127 Caudate nucleus and reward…: Reward processing is most closely associated with the nucleus accumbens, which is a subregion of the caudate. This region is also called the ventral striatum. For brevity, I refer to both as the caudate.

Wolfram Schultz and measurement of caudate activity…: Wolfram Schultz et al. “Neuronal activity in the monkey ventral striatum related to the expectation of reward.” Journal of Neuroscience 12, no. 12 (December 1992): 4595–4610.

16. A NEW WORLD

155 Dog brain images from University of Minnesota Canine Brain MRI Atlas (http://vanat.cvm.umn.edu/mriBrainAtlas/) by T. F. Fletcher and T. C. Saveraid, 2009.

156 Reverse inference…: Russell A. Poldrack. “The role of fMRI in cognitive neuroscience: where do we stand?” Current Opinion in Neurobiology 18, no. 2 (April 2008): 223–227.

Reverse inference in the caudate…: Dan Ariely and Gregory S. Berns. “Neuromarketing: the hope and hype of neuroimaging in business.” Nature Reviews Neuroscience 11, no. 4 (April 2010): 284–292.

157 Love and the caudate…: Arthur Aron et al. “Reward, motivation, and emotion systems associated with early-stage intense romantic love.” Journal of Neurophysiology 94, no. 1 (July 2005): 327–337.

17. PEAS AND HOT DOGS

164 Side preference in dogs…: Camille Ward and Barbara B. Smuts. “Quantity-based judgments in the domestic dog (Canis lupus familiaris).” Animal Cognition 10, no. 1 (January 2007): 71–80.

18. THROUGH A DOG’S EYES

169 Signal-to-noise ratio…: The SNR increases roughly by a factor of √N, where N is the number of repetitions. For example, 100 repetitions would increase the SNR by a factor of 10.

173 Dogs used attentional cues from humans…: Márta Gácsi et al. “Are readers of our face readers of our minds? Dogs (Canis familiaris) show situation-dependent recognition of human’s attention.” Animal Cognition 7, no. 3 (July 2004): 144–153. Dogs are sensitive to the social context…: Juliane Kaminski et al. “Domestic dogs are sensitive to a human’s perspective.” Behaviour 146, no. 7 (2009): 979–998. Alexandra Horowitz. “Theory of mind in dogs? Examining method and concept.” Learning and Behavior 39, no. 4 (December 2011): 314–317.

174 Knowing how to read people and how to behave in different social settings is the difference between success and failure…: Gregory Berns. Iconoclast: A Neuroscientist Reveals How to Think Differently (Boston: Harvard Business School Press, 2008).

19. EUREKA!

182 Nothing in the brain implies an understanding of meaning…: When I first presented the findings to a group of psychologists, this is exactly what they said.

Dogs’ ability to intuit the meaning of human social signals…: Brian Hare and Michael Tomasello. “Human-like social skills in dogs?” Trends in Cognitive Sciences 9, no. 9 (September 2005): 439–444. Brian Hare, Josep Call, and Michael Tomasello. “Communication of food location between human and dog (Canis familiaris).” Evolution of Communication 2, no. 1 (1998): 137–159. See also A. Miklósi et al. “Use of experimenter-given cues in dogs.” Animal Cognition 1, no. 2 (1998): 113–121.

Social cognition of wolves and chimpanzees…: Brian Hare et al. “The domestication of social cognition in dogs.” Science 298, no. 5598 (November 2002): 1634–1636. See also Brian Hare and Vanessa Woods. The Genius of Dogs: How Dogs Are Smarter than You Think (New York: Dutton, 2013).

183 Kool-Aid experiment…: Giuseppe Pagnoni et al. “Activity in human ventral striatum locked to errors of reward prediction.” Nature Neuroscience 5, no. 2 (2002): 97–98.

Dysfunctional caudate in addiction…: Nora D. Volkow et al. “Addiction: beyond dopamine reward circuitry.” Proceedings of the National Academy of Sciences of the United States of America 108, no. 37 (September 2011): 15037–15042.

Bonus effect in the caudate to social cues…: James K. Rilling et al. “A neural basis for social cooperation.” Neuron 35, no. 2 (July 18, 2002): 395–405. I. Aharon et al. “Beautiful faces have variable reward value: fMRI and behavioral evidence.” Neuron 32, no. 3 (November 8, 2001): 537–551.

20. DOES MY DOG LOVE ME?

186 We had finished the first scientific paper…: Gregory S. Berns, Andrew M. Brooks, and Mark Spivak. “Functional MRI in Awake Unrestrained Dogs.” Public Library of Science ONE 7, no. 5 (2012): e38027.

190 Mirror neurons…: Giacomo Rizzolatti and Luigi Craighero. “The mirror-neuron system.” Annual Review of Neuroscience 27 (2004): 169–192.

191 Mirror neurons are the basis of empathy…: Marco Iacoboni and Mirella Dapretto. “The mirror neuron system and the consequences of its dysfunction.” Nature Reviews Neuroscience 7 (December 2006): 942–951.

Imitation and empathy…: Marco Iacoboni. “Imitation, empathy, and mirror neurons.” Annual Review of Psychology 60 (January 2009): 653–670.

192 Brain activation to silent movie of dogs barking…: Kaspar Meyer et al. “Predicting visual stimuli on the basis of activity in auditory cortices.” Nature Neuroscience 13, no. 6 (June 2010): 667–668.

21. WHAT’S THAT SMELL?

196 Dog’s sense of smell is 100,000 times as sensitive…: John Bradshaw. Dog Sense.

197 Smell and control of movement…: Joel D. Mainland et al. “Olfactory impairments in patients with unilateral cerebellar lesions are selective to inputs from the contralesional nostril.” Journal of Neuroscience 25, no. 27 (July 6, 2005): 6362–6371.

198 Dogs can differentiate their own urine…: Marc Bekoff. “Observations of scent-marking and discriminating self from others by a domestic dog (Canis familiaris): tales of displaced yellow snow.” Behavioural Processes 55, no. 2 (August 15, 2001): 75–79.

202 McKenzie was not having a good day…: McKenzie came back three weeks later, after Mark and Melissa had practiced with her. She then performed like a champ and sat for more than seven hundred scans.

204 Dog brain activation looked like human activation to people they love…: Aron et al. “Reward, motivation, and emotion systems.”

22. FIRST FRIEND

207 Most of the dogs in the world are village dogs…: See the classic book on this topic: Raymond Coppinger and Lorna Coppinger. Dogs: A New Understanding of Canine Origin, Behavior, and Evolution (Chicago: University of Chicago Press, 2001).

208 Rapidity with which the dog has changed form…: Coppinger and Coppinger, Dogs, p. 297.

211 Dogs take the form of the people they live with…: Lance Workman, a psychologist at Bath Spa University in Britain, has studied both the physical resemblance of dogs to their owners as well as their personalities and finds evidence of such a relationship.