;Kalpouzos et al 2010).…”

Early dynamics of the semantic priming shift

“…The processes of activation and interference are also revealed by neural activities recorded in behaving monkeys during the processing of associated prime and target images (e.g., Miyashita, 1988;Miyashita & Chang, 1988;Rainer et al, 1999;Sakai & Miyashita, 1991).…”

“…Electrophysiological studies report that spike rates of neurons coding for a stimulus exhibit four main types of activities depending on the events considered during the protocol: (a) spontaneous low-frequency activity in the absence of the stimulus (e.g., Lehky, Kiani, Esteky, & Tanaka, 2011); (b) a high-frequency perceptual response during and immediately following the stimulus (e.g., Lehky et al, 2011;Miller & Desimone, 1994); (c) retrospective activity at an intermediate firing rate after the stimulus (Fuster, 2001;Miller & Desimone, 1994;Naya, Yoshida, & Miyashita, 2001, 2003Rainer, Rao, & Miller, 1999), supposed to underlie activity of the stimulus in working memory (Amit & Brunel, 1997); presented. Prospective activity starts at spontaneous activity level and increases during the prime-target SOA (Miyashita, 1988;Miyashita & Chang, 1988;Rainer et al, 1999;Sakai & Miyashita, 1991) to generate priming effects (Erickson & Desimone, 1999).…”

“…Prospective activity starts at spontaneous activity level and increases during the prime-target SOA (Miyashita, 1988;Miyashita & Chang, 1988;Rainer et al, 1999;Sakai & Miyashita, 1991) to generate priming effects (Erickson & Desimone, 1999).…”