When one claps one’s hands in the presence of a Great White Egret, this long-legged bird standing knee-deep in a pond will extend its large wings in preparation for flight. But if one ignores the bird, it will relax its wings to resume its foraging of aquatic insects, small fishes, and crustaceans. Kaneko et al. (2017) found that neurons of area V1 in mice exhibited an enhancement of activity (as measured with two-photon calcium imaging) to a visual stimulus that was presented during periods of locomotion and not during periods of immobility. Visual stimuli were presented across ten sessions spaced over ten days. Most importantly, the administration of a NMDA receptor antagonist abolished the enhancement suggesting that the enhancement represents long-term plasticity. The results conform to Vanderwolf’s (1969) observation that when animals are engaged in a volitional act, such as locomotion, the neocortex assumes low-voltage fast activity punctuated by theta, and during such volitional engagement the neocortex (and hippocampus) are more receptive to learning (Berry and Thompson 1978; Hoffman and Berry 2009).

That neurons of the temporal cortex of primates, including humans, respond to faces has been known for decades (Bruce et al. 1981; Schwarzlose et al. 2005) and that scanning eye movements are necessary for the consolidation of faces is well understood (Hebb 1949; Ingle 1973; Yarbus 1967). Recently it has been found that the spontaneous neural activity of V1, V4, and the temporal cortex is noise-correlated, when the neurons of these three areas are linked by responding maximally to a common feature such as a face belonging to a species. Papale et al. (2025) studied hundreds of neurons in V1, V4, and the temporal cortex of alert behaving monkeys as visual images were presented and as multiunit responses of the neurons were examined. It was found that the cells in the temporal cortex preferred the images of monkey faces, over other objects, and the activity of the neurons in V1, V4, and the temporal cortex preferring the same features were noise correlated both during the discharge period of a preferred item [i.e., with correlation coefficients: 0.26 for V1-V4 pairs; 0.26 for V1-temporal cortex pairs; 0.5 for V4-temporal cortex pairs] and during the spontaneous discharge activity prior to the presentation of a preferred item [i.e., with correlation coefficients: 0.43 for V1-V4 pairs; 0.39 for V1-temporal cortex pairs; 0.53 for V4-temporal cortex pairs]. The latter, the noise correlation during the spontaneous activity, suggests that Hebbian learning via the synapses (as regulated by GABA, Krnjević et al. 1966abc) is preset across a neural network to anticipate specific visual images, like the face of one’s mother, which is imprinted immediately after birth and dependent on intimate interactions. Such correlations may be indicative of the creation of a string of declarative conscious units that have been connected by the pattern of eye movements evoked during the consolidation of visual images (Hebb 1949; Ingle 1973; Yarbus 1967).

That sensation and the execution of movement co-occur was best appreciated by Held and Hein (1963). They raised two groups of kittens from birth: one group was allowed to locomote as they viewed a black and white vertically striped environment, and a second group was suspended in a gondola (and prevented from moving about on all fours) but each of these kittens was attached to a locomoting kitten whose view of the stripes was the same. It was found that the kittens that were allowed to move about developed depth perception, whereas those that were immobile (as suspended in a gondola) failed to develop depth perception. It is now understood that to develop stereopsis the neurons of the visual cortex must be programmed by sensorimotor experience during a critical period preceding adulthood (Hubel and Wiesel 1977). Such a critical period is also necessary for the development of language (Chomsky 1965), which similarly entails an infant moving about in the environment as it learns associations between sounds and objects (LeCun 2023).