The nidopallium, meaning nested pallium, is the region of the avian brain that is used mostly for some types of executive functions but also for other higher cognitive tasks. The region was renamed nidopallium in 2002 during the Avian Brain Nomenclature Consortium because the prior name, neostriatum, suggested that the region was used for more primitive functions as the neostriatum in mammalian brains is sub-cortical.
The avian nidopallium is an area of the cortical telencephalon of the avian forebrain, and is itself subdivided into smaller regions as a result of further functional localisation. It has been apportioned along the rostrocaudal (anteroposterior) axis into three hypothetical segments: the rostral, intermediate and caudal nidopallium. [1] These three regions are themselves trichotomised: the caudal nidopallium, for example, aggregates the nidopallium caudocentral (NCC), caudomedial (NCM) and caudolateral (NCL). It is the nidopallium caudolaterale which is thought to undertake many of the complex, higher order cognitive functions in birds. Rehkamper et al. (1985) further demarcated the nidopallium into 16 separate sections (distinguished by differing cell densities in these areas), although the previously stated anatomical divisions are generally accepted for most purposes for delineating between the nidopallium's various functional specialisations.
The entire nidopallium region is a compelling area for neuroscientific research, especially in relation to its capacity for complex cognitive function. [2] [3] More specifically, the nidopallium caudolateral appears particularly involved with the aspect of executive function in the avian brain. One study has been performed to demonstrate that this area is in fact largely analogous to the mammalian prefrontal cortex - the region of the brain covering the most rostral section of the frontal lobe, responsible for more complex cognitive behaviour in mammals, such as humans. [4] The experiment sought to measure the densities of various neurotransmitter receptors in both the avian NCL and the human prefrontal cortex, using quantitative in-vitro receptor autoradiography. It was found that the NCL contained lower absolute quantities of these neuronal receptors. However, the experiment also revealed that the relative densities of these receptors in both organisms were surprisingly similar. With this, there is the possible implication that the capability for such sophisticated mental processes in these structures is reliant on the receptor architecture of the neurons which comprise them. So despite the nidopallium and prefrontal cortex having evolved separately (an educated assumption), both have achieved similar functions of higher order thought processes via convergent evolution, as a result of influences at the molecular level.
The nidopallium is also heavily innervated by dopaminergic neurons from the direction of the brainstem. It is thought that the high concentration of dopamine (a neurotransmitter often involved with motivation, reward circuits and motor control) in this area may contribute to the ability of the NCL to execute higher order cognitive functions. [5] Furthermore, the neural activity of the nidopallium greatly increases when birds are exposed to reward-predicting visual stimuli. [6] This, once more, evidences the considerable presence of dopaminergic neurons in this area, as implied by their stereotypical activation in anticipation of reward.
Migration is one of the many intricate behavioural processes governed by the nidopallium in birds. Studies have shown that there is significant neuronal recruitment to this region of the avian brain during migratory flight, with the objective of enhancing cognitive potency in the nidopallium. As a result, the birds benefit from improved navigational capabilities during migration, prompted by the significant changes in spatial sensory stimuli. [7] This is a distinct example of neuroplasticity in the avian brain, and has been used to extend our understanding of the nidopallium. The experimental method is similar to that of lesion-deficit analysis, whereby scientists examine the deficiencies of patients with particular brain lesions in order to determine the function of the affected part of the brain. Alternatively, the avian migration experiment was able to analyse the role of the nidopallium because its functional capacity was enhanced, rather than diminished.
The striatum or corpus striatum is a nucleus in the subcortical basal ganglia of the forebrain. The striatum is a critical component of the motor and reward systems; receives glutamatergic and dopaminergic inputs from different sources; and serves as the primary input to the rest of the basal ganglia.
The basal ganglia (BG) or basal nuclei are a group of subcortical nuclei found in the brains of vertebrates. In humans and other primates, differences exist, primarily in the division of the globus pallidus into external and internal regions, and in the division of the striatum. Positioned at the base of the forebrain and the top of the midbrain, they have strong connections with the cerebral cortex, thalamus, brainstem and other brain areas. The basal ganglia are associated with a variety of functions, including regulating voluntary motor movements, procedural learning, habit formation, conditional learning, eye movements, cognition, and emotion.
The somatic nervous system (SNS) is made up of nerves that link the brain and spinal cord to voluntary or skeletal muscles that are under conscious control as well as to skin sensory receptors. Specialized nerve fiber ends called sensory receptors are responsible for detecting information within and outside of the body.
The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, spatial reasoning and language. The neocortex is further subdivided into the true isocortex and the proisocortex.
Brodmann area 10 is the anterior-most portion of the prefrontal cortex in the human brain. BA10 was originally defined broadly in terms of its cytoarchitectonic traits as they were observed in the brains of cadavers, but because modern functional imaging cannot precisely identify these boundaries, the terms anterior prefrontal cortex, rostral prefrontal cortex and frontopolar prefrontal cortex are used to refer to the area in the most anterior part of the frontal cortex that approximately covers BA10—simply to emphasize the fact that BA10 does not include all parts of the prefrontal cortex.
The nucleus accumbens is a region in the basal forebrain rostral to the preoptic area of the hypothalamus. The nucleus accumbens and the olfactory tubercle collectively form the ventral striatum. The ventral striatum and dorsal striatum collectively form the striatum, which is the main component of the basal ganglia. The dopaminergic neurons of the mesolimbic pathway project onto the GABAergic medium spiny neurons of the nucleus accumbens and olfactory tubercle. Each cerebral hemisphere has its own nucleus accumbens, which can be divided into two structures: the nucleus accumbens core and the nucleus accumbens shell. These substructures have different morphology and functions.
The claustrum is a thin sheet of neurons and supporting glial cells, that connects to the cerebral cortex and subcortical regions including the amygdala, hippocampus and thalamus of the brain. It is located between the insular cortex laterally and the putamen medially, encased by the extreme and external capsules respectively. Blood to the claustrum is supplied by the middle cerebral artery. It is considered to be the most densely connected structure in the brain, and thus hypothesized to allow for the integration of various cortical inputs such as vision, sound and touch, into one experience. Other hypotheses suggest that the claustrum plays a role in salience processing, to direct attention towards the most behaviorally relevant stimuli amongst the background noise. The claustrum is difficult to study given the limited number of individuals with claustral lesions and the poor resolution of neuroimaging.
Afferent nerve fibers are axons of sensory neurons that carry sensory information from sensory receptors to the central nervous system. Many afferent projections arrive at a particular brain region.
Dopaminergic pathways in the human brain are involved in both physiological and behavioral processes including movement, cognition, executive functions, reward, motivation, and neuroendocrine control. Each pathway is a set of projection neurons, consisting of individual dopaminergic neurons.
The solitary nucleus is a series of sensory nuclei forming a vertical column of grey matter in the medulla oblongata of the brainstem. It receives general visceral and/or special visceral inputs from the facial nerve, glossopharyngeal nerve and vagus nerve ; it receives and relays stimuli related to taste and visceral sensation. It sends outputs to various parts of the brain, such as the hypothalamus, thalamus, and reticular formation. Neuron cell bodies of the SN are roughly somatotopically arranged along its length according to function.
The ventral tegmental area (VTA), also known as the ventral tegmental area of Tsai, or simply ventral tegmentum, is a group of neurons located close to the midline on the floor of the midbrain. The VTA is the origin of the dopaminergic cell bodies of the mesocorticolimbic dopamine system and other dopamine pathways; it is widely implicated in the drug and natural reward circuitry of the brain. The VTA plays an important role in a number of processes, including reward cognition and orgasm, among others, as well as several psychiatric disorders. Neurons in the VTA project to numerous areas of the brain, ranging from the prefrontal cortex to the caudal brainstem and several regions in between.
The reticular formation is a set of interconnected nuclei that are located in the brainstem, hypothalamus, and other regions. It is not anatomically well defined, because it includes neurons located in different parts of the brain. The neurons of the reticular formation make up a complex set of networks in the core of the brainstem that extend from the upper part of the midbrain to the lower part of the medulla oblongata. The reticular formation includes ascending pathways to the cortex in the ascending reticular activating system (ARAS) and descending pathways to the spinal cord via the reticulospinal tracts.
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. It is the association cortex in the frontal lobe. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, and BA47.
The premotor cortex is an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex. It occupies part of Brodmann's area 6. It has been studied mainly in primates, including monkeys and humans. The functions of the premotor cortex are diverse and not fully understood. It projects directly to the spinal cord and therefore may play a role in the direct control of behavior, with a relative emphasis on the trunk muscles of the body. It may also play a role in planning movement, in the spatial guidance of movement, in the sensory guidance of movement, in understanding the actions of others, and in using abstract rules to perform specific tasks. Different subregions of the premotor cortex have different properties and presumably emphasize different functions. Nerve signals generated in the premotor cortex cause much more complex patterns of movement than the discrete patterns generated in the primary motor cortex.
Synaptic gating is the ability of neural circuits to gate inputs by either suppressing or facilitating specific synaptic activity. Selective inhibition of certain synapses has been studied thoroughly, and recent studies have supported the existence of permissively gated synaptic transmission. In general, synaptic gating involves a mechanism of central control over neuronal output. It includes a sort of gatekeeper neuron, which has the ability to influence transmission of information to selected targets independently of the parts of the synapse upon which it exerts its action.
In neuroanatomy, pallium refers to the layers of grey and white matter that cover the upper surface of the cerebrum in vertebrates. The non-pallial part of the telencephalon builds the subpallium. In basal vertebrates, the pallium is a relatively simple three-layered structure, encompassing 3–4 histogenetically distinct domains, plus the olfactory bulb.
The oddball paradigm is an experimental design used within psychology research. Presentations of sequences of repetitive stimuli are infrequently interrupted by a deviant stimulus. The reaction of the participant to this "oddball" stimulus is recorded.
Joni Wallis is a cognitive neurophysiologist and Professor in the Department of Psychology at the University of California, Berkeley.
Social cognitive neuroscience is the scientific study of the biological processes underpinning social cognition. Specifically, it uses the tools of neuroscience to study "the mental mechanisms that create, frame, regulate, and respond to our experience of the social world". Social cognitive neuroscience uses the epistemological foundations of cognitive neuroscience, and is closely related to social neuroscience. Social cognitive neuroscience employs human neuroimaging, typically using functional magnetic resonance imaging (fMRI). Human brain stimulation techniques such as transcranial magnetic stimulation and transcranial direct-current stimulation are also used. In nonhuman animals, direct electrophysiological recordings and electrical stimulation of single cells and neuronal populations are utilized for investigating lower-level social cognitive processes.
The avian brain is the central organ of the nervous system in birds. Birds possess large, complex brains, which process, integrate, and coordinate information received from the environment and make decisions on how to respond with the rest of the body. Like in all chordates, the avian brain is contained within the skull bones of the head.