What happens in your brain when you use cannabis?

Updated

Cannabis binds CB1 receptors, inhibiting neurotransmitter release. In the prefrontal cortex, it impairs working memory and decision-making; in the hippocampus, it disrupts memory formation; in the cerebellum, it affects motor coordination; in the basal ganglia, it alters movement and reward processing.

Prefrontal Cortex, Hippocampus, Cerebellum, Basal Ganglia, Amygdala lit up on the Brain Atlas 3D brain: what happens in your brain when you use cannabis
Figure. The brain regions that light up when you use cannabis, in order: Prefrontal Cortex (executive fog), then Hippocampus (memory lapse), then Cerebellum (motor wobble), then Basal Ganglia (altered movement), then Amygdala (emotional shift).

Watch it light up on the 3D brain

Brain regions that light up

OrderRegionWhat it does here
1Prefrontal CortexCannabinoids reduce prefrontal activity, impairing working memory and decision-making.
2HippocampusCannabinoid activation disrupts hippocampal encoding, causing short-term memory problems.
3CerebellumCannabinoids alter cerebellar signaling, leading to impaired coordination and balance.
4Basal GangliaCannabinoid effects on basal ganglia circuits change movement initiation and reward-driven behavior.
5AmygdalaCannabinoid signaling in the amygdala can alter anxiety and emotional responses.

1. Prefrontal Cortex: executive fog

Step 1 of what happens in your brain when you use cannabis: Prefrontal Cortex lit on the Brain Atlas 3D brain
Figure 1. Prefrontal Cortex, executive fog: Cannabinoids reduce prefrontal activity, impairing working memory and decision-making.

THC acts on CB1 receptors, which are abundant in the prefrontal cortex. This reduces glutamate release and alters prefrontal function. Studies suggest that acute cannabis use leads to deficits in tasks requiring executive control, such as planning and problem-solving. The impairment is thought to be dose-dependent and may vary between individuals.

2. Hippocampus: memory lapse

Step 2 of what happens in your brain when you use cannabis: Prefrontal Cortex, Hippocampus lit on the Brain Atlas 3D brain
Figure 2. Hippocampus, memory lapse: Cannabinoid activation disrupts hippocampal encoding, causing short-term memory problems.

The hippocampus is rich in CB1 receptors, particularly in inhibitory interneurons. THC reduces inhibition of principal cells, impairing synaptic plasticity essential for memory formation. This leads to difficulty forming new memories while under the influence, a hallmark of cannabis intoxication. Long-term heavy use may produce persistent changes, though the evidence is mixed.

3. Cerebellum: motor wobble

Step 3 of what happens in your brain when you use cannabis: Prefrontal Cortex, Hippocampus, Cerebellum lit on the Brain Atlas 3D brain
Figure 3. Cerebellum, motor wobble: Cannabinoids alter cerebellar signaling, leading to impaired coordination and balance.

The cerebellum contains CB1 receptors, especially in Purkinje cells and granule cells. Cannabis use can disrupt cerebellar timing and motor learning, causing ataxia and reduced fine motor control. This is why field sobriety tests often reveal impairment. The effects are transient and typically resolve as the drug clears.

4. Basal Ganglia: altered movement

Step 4 of what happens in your brain when you use cannabis: Prefrontal Cortex, Hippocampus, Cerebellum, Basal Ganglia lit on the Brain Atlas 3D brain
Figure 4. Basal Ganglia, altered movement: Cannabinoid effects on basal ganglia circuits change movement initiation and reward-driven behavior.

The basal ganglia, including the striatum and globus pallidus, express CB1 receptors. THC modulates dopamine and GABA signaling in these circuits, affecting motor control and habit formation. Users may experience slowed movements or altered motivation. These effects contribute to the acute motor and cognitive changes seen with cannabis.

5. Amygdala: emotional shift

Step 5 of what happens in your brain when you use cannabis: Prefrontal Cortex, Hippocampus, Cerebellum, Basal Ganglia, Amygdala lit on the Brain Atlas 3D brain
Figure 5. Amygdala, emotional shift: Cannabinoid signaling in the amygdala can alter anxiety and emotional responses.

The amygdala has high CB1 receptor density. THC can either increase or decrease anxiety depending on dose and context, reflecting biphasic effects on amygdala activity. Low doses may reduce stress responses, while high doses can trigger paranoia or panic. This variability is a key factor in individual reactions to cannabis.

Good to know

  • THC, the main psychoactive compound in cannabis, binds to CB1 receptors, which are widely distributed throughout the brain.
  • Cannabis use can cause short-term memory impairment by disrupting long-term potentiation in the hippocampus.
  • Regular heavy cannabis use during adolescence is associated with long-term cognitive changes, but causality is still debated.

Cannabis vs Alcohol on the Brain

Both substances impair coordination and cognition, but via different systems. Alcohol enhances GABA and inhibits glutamate broadly, while cannabis acts on specific CB1 receptors. Cannabis primarily alters prefrontal, hippocampal, and cerebellar function; alcohol additionally depresses brainstem arousal centers, increasing risk of coma. Cannabis does not directly suppress breathing like alcohol.

Test yourself

  1. Which brain region is most directly responsible for short-term memory impairment during cannabis use?

  2. THC primarily binds to which receptor in the brain?

  3. Which brain region is NOT typically impaired by acute cannabis use?

0 of 3 answered · 0 correct

Simplified: many regions work together at once, and this shows the main players in the order they act. For learning only, not medical advice.