The answer has a bearing on whether a cortex is needed for consciousness.
Key points
- Scientists debate whether emotions depend more on deep, ancient circuitry or the evolutionarily newer cortex.
- Some theories see emotions as mainly subcortical, innate, and experienced similarly in humans and animals.
- Other theories see conscious emotional experience as dependent on the cortex and shaped by human experience.
“The young and the old of widely different races, both with man and animals, express the same state of mind by the same movements.” — Charles Darwin, in The Expression of Emotions in Man and Animals (1872)1
Darwin assumed a universality of emotional expressions – that they are expressed the same way across cultures and many species. He proposed that emotions are evolutionary adaptations that have helped humans and animals survive and reproduce, and argued that certain emotional expressions are linked to particular physiological responses and behaviors.
Influenced by Darwin’s assumptions about emotional expression, in the second half of the twentieth century, a theory developed that postulated that there are several basic hardwired emotions arising from deep, ancient, subcortical parts of the brain and that these basic emotions are universally expressed by all humans and shared by many animal species.
Today, that theory is questioned. One way to frame the debate is as follows:
- Basic emotions theory posits that emotions arise principally from evolutionarily ancient subcortical regions of the brain, such as the brainstem and other deep brain structures shared by many animals. According to this theory, there exist core, “basic” (primitive) and universally expressed categories of emotions (e.g. joy, fear, anger) that are hardwired and shared by many species. Within humans, these basic emotions are thought to be experienced and expressed in similar ways across different cultures.
- Cognitive and cortical theories of emotions posit that fully formed emotions arise mainly from the cortex (the evolutionarily newer, outer part of the brain), constructed by higher cognitive processes, significantly influenced by cultural and individual differences. These theories view subcortical structures as contributing only raw affect (best described along dimensions of arousal and valence, rather than distinct emotional categories) that then require higher cognitive appraisal and interpretation in the cortex, to be experienced as well-defined conscious emotions.
In this post, we will focus on theories that are mainly aligned with basic emotions theory.
Ekman’s Six Basic Emotions
The psychologist Paul Ekman formulated an early and influential version of what later became known as basic emotions theory. In the 1960s and 1970s, Ekman conducted cross-cultural studies and identified what he believed to be six basic emotions that he argued were universally recognized through facial expressions: happiness, sadness, fear, disgust, anger, and surprise.
Panksepp’s Seven Primary Emotions
The neuroscientist Jaak Panksepp, known for his pioneering and influential work in the field of affective neuroscience, proposed that there are seven primary or core emotional systems: Seeking, Rage, Fear, Lust, Care, Panic/Grief, and Play.2,3 He argued that these emotional systems are foundational and evolutionarily ancient mechanisms that help animals respond to their environment and regulate their internal states, and that they produce both emotional behavior and subjective emotional experience. He delineated specific subcortical circuits that he believed to be the principal source for each of these basic emotional systems, biologically hardwired and shared across mammalian species, reflecting their shared evolutionary heritage.4
For example, Panksepp identified the amygdala and the periaqueductal gray (PAG) as the brain regions involved in the generation of fear. Both regions are subcortical. The amygdala is a region deep within the temporal lobe of the brain, one in each hemisphere. The PAG is a central region in the midbrain, which is part of the brainstem. As we shall see in Part 4, the neuroscientist Joseph LeDoux argues for a more complicated relationship between the amygdala and fear, in which the prefrontal cortex is necessary to experience a conscious feeling of fear.
Panksepp’s theory emphasized that subcortical circuits are capable of producing raw emotional feelings (such as fear) independently of the higher cortical areas, which he believed were needed only for more complex cognitive processing of emotions. He argued that the circuits in the subcortex provide sufficient foundation for the conscious experience of emotions, which are then modulated and further interpreted by the cortical areas of the brain. For him, the emphasis was on the innate, genetic, and neurobiological, i.e. hardwired, aspects of emotions.5
Mark Solms’s Hidden Spring of Consciousness
Mark Solms, a prominent neuropsychologist and psychoanalyst, collaborated with and built on Panksepp’s theory. Solms’s theory of emotions is broadly aligned with basic emotions theory but is reinterpreted within a broader framework of predictive coding and homeostasis.6 For Solms, the innate, core emotions defined by Panksepp can be thought of as instinctual programs, and these are adaptively supplemented by learning from experience.7 Solms allows for a role for the cortex in contributing to the elaboration of emotional experience.8,9
However, for the most part, Solms doesn’t think that a cerebral cortex is needed to experience emotion or, for that matter, even to experience consciousness. He argues that the primary form of consciousness is rooted in affective states or feelings, rather than thoughts or sensory perceptions. For Solms, affect is primary in the hierarchy of conscious experiences. He argues that every conscious state includes an emotional component, even if it is not immediately obvious. Emotions provide the drive and motivation behind thoughts and actions. He contends that emotion and therefore consciousness arise primarily from the primitive part of the brain (which he refers to as the “hidden spring” of consciousness) rather than from the cortex.10,11
Solms argues that PAG (mentioned above) is a critical component in the creation of conscious emotional experiences, whereas the PAG is conventionally viewed as involved in basic, unconscious survival functions and mechanistic, non-conscious aspects of emotion.12,13
Thus, Solms suggests that the brainstem (where the PAG is located), rather than the cerebral cortex, is what produces conscious emotions and therefore subjective experience. Furthermore, he argues (based on the work of neuroscientist Björn Merker) that children born without a cortex are conscious, as well as animals whose cerebral cortex has been experimentally removed.
While the claim that conscious emotional feeling does not require a cortex continues to be disputed, Solms does make a compelling point when he reformulates the famous “hard problem of consciousness” to “How and why do feelings arise?” He notes that affective feelings are often overlooked in theories of consciousness, and asserts that affect is the foundational form of consciousness.
References
1. Darwin, C. (1872). The expression of the emotions in man and animals. John Murray. Retrieved from https://www.gutenberg.org/ebooks/1227. Note that Darwin, like his contemporaries, used the term “race” to describe groups that we might today refer to as ethnicities or populations.
2. Panksepp, J. (1998). Affective neuroscience: The foundations of human and animal emotions. Oxford University Press. Further elaborated in Panksepp, J., & Biven, L. (2012). The archaeology of mind: Neuroevolutionary origins of human emotions. W.W. Norton & Company.
3. The capitalization served to distinguish them from colloquial usage, indicating that he was talking about whole brain functions, not only the feelings [Solms, M. (2021). The hidden spring: A journey to the source of consciousness (p. 105). Profile Books].
[Click ‘More’ to view footnotes 4-13].
4. Panksepp argued that all seven types of emotional affects can be reliably reproduced in all mammals, by stimulation of specific brain structures and chemicals that or shared by all mammals. And he and others have argued that many of these emotional affects can be evoked in birds too, and some in all vertebrates. [Solms (2021), p. 103].
5. Panksepp proposed that there are three levels of emotional processing (Panksepp & Biven, 2012):
— Primary-Process Emotions: These are the basic, instinctual emotional systems that are deeply rooted in subcortical circuits like the limbic system and brainstem (the term “limbic system” has become outdated and insufficiently accurate but is a useful approximation). These emotions are foundational and include the seven core emotional systems with their capitalized names. They represent raw, unconditioned emotional experiences that are shared across mammalian species.
— Secondary-Process Emotions: These involve learning and memory and are linked to conditioning processes (classical and operant conditioning) that integrate primary emotions with experiences. They involve emotional habits and learned responses that are mediated by structures such as the basal ganglia, which connect these learned emotional responses to the primary-process emotions.
— Tertiary-Process Emotions: These involve higher-order cognitive functions and are elaborated in the neocortical regions, particularly the medial-frontal areas. They encompass complex emotional experiences and cognitive processes such as thoughts about emotions, ruminations, and intentions.
While Panksepp emphasized primary emotions rooted in subcortical circuits, his recognition of neocortical involvement in complex emotions complements modern findings. His work illustrates the interaction between these levels of emotional processing – and their impact on psychiatric disorders. Contemporary neuroscience builds on this by studying networks like the Default Mode Network (DMN), Salience Network (SN), and Central Executive Network (CEN), which are involved in higher-order cognitive functions and emotional regulation. These networks are affected in disorders like depression, anxiety, schizophrenia, and autism.
6. Solms’s theory of emotion is broader, more dynamic and less fixed than Panksepp’s, as his theory incorporates the contemporary neuroscience theory of predictive coding (and he invokes Karl Friston’s free energy principle as an important part of predictive coding theory). Predictive coding is not the focus of the present post but will be discussed in Part 3 in relation to other theories of emotion. It proposes that the brain is constantly generating predictions about sensory inputs and updating those predictions based on actual sensory information. Solms suggests that emotions arise from the brain’s predictions about the body’s internal state, aimed at maintaining homeostasis. For example, hunger represents a prediction that the body needs nutrients, and the feeling of hunger prompts behaviors to satisfy this need. Emotions are thus seen as signals of mismatches between predicted and actual states, prompting corrective actions to restore balance. This homeostatic regulation is a continuous process, essential for maintaining the body’s optimal functioning and survival.
7. Solms (2021), p. 104. Panksepp’s theory did also include a role for learning from experience (see the above point about Secondary-Process Emotions).
8. For both Panksepp and Solms, a cortex is not necessary to experience subjective feelings of most if not all of the basic emotions. But Panksepp’s theory, like Solms’s, did allow for a role for the cortex – see the above point about Tertiary-Process Emotions. The differences between Panksepp’s and Solms’s views on the role of the cortex is one of emphasis.
9. Interestingly, Solms theorizes that the cortex contributes more to PLAY than to any of the other basic emotions, given its imaginative processes. “Its ‘as if’ quality is impossible to conceive without cortical mechanisms […] PLAY might well be a biological precursor of thinking in general (i.e., of all virtual versus real action) and the whole of cultural life.” [Solms (2021), p. 234].
10. Solms (2021).
11. There are compelling evolutionary theories of consciousness that propose that minimal forms of consciousness or very basic sentience (much more primitive than the consciousness that we humans experience) is present in a wide range of animals far beyond just mammals: namely all vertebrates, as well as coleoid cephalopods, and possibly even some arthropods. Only mammals have a cerebral cortex. But according to those theories, those forms of consciousness that may be present in non-mammals would not be based on conscious emotional feeling. Whereas, according to Solms, non-mammalian vertebrates that possess the ancient brainstem circuits responsible for generating affective states may have at least basic affective experiences (i.e., positive or negative affective states) and, therefore, a form of consciousness that is derived from those affective experiences (though he would agree that their consciousness differs from that of mammals with a well-developed cerebral cortex).
12. In support of his view, Solms notes that “All affective circuits converge on the PAG, which is the main output centre for feelings and emotional behaviours.” [Solms (2021), p. 136]. He argues that the emotional and affective states produced by the PAG form the foundational layer of conscious experience, providing the raw feelings that are essential to being consciously aware. He views the PAG as crucial not simply for basic survival functions but for the generation of the subjective quality of emotions that contribute to conscious awareness, and as also playing an important role in regulating a wide range of emotions. For Solms, the PAG provides the emotional context necessary for more complex conscious processes.
13. Solms also argues that the brainstem’s reticular activating system (RAS), which is traditionally viewed as regulating just arousal and wakefulness, is central to the creation of a unified conscious experience, by integrating and coordinating sensory and emotional inputs. He argues that the RAS does not simply modulate the quantitative level of consciousness, or “wakefulness.” Rather, the consciousness generated by the RAS has qualitative content of its own. This, he contends, is affect.
Further, drawing on Björn Merker’s theory, Solms sees consciousness as centered on a “decision triangle,” in which midbrain circuitry plays the major role (circuitry that includes the PAG, superior colliculi, and the midbrain locomotor region). According to Solms, the decision triangle functions to prioritize affective needs [Solms (2021), pp. 139, 329. See also Merker B. (2007). Consciousness without a cerebral cortex: a challenge for neuroscience and medicine. The Behavioral and brain sciences, 30(1), 63–134. https://doi.org/10.1017/S0140525X07000891].