2019-03-20 14:28:00

2:25

Don't You Worry 'Bout a Thing

Today's Topics

  • Quiz 3; Exam 2 review on Thursday
  • Biology of emotion
  • Happiness/pleasure and reward
  • Fear & stress

Biology of Emotion

  • What is emotion?
  • What are the types of emotions?
  • Biological systems involved in emotion

What is emotion?

  • Feelings
  • Physiological state
  • Actions (now)
  • Propensity to act (in the future)

What is cause? What is effect?

"Do we run from a bear because we are afraid or are we afraid because we run? William James posed this question more than a century ago, yet the notion that afferent visceral signals are essential for the unique experiences of distinct emotions remains a key unresolved question at the heart of emotional neuroscience."

(Harrison et al. 2010)

Competing views

  • James-Lange
    • Physiological response -> subjective feelings
  • Cannon-Bard
    • Severing CNS (spinal cord & vagus) from rest of body leaves emotional expression unchanged
    • Physiological states slow, don't differentiate among emotions

Competing views

  • Schacter-Singer
    • Physiological arousal + cognitive appraisal -> emotional states

What are the different types of emotions?

Emotions

  • Vary in valence
    • Positive/negative
  • Vary in intensity (arousal)
  • Vary in action tendency
    • Approach/avoid

Emotions (can) serve biological goals

  • Ingestion
  • Defense
  • Reproduction

  • Affiliation

Plutchik

Is emotion different from cognition?

(Swanson 2012)

Is emotion different from cognition?

(Pessoa 2008)

Here, I will argue that complex cognitive–emotional behaviours have their basis in dynamic coalitions of networks of brain areas, none of which should be conceptualized as specifically affective or cognitive. Central to cognitive–emotional interactions are brain areas with a high degree of connectivity, called hubs, which are critical for regulating the flow and integration of information between regions.

(Pessoa 2008)

Here, I will argue that complex cognitive–emotional behaviours have their basis in dynamic coalitions of networks of brain areas, none of which should be conceptualized as specifically affective or cognitive. Central to cognitive–emotional interactions are brain areas with a high degree of connectivity, called hubs, which are critical for regulating the flow and integration of information between regions.

Emotion as "computing" (or information processing)

  • Input
    • Internal states
    • External world
  • Processing/evaluation
  • Output
    • Internal states
    • External world

Happiness and reward

Components of happiness

  • Aristotle
  • Hedonia
    • Pleasure
  • Eudaimonia
    • Life satisfaction
    • Relates to motivation

"Computing" happiness

  • Inputs
    • External
    • Internal
  • Processing
  • Outputs
    • Feelings
    • Actions

Brain mechanisms

  • Circuits for signaling pleasure and pain
  • Similarities across animal species
    • Behavior & brain
  • Dopamine and endogenous opioid neurotransmitter systems involved

Neuroanatomy of 'happiness'

Rewards

  • A reward reinforces (makes more prevalent/probable) some behavior
  • Milner and Olds (Milner 1989) discovered 'rewarding' power of electrical self-stimulation
  • (Heath 1963) studied effects in human patients.

Electrical self-stimulation

"Reward" circuitry in the brain

Nodes in the "reward" circuit

  • Ventral tegmental area (VTA) in midbrain
  • Nucleus accumbens (nAcc), ventral striatum
  • Hypothalamus (Hyp)
  • Amygdala (Amy)
  • Hippocampus (HP)
  • Dorsal Raphe Nucleus/Locus Coeruleus (DR/LC)
  • Prefrontal cortex (PFC)

Nucleus accumbens and dorsal striatum

Psychopharmacology of 'happiness'

  • Dopamine
  • Opioids
  • Cannabinoids
  • Serotonin, Norepinephrine
  • ACh

Endogenous morphine-like NTs (endorphins) from hyp, NST

Endogenous cannabinoid system

  • Cannabinoids == psychoactive compounds found in cannibis
  • Cannabinoid receptors, CB1 in CNS; CB2 in body, immune system

Brain contains its own systems for binding drugs associated with 'pleasure'

  • Endogenous morphine-like compounds (endorphins)
    • Morphine an opioid
  • Endogenous cannabinoids, too

Generalizations about happiness/pleasure

  • Types of pleasure activate overlapping areas
  • Pleasure/happiness engage a network of brain areas
  • Pleasure/happiness signaling involves multiple neuromodulators, but DA especially important
  • “Reward” pathways activated by many different inputs

Fear and stress

Inducing "fear-like" behavior in animals

Rat vs. Human

Amygdala circuits

Amygdala's inputs

  • Convergent inputs
    • Thalamus ("direct" or "fast"")
    • Cerebral cortex ("indirect" or "slow")

Amygdala's outputs

  • Project to
    • CG (central gray matter) of tegmentum: behavior
    • LH (lateral hyp): ANS
    • PVN (paraventricular n. of hyp): hormones
  • Fast-acting, involuntary responses
  • Lesions of amygdala impair 'fear conditioning'

Cerebral cortex role

  • Response discrimination?
    • Cortex lesions cause generalized not cue-specific fear response
  • Fast, crude responses vs. slower, detailed ones
    • That’s a stick, not a snake!
    • Prefrontal cortex and response inhibition

But, are we really studying learned 'fear'?

  • Amygdala connected to other 'affective' nodes in neural network
  • Emotion not just about subjective feelings

Amygdala as processing hub

Amygdala as key hub in circuit for survival

Emotion as global physiological/behavioral "state"

"Emotional" stimuli serve multiple roles

Stress

Stressors linked with biological imperatives

  • Sustenance
    • Hunger, thirst
  • Well-being/defense
    • Threat

Stressors linked with biological imperatives

  • Reproduction
    • Rejection
  • Affiliation
    • Loneliness

Stress and the brain

Brain under stress

  • Acute stress
    • Short duration
    • Fast action required
    • HPA (Cortisol), SAM (NE/Epi) axes
  • Brain detects threat
  • Mobilizes physiological, behavioral responses

Brain under stress

  • vs. Chronic stress
    • Long duration, persistent

Glucocorticoids

  • Adrenal cortex releases hormones
    • Cortisol (hydrocortisone)
      • Increases blood glucose levels
      • Suppresses immune system
      • Reduces inflammation
      • Aids in metabolism
    • Receptors in brain and body

Cortisol and the brain

Glucocorticoid cascade hypothesis

  • Cort receptors in hippocampus, amygdala, hypothalamus
    • Hippocampus regulates HPA axis via hypothalamus
  • Prolonged cortisol exposure reduces hippocampus response
    • Reduces volume, connectivity in hippocampus
  • Hip critical for long-term memory formation
    • Chronic stress impairs long-term memory

But, cortisol -> stress link not straightforward

Stress and coping across the animal kingdom

  • Pain thresholds lower (sensitivity greater) when a mouse's cage mate is also in pain
  • Rats will cooperate to release distressed cage mage, foregoing food rewards
  • (Sapolsky 2016)

Why Zebras Don't Get Ulcers

Your (zebra) stress ain't like mine

  • Phasic (short-term) vs. chronic (long-term)
  • Physical stress (hunger, thirst, injury, disease) vs. social stress

Main points

  • Biological approach to emotion
    • Behavior
    • Physiological states
    • Subjective feelings
    • Adaptive function
  • Networks of brain systems, multiple NT systems

Next time

  • Quiz 3
  • Review Exam 2

References

Clapp, Peter, Sanjiv V. Bhave, and Paula L. Hoffman. n.d. “How Adaptation of the Brain to Alcohol Leads to Dependence.” http://pubs.niaaa.nih.gov/publications/arh314/310-339.htm.

Davis, Michael. 1992. “The Role of the Amygdala in Fear-Potentiated Startle: Implications for Animal Models of Anxiety.” Trends in Pharmacological Sciences 13. Elsevier: 35–41. doi:10.1016/0165-6147(92)90014-W.

Faresjö, Åshild, Elvar Theodorsson, Marios Chatziarzenis, Vasiliki Sapouna, Hans-Peter Claesson, Jenny Koppner, and Tomas Faresjö. 2013. “Higher Perceived Stress but Lower Cortisol Levels Found Among Young Greek Adults Living in a Stressful Social Environment in Comparison with Swedish Young Adults.” PLoS ONE 8 (9): e73828. doi:10.1371/journal.pone.0073828.

Flores, África, Rafael Maldonado, and Fernando Berrendero. 2013. “Cannabinoid-Hypocretin Cross-Talk in the Central Nervous System: What We Know so Far.” Neuropharmacology 7: 256. doi:10.3389/fnins.2013.00256.

Harrison, Neil A, Marcus A Gray, Peter J Gianaros, and Hugo D Critchley. 2010. “The Embodiment of Emotional Feelings in the Brain.” J. Neurosci. 30 (38): 12878–84. doi:10.1523/JNEUROSCI.1725-10.2010.

Heath, Robert G. 1963. “Electrical Self-Stimulation of the Brain in Man.” American Journal of Psychiatry 120 (6). Am Psychiatric Assoc: 571–77. doi:10.1176/ajp.120.6.571.

Kohls, Gregor, Coralie Chevallier, Vanessa Troiani, and Robert T Schultz. 2012. “Social ‘Wanting’dysfunction in Autism: Neurobiological Underpinnings and Treatment Implications.” Journal of Neurodevelopmental Disorders 4 (10). BioMed Central Ltd: 1–20. doi:10.1186/1866-1955-4-10.

Kringelbach, Morten L, and Kent C Berridge. 2009. “Towards a Functional Neuroanatomy of Pleasure and Happiness.” Trends in Cognitive Sciences 13 (11). Elsevier: 479–87.

LeDoux, Joseph. 2012. “Rethinking the Emotional Brain.” Neuron 73 (4): 653–76. doi:10.1016/j.neuron.2012.02.004.

McEwen, B. S. 2007. “Physiology and Neurobiology of Stress and Adaptation: Central Role of the Brain.” Physiological Reviews 87 (3): 873–904. doi:10.1152/physrev.00041.2006.

Medina, Javier F, J Christopher Repa, Michael D Mauk, and Joseph E LeDoux. 2002. “Parallels Between Cerebellum-and Amygdala-Dependent Conditioning.” Nature Reviews Neuroscience 3 (2). Nature Publishing Group: 122–31. doi:10.1038/nrn728.

Milner, Peter M. 1989. “The Discovery of Self-Stimulation and Other Stories.” Neuroscience & Biobehavioral Reviews, The Neural Basis of Reward and Reinforcement: A Conference in Honour of Peter M. Milner, 13 (2–3): 61–67. doi:10.1016/S0149-7634(89)80013-2.

Nestler, Eric J, and William A Carlezon. 2006. “The Mesolimbic Dopamine Reward Circuit in Depression.” Biological Psychiatry 59 (12). Elsevier: 1151–9. doi:10.1016/j.biopsych.2005.09.018.

Pessoa, Luiz. 2008. “On the Relationship Between Emotion and Cognition.” Nature Reviews Neuroscience 9 (2): 148–58. doi:10.1038/nrn2317.

Plutchik, Robert. 1980. Emotion: A Psychoevolutionary Synthesis. Harpercollins College Division.

Sapolsky, Robert M. 2016. “Psychiatric Distress in Animals Versus Animal Models of Psychiatric Distress.” Nature Neuroscience 19 (11): 1387–9. doi:10.1038/nn.4397.

Swanson, Larry W. 2012. Brain Architecture: Understanding the Basic Plan. Oxford University Press.