Time, Space, Memory and Brain-Body Rhythms

My Interpretation of the paper

1. Introduction: Physical vs. Experienced Time

According to the author, time and space are crucial concepts in neuroscience.

  • Physical Time: This is like a linear line measured by clocks and calendars. It is based on units agreed upon by society.
  • Experienced Time: This is subjective. It depends on changes within the brain and body. This is why we sometimes feel time is passing quickly and other times slowly.

The author argues that the brain does not possess a dedicated “clock” to measure time. Instead, rhythmic changes in the brain and body provide the sense of time passing.

2. Time Sense and Memory

  • Our personal memories are called episodic memory. This relies on three factors: “What happened, Where it happened, and When it happened”.
  • The hippocampus in the brain plays a key role in arranging these events into a sequential order.
  • Although “place cells” (cells that identify space) and “time cells” (cells that identify time) are identified distinctively, the author suggests they function similarly depending on the context.

3. Clock(s) in the Brain?

Contrary to popular belief, research suggests there is no single “central clock” in the brain. The author explains three main theories on how the brain tracks time:

  1. Single-neuron models: Some neurons increase or decrease their firing rate (ramping) as time passes. This acts somewhat like a sand clock.
  2. Population clocks (population coding): Groups of neurons activate one after another in a sequence. This “neuronal trajectory” informs the brain how much time has elapsed.
  3. Brain-body rhythms: This is the most critical aspect of the paper. Brain oscillations and body rhythms act as a structure to measure time.

4. Hierarchy of Brain-Body Rhythms

The author proposes that the brain understands time on a logarithmic scale (according to the Weber–Fechner law).

  • Hierarchy: There are many types of rhythms (oscillations) in the brain and body. These range from milliseconds to hours or days.
  • Very fast rhythms (e.g., gamma waves) track short durations.
  • Slow rhythms (e.g., heartbeat, respiration, digestive movements) monitor long-term durations.
  • All these rhythms are connected to one another (phase–amplitude coupling) and organize time in a structured manner.
  • The brain uses rhythmic patterns not just to measure time, but also to predict when future events may occur, supporting learning and decision-making.
  • Time and space are encoded using similar neural mechanisms; time cells and place cells function based on context rather than being strictly separate.
  • Phase–amplitude coupling allows faster brain waves (like gamma) to be organized within slower rhythms (like theta), giving structure to temporal memory and perception.

5. Warping Subjective Time

Why does time sometimes feel fast or slow?

  • Dopamine: The sense of time changes when dopamine levels in the brain increase or decrease. For example, time perception is altered in individuals taking certain drugs or in those with Parkinson’s disease.
  • Emotions: Emotions like fear or joy bring changes to the body (e.g., faster heartbeat), which alters the sense of time.
  • Body temperature: When body temperature increases, experienced time feels like it is passing more slowly (or rather, the internal speed is faster, so the world seems slower).

6. Role of the Body

The author strongly argues that internal signals from our body (interoception) are the cause of our “subjective feeling of time”.

  • Heart rhythm, breathing, and digestive system movements constantly send signals to the brain.
  • When we are idle (bored), we notice our body signals more, which is why time feels like it is passing slowly.
  • Brain regions called the insula and supplementary motor area (SMA) receive these physiological signals and help create the sense of time.

Conclusion

  • Time is not a “container” existing outside of us. It is merely a method of measuring change.
  • Physical time is something we created with clocks for our convenience.
  • “Experienced time” (lived time) is the sequence of changes happening in our brain and body. The rhythms of the body give us the feeling of time.
  • In short, the brain does not have a special device to measure time; we recognize time only through changes occurring in our body and waves in the brain.