Author: Joseph LeDoux
What are emotions, and how are they made? These are the main questions this book, written by one of the foremost researchers in the field, sets out to answer. Acknowledging that the ‘amazing and perplexing’ nature of emotions makes it difficult for scientists to agree on a definition for them, the author nevertheless conceives of emotions as ‘products of evolutionary wisdom‘ which seem to act independently to implement ‘their own agenda…without our wilful participation’ (page 22-23 and 36). Approaching the subject with the understanding that ‘there is no single emotion system‘, the book addressed each emotion as a ‘separate functional unit’; this is reflected by the author’s own research work which focuses mainly on the emotions which come under the fear system (pages 16, 21, and 127). The book also disregards the conventional study of emotions as purely psychological phenomena, rather treating the subject as legitimate ‘hard cognitive science’; in this way, the author makes a strong argument for unifying cognition and emotion under the single concept of mind science (page 39).
The book’s major theme comes out of the author’s fascinating research into the fear system, one that is preserved in all species and is readily studied in the laboratory (page 107). By studying how emotional memories are ‘established, stored, and retrieved’, the author’s research successfully established how the brain responds to fear (page 148). As with all elegant experiments, the author’s methodology is conceptually simple; after conditioning animals to respond to auditory fear stimuli, he measures their brain reactions as they respond by withdrawal, freezing, defensive aggression, or submission (page 131). In this way, he charted the fear conditioning pathway, starting from the auditory fibers, going through the thalamus, and ending up in the amygdala (pages 152-158). Describing the amygdala as the ‘hub of a wheel‘ in the pathway, he further describes how it receives inputs through its lateral nucleus, and sends projections out of its central nucleus. He further tracked the amygdala’s outflow fibers to the periaqueductal gray where the freezing and withdrawal fear responses are executed. Because this ‘quick and dirty‘ fear processing system completely bypasses the cortex, the author rightly concluded that ’emotional responses can occur without the involvement of the higher processing systems of the brain’ (pages 168-169 and 158-163).
Whilst the author’s research emphasised the role of the amygdala in the primary response to fear, it also identified cognitive processes as important in modulating secondary emotional responses, what the author called a ‘shift from reaction to action‘ (page 175). Although the primary emotional responses serve as automatic life-saving actions, the higher cognitive centres, in the prefrontal cortex and basal ganglia, are required to assess risk and plan longer-term responses (pages 176-177). The author emphasises that these higher cortical responses are important in preventing disproportionate emotional responses, in limiting the risk of developing clinical disorders of emotion, and in restricting the brain from triggering unhelpful constructed emotions (pages 66 and 178). The book however stressed that our higher cortical responses are not wholly under our control as they are largely determined by our genetic constitution, past experiences, and cognitive creativity (pages 165-168).
Beyond exploring the fear response, the key conceptual argument the book makes is to jettison the prevailing view that emotions and cognition are similar processes. The author particularly pointed to the Schachter-Singer dual theory which posits that emotions are products of cognitive interpretations of situations, the hypothesis that has been ‘the cornerstone of contemporary approaches to emotions’. In rejecting this so-called ‘appraisal theory‘ the author criticised it for exaggerating the contributions of cognition, and downplaying ‘the unique aspects of emotion that have traditionally distinguished it from cognition’ (pages 47-53). He discussed some of the discerning features of emotions, such as their more restricted range of responses than cognition, and their strong association with ‘intense bodily sensations‘ (pages 69 and 70). To further support his view that emotions are separate mind processes from cognition, he cites the mere exposure effect experiments of Robert Zajonc which clearly demonstrated that emotions, unlike cognition, may occur unconsciously, and often dominate over cognition; this, he explains, is why emotional actions, unlike cognitive ones, can occur ‘in the absence of conscious awareness of the stimuli’ (pages 53-55).
Beyond establishing that cognition are different mental processes from emotions, the book also invalidated several other established neuroscience concepts. In this regard, the most significant of these is the argument for the existence of a limbic system as a functional unit in the brain. In criticising this idea, championed by Paul MacLean, the author pointed out that the the term itself is imprecise because the constituent parts of the system have never been clearly delineated. Furthermore, he contended, many structures that are included in the limbic system, for example the hippocampus, are no longer considered as relevant to emotion as previously thought (pages 97-101). He therefore emphatically asserts that the limbic system does not exist, and arguing that the term ‘should be discarded’, he promoted ‘a new approach to the emotional brain’ which is based on the understanding that the different emotions are subserved by different systems or networks. This concept, he argues, fits in with the way the brain is known to work – through collections of modules serving different functions (pages 101-106). Another related concept the author similarly dismissed is that of the hierarchical triune brain which, by placing the emotions below cognition in an evolutionary context, downplays their contemporary relevance (page 98).
The practical implications of the concept of emotions the author outlined are profound and significant, particularly to healthcare. The author, for example, made the important point that ‘most mental disorders are emotional disorders‘ and ‘mental problems, to a large extent, reflect a breakdown of emotional order‘ (page 20). He demonstrated that emotional disorders emerge ‘when the fear system breaks loose from the cortical controls that usually keep our primitive impulses-the wild things in us-at bay’. He also illustrated the diverse ways a disrupted emotional system may manifest, from poor insight into emotions, to the display of inappropriate emotions. The book also reviewed a wide spectrum of clinical emotional disorders such as post traumatic stress disorders (PTSD), obsessive compulsive disorder (OCD), anxiety disorders, phobias, and panic attacks (pages 169 and 227). The author explored each of these disorders exhaustively, for example pointing out that subconscious memories, both traumatic and emotional, can act as ‘unconscious sources of anxiety‘ which can ‘exert their opaque and perverse influences throughout life’ (page 245). In a similar way, he discussed why people with PTSD frequently fail to recall their past traumatic events, explaining how chronic stress, by provoking adrenal hormone overactivity, causes the hippocampal memory cells to degenerate (pages 239-245).
This is an important book which addresses one of the most fundamental of human processes. Written by a leader in the field, the book describes several paradigm-shifting experiments which have redefined the concept of emotions, moving it from a single response system, to one that is multi-faceted and mediated by several brain networks. The idea that emotions override cognition not only reveals how important they are to survival, but it shows how vulnerable we are to their unchecked influences. The author’s introductory chapters were rather long-winded, and the exploration of some topics, such as memory, was perhaps more detailed than was relevant for the topic of emotions. The historical buildup to the author’s arguments is however very helpful in giving context to each subject. The author also provided very thought-out subheadings to reflect the topic at hand, with examples such as ‘the quick and the dead’, ‘the low and the high road’, and ‘journey to the centre of the amygdala’; these perhaps reflect the author’s artistic bent as a musician-scientist.
This is a very lucid, carefully thought out, and well-researched elucidation of a very academic subject. The focus on emotion-based disorders is relevant to healthcare because it aids the understanding of the pathogenesis and the treatment approaches to these common and disabling conditions. Some of the concepts, such as contextual memory systems, are difficult to grasp but this does not detract from the general understanding of the content. Using very helpful illustrative diagrams and simple prose, the author has made what is clearly an important but complex subject easily accessible.The subject of emotions is significant to healthcare, and this book provides the appropriate context in which to view it, and I recommend it to all doctors
Publisher, Place, Year: Phoenix, London, 1998
Number of chapters: 9
Number of pages: 384
Star rating: 5