Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Motivation

Motivation impels our behavior, implemented by FAPs and movement control in our nervous system, and muscles in our peripheral body.

Motivation is driven by the ongoing combination of emotion and cognition.

A key motivator of our lives, pleasure is central to learning, for you must find things like food, water, and sex rewarding in order to survive and pass our genetic material to the next generation. (Linden; Compass of Pleasure, 2)

Motivational states may be broadly classified into two types: (1) elementary drive states such as hunger, thirst, and temperature, and (2) personal or social aspirations. (Kandel; Principles of Neural Science, 998)

Pleasure is a key factor in controlling the motivated behavior of humans. (Kandel; Principles of Neural Science, 1007)

Activities that ensure long-term survival, such as sexual activity or caring for offspring, are pleasurable, and there is a great natural urge to repeat these behaviors. (Kandel; Principles of Neural Science, 999)

Once emotions occur, they become powerful motivators of future behaviors. (LeDoux; Emotional Brain, 19)

Emotion and motivation are linked by the property that both involve rewards and punishers. (Rolls; Emotion Explained, 1)

Memories conditioned by the history of reward and punishment during an animal's past behavior - key role in emotional responses and associated feelings. (Edelman; Wider than the Sky, 57)

Drives and motivations include hunger, thirst, curiosity and exploration, play and sex. (Damasio; Looking for Spinoza, 34)

Brain's reward center is central to learning and provides a motivation for doing something or the sense of feeling satisfied. (Ratey; User's Guide to Brain, 65)

The motivational circuitry of the brain connects the prefrontal cortex decision process to the premotor and motor cortex, which then use FAPs stored in the brain stem and spinal cord to produce movement. Basal ganglia and cerebellum are also involved in the movement. Interactions between the motivational circuitry and the thalamocortical system can at fleeting times become part of the dynamic core of consciousness.

Emotional-motivational output of the mammillary body reaches the cortex through the thalamus. (Arbib - Handbook of Brain Theory and Neural Networks; Mumford; Thalamus, 981)

Research Study — Reward Expectation Encoded in Cerebellar Granule Cells

Research Study — Altruistic Brain Wiring

Research Study — Nucleus Accumbens Social Reward, Oxytocin and Serotonin

Research Study — Nucleus Accumbens Motivation during Chronic Pain

Research Study — Dopamine Ramps in Striatum Motivate Distant Rewards

Research Study — Neural Mechanisms Underlying Motivation of Mental Versus Physical Effort

Orbitofrontal Cortex and Motivation

Dopaminergic neurons send their axons to the nucleus accumbens, the striatum, and the frontal cortex, three structures thought to be involved in motivation. (Kandel; Principles of Neural Science, 1009)

Midbrain dopamine neurons, which respond to unpredicted primary rewards, rapidly adapt to the information provided by reward-predicting stimuli, and through interactions with NAc, the amygdala, and the OFC, adjust the gain of reward-related responses participating in mechanisms that select the action associated with the largest reward. (Zald & Rauch; Orbitofrontal Cortex, 64)

Cingulate Gyrus and Motivation

Cingulate gyrus is the main link between motivation and emotion. (Ratey; User's Guide to Brain, 248)

The anterior and midcingulate regions have rich dopaminergic afferents and those to the anterior cingulate gyrus are the strongest such innervations of all cortical regions. (Vogt; Cingulate Neurobiology, 164)

The dopaminergic projections to cingulate and prefrontal cortices have been implicated in a variety of functions including cognition, reward-seeking behavior, and motor activity. (Vogt; Cingulate Neurobiology, 164)

Cingulate gyrus has the appropriate sensory inputs to receive processed visual, auditory, and olfactory information and also receives inputs that reflect the internal states of the body. (Ratey; User's Guide to Brain, 248)

Cingulate gyrus has outputs to the basal ganglia for motor reaction and to the brainstem for physiological arousal. (Ratey; User's Guide to Brain, 248)

Cingulate gyrus also has connections to the hippocampus, important for memory. (Ratey; User's Guide to Brain, 248)

With all of its connections, cingulate gyrus is able to assess motivational aspects of the environment and compare them with memory in order to give the incoming stimuli different motivational priorities. (Ratey; User's Guide to Brain, 248)

Cingulate gyrus and its connections provides a person with the ability to judge what is worth pursuing. (Ratey; User's Guide to Brain, 248)

Motivation is based upon Emotion and Cognition

The controlling modules of the prefrontal cortex (PFC) are influenced by the basal ganglia, which are closely connected with the motivation-related hypothalamus. (LaBerge, "Attention, Awareness, and the Triangular Circuit," Baars, Essential Sources, 292)

Decisions produced by working memory along with (fear -- pleasure) functionality in the limbic system provide inputs for motivational circuitry. Motivation is based upon both emotion and cognition.

Diseases that impair affective experience invariably affect motivation, emphasizing the specious nature of any distinction between motivation and emotion. (Watt; Emotion and Consciousness, 220)

Motivational circuitry along with movement program functionality of the basal ganglia and associated components provide inputs to the pre-motor cortex and thence to the motor cortex and spinal cord.

Behaviors experienced as rewarding and pleasurable depend on the release of dopamine from the ventral tegmental area (VTA) in the brainstem and its availability in the nucleus accumbens in the basal forebrain. (Damasio; Looking for Spinoza, 63)

RAS -- Reticular Activating System, believed to be the center of arousal and motivation in mammals. (Watt; Emotion and Consciousness, 219)

Basal ganglia have increasingly been implicated in motivation and the selection of adaptive behavioral plans. (Kandel; Principles of Neural Science, 665)

Motivational Systems

Motivational Systems of the Brain, (Pinel; Anatomy of Human Brain,187)

Hypothalamus and Eating, (Pinel; Anatomy of Human Brain,188)

Subfornical Organ and Deprivation-Induced Thirst, (Pinel; Anatomy of Human Brain,190)

Dopamine System and Pleasure, (Pinel; Anatomy of Human Brain,192)

Reticular Formation and Sleep, (Pinel; Anatomy of Human Brain,196)

Suprachiasmatic Nucleus and Circadian Rhythms, (Pinel; Anatomy of Human Brain,198)

Brain Stem Sex Circuits, (Pinel; Anatomy of Human Brain,200)

Cingulate gyrus links emotion and motivation

Motivation is the process that ties emotion to action. (Ratey; User's Guide to Brain, 247)

Because motivation is at the heart of all goal directed behavior, many levels of the brain are involved. (Ratey; User's Guide to Brain, 247)

Connections between parts of the striatal and the brain structures involved in motivation and emotion suggests that the striatum may be involved more generally in planning and execution of goal-oriented behavior. (Eichenbaum; Neuroscience of Memory, 240)

Ability to emotionally label certain stimuli or situations is the center of motivation. (Ratey; User's Guide to Brain, 248)

Cingulate gyrus is the main link between motivation and emotion. (Ratey; User's Guide to Brain, 248)

Cingulate gyrus has outputs to the basal ganglia for motor reaction and to the brainstem for physiological arousal. (Ratey; User's Guide to Brain, 248)

Cingulate gyrus also has connections to the hippocampus, important for memory. (Ratey; User's Guide to Brain, 248)

With all of its connections, cingulate gyrus is able to assess motivational aspects of the environment and compared them with memory in order to give the incoming stimuli different motivational priorities. (Ratey; User's Guide to Brain, 248)

Cingulate gyrus and its connections provides a person with the ability to judge what is worth pursuing. (Ratey; User's Guide to Brain, 248)

Several subcircuits are also involved in motivation. Structures of the limbic system, thalamus, and basal ganglia interact to perform different parts of the whole task of perceiving, assessing, and communicating motivational influences in the environment. (Ratey; User's Guide to Brain, 248)

The several circuits and subcircuits of cingulate gyrus, limbic system, thalamus, basal ganglia, and perhaps others, hold various motivations in working memory and compare conflicting goals. Ultimately, this leads to choice, inhibition, and the seeking of reward. (Ratey; User's Guide to Brain, 248)

Joseph LeDoux’s Discussion of Motivation

Joseph LeDoux’s discussion (LeDoux; Synaptic Self, 235-259) of motivation provides much insight. Motivational circuitry of the brain includes the prefrontal cortex, basolateral amygdala, and ventral pallidum. The dopaminergic projection from the ventral tegmental area (VTA) to the nucleus accumbens remains a key feature of the circuitry.

As I view it, motivation to action arises from a range of neural signals ranging from (1) fear of a perceived threat to (2) grasping for an expected pleasure.

Motivational circuitry of the brain, (diagram) - Dopaminergic projection from the ventral tegmental area (VTA) to the nucleus accumbens is a key feature of the circuitry. (LeDoux; Synaptic Self, 248)

Dopamine levels rise in the nucleus accumbens in response to natural rewards (food, water, and sexual stimuli), and conditioned incentives (stimuli associated with rewards). (LeDoux; Synaptic Self, 247)

LTP occurs in accumbens circuits. Dopamine facilitates Hebbian plasticity. (LeDoux; Synaptic Self, 248)

Interactions between the amygdala and nucleus accumbens contribute to motivation. (LeDoux; Synaptic Self, 250)

Motivation circuits include the hippocampus by way of its connections with the amygdala and accumbens. (LeDoux; Synaptic Self, 251)

Prefrontal cortex receives dopamine inputs, and is connected with the accumbens, amygdala and hippocampus. (LeDoux; Synaptic Self, 252)

When motivation is based on decisions, the prefrontal cortex will be involved. (LeDoux; Synaptic Self, 252)

Fear ------ Pleasure

The mechanisms of fear and pleasure provide inputs to the value system. Fear amygdala. Pleasure nucleus Accumbens, dopamine.

Human brain has evolved a neural organization that can generate pleasant or unpleasant sensations for those aspects of the world that are a benefit or detriment to gene survival. (Johnston; Why We Feel, 12)

Intensity of affects and emotions can be viewed as amplifications of the reproductive consequences of current physical or social circumstances. (Johnston; Why We Feel, 87)

Like bodily affects, the positive or negative hedonic tone of an emotion provides the necessary value system for learning to adapt to rapidly changing aspects of the environment. (Johnston; Why We Feel, 86)

Natural selection could evolve a value system that individuals can use to learn from their experiences. (Johnston; Why We Feel, 81)

Advantage of learning; adapt to rapidly changing aspects of environment; could not be achieved by natural selection alone. (Johnston; Why We Feel, 81)

Learning could complement biological evolution by allowing individuals to discover how to survive and reproduce within their own unique and changing environment. (Johnston; Why We Feel, 82)

Importance of feelings - emotions as well as affects - regulating how, what, and when we learn and in determining how we reason about the world around us. (Johnston; Why We Feel, 82)

Hedonic dimensions of feelings can be envisaged as ranging from extremely pleasant to extremely unpleasant. (Johnston; Why We Feel, 96)

Conscious experiences, like sensations and feelings, evolved because they dictated a dynamic organization of the nervous system that could prioritize experiences and distinguish between environmental events or circumstances that had a real influence on biological survival. (Johnston; Why We Feel, 127)

Orbital cortex may be especially involved in working memories about rewards and punishments. (LeDoux; Emotional Brain, 285)

Nucleus Accumbens

Release of dopamine onto the nucleus accumbens appears to underlie all reward feelings. (Johnston; Why We Feel, 116)

Dopamine is a neurotransmitter associated with positive emotions and feelings; it is essential for activation of the reward system because it sets in motion the neural circuits involved in motivation. (Cardoso; Hardwired for Happiness, 173)

Specific structures in the subcortical brain process motivational input; the nucleus accumbens is one of the most active. (Cardoso; Hardwired for Happiness, 172)

Stimulation of the nucleus accumbens in humans elicits smiling, laughter, pleasurable feelings, happiness, even euphoria. (Cardoso; Hardwired for Happiness, 173)

The Nucleus Accumbens receives inputs from cortical regions (Frontal Lobe, Cingular Gyrus) and from the sub-cortex (amygdala). Its major ouput is to the action-producing Basal Ganglia. Therefore, the N. Accumbens influences our “readiness” to act. Dopamine increases in the N. Accumbens (coming from the ventral tegmentum, a brain stem source of activating neuromodulators) is connected to the feeling of reward. The organism acts, feels good and is oriented.

This same region is involved in the pathology of cocaine addiction. When a person takes cocaine, the drug is picked up by the N. Accumbens and the person feels “high”, powerful, with thinking accelerated (although superficial) and ready to act. How does this end up in pathology? The cocaine substitutes for dopamine and the dopamine becomes depleted. The lowered dopamine level is associated with the inhibition of thinking, a painful mood, and inhibited action. The amygdala, as well as other sub-cortical centers send their activating (or de-activating) inputs to the basal ganglia via the N. Accumbens (at least, partially). Thus the cocaine addict, in the withdrawal phase, cannot renew his dopamine charge; consequently, his basal ganglia cannot be activated in a normal way. Re-entry also means that the cortical and sub-cortical mechanisms (the amygdala as well as the central gray matter, which give connections to emotional and physical pain perception) will receive messages from the Nucleus Accumbens – Basal Ganglia complex. The unfortunate outcome is that the addict is in for a long period of painful withdrawal before his dopamine metabolism can be restored. (One cocaine dose can throw off the Nucleus Accumbens for months.)

081 Basal ganglia: EXTERNAL view; (caudate + putamen + nucleus accumbens + globus pallidus + substantia nigra + subthalamic nucleus); striatum (caudate + putamen + nucleus accumbens); corpus striatum (striatum + globus pallidus) (Hirsch; Neuroanatomy, 162)

Nucleus Accumbens -- Dopamine

Release of dopamine onto the nucleus accumbens appears to underlie all reward feelings. (Johnston; Why We Feel, 116)

Cocaine causes a massive release of dopamine onto the nucleus accumbens, and the user experiences a sudden 'rush' of extreme pleasure. (Johnston; Why We Feel, 116)

Neural processing of emotions, limbic system, interconnected subcortical regions around the hypothalamus; pleasure pathway, releases dopamine onto the nucleus accumbens. (Johnston; Why We Feel, 119)

Opiods induce euphoria and tranquility. Enhanced release of dopamine from cells that project axons to the nucleus accumbens, a part of the basal ganglia with intimate connections to the limbic system, which regulates emotion. (Zeman; Consciousness, 126)

Many effects of dopamine-related drugs can be achieved by applying the drugs directly to the nucleus accumbens, a region of the striatum located in front of the amygdala near the bottom of the forebrain. (LeDoux; Synaptic Self, 235-259)

Amyglada

Cortical connections with the amygdala are far greater in primates than in other mammals. (LeDoux; Emotional Brain, 303)

Amygdala function established eons ago, at least since dinosaurs ruled the earth, maintained through diverse branches of evolutionally development. (LeDoux; Emotional Brain, 174)

The amygdala receives inputs from the latest stages of cortical processing within the sensory systems, but projects back to all stages of cortical processing, even the earliest. (LeDoux; Emotional Brain, 286)

Value Systems

Evolution has provided humans with a primary value system of pleasant and unpleasant feelings. (Johnston; Why We Feel, 106)

Human feelings appear to provide the important value system that underlies all human decisions. The shared element of feelings -- hedonic tone -- allows many different feelings to be combined and hence supply an overall assessment of the value associated with the various possible outcomes of a decision problem. (Johnston; Why We Feel, 179)

Value systems evolved early to take care of bodily functions. Value system is extensively connected to many different body organs, the endocrine system, and the autonomic nervous system. Value systems regulate heart and respiratory rate, sweating, digestive functions, as well as bodily cycles related to sleep and sex. (Edelman; Bright Air, 117)

Value systems are perfectly poised to signal the occurrence of important events to the entire brain. (Edelman; Universe of Consciousness, 89)

Diagram of a value system -- Noradrenergic system originating in the locus coeruleus projects diffusely to the entire brain and releases the neuromodulator noradrenaline. (Edelman; Universe of Consciousness, 89)

In higher vertebrates, a series of diffusely projecting neural value systems have evolved that are capable of continually signaling to neurons and synapses all over the brain. (Edelman; Universe of Consciousness, 88)

Locus coeruleus consists of only a few thousand neurons in the brainstem. These neurons give rise to a vast meshwork of axons that blanket the cortex, hippocampus, basal ganglia, cerebellum, and spinal cord. (Edelman; Universe of Consciousness, 89)

Neurons belonging to the value system often produce a sudden burst of firing whenever something important or salient occurs to the animal. (Edelman; Universe of Consciousness, 89)

Neurons in the locus coeruleus fire whenever an animal enters a novel environment or something unexpected happens. When they fire they release the neurotransmitter noradrenaline. (Edelman; Universe of Consciousness, 89)

Value constraints to develop categorical responses that are adaptive. (Edelman; Universe of Consciousness, 105)

Diffuse ascending value systems of the brain are known to be richly connected to the concept-forming regions of the brain, notably the frontal and temporal cortex. (Edelman; Universe of Consciousness, 105)

Value-category memory -- synaptic alterations that combine to develop various individual memories are essential to a model of primary consciousness. (Edelman; Universe of Consciousness, 105)

Value, emotional responses, and salience provide strong constraints on the establishment of a conceptual, category-based memory. (Edelman; Universe of Consciousness, 105).

Hippocampus and the value systems

Hippocampus is one of the regions engaged in matching perceptually significant input from sensory stimuli with subcortical signals arising from centers mediating adaptive internal values and hedonic states. Septal inputs and other subcortical inputs can influence the structure of firing patterns in the hippocampus and alter the efficiency of global mappings. Hippocampus role in attention states and in laying down long-term value-category memory in the cortex. Hippocampus inner-loop structure links the entorhinal area to the hippocampal subfields and the subiculum. (Edelman; Remembered Present, 129)

Neurotransmitters

Pathway that can transmit information directly to the amygdala from the thalamus; elicit fear responses without the aid of the cortex. (LeDoux; Emotional Brain, 158)

Direct thalamic input to the amygdala allow the cortex to be bypassed. (LeDoux; Emotional Brain, 158)

Subregion of the amygdala: central nucleus has connections with brain stem areas controlling heart rate and autonomic nervous system responses. (LeDoux; Emotional Brain, 158)

Different Outputs of the Amygdala Control Different Conditioned Fear Responses - (diagram) (LeDoux; Emotional Brain, 160)

Amygdala is composed of about a dozen or so subregions. (LeDoux; Emotional Brain, 161)

Information processing pathways in the Amygdala - (diagram) (LeDoux; Emotional Brain, 162)

Lateral Nucleus (LA) is the gateway into the amygdala. (LeDoux; Emotional Brain, 162)

Central Nucleus (CE) is the main connection with areas that control emotional responses. (LeDoux; Emotional Brain, 162)

It is possible that the direct thalamic pathway to the amygdala in mammals is simply an evolutionary relic, the brain's version of an appendix; however it has existed for millions of years and likely serves some useful function. (LeDoux; Emotional Brain, 163)

Fear Reaction

Innate

Pleasure

Dopamine potently augments the drive to obtain a rewarding stimulus, but it is not directly responsible for the hedonic experience itself. (Nature, Vol 443, 21 September 2006, p.289)

Cue-induced urges, drug addiction.

Sex

Food and Physical via Hypothalamus and Cortex

The hypothalamus has many small subregions whose functions are to regulate hunger, thirst, temperature, sexual behavior, and similar body operations. (Crick; Astonishing Hypothesis, 88)

Drugs stimulate pleasure center directly

Caffine

Euphoria, euphoric feeling

“Beauty” and Truth via the Neocortex

Beauty has many forms: Audio (Music) and Visual (Art, Sunset)

Scientific validation of Truth

Concept of Truth (Faith) may conflict with reality

Curiosity: seek and strive for Truth

Hedonic dimensions of feelings can be envisaged as ranging from extremely pleasant to extremely unpleasant. (Johnston; Why We Feel, 96)

Motivation is based on both emotion and cognition.

Motivation is connected to both motor cortex and basal ganglia.

Sex – sex act, anticipation of sex, Ideal image

Music, Dance

Cognition linked, Job well done

Distinguish Pleasure from Anticipation of pleasure

Motivation can result from external stimuli – sound trickling water can stimulate the urge to urinate.

Biological mechanisms of motivation in the brain are topics of intensive current research. Here is an example of one such research effort on monkeys’ lateral habenula, a structure closely positioned to the thalamus. As you can well imagine, there is a huge amount of brain functionality that is essentially unexplored.