Biol2052 Neuroscience: Complex brain function - Pleasure, reward and food

Vocabulary flashcards covering the key concepts of hedonic vs motivational reward and the neural substrates involved in food reward.

Hedonic circuits

Neural systems mediating the pleasurable (liking) aspect of reward, particularly in response to palatable foods; distinct from metabolic need.

Liking

The hedonic or pleasure component of reward, often measured via facial/orofacial responses and hedonic hot spots.

Wanting

The motivational or incentive-salience component of reward; drives seeking and consumption, strongly linked to dopamine.

Reward circuit

Neural network that receives and evaluates rewarding stimuli and integrates hedonic and motivational signals (includes VTA, NAcc, LH, amygdala, cortex).

Medial forebrain bundle (MFB)

Major reward pathway; electrical stimulation along the MFB yields robust self-stimulation, indicating a central reward circuit.

Nucleus Accumbens (NAcc)

Key ventral striatal region in the reward system; contains hedonic hotspots and receives dopamine from the VTA.

Ventral Tegmental Area (VTA)

Midbrain dopaminergic nucleus projecting to NAcc, amygdala, and cortex; central to the mesolimbic dopamine pathway.

Mesolimbic dopamine pathway

Dopamine pathway from VTA to NAcc and other limbic regions; essential for reward processing and incentive salience.

Lateral hypothalamus (LH)

Hypothalamic region coordinating reward and homeostatic signals; involved in feeding; orexin neurons project to reward circuits.

Dopamine

Neurotransmitter linked to the 'wanting' aspect of reward and incentive salience; changes correlate with seeking rather than pure pleasure.

Orexin (hypocretin)

Hypothalamic neuropeptide from the LH; coordinates reward and homeostatic signaling and can enhance hedonic responses.

Endogenous opioids

Endogenous peptides (enkephalins, dynorphins, endorphins) acting on mu, kappa, delta receptors; modulate hedonic 'liking'.

Opioid receptors

Mu, kappa, and delta G-protein-coupled receptors that mediate effects of endogenous opioids and opioid drugs.

Endocannabinoids

Lipid signaling molecules (anandamide, 2-AG) acting on CB1/CB2 receptors; modulate reward and hedonic processing and overlap with opioid hotspots.

CB1 receptor

Cannabinoid receptor type 1; CNS-predominant GPCR involved in regulating feeding and hedonic responses.

Hedonic hotspot

Localized brain region (notably within the NAcc) where mu-opioid receptor activation greatly enhances 'liking' reactions.

Hedonic coldspot

Brain regions where activation decreases 'liking' reactions; part of the distributed hedonic circuitry.

DAMGO

Mu-opioid receptor agonist used to map hedonic hotspots in the NAcc.

Naloxone

Opioid receptor antagonist that reduces 'liking' and feeding by blocking opioid signaling.

Fos plume

Technique mapping brain activation; c-Fos expression indicates activation and functional connectivity after drug injection.

Olds & Milner (1954)

Pioneering discovery of brain reward centers via self-stimulation in rodents, foundational for reward circuitry.

6-OHDA lesions

Chemical lesions of dopaminergic neurons used to test dopamine’s role; typically reduce 'wanting' without abolishing 'liking'.

Incentive-sensitization

Process by which repeated exposure to palatable rewards increases cue-triggered 'wanting' through dopaminergic system changes.

Berridge 2020 facial liking

Study proposing quantify affective orofacial reactions (lip/tongue movements) as a readout of hedonic 'liking'.

Endocannabinoid hotspots in NAcc

Regions in the nucleus accumbens where endocannabinoid signaling coordinates with opioidergic signaling to modulate hedonic responses.

THC (tetrahydrocannabinol)

Active cannabis compound that increases food intake, illustrating endocannabinoid system involvement in reward.

Orexin cross-talk between reward and homeostasis

Orexin neurons from the lateral hypothalamus project to reward structures, facilitating interaction between reward and homeostatic circuits.

Liking vs Wanting vs Reward

Clear distinctions: liking = hedonic pleasure; wanting = motivational drive; reward = integration of hedonic, wanting, and predictive aspects.