States of Mind (SoMs): TD:BU balance

Noa Herz, Shira Baror, and Moshe Bar discuss in a 2020 opinion article the Overarching States of Mind.
We all have our varying mental emphases, inclinations, and biases.
These individual dispositions are dynamic in that they can change over time and context. The opinion article proposes that these changing states of mind (SoMs) are holistic in that they exert all encompassing and coordinated effects simultaneously on our perception, attention,
thought, affect, and behavior.
Given the breadth of their reach, understanding how SoMs operate is essential. Evidence and a framework for the concept of SoM are provided. A unifying principle for the underlying cortical mechanism is proposed, whereby SoM is determined by the balance between top-down (TD) and bottom-up (BU) processing.
This novel global account gives rise to unique hypotheses and opens new horizons for understanding the human mind.

– An individual can demonstrate striking variability in their cognitive, affective, and behavioral inclinations in different contexts.
– To account for these dynamics, SOM offers evidence and a framework for a global concept, whereby all the diverse dimensions of functioning, from perception and attentionto thought, affect, and behavior, are clustered together and change in tandem.
– We further propose a unifying principle for the cortical mechanism underlying the overarching SoMs.
– This unifying principle postulates that SoM is determined by the balance between TD and BU cortical processing.
– This novel proposal can advance theories and approaches in psychology, neuroscience, and psychiatry.

Dimensions of State of Mind (SoM) and Their Proposed Neural Mechanism
(A) Illustration of SoM and its multiple dimensions of influence. The different dimensions are interconnected to one another and they change in tandem. A broad SoM (left) consists of perception that relies mostly on sensory input, global attention, broad thinking, exploratory disposition, and a positive mood – all involving increased bottom-up (BU) processing. A narrow SoM (right) consists of perception that is heavily influenced by predictions, local attention, narrow thinking, exploitatory disposition, and a negative mood – all involving increased top-down (TD) processing. The TD:BU ratio (green–blue axis) is the proposed mechanism for dictating the SoM, and affects where all dimensions are on the spectrum.
(B) A schematic description of the proposed neuronal mechanism, whereby the ratio between TD processing and BU processing determines how broad or narrow the SoM is. In broad SoM, the weights of the TD processing (WTD) are smaller, and thus TD influences are less dominant, whereas in narrow SoM less weight is given to the BU input.

The overarching framework to explain the global construct of SoM is described in the figure. Within this framework, SoM captures a qualitatively more sweeping effect of state over our mental life, encompassing cognition (including perception, attention, and thought), behavior (including openness to experience), and affect, which together we take as the principal dimensions of SoM. These dimensions are principal in that other mental dimensions (e.g., motivation, absorption) can be derived from their combination. They were chosen following our accumulated observations in the laboratory and from the literature (if new dimensions of our mental life are subsequently proposed that are affected by the overarching SoM, but cannot be constructed from the principal dimensions we describe, this will be a welcome addition to the evolution of this framework). Although seemingly unrelated, we propose that these dimensions are clamped together by the SoM, and that they change along a continuum ranging from narrow to broad.

The Principal Dimensions of SoM are State-Dependent
Scope of Perception: Incoming Sensory Information versus Predictions
Scope of Attention: Local versus Global
Scope of Thought: Narrow versus Broad Thinking Style
Openness to Experience: Exploitation versus Exploration
Affect: Negative versus Positive Mood

The Principal Dimensions of SoM Are Interdependent.
The dimensions comprising our overarching SoM range between broad and narrow depending on state. A wealth of research indicates that these principal dimensions are also dependent on each other and that they change together. According to these findings, perception guided by predictions goes hand in hand with local attention, narrow thought, exploitatory disposition, and negative affect (narrow SoM), whereas perception relying on incoming sensory information goes with global attention, broad thought, exploratory disposition, and positive affect (broad SoM).

Cognitive neuroscience research in a wide range of domains has provided the foundations for our proposal about the link between BU and TD processes and SoM.
TD processing implies reliance on predictions that are derived from past experiences, memory, and context.
BU processing, on the other hand, relies on the direct input from our senses without guidance (and possible distortion) from higher areas in the cortical hierarchies.
Our brain combines TD and BU signals to varying degrees, depending on state. The TD:BU ratio is a single mechanism that operates simultaneously on multiple continuous dimensions (Figure A), rather than reflecting a dichotomous dual-process typology.
In narrow SoM, increased inhibition constricts the breadth of activation, both for ‘reception’ (as in perception and attention) and in ‘transmission’ (as in thoughts and affect), and weights that give an advantage to TD processing are applied.
Similarly, the complementary weights and (reduced) inhibitions are deployed for a broad SoM, with an open scope and weights that give a higher emphasis to BU processing, increasing exploration, curiosity, and creativity, a broader scope for thought, attention, and perception, and a more positive mood.
In fact, the TD:BU ratio not only determines SoM, the TD:BU ratio is the SoM. All points along the continuum of SoM dimensions are derived from the TD:BU ratio.

A recent video lecture discussing the SOM by Moshe Bar is available on youtube:

A more recent article “From Objects to Unified Minds” elaborates:
The involvement of top-down processes in perception and cognition is widely acknowledged by now. In fields of research from predictions to inhibition, and from attentional guidance to affect, a great deal has already been charted.
Integrating this newer understanding with accumulated findings from the past has made it clear that human experience is determined by a combination of both bottom-up and top-down processes. It has been proposed that the ongoing balance between their relative contribution affects a person’s entire state of mind, an overarching framework that
encompasses the breadth of mental activity. According to this proposal, state of mind, in which multiple facets of mind are clumped together functionally and dynamically, orients us to the optimal state for the given circumstances.
These ideas are examined here by connecting a broad array of domains in which the balance between top-down and bottom-up processes is apparent. These domains range from object recognition to contextual associations, from pattern of thought to tolerance for uncertainty, and from the default-mode network to mood. From this synthesis emerge numerous hypotheses, implications, and directions for future research in cognitive psychology, psychiatry, and neuroscience

It is worth mentioning the presumed relation between DMN activity and SoM. DMN activity is not necessarily top-down. In other words, the fact that it is generated and occurs internally does not automatically make it a top-down process.
When one is in a broad SoM, one’s perception is oriented more toward bottom-up, sensory information, and less weight is assigned to top-down predictions. Thought pattern is also more broadly associative in this state because there is less top-down inhibition to constrict associative breadth, so DMN activity can be broadly associative.
In a narrow SoM, on the other hand, there is more topdown contribution to perception (i.e., more weight on predictions) and more top-down inhibition to limit the breadth of thought and DMN activity. Therefore, there are different forms of top-down involvement in the various dimensions of SoM (e.g., object predictions vs. inhibition signals), but all maintain the principle that top-down processes are weighted more heavily than bottom-up processes in narrow SoM and the reverse is true in broad SoM.

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