Working Memory Neurons in Pigeons

Abstract

Working memory, the ability to temporarily store and manipulate currently relevant information, is required for most cognitive faculties. In humans and other mammals, the prefrontal cortex (PFC) provides the underlying neural network for these processes. Within the PFC, working memory neurons display sustained elevated activity while holding active an internal representation of the relevant stimulus during its physical absence or retaining a motor plan for the forthcoming response. Working memory, however, is not a hallmark of higher vertebrates endowed with a neocortex. Birds also master complex cognitive problems invoking working memory, but they lack a laminated neocortex. Behavioral studies in pigeons show that the neostriatum caudolaterale (NCL) plays a central role in executive functions, such as working memory and response control. For neurons in the NCL of pigeons, we show activity changes during the delay of a working memory task, which were similar to those observed in PFC neurons and were related to the successful holding of information in memory and to the subsequent behavior. Thus, although the anatomical and morphological structure of the neuronal substrate in birds is radically different from the mammalian neocortical architecture, the neuronal mechanisms evolved to master equivalent cognitive demands seem to be very similar.

Sex differences in brain activation elicited by humor

“…There is extensive evidence that cognitive and affective processes intersect and interact, particularly in the PFC. This region, which houses much of the machinery for developing coherence, is innervated by a dopaminergic pathway originating in the ventral tegmental area, indicating that comprehension and amusement are most likely functionally connected (48,49). This integration may be crucial for expectancy of emotional stimuli as well as reward-directed attention and behavior (50,51).…”

Neuro-economics in chicks: Foraging choices based on amount, delay and cost

“…Furthermore, tract tracing studies [13,51,53] revealed that AI has massive descending projections to the midbrain tegmentum and optic tectum, quite different from the mammalian amygdala. When viewed solely from a functional standpoint, AI might be a part of nidopallium -ventral pallium complex involved in the mnemonic and executive control [14,15,19,27]. It is required to develop a common set of tasks and experimental procedures, so the data obtained in different brain areas can be systematically compared.…”

“…A brief list of such outstanding case studies includes; object constancy in newly hatched domestic chicks [37], episodic-like memory in food-storing scrub jays [11], categorical discrimination of paintings by Picasso and Monet in pigeons [49] (also see [50] for Van Gogh and Chagall), possible insight of other individuals cognition [16], and verbal labeling and communication in grey parrots [33]. System neurophysiological studies on "prefrontal cortex" of pigeon cerebrum for working memory and executive control of behaviors [14,15,27] are also highly suggestive of the commonality.…”

Out of Context: NMDA Receptor Antagonism in the Avian 'Prefrontal Cortex' Impairs Context Processing in a Conditional Discrimination Task.

“…Neuroanatomical studies showed the NCL to receive multimodal input from all secondary sensory areas of the forebrain (Leutgeb, Husband, Riters, Shimizu, & Bingman, 1996), to project to telencephalic motor output structures as well as to the basal ganglia (Kröner and Güntürkün, 1999), to be innervated by dopaminergic fibers from midbrain cell groups A8 -A10 (Metzger, Jiang, Wang, & Braun, 1996), and to be characterized by a high density of dopamine D 1 receptors (Schnabel et al, 1997). Physiological studies demonstrated that single units in the NCL code for the upcoming reward (Kalt, Diekamp, & Güntürkün, 1999), bridge the delay between stimulus and response by high sustained activity levels (Diekamp, Kalt, & Güntürkün, 2002), and code for the subjective reward value of a reinforcer (Kalenscher et al, 2005). Neurochemical analyses showed that relative (Divac, Mogensen, & Björklund, 1985) and absolute concentrations of catecholamines (Karakuyu, Diekamp, & Güntürkün, 2003) as well as the relation of different dopamine metabolites (Bast, Diekamp, Thiel, Schwarting, & Güntürkün, 2002) matched the data from the mammalian PFC.…”