THC Paper #3

Short Answer Questions:


  1. How did prenatal THC affect acquisition vs consolidation?

    1. Prenatal THC did not impair acquisition of learning tasks at any development stage. Offspring learning passive avoidance and spatial tasks normally. However, THC-exposed rats showed impaired memory consolidation, particularly in passive avoidance at PND 22. They failed to show increased latency at 1-day retention, indicating disrupted consolidation of fear memory. 

  2. What is reversal learning and how was it affected? 

    1. Reversal learning measures cognitive flexibility, or the ability to adapt when task rules change. 

In the active avoidance task (PND 45), prenatal THC:

  • Did not impair acquisition or retention

  • Impaired reveral learning in males, who made more errors during the first 10 minutes of reversal

  • Females were unaffected

This indicates impaired executive function, particularly in males. 


  1. What did the amphetamine challenge reveal?

    1. The amphetamine challenge (PND 60) assessed dopaminergic function using locomotor activity. 

Results showed:

  • No baseline locomotor differences

  • THC-exposed rats had a dampened locomotor response to amphetamine

This suggests prenatal THC alters dopamine system development, reducing responsiveness to psychostimulants. 


  1. Were there sex differences?

    1. Yes, but selective.

  • Passive avoidance: No sex differences

  • Reversal learning: Males were impaired; females were not 

  • Amphetamine response: No sex x treatment interaction, though females were more active overall

Thus, cognitive flexibility deficits were male-specific.


  1. Why is dampened amphetamine response important?

    1. Amphetamine increases dopamine release. A reduced response suggests: 

  • Altered dopaminergic maturation

  • Disrupted mesolimbic and nigrostriatal pathways

  • Long-term changes in reward and executive circuits 

This links prenatal THC exposure to potential vulnerability in disorders involving dopamine dysfunction (e.g., ADHD-like patterns).


  1. Which brain systems are implicated? 

    1. Prenatal THC likely alters:

  • Endocannabinoid system (CB1 receptors) 

  • Hippocampal and amygdala (memory consolidation)

  • Prefrontal cortex (exectutive function)

  • Dopamine pathways (mesolimbic and nigrostriatal systems)

These systems regulate synaptic plasticity, flexity, attention, and psychostimulant response. 



Essay Questions:


  1. Discuss how prenatal THC exposure differentially affects cognitive domains across development.

    1. Prenatal THC exposure produces selective and developmentally dynamic cognitive effects. Importantly, it does not impair basic acquisition of learning tasks, indicating intact fundamental learning mechanisms. However, higher-order executive and memory processes are selectively vulnerable.

At the juvenile stage (PND 22), THC exposed rats showed impaired memory consolidation in passive avoidance. Although they learned the task normally, they failed to retain the memory at 1-day testing. This suggests disruption of hippocampal-amygdala consolidation circuits.

During adolescence (PND 45), spatial acquisition and retention in the active place avoidance task were intact. However, reversal learning was impaired in males, indicating reduced cognitive flexibility. This points to prefrontal cortex dysfunction emerging later in development.

By adulthood (PND 60), subtle but significant impairments in sustained attention were observed. Fewer THC-exposed rats completed the task, and more trials were required. This suggests long-term executive dysfunction.

Additionally, adult offspring showed a dampened locomotor response to amphetamine, revealing altered dopamine system maturation.

Overall, prenatal THC selectively disrupts executive functions and dopamine-related processes while sparing basic learning. The pattern suggests increasing vulnerability of higher order cognitive systems across development.