The neuroscience of arousal | Emily Nagoski

Key Concepts

• Masters and Johnson's four-phase model of sexual response (arousal, plateau, orgasm, resolution)
• Helen Singer Kaplan's triphasic model (desire, arousal, orgasm)
• Rosemary Basson's model of responsive desire
• Sexual excitation system (accelerator/gas pedal)
• Sexual inhibition system (brakes)
• Dual control model of sexual response
• Affective keyboard of the nucleus accumbens shell
• Approach motivation vs. avoidance/threat motivation
• Internal and external context of sexual experience

History of Sex Therapy Models

The history of sex therapy is presented in three phases:

1. Masters and Johnson's Four-Phase Model: This initial model focused on the physiological aspects of sexual response, dividing it into arousal, plateau, orgasm, and resolution. Interventions, like sensate focus therapy, targeted specific phases where individuals experienced difficulties. A key limitation was the absence of desire as a factor.
2. Helen Singer Kaplan's Triphasic Model: Kaplan added desire to the model, creating the desire, arousal, orgasm model. This was revolutionary because it allowed therapists to address issues related to wanting sex, not just the physical aspects.
3. Dual Control Model (Janssen & Bancroft): This model, developed in the late 1990s, incorporates a neurobiological understanding of sex, viewing it as a balance between excitatory and inhibitory impulses in the brain.

The Dual Control Model: Accelerators and Brakes

The dual control model posits that sexual response is governed by two systems:

• Sexual Excitation System (Accelerator): This system notices sex-related stimuli in the environment (sights, sounds, smells, touch, taste, body sensations, thoughts, beliefs, and imagination). It sends a "turn on" signal. It functions unconsciously at a low level all the time.
• Sexual Inhibition System (Brakes): This system notices potential threats and reasons not to be turned on (sights, sounds, smells, touch, taste, body sensations, thoughts, beliefs, and imagination). It sends an "off" signal.

Arousal is a dual process of activating the "ons" and deactivating the "offs." Mainstream advice often focuses on adding stimulation (porn, role play, vibrators), but the speaker argues that problems are more often due to excessive stimulation of the brakes.

Interventions and Focus

Effective interventions should focus on reducing the factors that activate the brakes, such as:

• Stress
• Body image issues
• Trauma
• Relationship problems

These factors often have nothing to do with the sex itself.

Sex as a Brain Process

The speaker emphasizes that sex is primarily a brain process, not just a genital one. People with spinal cord injuries can still experience orgasms by training their bodies to respond to other forms of stimulation. The skin is the largest sex organ, but the brain is the most important.

Practical Application: Identifying Accelerators and Brakes

A simple starting point is to create lists of things that activate the accelerators and things that activate the brakes.

The Importance of Context

The perception of a sensation as pleasurable depends on the context in which it is experienced. This context includes:

• External Circumstances: The physical environment (e.g., locked door, clean sheets, sexy underwear).
• Internal State: Emotional and psychological state (e.g., stressed, depressed, anxious, playful, curious, ashamed of sexuality).

The same stimulus (e.g., tickling, spanking) can be perceived as pleasurable or irritating depending on the context.

The Affective Keyboard of the Nucleus Accumbens Shell

The speaker references the "affective keyboard of the nucleus accumbens shell" to explain how context influences pleasure.

• In a relaxed, playful, positive state, 90% of the nucleus accumbens shell is devoted to approach motivation, leading to curiosity and a desire to move toward stimuli.
• In a stressed, non-social, avoidance state, 90% of the nucleus accumbens shell is devoted to avoidance/threat motivation, leading to a desire to avoid stimuli.

Synthesis/Conclusion

The dual control model provides a more nuanced understanding of sexual response than earlier models. It highlights the importance of both excitatory and inhibitory processes, as well as the crucial role of context (both external and internal) in shaping our experience of pleasure. Effective interventions should focus on reducing the factors that activate the brakes and creating a context that promotes approach motivation. The brain is the most important sex organ, and understanding its role is key to improving sexual wellbeing.