Comprehensive Study Notes on the Origins and Evidence of Consciousness in Humans and Plants

Defining and Assessing Consciousness

  • Definition of Consciousness: Consciousness is defined as an awareness of the self within the environment.

  • The Glasgow Coma Scale (GCS):

    • Definition: The GCS is the most common scoring system utilized to describe the level of consciousness in an individual following a traumatic brain injury.

    • Clinical Utility: It is primarily used to help clinicians gauge the severity of an acute brain injury.

    • Educational Context: Instructional materials (such as those from EMS1) provide procedures for performing GCS assessments.

Scientific Research into Human and Non-Human Consciousness

  • Study 1: Recent Advances and Future Directions:

    • Citation: Front Psychol. 2013 Oct 31;4:625.

    • Full Title: "Consciousness in humans and non-human animals: recent advances and future directions."

    • Authors: Boly M, Seth AK, Wilke M, Ingmundson P, Baars B, Laureys S, Edelman DB, Tsuchiya N.

    • Affiliated Institutions:

      • Department of Neurology, University of Wisconsin Madison, WI, USA.

      • Department of Psychiatry, Center for Sleep and Consciousness, University of Wisconsin Madison, WI, USA.

      • Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liege and CHU Sart Tilman Hospital Liege, Belgium.

Neural Correlates of Visual Consciousness

  • Study 2: Relative Blindsight in Normal Observers:

    • Citation: Lau HC, Passingham RE. Proc Natl Acad Sci U S A. 2006 Dec 5;103(49):18763-8.

    • Objective: The researchers created experimental conditions where the subjective report of consciousness differed, but the objective ability to discriminate visual targets remained identical. This allowed for the study of the neural correlate of consciousness (NCC) with performance levels carefully matched in healthy subjects.

    • Experimental Task:

      • The team used a method of placing masks within short or long stimulus onset asynchronies (SOAs) from the stimulus.

      • This technique allows researchers to alter conscious perception without altering the actual accuracy of perception.

    • Results and Functional MRI (fMRI) Findings:

      • A comparison of neural activity associated with these conditions showed that conscious perception is specifically associated with activity in the mid-dorsolateral prefrontal cortex (area 46).

      • The results suggest that the prefrontal cortex is essential for the subjective aspects of conscious perception.

Unconscious Determinants of Free Decisions

  • Study 3: Brain Activity Preceding Awareness:

    • Citation: Soon CS, Brass M, Heinze HJ, Haynes JD. "Unconscious determinants of free decisions in the human brain." Nat Neurosci. 2008 May;11(5):543-5.

    • Hypothesis: Investigated whether subjectively 'free' decisions are determined by brain activity ahead of time.

    • Primary Finding: The outcome of a decision can be encoded in the brain activity of the prefrontal and parietal cortex up to 10 s10\,\text{s} before it enters conscious awareness.

    • Mechanism: This delay is presumed to reflect the operation of a network of high-level control areas that prepare an upcoming decision long before the individual is aware of it.

  • Experimental Procedure:

    • Subjects viewed a letter stream that was updated every 500 ms500\,\text{ms}.

    • Subjects made a spontaneous (free) decision to press either a left or right button using their index fingers.

    • Following the response, subjects were shown a response-mapping screen to report the exact time at which they consciously made the motor decision (intention-onset judgment).

  • Neural Decoding Data:

    • Spatial Specifics (Coordinates):

      • Pre-SMA: (−9,6,57)(-9, 6, 57).

      • Left motor cortex: (−42,−18,57)(-42, -18, 57).

      • Right motor cortex: (39,−18,57)(39, -18, 57).

      • Lateral frontopolar cortex: (33,69,12)(33, 69, 12).

      • SMA: (3,−6,54)(3, -6, 54).

      • Medial frontopolar cortex: (0,60,−3)(0, 60, -3).

      • Precuneus/posterior cingulate cortex: (12,−60,21)(12, -60, 21).

    • Statistical Thresholds: Decoding accuracy was significant at P < 0.05.

    • Chance Levels: The chance level for decoding a binary left/right choice is 50%50\%.

    • Key Observations from Results: Decoding accuracy was higher in cortical areas involved in the motor execution of the response than in the high-level areas shaping the decision before awareness. Frontopolar cortex showed discriminative patterns for choice before awareness.

Evidence for Consciousness in Plants

  • General Finding: Consciousness is not uniquely human; evidence suggests plants also possess forms of consciousness.

  • Plant Study 1: Anesthesia and Responsiveness:

    • Source: Annals of Botany via The New York Times (2018).

    • Observations: Plants can be frozen in place using the same anesthetics used for human surgery.

    • Experimental Examples:

      • Pea Plants: Trapped in glass chambers with ether.

      • Sensitive Plants and Garden Cress: Roots soaked in lidocaine.

      • Venus Fly Trap: Measured the electrical activity of cells. After exposure to anesthesia, the cells stopped firing. The trap failed to react to a stimulus resembling a crawling bug.

    • Recovery: When the anesthetics wore off, the plants "returned to life" similarly to humans regaining consciousness after surgery, suggesting they possess properties typically reserved for animals.

  • Plant Study 2: Risk Assessment and Nutrient Strategy:

    • Source: The New York Times (2016).

    • Researchers: Dr. Shemesh and Alex Kacelnik (Oxford University).

    • Experiment: Pea plants were grown with roots split between two pots. One pot provided constant nutrients, while the other provided varying (unpredictable) levels, though both matched in average.

    • Behavioral Findings:

      • Under low nutrient conditions, plants preferred the unpredictable (mystery) pot, showing a willingness to take risks.

      • Under abundant nutrient conditions, plants chose the pot with constant levels.

    • Conclusion: Plants demonstrated environmental awareness by knowing the optimal time to take risks based on nutrient availability.

Learning and Memory in Plants

  • Plant Study 3: The Mimosa Pudica Experiment:

    • Source: Monica Gagliano's research via Atlas Obscura.

    • Subject: Mimosa pudica, known for folding its leaves in response to mechanical stimuli.

    • The Experiment (Plant "Thrill Ride"): Gagliano used a rail to drop the plants repeatedly (77 sets of 6060 drops in one day).

    • Initial Response: The leaves shut tight upon being dropped.

    • Adaptation (Habituation): After repeated drops, the plants stopped reacting. To prove they weren't simply exhausted, Gagliano shook them; the plants reacted to the shaking by closing, showing they specifically learned that the drop was not a threat.

    • Long-Term Memory Retention:

      • 3 Days Later: Plants remained stoic and did not react to the drop.

      • 6 Days Later: Plants still remembered the training.

      • 1 Month Later: The plants continued to keep their leaves open when dropped.

    • Scientific Significance: In many animal studies (e.g., bees), a memory lasting 24 hours24\,\text{hours} is considered long-term. The Mimosa pudica demonstrated learning and long-term memory retention for weeks, meeting the criteria scientists routinely apply to determine intelligence in animals.