It was gestalt psychologists that took issue with elementalism (Kohler 1929), that all perception/consciousness can be broken down into component parts. The expression ‘the whole is greater than the sum of the parts’ originates from Gestaltism. Even though this field of study had little to say about how the brain processes perception/ consciousness (Schiller and Tehovnik 2015), variations of it were adopted by neuroscience, such as the expression ‘binding’, the idea that perceptual/conscious events had to be bound together to become meaningful to an organism (see Figure 1, Singer 2001). Hitherto many theories have been advanced on how the brain binds information to subserve perception/ consciousness, but no one theory has successfully advanced our understanding of how the brain combines information. Such a process is necessary for the generation of language, music, mathematics, art, and dance.
We would suggest that a key factor that binds information together is reward. (i.e., having a goal), and this binding not only pertains to perception/ consciousness but also to body movement (see Figure 2). Indeed, the brain is a sensorimotor machine and the study of perception/ consciousness in the absence of body movement would be like building robots that have advanced sensory systems without a way to use these systems to move about (Clark 1998). For example, neural recordings were made in the motor and somato- sensory cortex (i.e., M1 and S1) of monkeys performing a center-out task with a forelimb for juice reward (examining a total of 485 neurons studied in three monkeys, Ramakrishnan, Lebedev et al. 2017). Up to 27% of the neurons in M1 and S1 fired in anticipation of reward delivery. Some neurons responded to a mismatch between reward anticipation and amount delivered. For some cells, a lower-than-expected reward caused increased firing, and for other cells a higher-than-expected reward caused decreased firing. Firing about the time of the reward differed for early versus late trials on the task. They also found licking-related neurons that were modulated by licking frequency. Only a small fraction of the reward neurons was modulated by licking. Accordingly, the ubiquity of the reward signal in neocortex synchronizes the behavior toward a common goal—getting the reward.
Recovering from anesthesia (whereby neurons of the brain are disconnected synaptically and consciousness abolished) requires that the brain undergo synaptic reconnection of neurons en masse (Alkire et al. 2008). Taylor et al. (2016) has shown that optogenetic activation of the dopaminergic neurons in the ventral tegmental area during isoflurane-induced anesthesia of mice evokes EEG exhibited during wakefulness and it restores the righting reflex. Electrical stimulation of the ventral tegmental area (but not the substantia nigra) accelerates the emergence from isoflurane anesthesia (Solt, Brown et al. 2014). The return of the righting reflex in humans under anesthesia is correlated with the return of consciousness, and this is perhaps facilitated by D1 receptors in the neocortex and hippocampus (Leung 2017).
What binds perception and behavior is reward: a freezing person will walk miles in the snow to find warmth (e.g., climbers returning from Everest to arrive at base camp), a starving, thirsty person is willing to be killed as they search for relief (e.g., folks in the Gaza Strip), fleeing a predator an individual will travel for miles and for years (e.g., Whitey Bulger fleeing from the FBI), a sexually-deprived individual will pay an extraordinary sum for a few minutes of pleasure (e.g., Donald Trump vis-à-vis Stormy Danials), and a tired sleepless person will drive well into the night until a safe place can be found for sleep (e.g., me driving from Toronto to Boston). The hypothalamus regulates these functions (Mogenson 1977) and dopaminergic projections to the hypothalamus, accumbens, hippocampus and neocortex drive reward-seeking behavior (Breiter, Kahneman, Shizgal et al. 2001; Gallistel et al. 1981; Pallikaras and Shizgal 2022; Olds and Milner 1954; Wise 2004; Yeomans et al. 1988). The idea that some ephemeral state detached from behavior, i.e., a consciousness with no links to perception and body movement, is surely wrong if we are to accepts William James’s view that all consciousness is (eventually) expressed as a motor act (James 1890). Reward (not neocortical gamma activity) is what binds the behaving brain.
Figure 1: The images (A, B, C, & D) are examples of visual percepts studied by Gestalt psychologists. If an image is reduced to one of its elements, the apparent edges of the object are no longer perceived, indicating that all the elements need to be present for the brain to appreciate the object. From Wikipedia on June 17, 2024: https:// en.wikipedia.org/wiki/ Gestalt_psychology/media/File:Reification.svg.
Figure 2: The dopaminergic projections (from the ventral tegmental area and the substantia nigra) are summarized for the human brain (similar innervations exist in all mammals). Notice that the projections innervate the entire neocortex and striatum. As well projections are sent to the brain stem such that the cerebellum has access to the reward signal. This global reach allows perception and behavior to be bound together by the brain. The brain mediates entire behavioral repertoires created through operant learning, which takes place during both development and adulthood (Hebb 1949; also see Held and Hein 1963). The figure is adapted from fig. 2A from Dalley and Roiser (2012).
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